**4. Discussion**

42 Non-Flavivirus Encephalitis

**Leishmaniasis** - In one dog (0.2%) adult parasites of the genus *Leishmania* were isolated from a spinal granuloma in an extra-dural site compressing the spinal cord. The animal presented with lymphadenopathy and paraparesis. The lesion consisted of epidural adipose tissue infiltrated by inflammatory cells, primarily composed of macrophages, granulocytes, plasma cells and lymphocytes. In the cytoplasm of the macrophages, there was a large number of small spherical structures due to uniform amastigote forms of *Leishmania* spp.

**Nocardiosis** - In one dog (0.2%) *Nocardia asteroides* was isolated. Macroscopically, there was an abscess-like lesion in the brain stem (Fig. 19). The dog showed fever, depression, difficulty walking and cranial nerve deficits. Histology revealed a piogranulomatous infiltrate consisting of neutrophils, macrophages and lymphocytes. Moreover, aggregates of club-shaped eosinophilic bacteria were found. The diagnosis was confirmed by bacterial

**Protothecosis** - In one dog (0.2%) achlorophilic algae were isolated. The reported signs were gastrointestinal bleeding with chronic diarrhoea, depression, anorexia, and difficulty walking. Histology showed granulomatous lesions in the neuroparenchyma and meninges consisting of numerous macrophages, lymphocytes, plasma cells and some eosinophils. In the granulomatous foci there were numerous round bodies of variable size surrounded by a PAS positive capsule (Fig. 20), which were identified as achlorophilic algae of the genus

**Rickettsiosis** - In one dog (0.2%) a microorganism of the genus *Rickettsia* spp. was isolated The reported signs were fever, depression, lethargy, tetraparesis, ataxia, hyperesthesia, vestibular syndrome, seizures, and petechiae in the mucous membranes. Microscopically, there were a nonsuppurative meningo-encephalitis and vasculitis characterized by lymphohistiocytic-type cells and plasma cells infiltrating the nervous tissue and meninges; necrotic areas were also observed (Fig. 21). In this case the diagnosis was confirmed by PCR.

> Fig. 20. Dog. *Prototheca:* numerous algae with a periodic acid-Schiff (PAS) -positive (arrows)

(PAS, 40x)

The diagnosis was confirmed by IHC (Fig. 18).

Fig. 19. Dog. *Nocardia asteroides:* abscessual

lesion in the brain stem.

*Prototheca*. The diagnosis was confirmed by electron microscopy.

culture.

In this study we investigated and analyzed the prevalence of neurological zoonoses in Italy in the decade between January 2000 and December 2009.A total of 16 different zoonotic diseases were diagnosed in 271 subjects of different animal species: 7 diseases were caused by parasites, 6 by bacteria, 2 by viruses and one case was due to achlorophilic algae. Farm animals were the species most affected; no diseases were found in birds or wild animals.

In 82 (23%) cases involving dogs and cats, the disease was of **"unknown aetiology"**. Such inflammatory diseases are prevalent in the dog, with a clear preference for breed and sometimes with family involvement. In our study, the species most affected was the dog (Graph.2). These disorders may, in fact, be triggered by an as yet unidentified pathogen and are therefore to be considered "potential zoonoses" (Schwab et al., 2007). The histological lesions were often suggestive of viral infections, but no causative agent has ever been isolated so far. Both rabies and canine distemper have been suggested as possible causes, presumably as expressions of atypical infection with these viruses (Summers et al., 1995). New diagnostic techniques may be useful to identify the pathogens responsible for these diseases and assess their possible zoonotic risk.

In the group of defined zoonoses, **Encephalitozoonosis**, a parasitic disease, was found in 86% of the rabbits investigated (110 out of 128) coming from different provinces in Piedmont. *Encephalitozoon cuniculi*, an obligate intracellular parasite of microsporidia, can affect a wide range of mammals: rabbit, dog, cat, horse, fox, and humans as well. In the rabbit it usually presents as a chronic asymptomatic disease; in other species, especially in immunocompromised humans, more severe infections can lead to death (Mertens et al., 1997). The transmission route is probably by ingestion of food or water contaminated by spores shed with the urine of infected rabbits. Some authors suggest a vertical transmission in lagomorphs (Giordano et al., 2005). The disease is more common in pet rabbits (37-68%) than in the wild (Kunzel et al., 2010). In our study, 104 affected rabbits belonged to the group of meat animals, and only 6 were pets. Cases of human infection by microsporidia have been reported worldwide, but the natural reservoirs and modes of transmission remain to be elucidated (Furuya, 2009). *E. cuniculi* ranks third among the microsporidia that affect humans, after *E. bieneusi* and *E. bowel,* and it is also the cause of rare disseminated microsporidiosis forms, as described in a recent case of a woman with AIDS in Italy (Tasone et al. , 2002). Many authors believe that the reported data are underestimated. Infection control in rabbit-breeding is very important and should not underestimate the risks to food-

Zoonoses Surveillance in Italy (2000-2009):

bacterial meningoencephalitis (Christodoulopoulos, 2007).

least five of which in Sardinia (Turtas et al., 1989).

antihelminthics (Scala et al. , 2006).

Investigation on Animals with Neurological Symptoms 45

vomiting, dizziness, ataxia, petechiae, muscle pain, paralysis and hearing loss; sometimes toxic forms may develop, with septic shock leading to death (Lun et al., 2007). The histological lesions in humans resemble those found in pigs. The infection typically affects men between 47 and 55 years of age and is considered an occupational condition or it may be linked to particular dietary habits of a population. Previous studies using serological tests and nasopharyngeal swabs have found low positivity to serotype 2 *S. suis* in high-risk individuals such as veterinarians and pig farmers, confirming the role of humans as healthy carriers. Its prevalence, duration and importance in the spread of the disease remains to be investigated (Elbers et al., 1999; Wertheim et al., 2009). In this population subset, it probably behaves as an opportunistic pathogen that causes symptomatic lesions in special circumstances such as stress, AIDS and cancer. In Western countries the disease occurs only sporadically; in Italy three cases have been reported to date: one in a subject with neoplasia (Manzin et al., 2007), the other two were due to occupational exposure in a farmer and a butcher (Perseghin et al., 1995; Camporese et al., 2007). Most likely, prevalence data are underestimated because in its early stages of infection the disease is very often mistaken for a simple flu that resolves with generic antibiotic therapy in immunocompetent individuals. The difficulty of determining the true incidence of infection on farms makes real risk assessment problematic. For this reason it is important to maintain biosafety standards on farms and to consider potential *S. suis* infection in cases presenting with neurological signs. In 17 (5%) ruminants we diagnosed **Coenurosis,** an infection caused by the larval stage of *Taenia multiceps*, a flatworm that develops in the intestine of canids (definitive hosts) which release hundreds of eggs with the faeces. Ruminants are the intermediate hosts, and the oncospheres often spread via the bloodstream in the body with possible CNS involvement. Normally, it is a solitary lesion involving one hemisphere and clinical signs vary depending on the location (Scott, 2000); during their migration the larvae may carry bacteria causing

Only very rarely are humans affected; most cases have been reported in the developing countries (Africa and Asia) with a high mortality rate (Crusz , 1948; Fain, 1956; Raper and Edockeray, 1956; Hermos et al., 1970). In Europe coenurosis in sheep has been reported in England, Ireland and France; in Italy it is mainly present in Sardinia, Latium, Puglia and Sicily. Man is considered an accidental dead-end host, where the infection most often develops in nervous, muscular and subcutaneous tissues. The first case of human coenurosis dates to 1913 (Brumpt, 1913); to date only a few hundred human cases have been described (Ing et al., 1998; Scala et al., 2006), some of which occurred in Italy ( Sabbatani et al., 2004), at

In the CNS the parasite is localized predominantly in the submeningeal cortex, creating cysts that grow and compress the surrounding tissue, but it has also been found within the cerebral parenchyma and the spinal cord (Ing et al., 1998; Beniflá et al., 2007). In the Italian cases the cysts were generally located in the cerebral hemispheres in an eccentric position, and more rarely in the cerebellum. Several factors may increase the spread of the disease in sheep: illegal slaughtering, high number of dogs on the farm, and inappropriate use of

**Colibacillosis** was confirmed in 15 calves, 1 sheep and 5 pigs (6% of total), all under 2 months of age. *E. coli* is a bacterium that usually lives in symbiosis with animals and humans, colonizing the gut, but some strains have developed virulence through the production of toxins or attachment factors. In particular, *E. coli* O157: H7 causes severe haemorrhagic enteritis and the haemolytic uremic syndrome (HUS), a disease that has

industry workers. While the disease in rabbits is potentially transmissible to humans, it represents a significant risk only for individuals with severe immune system impairment. Didier et al. have identified three *E. cuniculi* strains (I rabbit, II mouse, III dog) based on the number of repeated sequences in the ribosomal internal transcribed region. All confirmed cases in humans since 1994, related to immunocompromised patients, mainly HIVseropositive, were due exclusively to the dog and rabbit strain (Weber et al. , 1997; Kunzel et al. , 2010). It would therefore be interesting to analyse the cases described in this study with accurate biomolecular investigation in order to determine which strain they belong to.

**Listeriosis**, an infectious bacterial disease caused by *Listeria monocytogenes*, accounted for 13.5% of the zoonoses reported here. The infection is transmitted mainly through the consumption of contaminated food, but also by direct contact with infected animals. Compared to other food-borne diseases, it has a low incidence and high mortality rate in invasive neurological forms (20-30%) (Matassa, 2007). *L. monocytogenes* is a neurotropic bacterium and is more efficient than other neuroinvasive Gram-positive bacteria, including those of the Streptococcus genus, and it is one of the most common causes of bacterial meningitis in North America and Western Europe (Drevets et al., 2008).

Immunocompromised individuals, diabetics, alcoholics, the elderly and children can develop an invasive, often fatal form that is characterised by meningitis, septicaemia, endocarditis, pneumonia, arthritis, osteomyelitis and hepatitis; in pregnant women its can cause abortion (Matassa, 2007; Ramaswamy et al., 2007). In our study, as reported by other authors, we found a higher prevalence of the disease in ruminants as compared with other domestic mammals, suggesting that these species may constitute an important source of human infection, given the variety of foods derived from them (Oevermann et al., 2008). An epidemiological human study detected the presence of the bacterium in the stool of asymptomatic healthy subjects, but further studies are needed to understand the impact of these subjects on transmission (Drevets et al., 2008). Listeriosis is now considered an endemic infection in France and northern Europe (with peaks during the summer), unlike in Italy where it occurs sporadically (Bianchi et al., 1995). Recently reported humans cases in Italy are: Genoa (n=1) (Viscoli et al., 1991); Monza (n=2) (Bianchi et al., 1995); Milan (n=1) (Ponticelli et al., 2005); and Naples (n=1) (Reynaud et al. , 2007).

Among the pigs investigated in this study, **Streptococcosis** was diagnosed in 26 (7.5%) cases, all involving very young animals from fattening farms. The disease is caused by *Streptococcus suis*, a Gram positive bacterium, facultative anaerobic, which persists in the tonsils, sinuses, reproductive and digestive systems and can cause severe forms of meningitis, endocarditis and septicaemia. Piglets become infected after contact with colonized sows, which are healthy carriers; the infection can be transmitted to humans through direct contact with symptomatic animals or carriers or through ingestion of contaminated meat (Wertheim et al. , 2009).

Higher rates of infection are attributed to stressing factors, poor hygiene and/or concurrent disease. *S. suis* has been isolated from other animals such as ruminants, dogs, cats, horses and wild animals, and it is believed to be a commensal in the intestinal flora (Staats et al. , 1997). According to the polysaccharide capsule, 35 serotypes have been identified, including serotype 2 which is the main cause of infections in humans. The first human case was reported in 1968 in Denmark (Arends et al., 1988); since then, hundreds of cases have been reported around the world, many of which fatal (Lun et al., 2007; Wertheim et al., 2009). These multiple and severe outbreaks of *S. suis* in humans have raised public concern about its role as a zoonotic agent. Human infection manifests as a purulent meningitis, fever,

industry workers. While the disease in rabbits is potentially transmissible to humans, it represents a significant risk only for individuals with severe immune system impairment. Didier et al. have identified three *E. cuniculi* strains (I rabbit, II mouse, III dog) based on the number of repeated sequences in the ribosomal internal transcribed region. All confirmed cases in humans since 1994, related to immunocompromised patients, mainly HIVseropositive, were due exclusively to the dog and rabbit strain (Weber et al. , 1997; Kunzel et al. , 2010). It would therefore be interesting to analyse the cases described in this study with accurate biomolecular investigation in order to determine which strain they belong to. **Listeriosis**, an infectious bacterial disease caused by *Listeria monocytogenes*, accounted for 13.5% of the zoonoses reported here. The infection is transmitted mainly through the consumption of contaminated food, but also by direct contact with infected animals. Compared to other food-borne diseases, it has a low incidence and high mortality rate in invasive neurological forms (20-30%) (Matassa, 2007). *L. monocytogenes* is a neurotropic bacterium and is more efficient than other neuroinvasive Gram-positive bacteria, including those of the Streptococcus genus, and it is one of the most common causes of bacterial

Immunocompromised individuals, diabetics, alcoholics, the elderly and children can develop an invasive, often fatal form that is characterised by meningitis, septicaemia, endocarditis, pneumonia, arthritis, osteomyelitis and hepatitis; in pregnant women its can cause abortion (Matassa, 2007; Ramaswamy et al., 2007). In our study, as reported by other authors, we found a higher prevalence of the disease in ruminants as compared with other domestic mammals, suggesting that these species may constitute an important source of human infection, given the variety of foods derived from them (Oevermann et al., 2008). An epidemiological human study detected the presence of the bacterium in the stool of asymptomatic healthy subjects, but further studies are needed to understand the impact of these subjects on transmission (Drevets et al., 2008). Listeriosis is now considered an endemic infection in France and northern Europe (with peaks during the summer), unlike in Italy where it occurs sporadically (Bianchi et al., 1995). Recently reported humans cases in Italy are: Genoa (n=1) (Viscoli et al., 1991); Monza (n=2) (Bianchi et al., 1995); Milan (n=1)

Among the pigs investigated in this study, **Streptococcosis** was diagnosed in 26 (7.5%) cases, all involving very young animals from fattening farms. The disease is caused by *Streptococcus suis*, a Gram positive bacterium, facultative anaerobic, which persists in the tonsils, sinuses, reproductive and digestive systems and can cause severe forms of meningitis, endocarditis and septicaemia. Piglets become infected after contact with colonized sows, which are healthy carriers; the infection can be transmitted to humans through direct contact with symptomatic animals or carriers or through ingestion of

Higher rates of infection are attributed to stressing factors, poor hygiene and/or concurrent disease. *S. suis* has been isolated from other animals such as ruminants, dogs, cats, horses and wild animals, and it is believed to be a commensal in the intestinal flora (Staats et al. , 1997). According to the polysaccharide capsule, 35 serotypes have been identified, including serotype 2 which is the main cause of infections in humans. The first human case was reported in 1968 in Denmark (Arends et al., 1988); since then, hundreds of cases have been reported around the world, many of which fatal (Lun et al., 2007; Wertheim et al., 2009). These multiple and severe outbreaks of *S. suis* in humans have raised public concern about its role as a zoonotic agent. Human infection manifests as a purulent meningitis, fever,

meningitis in North America and Western Europe (Drevets et al., 2008).

(Ponticelli et al., 2005); and Naples (n=1) (Reynaud et al. , 2007).

contaminated meat (Wertheim et al. , 2009).

vomiting, dizziness, ataxia, petechiae, muscle pain, paralysis and hearing loss; sometimes toxic forms may develop, with septic shock leading to death (Lun et al., 2007). The histological lesions in humans resemble those found in pigs. The infection typically affects men between 47 and 55 years of age and is considered an occupational condition or it may be linked to particular dietary habits of a population. Previous studies using serological tests and nasopharyngeal swabs have found low positivity to serotype 2 *S. suis* in high-risk individuals such as veterinarians and pig farmers, confirming the role of humans as healthy carriers. Its prevalence, duration and importance in the spread of the disease remains to be investigated (Elbers et al., 1999; Wertheim et al., 2009). In this population subset, it probably behaves as an opportunistic pathogen that causes symptomatic lesions in special circumstances such as stress, AIDS and cancer. In Western countries the disease occurs only sporadically; in Italy three cases have been reported to date: one in a subject with neoplasia (Manzin et al., 2007), the other two were due to occupational exposure in a farmer and a butcher (Perseghin et al., 1995; Camporese et al., 2007). Most likely, prevalence data are underestimated because in its early stages of infection the disease is very often mistaken for a simple flu that resolves with generic antibiotic therapy in immunocompetent individuals. The difficulty of determining the true incidence of infection on farms makes real risk assessment problematic. For this reason it is important to maintain biosafety standards on farms and to consider potential *S. suis* infection in cases presenting with neurological signs.

In 17 (5%) ruminants we diagnosed **Coenurosis,** an infection caused by the larval stage of *Taenia multiceps*, a flatworm that develops in the intestine of canids (definitive hosts) which release hundreds of eggs with the faeces. Ruminants are the intermediate hosts, and the oncospheres often spread via the bloodstream in the body with possible CNS involvement. Normally, it is a solitary lesion involving one hemisphere and clinical signs vary depending on the location (Scott, 2000); during their migration the larvae may carry bacteria causing bacterial meningoencephalitis (Christodoulopoulos, 2007).

Only very rarely are humans affected; most cases have been reported in the developing countries (Africa and Asia) with a high mortality rate (Crusz , 1948; Fain, 1956; Raper and Edockeray, 1956; Hermos et al., 1970). In Europe coenurosis in sheep has been reported in England, Ireland and France; in Italy it is mainly present in Sardinia, Latium, Puglia and Sicily. Man is considered an accidental dead-end host, where the infection most often develops in nervous, muscular and subcutaneous tissues. The first case of human coenurosis dates to 1913 (Brumpt, 1913); to date only a few hundred human cases have been described (Ing et al., 1998; Scala et al., 2006), some of which occurred in Italy ( Sabbatani et al., 2004), at least five of which in Sardinia (Turtas et al., 1989).

In the CNS the parasite is localized predominantly in the submeningeal cortex, creating cysts that grow and compress the surrounding tissue, but it has also been found within the cerebral parenchyma and the spinal cord (Ing et al., 1998; Beniflá et al., 2007). In the Italian cases the cysts were generally located in the cerebral hemispheres in an eccentric position, and more rarely in the cerebellum. Several factors may increase the spread of the disease in sheep: illegal slaughtering, high number of dogs on the farm, and inappropriate use of antihelminthics (Scala et al. , 2006).

**Colibacillosis** was confirmed in 15 calves, 1 sheep and 5 pigs (6% of total), all under 2 months of age. *E. coli* is a bacterium that usually lives in symbiosis with animals and humans, colonizing the gut, but some strains have developed virulence through the production of toxins or attachment factors. In particular, *E. coli* O157: H7 causes severe haemorrhagic enteritis and the haemolytic uremic syndrome (HUS), a disease that has

Zoonoses Surveillance in Italy (2000-2009):

(Lobato et al., 2006).

the infection is possible.

coast of Liguria (Italy).

intermediate host (Dubey et al., 1996; Cantile et al. , 2002).

Investigation on Animals with Neurological Symptoms 47

retina), except for a solitary cyst in the eye muscle. The oocysts of the parasite have been isolated only from the faeces of dogs, which is considered to be both a definitive and

It can be transmitted both orally and vertically; in cattle the infection is feared especially because of severe economic losses due to its effects on reproduction, such as embryo absorption, abortion, return to heat, infertility and increased neonatal mortality with severe CNS infection in the calf (Dubey et al., 2003). In this study we observed lesions compatible with congenital or neonatal infection in calves, prevalently CNS lesions in adult dogs, and peripheral nervous system lesions (poliradiculoneuritis) in young subjects, as reported elsewhere (De Meerschman et al., 2005; Cantile et al., 2002). Although some authors have claimed no zoonotic role for *Neospora caninum* (Dubey , 2003), there is recent evidence that the protozoan may be responsible for neurological syndromes in immunocompromised HIV-seropositive individuals, causing opportunistic infections with *Toxoplasma gondii*

In 2% of cases **toxoplasmosis** was diagnosed**,** a parasitic infection caused by *Toxoplasma gondii*, an intracellular protozoa of the genus *Toxoplasma*, which affects several species of birds and mammals, including humans. The cat is the definitive host that spreads the oocysts into the environment through faeces, and other animals become infected through

In our study all cases presented with neurological signs, one of the dogs also showed a concomitant infection with *Neospora caninum*. In domestic animals the disease generally has a very low prevalence, but it can represent a real risk of transmission to humans directly or through food. In pigs the reproductive (still-born and premature births) and respiratory (pneumonia) systems are most often affected, only rarely have myocarditis and encephalitis been reported, with a mortality rate of over 50% (Dubey et al., 2008). Among poultry, toxoplasmosis is very rare, mainly occurring in family-owned farms (Goodwin et al., 1994), while symptomatic toxoplasmosis in the horse has not yet been reported to date, although

Sheep and goats have a high rate of abortion and still births, but there have been reports of lambs seven months of age with numerous cysts distributed throughout the carcass after slaughter (Dubey et al., 1989). In cats, as in humans, most infections are asymptomatic and rarely involve other organs or the CNS, as in kittens with congenital infection or immunodeficiency (FIV-FeLV) (Davidson et al., 1993). In dogs the disease is more severe in pups; the most frequent signs are pneumonia, hepatitis and encephalitis. The two dolphins analyzed in this study were from strandings that occurred between 2007 and 2009 along the

This fact is of considerable importance for studying the pathogen's epidemiology and for the safety of public health and cetaceans. Many authors believe that toxoplasma may have infected the sea through the discharge of sewage along the coastline or ship ballast waters

In this way, the dolphins may have been infected following ingestion of contaminated water and fish. The prevalence of this disease in animals is probably underestimated: the data are few and often not comparable because of differences in methods and the types of samples analyzed. One third of the human population is seropositive against *T. gondii* and this seroprevalence makes it an important agent of zoonosis. EC Directive 99/2003 provides that Member States report, depending its epidemiological status, all cases of disease and seropositivity detected, until a common control and surveillance system has been adopted.

contaminated by onboard rodents, cats, or contaminated soil.

contaminated food and water. Toxoplasma can cause subclinical or clinical infection.

recently raised concern for the health of infants. HUS affects mostly very young children and the elderly and is characterized by acute renal failure and haemolytic anaemia; the mortality rate is 5%.

A serious complication, more common in adults, is thrombotic thrombocytopenic purpura which produces neurological signs. The syndromes caused by *E. coli* O157: H7 verocytotoxin belong to both the food-borne diseases and zoonoses because ruminants, particularly cattle, are the main reservoir of the bacterium. Milk, dairy products and undercooked meat carry the infection; human transmission is also very common (Matassa, 2007).

In adult cattle the course of infection is asymptomatic, except for cases of necrotizing mastitis in dairy cows. In calves, as occurred in the cases we report here, very serious septicaemic forms may appear starting from the earliest days of life, whereas lambs and piglets are less likely to be affected. In Italy the first case of *E. coli* O157 infection was reported in 1988. Since notification of the disease is not required and all reports are made on a voluntary basis, the final data are certainly underestimated. The most affected regions are Lombardy, Piedmont, Latium and Puglia. As of 2004 there were 439 reported cases of HUS, the majority of which occurred in children between 0 and 6 years of age (80%) (Matassa , 2007).

**West Nile Disease (WNV),** a zoonoses caused by a flavivirus (RNAvirus), is transmitted by mosquitoes of the genus *Culex*. In this series it was found in 15 horses (4%) and probably it is understimated. Host amplifiers of the virus are migratory wild birds. The disease has seasonal trends and is more common in wetlands and marshy areas or near rivers, along the route of migratory birds (Castillo-Olivares et al. , 2004).

The virus can infect several species of vertebrates (mammals, birds and reptiles); humans and the horse are accidental dead-end hosts because viraemia is short and does not favour the spread. In the horse, the course of the disease is often asymptomatic or mildly symptomatic, rarely is it fatal. In our series, 10 horses had mild clinical signs and recovered, three were asymptomatic but sero-positive, and only two showed severe signs and were slaughtered. In humans, it appears as a influenza-like syndrome, and only 1% of cases are fatal.

WNV in Italy was first reported in Tuscany in 1998 (Cantile et al., 2000); it then reappeared 10 years later around the Po Delta in 2008, where the virus resulted phylogenetically very close to that found in Tuscany where the disease is now endemic. In July 2009, the infection recurred as in 2008 but then spread to other regions. Since 2002, the Ministry of Health has established a national surveillance plan, both active and passive, to control the introduction and circulation of the virus and insect vectors in areas considered at risk.

The viral agent may induce a variety of clinical signs depending on the subtype and its geographic distribution (Gubler, 2007; Zeller et al., 2004). In our cases, the course of disease was short, evolving toward rapid improvement; neurological symptoms may sometimes go unrecognized and show only nonspecific signs. Therefore, the presence of asymptomatic or mildly symptomatic horses could lead to underestimation of the spread of disease. The WNV is a notifiable zoonosis, potentially fatal for humans, especially in the elderly, children and immunocompromised; therefore, monitoring of virus circulation in the country and wetland reclamation are important for reducing insect vectors.

During our investigations, **Neosporosis** due to *Neospora caninum* was found in 15 (4%) subjects (4 cattle and 11 dogs). It is a protozoan of the family *Sarcocystidae*, whose life cycle is not yet clear; tachyzoites and cysts are the only stages of the cycle identified to date. The presence of cysts has been described only in nervous tissue (brain, spinal cord, nerves and

recently raised concern for the health of infants. HUS affects mostly very young children and the elderly and is characterized by acute renal failure and haemolytic anaemia; the

A serious complication, more common in adults, is thrombotic thrombocytopenic purpura which produces neurological signs. The syndromes caused by *E. coli* O157: H7 verocytotoxin belong to both the food-borne diseases and zoonoses because ruminants, particularly cattle, are the main reservoir of the bacterium. Milk, dairy products and undercooked meat carry

In adult cattle the course of infection is asymptomatic, except for cases of necrotizing mastitis in dairy cows. In calves, as occurred in the cases we report here, very serious septicaemic forms may appear starting from the earliest days of life, whereas lambs and piglets are less likely to be affected. In Italy the first case of *E. coli* O157 infection was reported in 1988. Since notification of the disease is not required and all reports are made on a voluntary basis, the final data are certainly underestimated. The most affected regions are Lombardy, Piedmont, Latium and Puglia. As of 2004 there were 439 reported cases of HUS, the majority of which occurred in children between 0 and 6 years of age (80%) (Matassa ,

**West Nile Disease (WNV),** a zoonoses caused by a flavivirus (RNAvirus), is transmitted by mosquitoes of the genus *Culex*. In this series it was found in 15 horses (4%) and probably it is understimated. Host amplifiers of the virus are migratory wild birds. The disease has seasonal trends and is more common in wetlands and marshy areas or near rivers, along the

The virus can infect several species of vertebrates (mammals, birds and reptiles); humans and the horse are accidental dead-end hosts because viraemia is short and does not favour the spread. In the horse, the course of the disease is often asymptomatic or mildly symptomatic, rarely is it fatal. In our series, 10 horses had mild clinical signs and recovered, three were asymptomatic but sero-positive, and only two showed severe signs and were slaughtered. In humans, it appears as a influenza-like syndrome, and only 1% of cases are

WNV in Italy was first reported in Tuscany in 1998 (Cantile et al., 2000); it then reappeared 10 years later around the Po Delta in 2008, where the virus resulted phylogenetically very close to that found in Tuscany where the disease is now endemic. In July 2009, the infection recurred as in 2008 but then spread to other regions. Since 2002, the Ministry of Health has established a national surveillance plan, both active and passive, to control the introduction

The viral agent may induce a variety of clinical signs depending on the subtype and its geographic distribution (Gubler, 2007; Zeller et al., 2004). In our cases, the course of disease was short, evolving toward rapid improvement; neurological symptoms may sometimes go unrecognized and show only nonspecific signs. Therefore, the presence of asymptomatic or mildly symptomatic horses could lead to underestimation of the spread of disease. The WNV is a notifiable zoonosis, potentially fatal for humans, especially in the elderly, children and immunocompromised; therefore, monitoring of virus circulation in the country and

During our investigations, **Neosporosis** due to *Neospora caninum* was found in 15 (4%) subjects (4 cattle and 11 dogs). It is a protozoan of the family *Sarcocystidae*, whose life cycle is not yet clear; tachyzoites and cysts are the only stages of the cycle identified to date. The presence of cysts has been described only in nervous tissue (brain, spinal cord, nerves and

and circulation of the virus and insect vectors in areas considered at risk.

wetland reclamation are important for reducing insect vectors.

the infection; human transmission is also very common (Matassa, 2007).

route of migratory birds (Castillo-Olivares et al. , 2004).

mortality rate is 5%.

2007).

fatal.

retina), except for a solitary cyst in the eye muscle. The oocysts of the parasite have been isolated only from the faeces of dogs, which is considered to be both a definitive and intermediate host (Dubey et al., 1996; Cantile et al. , 2002).

It can be transmitted both orally and vertically; in cattle the infection is feared especially because of severe economic losses due to its effects on reproduction, such as embryo absorption, abortion, return to heat, infertility and increased neonatal mortality with severe CNS infection in the calf (Dubey et al., 2003). In this study we observed lesions compatible with congenital or neonatal infection in calves, prevalently CNS lesions in adult dogs, and peripheral nervous system lesions (poliradiculoneuritis) in young subjects, as reported elsewhere (De Meerschman et al., 2005; Cantile et al., 2002). Although some authors have claimed no zoonotic role for *Neospora caninum* (Dubey , 2003), there is recent evidence that the protozoan may be responsible for neurological syndromes in immunocompromised HIV-seropositive individuals, causing opportunistic infections with *Toxoplasma gondii* (Lobato et al., 2006).

In 2% of cases **toxoplasmosis** was diagnosed**,** a parasitic infection caused by *Toxoplasma gondii*, an intracellular protozoa of the genus *Toxoplasma*, which affects several species of birds and mammals, including humans. The cat is the definitive host that spreads the oocysts into the environment through faeces, and other animals become infected through contaminated food and water. Toxoplasma can cause subclinical or clinical infection.

In our study all cases presented with neurological signs, one of the dogs also showed a concomitant infection with *Neospora caninum*. In domestic animals the disease generally has a very low prevalence, but it can represent a real risk of transmission to humans directly or through food. In pigs the reproductive (still-born and premature births) and respiratory (pneumonia) systems are most often affected, only rarely have myocarditis and encephalitis been reported, with a mortality rate of over 50% (Dubey et al., 2008). Among poultry, toxoplasmosis is very rare, mainly occurring in family-owned farms (Goodwin et al., 1994), while symptomatic toxoplasmosis in the horse has not yet been reported to date, although the infection is possible.

Sheep and goats have a high rate of abortion and still births, but there have been reports of lambs seven months of age with numerous cysts distributed throughout the carcass after slaughter (Dubey et al., 1989). In cats, as in humans, most infections are asymptomatic and rarely involve other organs or the CNS, as in kittens with congenital infection or immunodeficiency (FIV-FeLV) (Davidson et al., 1993). In dogs the disease is more severe in pups; the most frequent signs are pneumonia, hepatitis and encephalitis. The two dolphins analyzed in this study were from strandings that occurred between 2007 and 2009 along the coast of Liguria (Italy).

This fact is of considerable importance for studying the pathogen's epidemiology and for the safety of public health and cetaceans. Many authors believe that toxoplasma may have infected the sea through the discharge of sewage along the coastline or ship ballast waters contaminated by onboard rodents, cats, or contaminated soil.

In this way, the dolphins may have been infected following ingestion of contaminated water and fish. The prevalence of this disease in animals is probably underestimated: the data are few and often not comparable because of differences in methods and the types of samples analyzed. One third of the human population is seropositive against *T. gondii* and this seroprevalence makes it an important agent of zoonosis. EC Directive 99/2003 provides that Member States report, depending its epidemiological status, all cases of disease and seropositivity detected, until a common control and surveillance system has been adopted.

Zoonoses Surveillance in Italy (2000-2009):

early stage of disease.

disorders (Ludwig et al., 1997; Richt et al., 2001).

Investigation on Animals with Neurological Symptoms 49

affects the gray matter of the CNS. The wide spectrum of susceptible species also includes human beings in which it is still uncertain whether the virus is responsible for the development of some forms of nervous disorders. Recent studies have shown a high prevalence of specific antibodies in the serum and/or CSF of patients with neuropsychiatric

**Chlamydiosis** is caused by an obligate intracellular organism of the genus *Chlamydia* that can infect many birds and mammals, including humans. Transmission can occur by digestive, respiratory, venereal and congenital routes, whereas aborted foetuses from infected animals and animals with subclinical infections cause the pathogen to spread into the environment (Nietfeld, 2001; McCafferty, 1990). *Chlamydiae* are primary causes of pneumonia, polyarthritis, conjunctivitis and encephalitis, and sheep is the species most affected. In the cow the infection usually manifests in a generalized form affecting mainly foetuses (vertical transmission) and calves under 6 months of age (Storz et al., 1971). In bibliography have been described cases of sporadic encephalitis in adult cattle with aetiology unclear ; often Chlamydia infection and viruses has been reported as cause of this disease. (Theil et al.., 1998). In our series a chlamydial infection was detected in only one case, a 7-year-old cow with less severe neuropathological lesions than those described previously (Piercy et al., 1999; Storz et al., 1971); probably this animal could have been at an

Some authors have reported marked seropositivity in people in close contact with animals infected by Chlamydia, confirming the hypothesis that animals can be a source of infection for humans (Schachter et al., 1973; Storz et al., 1971). In humans the disease can appear with unapparent forms or with pneumonia, septicaemia and death; sometimes therapy-resistant conjunctivitis can occur. Because of the pathogen's wide diffusion and the few cases reported in humans, many others may not have been recognized (Shewen, 1980). However, cases have been reported of human chlamydiosis transmitted from sheep (Roberts et al., 1967), cattle (Sarateanu et al., 1961) and cats (Schachter et al., 1969; Ostler et al., 1969), or due to laboratory accidents while handling infected samples (Barwell, 1955; Vulgar et al. , 1974). **Leishmaniasis** is a parasitic disease caused in the Mediterranean by *L. infantum*, a protozoan of the genus *Leishmania*, an obligate intracellular parasite of macrophages and dendritic cells of the skin. It is transmitted by the bite of bloodsucking vectors of the genus *Phlebotomus*; it affects several species, particularly dogs and humans. The disease can be subacute and follow a chronic course with variable symptoms; in more severe cases the animal often dies from renal failure. Other affected organs are those of the reticuloendothelial system (lymph nodes, spleen, liver and bone marrow) and sometimes associated with polymyositis and arthrosynovitis (Matassa, 2007). The CNS is a rather unusual target of the parasite, but some cases have been reported in both dogs and humans (Vinuelas et al., 2001; Melo et al., 2009). In humans the disease is always severe, especially in the immunocompromised, such as HIV-seropitive individuals or transplant recipients. Sometimes, the symptoms are very severe with loss of sensation in the lower limbs, deafness, multiple paralysis of cranial nerve and axonal demyelination and degeneration (Hashim et al., 1995). In recent decades, various climatic factors have changed the normal areal of carriers and new leishmaniasis outbreaks have occurred in areas that were previously considered free, like the foothills of the Alps. Since 1995, outbreaks have been reported in Liguria, Tuscany, Lombardy, Piedmont and

Valle D'Aosta, and rarely also in Veneto, Trentino and Friuli (Matassa, 2007).

**Nocardiosis** is a bacterial disease caused by the Gram-positive bacterium *Nocardia asteroides*. Usually, the infection arises in the lung following inhalation of spores; CNS involvement

**Cryptococcosis** is an occasional systemic infection caused by *Cryptococcus neoformans*, an opportunistic yeast-like fungus of the genus *Cryptococcus*. This disease is rare among domestic animals except dogs and cats; in fact, these two species were the only ones involved in our study. The most frequently isolated species are *C. neoformans* (serotype AD) and *C. gattii* (serotype BC). The latter are considered the most aggressive serotype (Lacaze et al., 2002). Pigeons are considered the main vector because their high body temperature protects them from disease. In immunocompetent birds cryptococcosis remains confined to the upper airways and sinuses because it prefers temperatures below 40 °C. The cat is the species most often affected and the most common route of infection is through the respiratory system; often, as in dogs, it also involves the eye and the CNS (15% of cases) (Berthelin et al., 1994). In natural conditions the immune response in humans provides resistance to infection, but in 85% of cases cryptococcosis affects the lungs and the CNS in debilitated patients within settings such as AIDS, tuberculosis, leukaemia and lymphoma (Summers et al., 1995; Kerl, 2003; Chuck et al., 1989; Nagrajan et al., 2000; Fernandes et al., 2000). *C. gattii* has also been reported in association with skin lesions in patients undergoing prolonged corticosteroid therapy (Bellissimo-Rodrigues et al., 2010). Even in the cat prolonged corticosteroid use may aggravate the infection, but there are no data demonstrating whether immunosuppressive diseases such as FIV and FeLV may predispose individuals to cryptococcosis (Gerds-Grogan et al., 1997; Kerl, 2003). In our cases, histopathological lesions were similar to those described previously (Summers et al., 1995). The cats showed low to moderate nonsuppurative inflammatory response, despite wide dissemination of the cyst both in the meninges and the neuroparenchyma; the response in the dogs was much more cellular, with granulomatous lesions and epithelioid macrophages, lymphocytes and plasma cells in the brain and meninges.

*Halicephalobus gingivalis*, a nematode which lives in soil and decaying plant material, was identified in two case of equine meningo-encephalitis. The parasite is pathogenic in the horse and man and infection occurs through skin injuries with spreading of the worm to other organs, including the CNS. In our cases *H. gingivalis* was found in two horses, one from Tuscany and the other from Veneto. In the horse the pathology is characterized by disseminated granulomas in the skin and other organs; granulomatous encephalomyelitis is often reported. In humans the infection is always fatal and affects the CNS (Gardiner et al., 1981). In our series only the CNS was involved and the histological lesions were similar to those described elsewhere (Mandrioli et al., 2002). The parasite was first fully described by Stefanski in 1954, from a gingival granuloma in a horse in Poland (Anderson et al., 1982). Four cases in horses have been reported so far in Italy, all native animals which apparently had never left the country, confirming the presence of the parasite in Italy (Cantile et al., 1997; Mandrioli et al., 2002). Worldwide, only three humans cases with fatal outcome have been reported, in all of which the CNS was involved (Akagami et al., 2007; Gardiner et al., 1981; Shadduck et al., 1979), but no human case has been reported in Italy so far.

**Borna disease** was diagnosed in 2 sheep. This infectious disease caused by an RNA virus of the Bornaviridae family affects domestic and wild animals, mainly horses and sheeps. In these species Borna virus has a low morbidity, but subclinical persistent infection is probably common (Summer 1995). The virus is transmitted through salivary, nasal and conjunctival secretions, water and contaminated food. Il virus is highly neurotropic, with constant replication in the CNS and spinal cord; however, it can spread throughout the body in infants or the immunocompromised. The disease is characterized, as in our cases, by a nonsuppurative meningo-encephalomyelitis, with infiltration of mononuclear cells that

**Cryptococcosis** is an occasional systemic infection caused by *Cryptococcus neoformans*, an opportunistic yeast-like fungus of the genus *Cryptococcus*. This disease is rare among domestic animals except dogs and cats; in fact, these two species were the only ones involved in our study. The most frequently isolated species are *C. neoformans* (serotype AD) and *C. gattii* (serotype BC). The latter are considered the most aggressive serotype (Lacaze et al., 2002). Pigeons are considered the main vector because their high body temperature protects them from disease. In immunocompetent birds cryptococcosis remains confined to the upper airways and sinuses because it prefers temperatures below 40 °C. The cat is the species most often affected and the most common route of infection is through the respiratory system; often, as in dogs, it also involves the eye and the CNS (15% of cases) (Berthelin et al., 1994). In natural conditions the immune response in humans provides resistance to infection, but in 85% of cases cryptococcosis affects the lungs and the CNS in debilitated patients within settings such as AIDS, tuberculosis, leukaemia and lymphoma (Summers et al., 1995; Kerl, 2003; Chuck et al., 1989; Nagrajan et al., 2000; Fernandes et al., 2000). *C. gattii* has also been reported in association with skin lesions in patients undergoing prolonged corticosteroid therapy (Bellissimo-Rodrigues et al., 2010). Even in the cat prolonged corticosteroid use may aggravate the infection, but there are no data demonstrating whether immunosuppressive diseases such as FIV and FeLV may predispose individuals to cryptococcosis (Gerds-Grogan et al., 1997; Kerl, 2003). In our cases, histopathological lesions were similar to those described previously (Summers et al., 1995). The cats showed low to moderate nonsuppurative inflammatory response, despite wide dissemination of the cyst both in the meninges and the neuroparenchyma; the response in the dogs was much more cellular, with granulomatous lesions and epithelioid macrophages,

*Halicephalobus gingivalis*, a nematode which lives in soil and decaying plant material, was identified in two case of equine meningo-encephalitis. The parasite is pathogenic in the horse and man and infection occurs through skin injuries with spreading of the worm to other organs, including the CNS. In our cases *H. gingivalis* was found in two horses, one from Tuscany and the other from Veneto. In the horse the pathology is characterized by disseminated granulomas in the skin and other organs; granulomatous encephalomyelitis is often reported. In humans the infection is always fatal and affects the CNS (Gardiner et al., 1981). In our series only the CNS was involved and the histological lesions were similar to those described elsewhere (Mandrioli et al., 2002). The parasite was first fully described by Stefanski in 1954, from a gingival granuloma in a horse in Poland (Anderson et al., 1982). Four cases in horses have been reported so far in Italy, all native animals which apparently had never left the country, confirming the presence of the parasite in Italy (Cantile et al., 1997; Mandrioli et al., 2002). Worldwide, only three humans cases with fatal outcome have been reported, in all of which the CNS was involved (Akagami et al., 2007; Gardiner et al.,

1981; Shadduck et al., 1979), but no human case has been reported in Italy so far.

**Borna disease** was diagnosed in 2 sheep. This infectious disease caused by an RNA virus of the Bornaviridae family affects domestic and wild animals, mainly horses and sheeps. In these species Borna virus has a low morbidity, but subclinical persistent infection is probably common (Summer 1995). The virus is transmitted through salivary, nasal and conjunctival secretions, water and contaminated food. Il virus is highly neurotropic, with constant replication in the CNS and spinal cord; however, it can spread throughout the body in infants or the immunocompromised. The disease is characterized, as in our cases, by a nonsuppurative meningo-encephalomyelitis, with infiltration of mononuclear cells that

lymphocytes and plasma cells in the brain and meninges.

affects the gray matter of the CNS. The wide spectrum of susceptible species also includes human beings in which it is still uncertain whether the virus is responsible for the development of some forms of nervous disorders. Recent studies have shown a high prevalence of specific antibodies in the serum and/or CSF of patients with neuropsychiatric disorders (Ludwig et al., 1997; Richt et al., 2001).

**Chlamydiosis** is caused by an obligate intracellular organism of the genus *Chlamydia* that can infect many birds and mammals, including humans. Transmission can occur by digestive, respiratory, venereal and congenital routes, whereas aborted foetuses from infected animals and animals with subclinical infections cause the pathogen to spread into the environment (Nietfeld, 2001; McCafferty, 1990). *Chlamydiae* are primary causes of pneumonia, polyarthritis, conjunctivitis and encephalitis, and sheep is the species most affected. In the cow the infection usually manifests in a generalized form affecting mainly foetuses (vertical transmission) and calves under 6 months of age (Storz et al., 1971). In bibliography have been described cases of sporadic encephalitis in adult cattle with aetiology unclear ; often Chlamydia infection and viruses has been reported as cause of this disease. (Theil et al.., 1998). In our series a chlamydial infection was detected in only one case, a 7-year-old cow with less severe neuropathological lesions than those described previously (Piercy et al., 1999; Storz et al., 1971); probably this animal could have been at an early stage of disease.

Some authors have reported marked seropositivity in people in close contact with animals infected by Chlamydia, confirming the hypothesis that animals can be a source of infection for humans (Schachter et al., 1973; Storz et al., 1971). In humans the disease can appear with unapparent forms or with pneumonia, septicaemia and death; sometimes therapy-resistant conjunctivitis can occur. Because of the pathogen's wide diffusion and the few cases reported in humans, many others may not have been recognized (Shewen, 1980). However, cases have been reported of human chlamydiosis transmitted from sheep (Roberts et al., 1967), cattle (Sarateanu et al., 1961) and cats (Schachter et al., 1969; Ostler et al., 1969), or due to laboratory accidents while handling infected samples (Barwell, 1955; Vulgar et al. , 1974).

**Leishmaniasis** is a parasitic disease caused in the Mediterranean by *L. infantum*, a protozoan of the genus *Leishmania*, an obligate intracellular parasite of macrophages and dendritic cells of the skin. It is transmitted by the bite of bloodsucking vectors of the genus *Phlebotomus*; it affects several species, particularly dogs and humans. The disease can be subacute and follow a chronic course with variable symptoms; in more severe cases the animal often dies from renal failure. Other affected organs are those of the reticuloendothelial system (lymph nodes, spleen, liver and bone marrow) and sometimes associated with polymyositis and arthrosynovitis (Matassa, 2007). The CNS is a rather unusual target of the parasite, but some cases have been reported in both dogs and humans (Vinuelas et al., 2001; Melo et al., 2009).

In humans the disease is always severe, especially in the immunocompromised, such as HIV-seropitive individuals or transplant recipients. Sometimes, the symptoms are very severe with loss of sensation in the lower limbs, deafness, multiple paralysis of cranial nerve and axonal demyelination and degeneration (Hashim et al., 1995). In recent decades, various climatic factors have changed the normal areal of carriers and new leishmaniasis outbreaks have occurred in areas that were previously considered free, like the foothills of the Alps. Since 1995, outbreaks have been reported in Liguria, Tuscany, Lombardy, Piedmont and Valle D'Aosta, and rarely also in Veneto, Trentino and Friuli (Matassa, 2007).

**Nocardiosis** is a bacterial disease caused by the Gram-positive bacterium *Nocardia asteroides*. Usually, the infection arises in the lung following inhalation of spores; CNS involvement

Zoonoses Surveillance in Italy (2000-2009):

Investigation on Animals with Neurological Symptoms 51

inflammation not classified and potentially constituting a health risk. The results of this research show that animals can be an important reservoir for agents of neurozoonoses; therefore, monitoring of neurological diseases of animals should be designed to reduce the number of infections in humans and may be a good model for the study of therapeutic strategies in cases of infection. Neurozoonosis monitoring in animals may also allow for the

From available literature data it is clear that the population segments most affected by zoonoses are children, the elderly and the immunocompromised, particularly those with AIDS and chemotherapy or transplant recipients. The best way to protect these at-risk groups is through prevention, which can only be done through a national surveillance network. Further studies should also aim to identify the pathogenesis and the possible etiologic agents of idiopathic inflammatory disease or those of "unknown aetiology" to

We thank Debora Corbellini, Caterina Lucia Florio, Paola Gazzuola, Tiziana Avanzato and

The authors declare that this study was carried out under the following Research Projects: IZSPLV 14/06; IZSPLV 13/08 ; Monitoring Project "A new strategy to deal with the TSE in Italy" funded by the Ministry of Health; Research Project "Monitoring of Streptococcus suis

Akagami, M.; Shibahara, T.; Yoshiga, T. et al. (2007). Granulomatous nephritis and

Anderson, R.C.; Bain, O. (1982). Keys to genera of the superfamilies Rhabditoidea,

Asjo, B.; Kruse, H. (2007). Zoonoses in the Emergence of Human viral diseases. *Emerging*

Barwell, C.F. (1955). Laboratory infection in man with virus of enzootic abortion of ewes.

Bellissimo-Rodrigues, F.; Baciotti, M.; Zanatto, M.P.; Silva, J.O.; Martins, M.A.; Martinez, R.

Beninati, T.; Lo, N.; Noda, H.; Esposito, F.; Rizzoli, A.; Favia, G..; Genchi, C. (2002). First

(2010). Cutaneus cryptococcosis due to Cryptococcus gattii in a patient on chronic corticotherapy. *Revista da Sociedade Brasileira de Medicina Tropical*, 43(2): 211-212 Benifla, M.; Barrelly, R.; Shelef, I.; El-On, J.; Cohen, A.; Cagnano, E. (2007). Huge

hemispheric intraparenchymal cyst caused by Taenia multiceps in a child. *J.*

detection of Spotted Fever Group Rickettsiae in Ixodes ricinus from Italy. *Emerging*

Nematode *Parasites of Vertebrates*, Commonwealth Agricultural Bureaux Arends, JP.; Zanen, H.C. (1988). Meningitis caused by Streptococcus suis in humans. *Rev.*

meningoencephalitis caused by Halicephalobus gingivalis in a pony gelding. *J Med*

Dioctophymatoidea, Trichinelloidea and Muspiceoidea p 1-8 in: CIH Keys to the

infections in pigs fattening farm " funded by Cassa di Risparmio di Cuneo.

surveillance of possible emerging or re-emerging infectious agents.

exclude the likelihood of potentially zoonotic agents.

Saverio Bessone for their technical assistance.

*Vet Sci*, 69, 1187-1190

*Infect Dis*, 10: 131-137

*Lacent 2*, 1369-1370

*Viruses in Human Population*, 15-41

*Infection Diseases,* 8: 983-986

*Neurosurg*. (6 suppl. Pediatrics), 107: 511-514

**6. Acknowledgment**

**7. References**

occurs in 13% of cases (Bosnic et al. , 2010; Cianfoni et al., 2010). As highlighted in our case, *Nocardia* generally causes solitary brain lesions, but cases have also been reported of multiple abscesses, which are very rare in dogs (Smith et al., 2007; Munana, 1996; Kaplan, 1985). The disease has been reported in the brain of immunocompromised dogs and humans due to concomitant diseases (systemic lupus erythematosus or AIDS) or immunosuppressive therapy (cyclosporine, chemotherapy) (Smith et al., 2007). Brain infections can occur after penetrating trauma, due to extension of infection to adjacent structures (internal ear and dental root) or via the bloodstream (Dow et al. , 1988; Munana, 1996). Drug therapy is not always effective.

**Protothecosis** is caused by achlorophil algae of the genus *Prototheca*, including five species widely distributed in the environment, especially in organic matter. It is considered an emerging disease in humans and animals. Infection occurs primarily through skin lesions in contact with contaminated water, but the algae can colonize the skin, even the nails, the respiratory and digestive systems. In cattle the algae cause clinical and subclinical mastitis refractory to treatment, with high economic losses and potential risk to public health; systemic forms are rare (Marques et al., 2006). In dogs and cats it can present both as localized cutaneous and systemic forms (Ginel et al., 1997; Dillberger et al., 1988; Krohne, 2000); respiratory and cutaneous forms have also been reported in the goat (Macedo et al., 2008).

Systemic protothecosis involving the eye and the CNS have been reported in dogs (Stenner et al., 2007); in our case only cerebral lesions were found. In humans the disease has low pathogenicity in immunocompetent subjects, with local indolent skin lesions, whereas in the immunocompromised it may occur as a scattered form and not infrequently associated with such other pathogens as *Candida*, *Staphylococcus aureus*, herpes simplex, and *Cryptococcus* spp. (Lass-Florl et al. , 2007).

**Rickettsiosis** was diagnosed in only one subject in this series; the disease is caused by an obligate intracellular organism considered to be an intermediate form between a virus and a bacterium of the genus *Rickettsiae*. The disease is a tick-borne zoonosis. Many *Rickettsiae* cause diseases involving the CNS in animals and humans (Parola et al., 2005), one of the most important is *R. conorii* transmitted by the dog tick (*Rhipicephalus sanguineus*) that causes Mediterranean spotted fever in humans. In recent years, the number of cases of rickettsiosis in dogs and humans has increased significantly in Italy, in conjunction with climate change (temperature and rainfall) and environmental (human-dog contact) factors that allow for prolonged survival of the carrier. The most affected regions are Sicily, Sardinia, Latium, Liguria and Piedmont (Garavelli et al., 1990; Cocco et al., 2003; Cascio et al., 2006; Beninati et al., 2002).

Given the wide diffusion of the vector and the pathogen in Italy, the incidence of rickettsiosis was surprisingly low in this series, which may have been due to the fact that many cases go undiagnosed or are asymptomatic without showing neurological signs and are not recognized. Vector control is an indispensable means to prevent diseases transmitted by ticks; rickettsioses should therefore always be included in the differential diagnosis of cases with neurological signs, especially following an arthropod bite.