Common Parasitic Zoonoses Research Articles

Prevalence of antibodies against Toxoplasma gondii and Neospora caninum in moose ( Alces alces) and roe deer ( Capreolus capreolus) in Sweden

Toxoplasma gondii and Neospora caninum are two coccidian parasites with a worldwide distribution. T. gondii is one of the more common parasitic zoonoses in the world and in young children and immunocompromised persons, infection can lead to severe disease and death. N. caninum is an important cause of abortions in cattle. Wildlife have been identified as reservoirs and transmitters for both parasites. The purpose of this study was to investigate the seroprevalences of T. gondii, and N. caninum in moose ( Alces alces), and roe deer ( Capreolus capreolus) in Sweden. Blood samples were collected from 417 moose during 2000–2005 and from 199 roe deer during 1990–2007. The samples were investigated for presence of antibodies by a T. gondii direct agglutination test and a N. caninum iscom ELISA. Because the iscom ELISA has not been validated for moose or roe deer, sera that gave a positive result were further investigated by immunoblot analysis to verify presence of antibodies. Antibodies to T. gondii were detected in 85 (20%) and 68 (34%) moose and roe deer sera, respectively. In moose the seroprevalence was higher in south and central Sweden than in the north, whereas there was no difference between the regions for roe deer. Adult moose and roe deer had higher odds of being seropositive than young animals but there were no difference in seroprevalence between males and females. One roe deer was positive by immunoblotting and was regarded as N. caninum positive, whereas all moose sera were negative. The results show that T. gondii infection is widely spread in the Swedish moose and roe deer populations. Precautions should therefore be taken when handling internal organs and carcasses of harvested cervids. Proper handling and cooking of game meat also is important to prevent toxoplasmosis in humans.

Human toxoplasmosis and the role of veterinary clinicians

Human toxoplasmosis is one of the most common parasitic zoonoses worldwide. As for other zoonoses, veterinarians play an important role in the education of the human population regarding the risk of infection. Knowledge of the parasite's biological charateristics, life cycle and trasmission routes is necessary to correctly illustrate real risk factors to those people who have direct contact with animals (farm animals, pets, etc). Toxoplasmosis represents one of the more difficult “educational” challenges for small animal clinicians. Veterinarians are often faced with the need to explain to their clients that it is not necessary, for example, to give away one's cat during pregnancy and that if they follow a few very simple “rules”, living with their pets need not represent any risk for infection with Toxoplasma gondii. Cats are the definitive host of T. gondii; they are the only animals that pass oocysts in their feces. They become infected by eating infected rodents, birds, or other small animals. Once oocysts are shed, they require 1 to 5 days to sporulate and become infective. Cats pass oocysts for only 2 to 3 weeks following primary infection. Mature cats are less likely to shed Toxoplasma if they have been previously infected. Litter box hygiene is the main precaution in preventing transmission of toxoplasmosis from pet cats 1. A Toxoplasma-infected cat that is shedding the parasite in its feces (approximately 2% of the cat population at any given time) contaminates the litter box. If the cat is allowed outside, it can contaminate the soil or water in the environment as well. Litter boxes should be cleaned daily and not placed in kitchen or dining areas. Pregnant women should avoid changing cat litter if possible. If no one else can perform the task, they should wear disposable gloves and wash their hands thoroughly with soap and water afterwards. Direct contact with cats is unlikely to result in transmission of toxoplasmosis because most cats do not leave feces on their fur for the 1 to 5 days required for oocyst sporulation. Interestingly, cat ownership has not been associated with an increase in Toxoplasma seroconversion among HIV-infected persons 2. Along with their pregnant owners, cats should also avoid becoming infected with T. gondii. Therefore, cats should not be allowed to hunt and should not be fed raw or undercooked meat. This is extremely important, in that raw or undercooked meat is one of the most common routes of transmission for T. gondii, for both humans and animals 3. Pregnant women at risk must not only avoid eating raw meat, but should also wash their hands thouroughly after handling it. Because outdoor cats frequently defecate in gardens and T. gondii oocysts may survive for months under appropriate conditions, pregnant women should wear gloves when gardening or working with soil and should immediately wash their hands afterwards. They should also avoid eating unwashed fruits or vegetables from a garden. Finally, because young cats more often eliminate oocysts compared to older cats, pregnant women should not adopt or handle kittens and should avoid getting a new cat during pregnancy. A recent study 4 has shown that communication between physicians and veterinarians about zoonotic diseases is largely absent. Enhancing such communication could help prevent transmission of zoonotic agents. Links between the professions on a broader scale (e.g., through combined veterinary/medical student training and continuing education) to foster a broader consensus about zoonotic disease risks and prevention should also be encouraged. This is particularly true with regards to T. gondii, where the consequences of infection can be very severe, while the risk of living with one's beloved cat is practically nill.

Landscape, herd management and within-herd seroprevalence of Toxoplasma gondii in beef cattle herds from Champagne-Ardenne, France

Toxoplasmosis is the most common parasitic zoonosis worldwide. Its prevalence and impact on human health are highly variable geographically. Humans may be infected by ingesting oocysts from the environment, or bradyzoits contained in meat products from various domestic species, thus data on the dynamics of toxoplasmosis in domestic herds is needed. However, few information is available on the factors that determine the level of infection of cattle herds. In this study, we aimed to estimate within-herd seroprevalence of toxoplasmosis in bovine herds and analyze its variability in relation with environmental characteristics and herd management. We tested the presence of anti Toxoplasma gondii antibodies in 1329 cattle from 24 beef herds in the Champagne-Ardenne region, using the Modified Agglutination Test. Information on herds was collected using a questionnaire. After describing the relationships between explanatory variables, we built a multivariate model using logistic Generalized Linear Models (GLMs) and estimated parameters with a Generalized Estimating Equations (GEE) procedure. The crude seroprevalence at threshold 1:24 equalled 7.8%, which is low, however positive individuals were found in 21 out of 24 herds. The final multivariate model showed that within-herd seroprevalence was highest in herds that were both small and isolated. The presence of cats modified the age-prevalence relationship: maximal seroprevalence was observed in oldest cows in farms without cats, and in youngest individuals in farms with cats. Finally, using a natural water point on pastures was associated to a high within-herd seroprevalence (Odds-Ratio: 1.93). Cows are often exposed to toxoplasmosis, however landscape characteristics (water point, isolation) and herd management (herd size, cats) may affect seroprevalence. Our results may help to find ways of reducing T. gondii prevalence in cattle.

Paragonimiasis in Cameroon: molecular identification, serodiagnosis and clinical manifestations

Paragonimiasis is a common parasitic zoonosis in Cameroon and neighbouring countries in Western Africa. Serum, sputum and faecal samples were collected in an endemic area of South West Province, Cameroon, after administration of a questionnaire to identify individuals with appropriate symptoms and histories. Microscopic examination revealed eggs in sputum from 16 people, but none in any faecal sample. These 16 were among the 25 and 26 people, respectively, positive by ELISA and by immunoblot using Paragonimus africanus crude antigens. Copro-DNA detection was attempted using 23 faecal samples (18 from sputum egg-negative and five from sputum egg-positive individuals). Copro-DNA was detected in four of the five sputum egg-positive individuals. These results strongly suggest that: (1) serology is much more sensitive than sputum examination for diagnosis of paragonimiasis; and (2) a copro-DNA test may be more sensitive than a microscopic search for eggs in faeces. Molecular sequence data from ITS2 and cox1 genes confirmed that adult worms experimentally raised in cats were P. africanus and that eggs from sputum or other worm products from human faeces also belonged to this species. Based on these results, 26 of 168 persons (15.5%) were diagnosed as suffering from paragonimiasis.

Toxoplasmosis in Bennett’s wallabies ( Macropus rufogriseus) in Spain

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. In this study, an epizootic of toxoplasmosis among captive Bennett’s wallabies ( Macropus rufogriseus) from different locations is reported. By means of light microscopy, Toxoplasma gondii-like tachyzoites were observed associated to interstitial pneumonia, non-suppurative myocarditis, cholangiohepatitis and severe gastroenteritis. The protozoa stained positively with a T. gondii antibody and ultrastructurally were similar to T. gondii. Strikingly, tachyzoites appeared sometimes in an intranuclear location within granulocyte-like cells. Feral cats or reactivation of a latent infection are discussed as the possible sources of infection. As far as we know, this is the first confirmed report of toxoplasmosis in Bennett’s wallabies in Spain and Europe, and may constitute a risk of infection for humans since new alimentary habits are being imposed in our countries.

Food-borne parasitic zoonosis: Distribution of trichinosis in Thailand

Trichinosis is among the most common food-borne parasitic zoonoses in Thailand and many outbreaks are reported each year. This paper investigates the distribution of the disease in regions of north, north-east, central and south Thailand. Between the earliest recorded of outbreak of trichinosis in Mae Hong Son Province in 1962 and 2006, there have been 135 outbreaks involving 7340 patients and 97 deaths in Thailand. The highest number of cases, 557, was recorded in 1983. Most infected patients were in the 35-44 year age group, and the disease occurred more frequently in men than women during 1962-2003, with no significant sex difference during 2004-2006. Outbreaks were most common in the northern areas, especially in rural areas where raw and under-cooked pork and/or wild animals are eaten. Human infections occur annually in northern Thailand during communal feasts celebrating the Thai New Year. Trichinosis causes have been reported every year, supporting the need for planning education programs.

Prevalence of antibodies to Toxoplasma gondii infection in humans and domestic animals in Samsun province, Turkey

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. It is caused by T. gondii which is a facultatively heteroxenous protozoan that has developed several potential routes of transmission within and between different host species (Tenter et al. 2000; Sroka 2001). Humans become infected with T. gondii mainly by ingesting uncooked meat containing viable tissue cysts or by ingesting food or water contaminated with oocysts from the faeces of infected cats (Dubey 2004). Transmission may also occur via tachyzoites contained in blood products, tissue transplants or unpasteurised milk (Dubey et al. 1985; Tenter et al. 2000). Apart from causing significant economic losses in animal husbandry, T. gondii also causes toxoplasmosis in humans in Turkey through the consumption of rare or raw meat of infected sheep and cattle (Altintas et al. 1997a,b; Sevgili et al. 2005). While the parasite has been frequently isolated from sheep meat, it is not so readily isolated from cattle meat (Dubey 1992; Redondo and Innes 1997). Cattle, like deer and horses, are susceptible to infection but are resistant to disease induced by T. gondii. Sheep with toxoplasmosis do not display specific clinical signs but it causes significant economic losses due to prenatal death and abortion. A broad range of serological tests has been developed to diagnose infections with T. gondii in intermediate hosts Trop Anim Health Prod (2008) 40:311–315 DOI 10.1007/s11250-007-9101-6

Investigation of correlation between Toxoplasma gondii IgG positivity and Hs-CRP

Toxoplasmosis is a disease caused by the intracellular protozoan parasite, Toxoplasma gondii (T. gondii). Toxoplasmosis is 1 of the more common parasitic zoonoses worldwide and it has been estimate...

Trichinosis: Epidemiology in Thailand

Trichinosis is one of the most common food-borne parasitic zoonoses in Thailand and many outbreaks are reported each year. This paper reviews the history, species, and epidemiology of the disease and food habits of the people with an emphasis on the north, northeast, central and south regions of Thailand. The earliest record of trichinosis in Thailand was in 1962 in the Mae Sariang District, Mae Hong Son Province. Since then, about 130 outbreaks have been reported involving 7392 patients and 97 deaths (1962-2005). The highest number of cases, 557, was recorded in 1983. The annual epidemiological surveillance reports of the Bureau of Epidemiology, Department of Disease Control, Ministry of Public Health, Thailand, show that trichinosis cases increased from 61 in 1997 to 351 in 1998. In contrast to these figures, the number of reported cases decreased to 16 in 1999 and 128 cases in 2000. There was no record of trichinosis in 2001, but then the figures for 2002, 2003 and 2004 were 289, 126 and 212 respectively. The infected patients were mostly in the 35-44 years age group and the disease occurred more frequently in men than women at a ratio of 1.7-2.0:1. There were 84 reported cases of trichinosis in Chiang Rai, Nan, Chiang Mai, Si Sa ket, Nakhon Phanom, Kalasin, Nakhon Ratchasima, Nakhon Nayok, Nakhon Pathom and Surat Thani, provinces located in different parts of Thailand in 2005. The outbreaks were more common in the northern areas, especially in rural areas where people ate raw or under-cooked pork and/or wild animals. This indicates the need for health education programs to prevent and control trichinosis as soon as possible in the high-risk areas.

High-Resolution Computed Tomography Findings of P. westermani

Paragonimiasis westermani, or Oriental lung fluke, is a common parasitic zoonosis, which is acquired from eating the flesh of wild boar or freshwater crabs. After being ingested by humans, the larvae of P. westermani migrate across small intestinal mucosa into the intra-abdominal space, and then finally into to the pleural space and lung parenchyma. High-resolution CT findings of P. westermani consist of worm cysts, migration track, peripheral density, bronchial wall thickening, and centrilobular nodules, which prompt serological tests and detection of eggs in sputum or BAL fluid for definitive diagnosis.

A Possible Role of TARC in Antigen-Specific Th2-Dominant Responses in Patients with Paragonimiasis westermani

Background: Paragonimiasis westermani (Pw), a common parasitic zoonosis in Asia, is typically associated with eosinophilia. Th2 cytokines seem to have an important role in the clinical manifestations of this disease. Thymus and activation-regulated chemokine (TARC) is a potential key regulator of Th2-mediated inflammation. The purpose of the present study was to evaluate the antigen-specific Th2-dominant responses in patients with Pw. Methods: The concentrations of cytokines and chemokines in supernatants of peripheral blood mononuclear cell (PBMC) cultures with or without antigen stimulation were measured by enzyme-linked immunosorbent assay (ELISA). TARC levels in serum from Pw patients were also evaluated by ELISA. The number of Th2 cells expressing the CC-chemokine receptor 4 (CCR4) in the peripheral blood was evaluated by flow cytometry. Results: Antigen-stimulation induced production of IL-5 and IL-13, but not IFN-γ from PBMC cultures in patients with Pw. Pw patients had elevated serum TARC levels and a higher proportion of CCR4-expressing cells among CD4+ T cells in the peripheral blood. There were also higher levels of TARC, but not IP-10, in supernatants of antigen-stimulated PBMC culture compared to unstimulated PBMC culture in patients with Pw. Conclusion: Our findings clarify antigen-specific Th2-dominant responses in patients with Pw and suggest a possible role for TARC in Th2-dominant responses.

Toxoplasmosis, an overview with emphasis on ocular involvement

Toxoplasmosis is a common parasitic zoonosis and an important cause of abortions, mental retardation, encephalitis, blindness, and death worldwide. Although a large body of literature has emerged on the subject in the past decades, many questions about the pathogenesis and treatment of the disease remain unanswered. This review aims to provide an overview of the current insights regarding the causative parasite and the mechanisms leading to symptomatic infection with emphasis on ocular toxoplasmosis.

Toxoplasma gondii: from animals to humans

Toxoplasmosis is one of the more common parasitic zoonoses world-wide. Its causative agent, Toxoplasma gondii, is a facultatively heteroxenous, polyxenous protozoon that has developed several potential routes of transmission within and between different host species. If first contracted during pregnancy, T. gondii may be transmitted vertically by tachyzoites that are passed to the foetus via the placenta. Horizontal transmission of T. gondii may involve three life-cycle stages, i.e. ingesting infectious oocysts from the environment or ingesting tissue cysts or tachyzoites which are contained in meat or primary offal (viscera) of many different animals. Transmission may also occur via tachyzoites contained in blood products, tissue transplants, or unpasteurised milk. However, it is not known which of these routes is more important epidemiologically. In the past, the consumption of raw or undercooked meat, in particular of pigs and sheep, has been regarded as a major route of transmission to humans. However, recent studies showed that the prevalence of T. gondii in meat-producing animals decreased considerably over the past 20 years in areas with intensive farm management. For example, in several countries of the European Union prevalences of T. gondii in fattening pigs are now <1%. Considering these data it is unlikely that pork is still a major source of infection for humans in these countries. However, it is likely that the major routes of transmission are different in human populations with differences in culture and eating habits. In the Americas, recent outbreaks of acute toxoplasmosis in humans have been associated with oocyst contamination of the environment. Therefore, future epidemiological studies on T. gondii infections should consider the role of oocysts as potential sources of infection for humans, and methods to monitor these are currently being developed. This review presents recent epidemiological data on T. gondii, hypotheses on the major routes of transmission to humans in different populations, and preventive measures that may reduce the risk of contracting a primary infection during pregnancy.