**Tropical Diseases Due to Protozoa and Helminths**

136 Current Topics in Tropical Medicine

Zeller H.G. Dengue, arbovirus and migrations in the Indian Ocean. Bull Soc Pathol Exot,

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1998; 91: 56-60

**10**

*USA*

**Malaria Chemoprophylaxis for the**

 **International Traveler, Current**

*Uniformed Services University of the Health Sciences*

Ross Parker and Kevin Leary

**Options and Future Possibilities**

Malaria remains the most important parasitic disease in the world, causing approximately 250 million infections annually and one million deaths, mostly in African children. International travelers are at risk of developing malaria when visiting endemic regions, and account for an estimated 30,000 cases of malaria annually (World Health Organization, 2011). The parasite is transmitted by the female Anopheles mosquito and is caused by four protozoa of the *Plasmodium* genus *(P. falciparum, P. vivax, P. ovale* and *P. malaria)*. *P. falciparum* causes the most significant disease burden with the highest morbidity and mortality. In addition to mosquito control and avoidance measures, chemoprophylaxis remains a critical component for preventing malaria infection in non-

Addressing malaria chemoprophylaxis for the international traveler can be challenging. In addition to patient-specific factors, the provider must consider a wide array of other variables, such as the predicted risk of malaria associated with the destination, type and duration of exposure during the trip as well, as the profile of the drug being prescribed. Seasonal, geographic, and climate are among the environmental variables that should be addressed to appreciate risk of malaria transmission. There can be upwards of a 200-fold difference in relative risk of contracting malaria depending on geographic variables for the international traveler, with sub-Saharan Africa conferring the greatest risk (Leder et al., 2004; Freedman, 2008). The traveler's accommodations, anticipated understanding and adherence to mosquito avoidance and control measures, chemoprophylaxis and access to appropriate medical care

Patient-specific variables can also present challenges to the provider. Pregnant, nursing and pediatric travelers present unique considerations when determining the most appropriate chemoprophylactic regimen. Pregnant patients incur a much higher risk of mortality and morbidity from malaria than non-pregnant travelers, and require extensive counselling on the risks and benefits of proposed travel to areas at risk of transmission. Emerging parasite drug resistance patterns, side-effect profiles, both long and short term, contraindications and poor adherence are additional challenges that need to be considered when selecting an appropriate antimalarial chemoprophylactic agent. In addition, how to address chemoprophylaxis in long-term travelers, generally defined as travel greater than six-

contribute to the risk of morbidity and mortality associated with malaria.

**1. Introduction**

immune travelers.


**7. Bioassay**

At this point of the bioassay with the most active pure compound, the methodology chosen should be definitive and not the whole array of test for the particular disease of interest.

#### **7.1. The experimental model of a disease**

The experimental model of a disease aids not only the understanding of the pathophysiology of the disease but also the development of drugs for its treatment [30]. In the bias of the relaying researcher, the several animal models existing for studying diabetes mellitus (DM) are treated below. And with this knowledge, the reader can deduct relevant idea to use in her/his field of interest. It should be noted that certain disease state may have more than one model for scientific study. And the choice of test may be the use of more than one model which would be sufficient to satisfy the general entity of the pathophysiology of the disease state.

#### *7.1.1 Normoglycemic animal model*

Normal healthy animals are used for testing potential oral hypoglycemic agents. This method allows for the effect of the drug to be tested in the animal with an intact pancreatic activity [30]. This is a valid screening method often used in addition to diabetic animal models [31]. This means that using this model alone would not be sufficient for the study of this disease of interest.

#### *7.1.2 Oral glucose loading animal model*

In this method the animals are fasted overnight, then an oral glucose load (1.0–2.5 g/kg body weight) is given, and blood glucose level is monitored. This method is often referred to as physiological induction of DM because there is no damage to the pancreas even with raised blood glucose level. And in the clinical setting, it is referred to as oral glucose tolerance test (OGTT), used for diagnosis of borderline DM [30].