**2. Reactor description**

The AGN-201 nuclear reactor is a solid-core reactor with no active cooling system. The core is constructed of nine 25.6-cm diameter fuel disks (see **Figure 1**). Four of the disks are 4-cm thick, three of the disks are 2-cm thick and two of the

### *Idaho State University AGN-201 Low Power Teaching Reactor: An Overlooked Gem DOI: http://dx.doi.org/10.5772/intechopen.105799*

disks are 1-cm thick. Each 4-cm thick fuel disk contains 96 g of 235U, each 2-cm thick fuel disk contains 58 g of 235U, and each 1-ck thick fuel disk contains 29 g of 235U. The overall core height is 24 cm. A graphite reflector surrounds the core both radially and axially. The graphite reflector is 20-cm thick and has a density of 1.75 g/ cm3 . The reactor fuel consists of slightly less than 20 wt. % enriched uranium. The uranium is in the form of 15-micron diameter particles of UO2. The UO2 particles are pressed with 100-micron diameter polyethylene particles. The density of 235U in the UO2-polyethelyene fuel is 61 mg/cm3 and the overall uranium density in the fuel is 305 mg/cm3 . The mass ratio of uranium to polyethylene is 1:3.16. The approximate critical mass of the AGN-201 reactor is 665 g 235U [1].

The reactor uses a total of four control rods; two safety rods, one adjustable coarse rod, and one adjustable fine rod. The control rods are made from the same UO2 polyethyelene fuel as the core. To ensure safety, the fueled control rods enter the core from the bottom (see **Figure 1**) so that gravity, along with compressed springs, ensure rapid removal upon reactor SCRAM. The bottom four fuel disks as well as the lower reflector have holes drilled through them to accommodate the control rods.

In addition to the control rods, the AGN-201 reactor is equipped with a thermal fuse as an ultimate reactor safety shutdown device. The thermal fuse is located just below the core center line (see **Figure 1**). The fuse is similar in construction to the

**Figure 1.**

*AGN-201 reactor core, reflector, and control rods [1].*

reactor fuel with two key differences. First, rather than polyethylene, the fuse uses polystyrene. Second, the density of uranium in the fuse material is double the value used in the fuel. The two differences coupled with the location of the fuse results in maximizing the fission rate in the fuse compared to all other locations in the core. In the event of a runaway power transient, heat will be generated in the thermal fuse at a greater rate than any other location in the core. As the fuse temperature rises, it will tend to soften when it reaches 100°C and will melt before any the reactor fuel reaches its melting point of 200°C. The AGN-201 reactor design has the lower portion of the core and reflector held in place by the thermal fuse. In the event of the thermal fuse melting, the lower portion of the core and reflector will move downward approximately 5 cm compared to the upper portion of the core which is stationary since it is supported separate from the thermal fuse. The net result will be a dramatic increase in neutron leakage which will terminate the transient. It must be noted that the thermal fuse is a single use safety device.

The reactor core and a portion of the reflector are contained within a gas tight core tank. The core tank is then located within the remainder of the graphite reflector (see **Figure 2**). Surrounding the graphite reflector is a 10-cm thick lead shield. The lead shield is primarily used for gamma ray shielding. The reactor core, reflector, and lead shielding are located within the reactor tank. A graphite thermal column is located on the top lead shielding to support experiments and measurements involving thermalized neutrons. The reactor tank is then located within a 200-cm diameter water filled tank. The radial thickness of the water is approximately 55 cm. The water filled tank is used to absorb neutrons that escape from the core.

To provide access for experiments, a 2.54-cm diameter hole traverses the reactor tank, lead shielding, graphite reflector, and reactor fuel. The hole through the center of the reactor core is commonly referred to as the "glory hole". The glory hole aluminum pipe ensures the core, reflector, lead shield, and water remain properly

**Figure 2.** *Reactor tank assembly [1].*

#### *Idaho State University AGN-201 Low Power Teaching Reactor: An Overlooked Gem DOI: http://dx.doi.org/10.5772/intechopen.105799*

sealed. When not in use, the glory hole is typically open to the air atmosphere. When starting the reactor, a neutron source is placed in the glory hole and when the reactor is shut down and not in use, a cadmium neutron absorber is placed in the glory hole to ensure reactor startup cannot occur. In addition to the glory hole, there are four access ports located in the graphite reflector (see **Figure 2**). The access ports are 10.16 cm in diameter and penetrate through the reactor tank, lead shielding and graphite reflector. When not in use, the access ports are typically filled with graphite, lead, and wood (to simulate water).

The reactor radial thermal flux profile is provided in **Figure 3**. The flux profile shows a general Bessel function trend in the core region followed by an exponential drop in the reflector, lead, and water regions. It should be noted that, unlike water reflected thermal reactors, the AGN-201 reactor does not experience an increase in the thermal neutron flux as neutrons enter the reflector. This is primarily due to the difference in neutron scattering properties of water compared to graphite. The flux profile plot demonstrates the effectiveness of the neutron shielding associated with the water shielding tank. The thermal neutron flux at the outer edge of the shielding tank is four orders of magnitude lower than at the center of the reactor.

Reactivity control is carried out using four control rods. Two safety rods, each with a reactivity worth of 1.25% Δk/k (\$1.68), are operated in a binary fashion. When starting the reactor, the safety rods are driven fully into the core. No intermediate stopping locations are used for the safety rods. When the reactor is SCRAMed, the safety rods are completely removed form the core. The removal mechanism relies on both gravity as well as compressed springs. A single coarse control rod with

**Figure 3.** *Reactor radial flux profile [1].*

a reactivity worth identical to the safety rods (1.25% Δk/k (\$1.68)) is raised into the core region during reactor startup. Typically, the coarse control rod is driven to its maximum insertion location, although there are scenarios where the coarse control rod is stopped short of the maximum insertion location. Similar to the safety rods, upon reactor SCRAM, the adjustable coarse control rod is rapidly ejected from the core by relying upon gravity and compressed springs. Finally, the fine control rod has a reactivity worth of 0.31% Δk/k (\$0.42). The fine control rod is typically driven into the reactor until criticality occurs. Adjustments in the coarse control rod and the fine control rod can then be made to adjust the desired reactor power. Unlike the safety rods and the coarse control rod, the fine control rod is not rapidly ejected from the core when the reactor is SCRAMed. Rather, the fine control rod is driven out of the core at the same rate that it can be driven into the core.

Three monitoring channels are used in the ISU AGN-201 reactor. The three monitoring channel detectors are located within the water filled reactor tank as shown in **Figure 4**. The AGN-201's nuclear instrumentation consists of three different nuclear instrument channels and offer students the opportunity to understand the functions performed by separate portions of the circuit as the incoming signal is processed. Students can study the nuclear instrument channels in a laboratory and then observe them at the reactor.

The three channels are comprised of commercial-grade components. They are more accessible than power plant channels to students and others who wish to study them and their operation over a wide range of neutron flux at an actual reactor. Students can study the instrument systems and their theory and design, and then observe the systems in operation at a wide range of neutron flux. Analog and digital designs of nuclear instrument systems, with a variety of neutron detectors, can be evaluated by using the AGN-201. The AGN-201's nuclear instrumentation consist of the three commonly-found types of nuclear instrument channels that follow the same operating approaches and perform the same functions as the nuclear instrument channels typically found in most reactors. Each channel has a unique but complementary principle of operation. Together, they provide the reactor operators and others with indications of reactor power and the rate of change in power over the entire operating range. Of course they also supply signals for reactor trips.

**Figure 4.** *Reactor assembly plan view [1].*

Channel 1 is the startup, source range, channel and uses a BF3 filled proportional counter. The source range channel illustrates a standard approach that allows the source range channel to display a very low neutron flux in the presence of significant gamma radiation. A proportional-type BF3 neutron detector produces pulses when gamma radiation and neutrons interact with the BF3 that fills the detector. The pulses are amplified and shaped, the lower-amplitude pulses due to gamma interactions within the detector are rejected while the remaining higher-amplitude pulses from neutron interactions are further amplified and displayed. The channel displays count rates from the reactor without a source to well above critical. Channel 1 is designed to initiate a SCRAM signal for low power situations when the count rate falls below the setpoint.

Channel 2 is used to monitor the reactor power using a log scale as well as for indication of the reactor period. The channel 2 detector is a BF3 filled ionization chamber. Channel 2 generates a SCRAM signal when the reactor power falls below 3 x 10−13 W or when the reactor power exceeds 5 W. Additionally channel 2 generates a scram signal if the reactor period is less than 5 seconds. The wide range logarithmic neutron instrument channel (channel 2) illustrates a standard approach that allows the channel to detect and display a current signal that is proportional to power over 7 decades. Channels 1 and 2 rely on different applications of wide-range logarithmic amplifiers. The source range nuclear instrument channel's wide-range logarithmic amplifier converts the frequency of incoming pulses from neutron interactions to voltage. The wide range logarithmic current channel's amplifier converts a direct current to a voltage. In both cases, variations in count rate or current level that are due to the normal and expected variations in neutron flux are often misinterpreted as 'noise' that can lead to the period meters having too much variation to be useful indicators to the reactor operators, and the period circuits spuriously tripping. Circuit designers frequently assume the neutron signal is relatively constant and do not anticipate the large noise component that is inherent due to sources. The AGN-201 provides the actual variations in neutron flux that drive oscillations in period meters and indications of reactor power and can be used to evaluate the effect of circuit modifications to reduce the amplitudes of the oscillations.

Channel 3 is used to monitor reactor power using a linear scale. The channel 3 detector is a BF3 filled ionization chamber. Channel 3 generates a SCRAM signal when the reactor power exceeds 5 W or whenever the linear rotating switch indicator is less than 5% or greater than 95% of full scale.

**Figure 5** shows the SCRAM circuit arrangement for the three monitoring channels. It is important to recognize that the SCRAM circuit arrangement is a single signal SCRAM [4]. If any one of the channels identifies a situation that triggers a SCRAM, the reactor will be SCRAMed. That is, the AGN-201 SCRAM circuit is not a two-out-of-three arrangement.

In addition to the monitoring channels, a series of additional interlock circuits are used to prevent reactor startup or to SCRAM the reactor in the event of undesired situations (see **Figure 6**) [4]. The reactor shielding tank water temperature is monitored to ensure that the maximum allowed excess reactivity is not exceeded. If the reactor water temperature falls below 15°C the reactor excess reactivity is unacceptably large and reactor operation is prevented or discontinued. The reactor shielding tank water level is monitored to ensure sufficient shielding is present. Finally, a seismically activated switch is used to prevent reactor operation or discontinue reactor operation in the case of a seismic event. Similar to the reactor monitoring channels, the interlocks follow a series approach so that if any one of the interlocks is triggered, the reactor will not be allowed to operate.

The reactor is operated from a relatively simple console located in the same room as the reactor. The original console was used for approximately fifty years. In

**Figure 5.** *SCRAM circuit arrangement [1].*

**Figure 6.** *Interlock circuit [1].*

2020, the original console was replaced with an upgraded console (see **Figure 7**). The primary motivation for upgrading the console centered on the use of vacuum tubes for the SCRAM circuits in the old console. Obtaining replacement vacuum tubes became very difficult since these items are no longer manufactured in large quantities. The upgraded console uses solid state relays rather than vacuum tubes. In addition to the use of solid-state relays, the upgraded console has all new wiring, instrumentation, switches, and knobs.

While the AGN-201's core will essentially never be exhausted, support systems such as the instrument systems and their neutron detectors, reactor controls and control rod drives require periodic upgrading. The current financial state of universities and the perceived difficulty in conforming to regulatory requirements tends to encourage using the original 60-year-old tube-based control systems and other equipment until their failure rates leave no choice but to modernize. The cost of the engineering and manufacturing of upgraded instrumentation and equipment by outside firms can be too great for universities. Idaho State University recruited community volunteers with experience in project management and expertise in the design, construction, operation and startup of instrumentation and control, licensing of reactors and other relevant subjects for the university's second attempt to replace the original tube-based control system. The first attempt involved the design and construction of a complex, multiple-level printed circuit board that could not easily be modified. The second and successful attempt used a breadboard approach of circuit boards with holes that could be used to mount components. The *Idaho State University AGN-201 Low Power Teaching Reactor: An Overlooked Gem DOI: http://dx.doi.org/10.5772/intechopen.105799*

**Figure 7.** *Upgraded console installed in 2020 [1].*

second attempt had very few changes to the design, a likely result of the lifetimes of experience of the community members in designing, repairing and maintaining analog systems. One of the main considerations was if the replacement system was to be analog or digital. The advantages and disadvantages of replacing the existing analog control system with a functionally equivalent analog system or attempting to replace it with a digital system were weighted. A replacement analog functional replacement appeared to be simpler and easier from a regulatory standpoint.

From a lifecycle cost standpoint, the analog system's lifetime was envisioned to be decades, whereas digital technology is rapidly advancing, and the lifetime of a digital system was envisioned to be a few years. Analog enjoys far superior cyber security than digital, and maintaining cyber security appeared to be an unnecessarily potential burden to the university. It was decided to replace the system under a 10 CFR 50.59 evaluation. The community expert in licensing helped write the 10 CFR 50.59 document and helped ensure applicable codes and standards had been followed. The community member also purchased and donated some of the components. Another community member and two graduate students worked with the community members to document the project in their thesis. One of the community members became the Project Manager and kept the project moving even during the height of the COVID-19 pandemic shutdown. He also reviewed the design and construction and assisted with troubleshooting. The collaboration of community and university personnel worked well to produce and complete the replacement instrumentation and had the time to transfer knowledge. It is anticipated that the same model will be applied to other modernization efforts going forward.


**7.1 Tamarind pulp**

The most important and generally utilized part of the tamarind tree is its natural product pulp. It establishes 30–50% of the ripe fruit, the shell and fiber represent 11–30%, and the seed around 25–40% [9]. Pulp is rich in pectin and reducing sugars and contains critical measures of organic acids, 98% of which is tartaric acid. It is a unique plant acid that is generated from the principal carbohydrate products of photosynthesis and is not utilized metabolically by the plant once formed. The primary flavor compound of the pulp is 2-acetyl furan. The quantity of tartaric acid does not diminish as the fruit ripens, implying that it is stable, in the development of fruit. Reducing sugars grow to 30–40% during this stage of fruit development, giving the sour fruit a sweeter taste.

Tamarind pulp was assessed based on its physicochemical properties such as crude protein, crude fiber, fat, ash, moisture content, water activity (Aw), particle shape, particle size distribution, and density (**Figure 11** and **Table 2**) [10].

**Table 2.** *Proximate analysis of tamarind pulp.*


*Review* **Specific versus Non-Specific Exercises for Chronic Neck or Shoulder Pain: A Systematic Review**

**Lirios Dueñas 1,2,† , Marta Aguilar-Rodríguez 1,\* ,† , Lennard Voogt 3,4, Enrique Lluch 1,2,4, Filip Struyf 5 , Michel G. C. A. M. Mertens 4,5 , Kayleigh De Meulemeester 4,6 and Mira Meeus 4,5,6**

**Abstract:** The current systematic review aimed to compare the effect of injury-focused (specific) exercises versus more general (non-specific) exercises on pain in patients with chronic neck or shoulder pain. We searched PubMed, EMBASE, and Web of Science. Two reviewers screened and selected studies, extracted outcomes, assessed risk of bias, and rated the quality of evidence. A total of nine eligible studies, represented in 13 articles, were identified, with a considerable risk of bias. One article investigated the acute effect of single bouts of exercise on pain and reported an immediate pain reduction after non-specific exercise. Regarding short-term effects, seven out of the nine studies found no differences in pain between interventions, with inconsistent results among two other studies. Concerning the long-term effects, while pain reduction seems to be favored by specific exercises (two out of four articles), the best format is still unclear. Based on the acute effects, a single bout of non-specific exercise seems to be a better option for pain-relief for patients with chronic neck or shoulder pain. For short-term effects, there are no differences in pain between specific and non-specific exercises. Regarding long-term effects, specific exercises seem to be the best option. Nevertheless, more studies are warranted.

**Keywords:** chronic pain; musculoskeletal pain; exercise therapy; neck pain; shoulder pain; systematic review

### **1. Introduction**

The prevalence of neck pain has steadily increased during the past two decades [1] and is now, second to back pain, the most common musculoskeletal disorder [2,3]. Additionally, shoulder pain is responsible for approximately 16% of all musculoskeletal complaints [4], with a yearly incidence of 15 new episodes per 1.000 patients seen in primary care settings [5]. Neck and shoulder symptoms are often persistent and recurrent, with from 40% to 50% of patients reporting persistent symptoms after 6 to 12 months [6] and 14% of patients continuing care after 2 years [7].

Successfully treating patients with chronic neck or shoulder pain (CNSP) is a challenging issue for clinicians. Exercise therapy is found to be an effective treatment strategy

**Citation:** Dueñas, L.;

Aguilar-Rodríguez, M.; Voogt, L.; Lluch, E.; Struyf, F.; Mertens, M.G.C.A.M.; Meulemeester, K.D.; Meeus, M. Specific versus Non-Specific Exercises for Chronic Neck or Shoulder Pain: A Systematic Review. *J. Clin. Med.* **2021**, *10*, 5946. https://doi.org/10.3390/jcm10245946

Academic Editors: Jo Nijs and Patrice Forget

Received: 16 October 2021 Accepted: 11 December 2021 Published: 18 December 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

to relieve pain and improve patient's level of functioning in daily activities in various chronic musculoskeletal pain disorders, including chronic neck pain [8–11] and chronic shoulder pain [12,13]. However, although the evidence for exercise therapy is strong, it is still difficult to demonstrate the superiority of one exercise approach over another in chronic pain populations [14].

Exercise interventions aim to correct biomechanical disturbances, but can also be directed to specific psychological and behavioural characteristics of chronic pain problems [14]. Naugle et al. [15] summarized the neurophysiological and hypoalgesic, effects of acute bouts of exercise in healthy and chronic pain populations in a meta-analytic review. In healthy populations, the evidence suggests that different types of acute bouts of exercise decrease the perception of experimentally induced pain. However, in patients with local muscular pain (e.g., shoulder myalgia), exercising non-painful muscles (non-specific exercises (NSE)) seems to activate generalized endogenous hypoalgesia, but exercising painful muscles (specific exercises (SE)) increases pain sensitivity in both the exercising muscle and distant locations [15,16]. While healthy people present exercise-induced hypoalgesia, regardless of the type of exercise, this mechanism seems to fail in subgroups of chronic pain patients. Among these patients, a bout of exercise can even result in a hyperalgesic response, indicating that exercise therapy should be tailored to prevent symptom flares. Nevertheless, the long-term responses to exercise therapy seem to be effective for a wide variety of chronic pain diagnoses (for a review, see Kroll, 2015 [14]).

Considering this, designing an optimal, tailor-made, exercise program for a person with CNSP requires an understanding of the underlying working mechanisms of different exercise interventions [14,17]. Additionally, the differences between the acute effects of one bout of exercise and training effects (acute, short-term, and long-term effects) should be taken into account when addressing exercise for chronic pain patients. Based on the stateof-the-art, as summarized above, the question remains as to which type of exercise, specific or non-specific, is more convenient for pain relief in people with CNSP. The aim of this systematic review was to provide a constructive overview of the existing literature reporting pain experience, following specific versus non-specific exercise therapy in CNSP patients.

#### **2. Materials and Methods**

#### *2.1. Data Sources and Searches*

This systematic review is registered in the PROSPERO register of systematic reviews (registration number: CRD42020145234) and is in accordance with the PRISMA guidelines [18]. An extensive search was conducted of the online databases PubMed, Web of Science, and Embase. Databases were searched within a 2-day period, retrospective of inception, to May 2020, with a subsequent update to January 2021. The search strategy was based on the Population, Intervention, Comparison, Outcome, Study Design (PICOS) framework and was conducted to find controlled studies (S) evaluating the effect of specific exercise programs, including neck or shoulder exercises (I), on pain (O) in CNSP patients (P), compared to non-specific exercise programs (i.e., exercises that do not specifically involve the affected region) (C). Key words from these groups were combined. The construct of the search strategy is presented in Table 1.

Abbreviations: MeSH, Medical Subject Headings.

#### *2.2. Study Selection*

To be included in this review, studies had to meet the following inclusion criteria: (1) the study sample consisted of human adults (>18 years) with chronic (>3 months) neck and/or shoulder pain; (2) both treatments, SE (those focused on the neck or shoulder region) and NSE (including more generic training such as aerobic exercise, general fitness training, chain-stretching, body–mind, or other generic movement-related approaches), had to be compared in the study; (3) pain was measured as an outcome (both subjectively

and objectively); (4) articles had to be written in English, Spanish, French, Dutch, or German; (5) full-text articles of original research had to be available; (6) only controlled clinical trials were allowed. Exclusion criteria determined that: (1) secondary research (reviews and meta-analysis) was not allowed; and (2) widespread pathologies and other co-morbidities could not be present.

The literature search was independently conducted, and the obtained articles were screened by two of the researchers (L.D. and M.A., both PhDs and experienced in chronic populations in a clinical setting), based on title and abstract. The full-text article was retrieved if the citation was considered potentially eligible and relevant. In the second phase, each full-text article was independently evaluated by the two researchers to see whether it fulfilled the inclusion criteria. If any of the eligibility criteria were not fulfilled, then the article was excluded. In case of disagreement, a third researcher was consulted (M.M., PhD, experienced in chronic pain research).

#### *2.3. Data Extraction and Analysis*

Important information from each study was selected and reported in an evidence table. The evidence table was composed of the following items: (1) reference; (2) participants' characteristics; (3) specific intervention(s); (4) non-specific intervention(s) and reference intervention if any; (5) outcome measures and timing; (6) main results. The results regarding training effects were clustered into acute, short-term, and long-term effects; for the first days of intervention, post-intervention, and after follow-up, respectively.

#### *2.4. Quality Assessment and Data Synthesis*

The Cochrane Collaboration's tool for assessing risk of bias was used (http://handbook. cochrane.org/, accessed on 24 May 2020) to assess the following domains: (1) the randomization process; (2) treatment allocation; (3) blinding of participants and personnel; (4) blinding of outcome assessors; (5) completeness of the outcome data; (6) reporting of results; (7) accounting for co-interventions; (8) other sources of bias. Item 8 was specifically focused on sample size calculation. With reference to a Cochrane review, sample size was considered inadequate if there were fewer than 50 participants per group and if power analysis was not applied and reported for relevant outcome measures [19].

After clustering the results based on exercise modes and timing of assessments, the overall quality of evidence per cluster was determined by applying the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach [20]. For every cluster, a GRADE summary statement is provided under the respective paragraph in italics.

Risk of bias assessment and grading of evidence was performed by two authors (L.D. and M.A.) independently, who were blinded from each other's assessment. After rating the selected articles/clusters, the results of both researchers were compared, and differences were analyzed. In case of disagreement, the reviewers assessed the article/cluster a second time to obtain a consensus. When consensus could not be reached, a third opinion was provided by the last author (M.M.).

#### **3. Results**

#### *3.1. Search Results*

The initial search of all databases resulted in 852 hits. Following two consecutive screening phases on title/abstract and full text, 10 eligible records remained. After manual searching of the reference lists, two more eligible articles were identified for inclusion. A recent update identified 57 new articles, leaving one of them for inclusion in the review, after the screening phases. Thus, a total of 13 articles, reporting the results of nine different randomized controlled trials, met the inclusion criteria. The corresponding flowchart is shown in Figure 1.

**3. Results**

*3.1. Search Results*

shown in Figure 1.

The initial search of all databases resulted in 852 hits. Following two consecutive screening phases on title/abstract and full text, 10 eligible records remained. After manual searching of the reference lists, two more eligible articles were identified for inclusion. A recent update identified 57 new articles, leaving one of them for inclusion in the review, after the screening phases. Thus, a total of 13 articles, reporting the results of nine different randomized controlled trials, met the inclusion criteria. The corresponding flowchart is

**Figure 1.** PRISMA flowchart of articles selection (adapted from Moher et al. [18]).

#### **Figure 1.** PRISMA flowchart of articles selection (adapted from Moher et al. [18]). *3.2. Risk of Bias and Quality of Evidence*

*3.2. Risk of Bias and Quality of Evidence* Detailed information on the individual risk of bias can be found in Figure 2. In most cases (85.6% or 89 of 104 items), the two researchers agreed. After a comparison of the 15 differences, the reviewers reached a consensus for six items. The remaining nine points of discussion were solved after a third opinion. Nine of the 13 articles provided insufficient information about the allocation concealment [21–29]. None of the studies reported that the therapist was blinded. Additionally, blinding of the patients was impossible, given the nature of the therapy. In one study, the patients were kept naïve for the different interventions (specific or global stretching). This study was considered as having an unclear risk of bias, because the assumptions of patients were unclear [27]. Attrition and reporting bias were mainly low. Two of the 13 articles accounted for co-interventions by recording medications and other treatments received in a diary [30] and by registering medication Detailed information on the individual risk of bias can be found in Figure 2. In most cases (85.6% or 89 of 104 items), the two researchers agreed. After a comparison of the 15 differences, the reviewers reached a consensus for six items. The remaining nine points of discussion were solved after a third opinion. Nine of the 13 articles provided insufficient information about the allocation concealment [21–29]. None of the studies reported that the therapist was blinded. Additionally, blinding of the patients was impossible, given the nature of the therapy. In one study, the patients were kept naïve for the different interventions (specific or global stretching). This study was considered as having an unclear risk of bias, because the assumptions of patients were unclear [27]. Attrition and reporting bias were mainly low. Two of the 13 articles accounted for co-interventions by recording medications and other treatments received in a diary [30] and by registering medication type and frequency [27]; the other articles did not account for co-interventions. Five articles conducted a sample size calculation [23,26,27,30,31]. Two of the 13 articles [32,33] included more than 50 subjects per group.

cluded more than 50 subjects per group.

**Figure 2.** Risk of bias summary. These graphs illustrate the review authors' judgements about each risk of bias item for each included study (**a**) and presented as percentages across all included studies (**b**). Review Manager (RevMan) 5.3. [34]. Legend: (+) indicates "low risk of bias"; (?) indicates "unclear risk of bias"; (−) indicates "high risk of bias". **Figure 2.** Risk of bias summary. These graphs illustrate the review authors' judgements about each risk of bias item for each included study (**a**) and presented as percentages across all included studies (**b**). Review Manager (RevMan) 5.3. [34]. Legend: (+) indicates "low risk of bias"; (?) indicates "unclear risk of bias"; (−) indicates "high risk of bias".

ters started from a GRADE level of moderate.

Information on risk of bias and the level of evidence, following the GRADE system, is presented per cluster in Table 2. Since none of the studies was double-blinded, all clus-Information on risk of bias and the level of evidence, following the GRADE system, is presented per cluster in Table 2. Since none of the studies was double-blinded, all clusters started from a GRADE level of moderate.

type and frequency [27]; the other articles did not account for co-interventions. Five articles conducted a sample size calculation [23,26,27,30,31]. Two of the 13 articles [32,33] in-

**Table 2.** Risk of bias and grading the evidence per clusters based on exercise type and exercise effects over time OR follow-up (acute, short- and long-term effects). *J. Clin. Med.* **2021**, *10*, 5946 7 of 24 *J. Clin. Med.* **2021**, *10*, 5946 7 of 24


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## Colorectal Cancer Biology From Genes to Tumor

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**8.4 Digital PCR (dPCR)**

Digital PCR technology (dPCR) is one of the most reliable techniques among the currently used technology for GMO quantification. The process is accomplished through dividing the mixture of PCR into a sizeable number of distinct reactions which include null, single or least target DNA copies. After completion of PCR, the positive (i.e., observed replicated desired segments) and negative (i.e., observed non-replicated segments) samples are analyzed and then the total copy number of the desired gene in an original sample is determined by the application of binomial Poisson statistics [59]. Most recently, duplex assays, including one GMO specific marker with one soybean, maize, or rice taxon specific marker, were performed by using the dPCR system to quantify 12 GM soybean, 16 GM maize, and two GM rice events [60].


**1. Introduction**

The pelvic floor has an important holding and support function in a woman's body. If this substantial holding apparatus suffers from disorders, this can have a huge impact on a woman's quality of live, as taking part in everyday life can be considerably restricted by pelvic floor disorders. The pelvic floor consists of fasciae (endopelvic fascia, rectovaginal septum, perirectal fascia), ligaments (ligg. Sacrouterina, arcus tendineus etc.) and muscles (pelvic diaphragma, urogenital diaphragma), which are already exposed to a high load due to the upright gait. Other events in a woman's life like injuries, chronic overload or giving birth contribute to further stress on the pelvic floor and can lead to disorders. Vaginal delivery, an event most women experience at least once in their lifetime, can lead to damage to connective tissue, ligaments and muscles up to tearing of muscular

structures and stretching of pelvic nerves. Hereditary connective tissue weakness contributes further to the weakness of the pelvic floor. In summary, pelvic floor disorders have multifactorial reasons and can result in descensus of the bladder, the uterus, the vagina or the rectum as well as incontinence. In most women, symptoms occur in an advanced stage, with the woman being able to compensate the symptoms through training of the pelvic floor muscles in earlier stages. As muscle strength decreases, the level of suffering increases, while fecal and urinary incontinence may also occur at earlier stages. Women present to their gynecologist with urinary incontinence or prolapse symptoms, while anal incontinence is still highly taboo.


**2.1 C-reactive protein (CRP)**

CRP is the best studied inflammation marker associated with CV events. It is the prototypical acute phase response protein produced by the liver under the control of various proinflammatory cytokines, namely interleukin-6, interleukin-1, and tumor necrosis factor-α. Its uniquiness is due to rapid (within 6 hours) and dramatic increases (up to 1000 fold) in circulating concentrations after a cytokine-mediated response to most forms of tissue injury, infection, and inflammation. Moreover, it was shown that plasma half-life (19 hours) and fractional clearance rates of CRP were nearly constant in normal subjects, as well as in patients with infectious, inflammatory, and neoplastic conditions. This marks CRP as a 'precise objective index' of overall inflammatory activity and a surrogate of underlying cytokine stimulus (Arici& Walls, 2001; Pepys&Baltz, 1983; Vigushin et al., 1993).

Several observations have demonstrated that in a significant proportion of hemodialysis patients CRP is elevated for no apparent reason. A wide variety of factors in hemodialysis patients may be responsible for this elevation. First, the uremic state is associated with an altered immune response and uremia per se may cause a proinflammatory status with ongoing acute phase response. Also, extracorporeal circulation of blood during each hemodialysis session may act as a fresh stimulus for acute phase response. Increased cytokine release, the role of dialysis membranes, the dialysate and the patient-specific processes, such as the type of vascular access or unrecognized infections, may also play a role in inciting an inflammatory response (Arici&Walls, 2001; Stenvinkel, 2002a, 2002b).

The predictive value of CRP in CV risk and mortality in hemodialysis patients was shown in numerous studies, and evidence from experimental and clinical studies showed that CRP may contribute directly to the pathogenesis of atherosclerosis and its complications through a variety of mechanisms (Arici&Walls, 2001; Yeun&Kaysen, 2000; Zimmermann et al., 1999).

So it has been suggested that this hepatic–derived protein is not only a marker, but also a mediator, of vascular disease (Lagrand et al., 1997; Torzewski et al., 1998). Although a wide variety of potential sources may be associated with elevated CRP in this patient population, underlying silent CV disease may be one of the possible links for this elevation. So the clear association between CRP and CV disease in the hemodialysis population has added CRP as a new predictive CV risk factor which may actually be in a midway position between traditional and uremia-related CV risk factors (Arici&Walls, 2001).

One of the studies investigated the associations of different risk factors with carotid artery intima-media thickness in non-diabetic hemodialysis patients who had no clinical evidence

Chronic inflammation is one of the well-known non-traditional cardiovascular risk factors in hemodialysis patients. Chronic kidney disease results in a chronic, low-grade inflammatory process that becomes evident even in the early stages of the disease. After the start of dialysis treatment, various factors associated with the dialysis procedure may also contribute to a stronger, more active inflammatory response. All available evidence suggests that chronic inflammation in hemodialysis patients may contribute significantly to the development and progression of CV disease (Filiopoulos&Vlassopoulos, 2009; Stenvinkel,

Although few studies are available concerning the relationship between inflammatory status and CV risk in hemodialysis patients without co-morbid diseases, the studies that do exist in

CRP is the best studied inflammation marker associated with CV events. It is the prototypical acute phase response protein produced by the liver under the control of various proinflammatory cytokines, namely interleukin-6, interleukin-1, and tumor necrosis factor-α. Its uniquiness is due to rapid (within 6 hours) and dramatic increases (up to 1000 fold) in circulating concentrations after a cytokine-mediated response to most forms of tissue injury, infection, and inflammation. Moreover, it was shown that plasma half-life (19 hours) and fractional clearance rates of CRP were nearly constant in normal subjects, as well as in patients with infectious, inflammatory, and neoplastic conditions. This marks CRP as a 'precise objective index' of overall inflammatory activity and a surrogate of underlying

Several observations have demonstrated that in a significant proportion of hemodialysis patients CRP is elevated for no apparent reason. A wide variety of factors in hemodialysis patients may be responsible for this elevation. First, the uremic state is associated with an altered immune response and uremia per se may cause a proinflammatory status with ongoing acute phase response. Also, extracorporeal circulation of blood during each hemodialysis session may act as a fresh stimulus for acute phase response. Increased cytokine release, the role of dialysis membranes, the dialysate and the patient-specific processes, such as the type of vascular access or unrecognized infections, may also play a role in inciting an inflammatory response (Arici&Walls, 2001; Stenvinkel, 2002a, 2002b). The predictive value of CRP in CV risk and mortality in hemodialysis patients was shown in numerous studies, and evidence from experimental and clinical studies showed that CRP may contribute directly to the pathogenesis of atherosclerosis and its complications through a variety of mechanisms (Arici&Walls, 2001; Yeun&Kaysen, 2000; Zimmermann et al., 1999). So it has been suggested that this hepatic–derived protein is not only a marker, but also a mediator, of vascular disease (Lagrand et al., 1997; Torzewski et al., 1998). Although a wide variety of potential sources may be associated with elevated CRP in this patient population, underlying silent CV disease may be one of the possible links for this elevation. So the clear association between CRP and CV disease in the hemodialysis population has added CRP as a new predictive CV risk factor which may actually be in a midway position between

One of the studies investigated the associations of different risk factors with carotid artery intima-media thickness in non-diabetic hemodialysis patients who had no clinical evidence

cytokine stimulus (Arici& Walls, 2001; Pepys&Baltz, 1983; Vigushin et al., 1993).

traditional and uremia-related CV risk factors (Arici&Walls, 2001).

**2. Markers of inflammation**

2006; Zimmermann et al., 1999).

**2.1 C-reactive protein (CRP)**

this area also support the role of inflammation.

of atherosclerosis and no comorbidities (Zumrutdal et al., 2005). Seventy-two patients (43 men, 29 women; mean age 34.5 ± 10.6 years, mean time on hemodialysis 47.9 ± 40.0 months) were included in the study. Patients without history or evidence of myocardial, cerebrovascular or peripheral vascular disease, those without diabetes mellitus, and those who had been stabilized on hemodialysis therapy for more than six months and were less than 55 years old were enrolled. Patients were excluded whose chest radiograph showed calcified plaques in the aortic arch, or who had ischaemic findings on electrocardiography and/or ventricular wall motility disorders or valvular calcifications on echocardiography. Additionally, patients with conditions known to be associated with acute-phase responses were excluded. The control group consisted of 40 age-and sex-matched healthy subjects, who had been recruited from hospital staff. Body mass index, triglycerides, lipoprotein (a), fibrinogen, CRP, haematocrit-corrected erythrocyte sedimentation rate, serum cardiac troponin I, beta2 microglobulin, and homocysteine levels were found to be significantly different in patients on hemodialysis compared with control subjects. The mean value of the right and left carotid intima media thickness was 0.59 ± 0.06 mm for patients and 0.53 ± 0.07 mm for control subjects. The difference was significant (p=0.002). The carotid intima-media thickness of patients was correlated with age, body mass index, CRP, haematocrit-corrected erythrocyte sedimentation rate, beta2 microglobulin, serum cardiac troponin I, triglyceride, and fibrinogen. CRP, haematocrit-corrected erythrocyte sedimentation rate, serum cardiac troponin I, and fibrinogen were significantly correlated with each other, but not with beta2 microglobulin. The only parameter correlated with beta2 microglobulin was time on hemodialysis. The mean carotid intima-media thickness was significantly greater in patients with both left ventricular hypertrophy and a CRP level > 6.0 mg/L than it was in those with a CRP level ≤ 6.0 mg/L. In that study, multivariate regression analysis showed that age, CRP, beta2 microglobulin, and left ventricular hypertrophy were independent predictors of carotid artery intima-media thickness. The results of that study supported the hypothesis of an 'accelerated atherogenesis' in the hemodialysis population, even if those patients do not have clinical evidence of atherosclerosis. And CRP was found to be one of the independent predictors of early-onset atherosclerosis.

Most investigations of CV risk in patients on hemodialysis have been cross-sectional in nature and representative of the general hemodialysis population. In the previous study, the same subgroup of hemodialysis patients was followed up over the course of one year and the determinants of the progression of carotid artery intima-media thickness were assessed again (Zumrutdal et al., 2006). Fifty-four of the 72 patients completed the study and retested under the same standardized conditions after 12 months. The findings at 12 months showed that carotid artery intima-media thickness had progressed in 75.9 % patients. Age, CRP, beta2 microglobulin and left ventricular hypertrophy were independently related with baseline carotid artery intima-media thickness. At 12 months, age and CRP were found to be independent variables related with carotid artery intima-media thickness. The independent risk factors related with the change in carotid artery intima-media thickness from baseline to 12-month stage were age and male sex.

According to those results, age and male sex were related to progression of carotid artery intima-media thickness as unavoidable risk factors in this subgroup of the hemodialysis population. That agreed with the results of major clinical and epidemiological studies of the general population. The independent relation between CRP and carotid artery intima-media thickness both at baseline and 12 months supports the additional role of non-specific inflammation in hemodialysis patients without comorbidities.

Determinants of Cardiovascular Risk in Hemodialysis Patients Without Significant Comorbidities 285

factor-alpha were found to be independently associated with silent myocardial damage

In hemodialysis patients without comorbidities, mean carotid intima-media thickness, which reflects generalized atherosclerosis and CV risk, was significantly greater in patients with left ventricular hypertrophy, than it was in patients without left ventricular hypertrophy. Mean carotid intima-media thickness in subjects in the heathy control group was significantly lower than it was in hemodialysis patients both with and without left ventricular hypertrophy. The mean serum cardiac troponin I level in the control group was significantly lower than it was in patients both with and without left ventricular hypertrophy. The mean serum cardiac troponin I level was significantly higher in patients with left ventricular hypertrophy than it was in those without left ventricular hypertrophy (Zumrutdal et al., 2005). The relationship between carotid artery intima-media thickness, serum cardiac troponin I levels and left ventricular hypertrophy may demonstrate that subclinical atherosclerotic changes and/or adaptation may occur along with cardiac alterations. So it may be reasonable to apply early strategies for prevention and treatment of left ventricular hypertrophy in hemodialysis patients before clinically evident CV disease.

Cardiac troponins are the most specific biomarkers for myocardial damage, although they may be elevated in situations other than acute coronary syndrome. Hemodialysis patients often have raised cardiac troponin I and T levels in the absence of acute ischaemic symptoms. The source of this increase has been a point of confusion over the past decade. At the beginning, some authors suggested that this might be related to the cardiac expression of troponins, while others argued for the skeletal muscle as a possible extracardiac source of abnormally elevated cardiac troponins in hemodialysis patients (Bodor et al., 1997; Kals et

In initial experience with two troponin subunits, serum troponin T was elevated more frequently than troponin I in patients with renal failure, and that led the clinicians to question its specificity for the diagnosis of myocardial infarction. Additionally, the poorer specificity of troponin T was attributed to subclinical myocardial injury in the setting of left ventricular hypertrophy or to uremia-induced skeletal muscle expression of the cardiac isoform of troponin T, while cardiac troponin I has been exclusively of cardiac origin and does not express in the skeletal muscle at any developmental stage. Thus, troponin I was proposed to be a better marker of myocardial injury in renal failure than T (Yeun&Kaysen, 2000). However, subsequent studies reported the absence of extracardiac cardiac troponin T expression in truncal skeletal muscle biopsy specimens from patients with end-stage renal failure at the RNA and protein levels (Haller et al., 1998). Another study, based on the electromyographic evaluation of 50 chronic hemodialysis patients, investigated the relationship between increased cardiac troponin T levels and uremic myopathy. Proximalextremity muscles-deltoid, biceps, vastus laterali-, which were the most common targets of uremic myopathy, were studied. Five of 50 patients (10%) had a positive troponin T test, but only 1 of those patients had characteristic electromyographic findings. Totally, 4 of 50 patients (8%) had electromyographic findings characteristic of uremic myopathy. Positive troponin test results were not associated with calcium, phosphate, parathormone levels. There was no association between serum cardiac troponin T levels and uremic myopathy

(Afsar et al., 2009).

**3.2 Cardiac troponins**

al., 2011; McLaurin et al., 1997).

(Zumrutdal AO et al., 2000).


**Abstract**

The demographic patterns of COVID-19 spread can provide clues to develop roadmaps for devising better prevention and control. It is high time to analyze and re-evaluate the zoonotic/reverse zoonotic spread of SARS-CoV-2 globally. To this end, lessons from epidemiology and associated determinants from previous outbreaks of SARS-CoV-1 and MERS need to be cultured and re-visited. Ways to minimize the rates of infection and promote the well-being of the masses need urgent attention owing to the subsequent waves of the global pandemic in most countries. Efforts are being directed for the provision of efficient and cost-effective diagnostics, prophylaxis and therapeutic options for COVID-19. The chapter provides insights, suggesting a potential roadmap for efficiently preventing the future outbreaks of COVID-19, based on the tools of epidemiology, transmission probabilities and public health safety concerns.

**Keywords:** COVID-19, Zoonotic, reverse zoonotic, Epidemiological tools, public health

## **1. Introduction**

An outbreak with the name of CoVID-19 was reported from Wuhan, China on December 29, 2019. Initially, it was treated as pneumonia of unknown origin and reported to the local office of the World Health Organization (WHO) in China on December 31, 2019 [1]. The most recent outbreak owing to the probable zoonotic and human-human transmission of coronavirus disease virus, 2019 (COVID-19) has entrapped 220 countries and territories with 162, 773, 940 confirmed cases reported by WHO as of 17 May 2021 more than One Hundred Fifty-eight million people (WHO) affected. The host, agent and environmental factors are crucially involved in the chain of infection following the entry of the 2019 novel Coronavirus (2019-nCoV or SARS-CoV-2) in a susceptible host. The progression of the virus within the host may be as quick as 5–6 days (average), leading to severe clinical symptoms that warrant intensive care. The virus later on named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the international committee on taxonomy of viruses on February 11, 2020 [2]. Bats and Pangolins were considered

the reservoir host and initially blowout through the exposure of human beings to the seafood market in Wuhan, China [3]. The worldwide distribution of the virus was attributed to commercial air travels from epidemic countries to non-epidemic countries including, Taiwan, Japan, Korea, Malaysia, Russia, America, Saudi Arabia, United Arab Emirates, Germany, France, Spain, Italy and Iran etc. [4]. To date, the number of highest positive cases has been encountered by the USA followed by India, Brazil, Europe, UK, Africa and Middle East [5]. In order to respond to the outbreak swiftly and accurately, the public health authorities and policy makers direly need to know the epidemiology and associated risk factors [6]. The risk factors may include; how much time it takes to show the symptoms and which specific individuals having specific characteristics are more prone to infection.

According to CDC, currently several registered vaccines are available in United States to provide protection against CoVID-19. These vaccines are named as Pfizer-BioNTech, Moderna and Johnson & Johnson's Janssen. Other two vaccines Novavax and AstraZeneca are in phase 3 clinical trials.

It is necessary to strictly follow the precautionary measures i.e. wearing mask, social distancing, avoid arranging events and frequently hand washing along with the vaccination because vaccines alone will not prevent the transmission or end the pandemic. Until high level of global vaccine mediated defense is attained throughout the world.

As documented by the WHO, mathematical models specifically designed in a timely fashion may play an important role in providing evidence-based knowledge to public health authorities and policy makers. Moreover, modeling can help in understanding different aspects of the outbreak including (i) the ability of transmission of disease, (ii) prediction of peaks of infections during the progression of the disease, (iii) severity of infection and (iv) the effectiveness of preventive strategies for the intervention of disease. The modelers of infectious diseases worldwide had accepted the challenge of developing simulation models for transmission and dynamics of the disease and promptly reacted to the emerging outbreak of CoVID-19. Various epidemiological models that have been developed by modelers worldwide included: In China, Susceptible-Exposed-Infected-Resistant (SEIR) Model [7–9], Bats-Host-Reservoir-People (BHRP) transmission network model [10], Markov Chain Monte Carlo (MCMC) methods [11], Susceptible individuals (S)-Asymptomatic individuals (E)- Infectious individuals with symptoms(I)- Isolated individuals with treatment (J)- Recovered individual (R) (SEIJR) dynamic compartmental model [12], Exponential growth (EG) and Maximum Likelihood (ML) estimation method [13–15], Incidence Decay and Exponential Adjustment (IDEA) model [16], Susceptible-Exposed-Infected-Recovered-Death-Cumulative (SEIRDC) model [17], Computational modeling of potential epidemic trajectories [18], Simulation of early outbreak trajectories [19], Traveling network based modeling [20], Susceptible-Infected-Recovered (SIR) model and Quarantine model [5] in Italy, Susceptible-Exposed-Infected-Recovered (SEIR) model, Exponential growth (EG), Maximum Likelihood (ML) estimation, Sequential Bayesian (SB) method and Estimation of Time Dependent (TD) reproduction numbers in India [21, 22].

All of these simulation models estimated the Basic Reproduction Number (R0) of the virus. The R0 indicates the transmissibility of the virus from an infected person to a naïve or unexposed population. A value R0 > 1 represents that the number of cases will increase in the future while R0 < 1 represents that the disease will diminish in the near future. The reason for higher R0 estimates may be attributed to lower numbers of cases and minimum onset time of infection. However, the estimation error will start to decrease as the number of cases increased and real-time pictures of the cases will be available for accurate estimates [13]. In this scenario, statistical models are primarily used to determine the basic viral replication

*Epidemiology, Zoonotic and Reverse Zoonotic Potential of COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.98443*

number, the serial interval between primary and secondary cases and virus doubling time which are important epidemic parameters [23, 24]. Additionally, some other approaches may also be required to include mild or asymptomatic cases which may be missed due to limitations of diagnostic methods applied [25]. With time, treatment options of clinical patients were improved and the spread of disease is being controlled through more strict methods like the restricted movement of individuals. The effects of such measures may be measured through statistical reasoning [26, 27]. On the other hand, mathematical models are based on dynamical Equations [28] can give more details related to epidemic characteristics as compared to statistical methods [29].

### **2. Reverse zoonotic potential of coronaviruses**

Sporadic detection of natural SARS-CoV-2 infections together with successful experimental infections of certain animals raises concerns about reverse zoonosis (also termed as zooanthroposis: transmission of the infection from humans to animals. As a result of close contact with infected humans, several cats, dogs and zoo animals tested positive for SARS-CoV-2 [30, 31]. However, the incidence of natural infections in these animals has not been ruled out due to limited information on clinical features of the infections in animals. The existing data suggest that clinical features may range from asymptomatic infections to symptomatic disorders with signs that may include sneezing, coughing, nasal discharge, respiratory distress, vomiting, diarrhea, ocular discharge, lethargy and fever etc. [32]. A study from Hong Kong in February 2020 confirmed the transmission of SARS-CoV-2 infection to asymptomatic dogs from their previously diagnosed COVID-19 positive owner. A 17-year-old Pomeranian breed dog and a 2-year-old German shepherd were tested positive for SARS-CoV-2 RNA by RT-PCR on multiple oral and nasal swabs. However, virus isolation and serological testing could not be executed [33]. A summary of potential zoonotic relations of some coronaviruses has been given in **Figure 1**.

As a result of the death of a geriatric dog; presumably due to other underlying health issues, it was concluded that the dog either was contaminated by close contact with an infected individual or had a low level of infection. Similarly, a six-year male German shepherd tested positive for SARS-CoV-2 RNA in the USA in mid-April 2020, who contracted the infection from his COVID-19 positive owner. After five days of infection, he developed active infection followed by nasal discharge, lethargy and difficulty in breathing, blood in urine and vomit, weight loss and difficulty in walking, along with heart murmurs and lymphoma [34]. A case report in March 2020 revealed a cat belonging to a COVID-19 positive owner, tested

**Figure 1.** *Probable zoonotic potential of various coronaviruses.*

positive for SARS-CoV-2 RNA by RT-PCR in Belgium, presenting gastrointestinal disease and transient respiratory disorders. While in another report on April 01, 2020, a pet cat belonging to a COVID-19 positive owner was tested positive for SARS-CoV-2 without showing disease symptoms [35]. A report on April 05, 2020, showed transmission of SARS-CoV-2 from a zoo employer who was an asymptomatic carrier of SARS-CoV-2 to one tigress, five tigers and lions at Bronx zoo in New York [35].

In the USA on August 14, 2020, 13 cases of pet cats and 14 cases of dogs were tested positive for SARS-CoV-2 by virus neutralization antibody tests or RT-PCR having close contact history with infected humans [31]. It has also been proven experimentally that susceptible pet cats can also transfer this virus to other healthy cats via short-distance aerosols or droplets due to greater similarity between ACE-2 receptors of feline and humans [36]. In a study, two dogs, two cats, three lions and four tigers were tested positive for the presence of SARS-CoV-2 due to close contact with their COVID-19 positive caretakers [37]. It also provides important information about animal management for COVID-19 control, animal models for SARS-CoV-2 and significant replication of this virus in both lower and upper respiratory tracts of ferrets and cats. Transmission of this virus can occur in ferrets through direct contact and in cats through droplets or aerosols. The presence of this virus in cats from Wuhan, China showed that cats may get infected by this virus by the environment or humans [38]. In a study, 15% of cats were tested positive for the presence of SARS-CoV-2 using an Indirect Enzyme-Linked Immunosorbent Assay while cats tested before the outbreak showed negative results [39]. A study provides important insight about the high susceptibility risk of animals having close contact with humans especially cats and ferrets while poor susceptibility risk in animals like pigs, dogs, ducks and chickens [40].

Based on these findings we may conclude that SARS-CoV-2 has the potential of reverse zoonosis as well. Although the risk of disease transmission from humans to animals and companion or zoo animals to humans or other animals is much less and it depends upon how this virus spreads in various animal species. Therefore, planned investigations, targeted surveillance and continuous monitoring of specific animal species having close contact with their COVID-19 positive or suspected owners or caretakers are mandatory at local or national levels. Although, currently there is no specific testing facility available for SARS-CoV-2 infections in animals. But the situation may change in the future to control and management of COVID-19 infections. To test samples for companion animals, a laboratory in the USA known as IDEXX Laboratories has started a test under the commercial name of SARS-CoV-2 (COVID-19) [41]. Several private and government veterinary laboratories are now trying to develop and use nucleic acid-based tests and serological assays to diagnose SARS-CoV-2 transmission in zoo and pet animals [42].

## **3. Reverse zoonosis in other coronaviruses**

#### **3.1 SARS-CoV**

To probe into the proximal origin of SARS-CoV from china in 2002–2003, an epidemiological surveillance survey was conducted in the animal market of china and adjoining areas during the outbreak from wild, companion and livestock animals to check out their susceptibility for this virus and more importantly to devise means for the management and control of this first documented outbreak [43]. In this report, dogs and goats were tested negative while wild boars and cats were

*Epidemiology, Zoonotic and Reverse Zoonotic Potential of COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.98443*

found to be positive for the presence of SARS-CoV using viral detection assays [43]. Chen et al. conducted a field-based surveillance study on different animals through antibody and antigen-based tests. In this study, two pigs were tested positive for SARS-CoV antibodies while cats, dogs and cattle were tested negative. Based on sequence data analysis this study also suggests that transmission is from humanrelated SARS-CoV [44].

#### **3.2 MERS-CoV**

During the MERS-CoV outbreak very few reports appeared regarding the chances of human-animal transmission of this virus [45]. Kasem et al. conducted a study to check out the incidence of MERS-CoV infections in goat, sheep and cattle samples due to close contact with MERS-CoV positive individuals. In this study, all the tested samples were negative for MERS-CoV suggesting that no cross-species transmission was occurred [46]. El-Duah et al., conducted a field-based surveillance study on MERS-CoV by taking samples from sheep, pigs, goats, donkeys and cattle of the Ghana area. This study showed that none of the samples were found to be positive for the presence of MERS-CoV [47]. Kandeli et al. conducted an epidemiological surveillance study in Tunisia, Egypt and Senegal area from the field samples received from buffaloes, sheep, cattle, goats, mules, horses and donkeys using PCR and antibody detection kit. The results of this study revealed that both antibody detection tests and PCR were found to be positive for MERS-CoV in goats, sheep, cattle and donkeys. While PCR was negative in horses [48]. These reported studies suggest that transmission of MERS and SARS-CoVs occurred in humanswild, domestic and companion animals making the possibility of reverse zoonosis [49]. However, still it is not clear whether infected animals shed the virus and are involved in the disease transmission cycle.

### **4. Promoting public health**

There are at least 360,497 research studies worldwide, on diagnosis, treatment and prophylaxis of coronavirus that are being supported by NIH [50]. Combined efforts of global health organizations including the World Health Organization (WHO), Centers for Disease Control and Prevention (CDC) and many International, Regional and National NGOs, Government and private bodies are funding, supporting and helping approaches for public health. Food and Drug Administration (FDA) on the other hand, is rapidly analyzing and approving medicines and diagnostics for public use. Some major areas to be considered for tackling the current situation and developing roadmaps for future pandemics have been given in this section.

#### **4.1 Elucidating the concept of quarantine and isolation**

The COVID-19 crisis is continuously becoming a grave threat to the world and the number of cases is escalating globally. The present pandemic has redefined the human strategies against the control and prevention of this contagious agent responsible for disease outspread [4]. This virus is very lethal and contagious, and the WHO devised measures to control the infectivity and spread of the virus through quarantine and isolation. Some major myths and their busters associated with COVID-19 have been re-developed using WHO research-supported guidelines in **Figure 2**.

#### **Figure 2.**

*Major myths and their busters associated with COVID-19.*

Quarantine is separation and restricting the movement of people who have been exposed to a SARS-CoV-2 disease to see if they become sick, according to the CDC. Generally, this quarantine practice takes place at home or generalized facility or restricted movement areas specified for this practice. It can be imposed on individuals or communities constituting exposed individuals. Contact surveillance is required either passively or actively to monitor the individual if they develop the symptoms of the disease. Duration of the quarantine is based on a person's test results for disease or having experienced disease symptoms. If individual tests positive so after that, they are separated or isolated for treatment and monitoring purposes and if the individual is negative for diagnostic test and not showing any disease symptoms, then discharge from the quarantine center [8]. Monitoring must be done in case of quarantined person shows any of the disease symptoms. Government and other global authorities must implement border restriction if necessary, to overcome the spread of disease. The efficacy of this approach allows us to overcome the spread of disease with the early detection of diseased individuals.

Here the question arises after or during this "Quarantine session" what would be our approach if a person is positive for SARS-CoV-2. This question leads us to the term 'isolation'. The Center for Disease Control (CDC) has defined "Isolation" as the separation of sick people with any contagious disease from others who are not sick or at-risk population. This is important to flatten the disease curve so that fewer people become infected over a while. It can be explained as separation and restriction of movement of sick individuals who have a contagious disease, to prevent it from being transmitted to others. These measures are implemented to ensure the close monitoring of individuals with proper treatment and release after full recovery into the community or population to minimize or eliminate the risk of spread of this contagion. However, these individuals can still be monitored for weeks or two, to ensure they do not re-infect or develop severe symptoms after discharge from medical facilities.

#### **4.2 Measures for cleaning and disinfection**

From the sanitation/disinfection point of view, the Environment Protection Agency (EPA) recommends the use of List N disinfectants for use against COVID-19.

#### *Epidemiology, Zoonotic and Reverse Zoonotic Potential of COVID-19 DOI: http://dx.doi.org/10.5772/intechopen.98443*

Cleaning the surfaces before applying disinfectants and observing the appropriate contact time are important considerations for efficient utilization. Among the most accessible ones are sodium hypochlorite, hydrogen peroxide, and quaternary ammonium compounds with or without alcohol or phenols. The forms of these disinfectants may be solid, vapor, wipe, dilute-able, which could be easily used to disinfect surfaces. These compounds in their commercial preparations could be safely applied to disinfect keys, doorknobs/handles, slabs, floors, switchboards, equipment, keyboards, tables, cell phones, remote controls, cars, bikes, etc.

Case definitions and their importance to the general public may be well-communicated. Also, smart solutions for handling a large number of outdoor patients may be sought. Un-necessary exposure and increase in case of loads at emergency and intensive care units could be minimized using efficient telemedicine and consultation services. For laboratory testing facilities, it is important to consider biosafety guidelines of level-3 or above, owing to the transmissibility of the virus. Also, solid waste management should be very well planned and executed to spare the risk of dissemination to the general public [51].

#### **4.3 Management of COVID-19 patients**

It is important to consider the difference of COVID-19 with other prevailing respiratory viral infections e.g. influenza that involves nasopharyngeal or lower respiratory tract infections. Polymerase chain reaction (PCR) is necessary to confirm COVID-19. Further hospitalization of patients involves various factors inclusive of which are the age of patients (≈60 years old); patient having 40% allied morbid conditions like diabetes and cardiac diseases; children exposed, pregnant women with severe illness although there are mild symptoms so far in majority cases and the onset of symptoms and admission to ICU (9–10 days critical) as twothird of patients met criteria of acute respiratory distress syndrome (https://www. ecdc.europ a.eu/en/geographical-distribution-2019-ncov-cases).

The patient's care should be divided into four categories (1) Usual critical care, (2) Modification to usual critical care, (3) Facility planning, (4) COVID-19 specific consideration. Usual critical care will include: Conservative intravenous fluid strategies; Empirical early antibiotics for bacterial pneumonia; Consideration for early invasive ventilation; Lung protective ventilation strategies; Periodic prone position during mechanical ventilation; Consideration of extracorporeal membrane oxygenation. Modification to usual critical care involves: Admission of patients with the suspected disease to private rooms when possible; Use of medical face masks for symptomatic patients during assessment and transfer; Maintain a distance of at least 2-meter distance between patients; Caution when using high-flow nasal oxygen or non-invasive ventilation due to the risk of dispersion of aerosolized virus in the health care setup with poorly fitting masks; Clinicians involved with aerosol-generating procedures should use addition airborne precautions including N95 respirators and eye protection. COVID-19 Specific consideration; Ensure staff updated training in infection prevention and control including PPE; planning at local and regional levels for a potential surge in the need for critical care resources. The facility planning involves: Antiviral or immunomodulatory therapies are yet to be approved, so patients should be left on supportive or targeted therapies.

Three lines of treatments are generally followed (a) COVID-19 with mild acute respiratory distress syndrome (ARDS), (b) COVID-19 with mild ARDS, (c) Adjunct therapies. In the first case ventilator, supply while conservative fluid therapy, and empiric antibiotics are considered. Systematic corticosteroids are uncertain to be used on this occasion. In the second phase, short courses of systemic corticosteroids are considered. In adjunct/rescue therapy (3rd phase), antiviral,

chloroquine, and anti-interleukin 6 are uncertain to be used. The hypoxic conditions will be dealt with differently. It is important not to delay intubation if the situation is worsening. COVID-19 hypoxia travels to endotracheal intubation, then it is important to: follow endotracheal intubation, an expert should do intubation in the airway, N95/FFP-2 or equivalent personal protection equipment is necessary, infection control is followed, and staff in the room is minimally kept. In case if the situation is not getting better, endotracheal intubation should immediately be done.

## **4.4 Ensuring mental well-being**

Due to social distancing and remote working, maintenance of psychological well-being is pivotal. Social, electronic, print media could play a significant positive role in effectively communicating the risks while assuring mental health. Nonprofessional people who have a lot of apprehensions about the current pandemic may be discussing their concerns through telecommunication [52, 53]. Another important aspect of lockdown amidst outbreaks worldwide is the less privileged or daily wager community, migrants and internally displaced persons (IDPs). The anxiety due to uncertainty of fiscal matters may affect the mental health of the masses. Also, patients with other diseases, particularly those with chronic diseases may suffer a psychological breakdown. Apart from mental health issues, India has reported suicide due to fear of contracting COVID-19 [54]. It is, therefore, high time to spread hope, offer support and positivity all around.

Studies from one highly infected country *i.e.* Iran have revealed moderate to severe anxiety symptoms in apparently healthy citizens [55]. Suspected patients and cases, belonging to different age groups, may also require support for mental wellbeing amidst strict isolation. The healthcare workers in the frontline of combating the pandemic may need psychological/moral support, medical insurance and proper PPE. Government, NGOs, private stakeholders, media persons, celebrities, doctors and allied healthcare staff, scientists need to develop stronger communication with the public. These people can motivate people to adopt safety measures and promote public health safety.