Seroprevalence and risk factors for Toxoplasma gondii infection in domestic cats in The Netherlands

Toxoplasma gondii genotypes and frequency in domestic cats from Romania

BACKGROUND

Toxoplasma gondii is a zoonotic protozoan parasite with a heteroxenus life cycle that involves felids as the definitive hosts and any warm-blooded animal, including humans, as intermediate hosts. Cats are key players in parasite transmission as they are capable of shedding high numbers of oocysts in their feces that contaminate the environment.

METHODS

The study was performed on 31 domestic cats (31.23 ± 27.18 months old) originating from rural and urban areas (5.17:1) in the center and north-west Romania. Feces (n = 31), blood (n = 28), and heart samples (n = 27) were collected. Fecal samples were analyzed by flotation technique, and PCR (529 bp repetitive element). Fecal samples with T. gondii oocysts were bioassayed in mice. Serum samples were analyzed by modified agglutination test and ImmunoComb for the detection of specific anti-T. gondii IgG antibodies. Heart samples were bioassayed in mice, and analyzed by PCR. Toxoplasma gondii positive samples were genotyped by nPCR-RFLP targeting eleven genetic loci (SAG1, SAG2, alt-SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico).

RESULTS

Toxoplasma gondii oocysts were found in 2 out of 31 fecal samples collected from a 3-months old stray kitten, and a 4-years old female. In total, 17 out of 27 sera were positive for T. gondii IgG antibodies. The antibody titers in MAT ranged from 1:6 to 1:384. Toxoplasma gondii DNA was detected in 7 out of 27 heart samples, and four of them were positive also by bioassay. Six T. gondii DNA samples from bioassayed mice could be assigned to ToxoDB PCR-RFLP genotype #1 or #3 (Type II) and one T. gondii DNA from heart digest to genotype #2 (Type III). Both of these genotypes are common in Europe.

CONCLUSIONS

Our results revealed that the infection with T. gondii is still high in cats from Romania. The oocysts shedded by these cats represent an important source of infection for intermediate hosts, including humans. Further studies on a wider range of cases are necessary for a more exhaustive definition of the T. gondii genotypes circulating in Romania.

Geoepidemiology, seroprevalence and factors associated with Toxoplasma gondii infection in domicilied cats from Paraíba (Brazil)

Toxoplasma gondii is a parasite responsible for toxoplasmosis, an emerging and often neglected zoonosis in South America, particularly Brazil. Felines, the only definitive hosts, excrete oocysts in their feces, potentially infecting all homeotherms. Domestic cats are primarily responsible for contaminating human environments with these oocysts. Monitoring their populations is therefore essential to ensure proper toxoplasmosis prophylaxis. The aim of this study was to estimate the prevalence of T. gondii and exposure factors in a population of owner cats in the city of João Pessoa, Paraíba, Brazil. A total of 267 blood samples were collected from domestic cats aged between 1 and 15 years and tested with an immunofluorescence antibody test. The seroprevalence of antibodies against T. gondii was only 17.22% (46/267 individuals). This result therefore suggests a low contribution of domestic cats to T. gondii contamination of the urban environment. The cats' age and living environment were identified as risk factors for cat exposure to T. gondii.

Toxoplasma gondii Infection in the Eurasian Beaver (Castor fiber) in Switzerland: Seroprevalence, Genetic Characterization, and Clinicopathologic Relevance

Toxoplasma gondii is a coccidian parasite able to infect all warm-blooded animals and humans. Rodents are one of the most important intermediate hosts for T. gondii, but little is known about infection in beavers and its clinical relevance. Toxoplasmosis was not considered an important waterborne disease until recently, but with increased outbreaks in humans and animals this perspective has changed. Serum samples from 247 Eurasian beavers (Castor fiber) collected from 2002 to 2022 were tested for antibodies to T. gondii by a commercial ELISA. Antibodies to T. gondii were found in 113 (45.8%) beavers. Higher weight and proximity to urban areas were found to be significant predictors for seropositivity. Additionally, T. gondii DNA was detected in 23/41 brain tissue samples by real-time PCR. Histopathologic examination of brain sections revealed inflammatory changes in 26/40 beavers, mainly characterized by encephalitis, meningitis, choroid plexitis, or a combination of them. In six of these cases the lesions were in direct association with parasitic stages. With an adapted nested PCR multilocus sequence typing and in silico restriction fragment length polymorphism analysis approach, three different T. gondii genotypes were detected in brain samples: the clonal Type II strain (ToxoDB 1), a Type II variant (ToxoDB 3), and a novel genotype exhibiting both Type II and I alleles in a further animal. Toxoplasma gondii infections in beavers have epidemiologic and clinical significance. The high seroprevalence indicates frequent contact with the parasite, and as competent intermediate hosts they may play an important role, contributing to maintaining the life cycle of T. gondii in semiaquatic habitats. In addition, although most beavers appear to develop subclinical to chronic disease courses, acute and fatal outcomes, mainly characterized by encephalitis and generalized infection, do also occur.

Prevalence of Toxoplasma gondii in Endangered Wild Felines (Felis silvestris and Lynx pardinus) in Spain

The wildcat (Felis silvestris) and the Iberian lynx (Lynx pardinus) are important species in Spain, considered as near-threatened and endangered, respectively. Both can be infected by Toxoplasma gondii, a parasite that can cause morbidity and mortality in transplacentally-infected or immunocompromised mammals. The data on the prevalence of this parasite in wild populations of these species in Spain are outdated. The objective of this study was to update information and evaluate the role of these felines in parasite epidemiology and the potential impact of the parasite on their conservation. Blood and fecal samples were collected from captured animals, as well as the tongue, diaphragm, and spleen, from animals killed in road accidents in central Spain. An indirect fluorescent antibody test (IFAT) was used to detect parasite antibodies in serum, microscopy and molecular analysis were used to detect oocysts in feces, and molecular analysis was used to determine the existence of tissue cysts. Seroprevalence was 85% in wildcats and 45% in lynx, and parasite DNA was detected in the feces of one wildcat and in tissue samples from 10 wildcats and 11 Iberian lynxes. These results highlight the epidemiological importance and high risk of T. gondii infection in animals and humans in the studied areas. Considering feline susceptibility to infection, monitoring programs are needed to assess the health status of wild felines.

Seroprevalence of Toxoplasma gondii and associated risk factors for infection in the Netherlands: third cross-sectional national study

A third nationally representative serosurvey was performed to study the changes in Toxoplasma gondii (T. gondii) seroprevalence in the Netherlands over a 20-year time span and to identify and confirm risk factors for acquired toxoplasmosis. This cross-sectional study (conducted in 2016/2017) was designed similarly to the previous two studies (1995/1996 and 2006/2007) and included a questionnaire and serum sampling among Dutch residents. Factors associated with seropositivity for T. gondii were determined using multivariable analysis of the questionnaire-derived data. The earlier observed decrease in T. gondii seroprevalence between 1995/1996 and 2006/2007 (from 40.5% to 26.0%) did not continue into 2016/2017 (29.9%). Similarly to the previous studies, the seroprevalence increased with age and varied among regions. In all studies, higher T. gondii seropositivity was associated with increasing age, lower educational level, not living in the Southeast, and eating raw or semi-cooked pork. The incidence of congenital toxoplasmosis was estimated at 1.3/1000 (95% CI 0.9-1.8) live-born children in 2017. As the seroprevalence of T. gondii in the Netherlands did not decrease over the last decade, an increase in public health awareness is needed and prevention measures may need to be taken to achieve a further reduction in T. gondii infections in the Netherlands.

Seroprevalence of and Risk Factors for Toxoplasma gondii Infection in Cats from Greece

Toxoplasmosis is one of the most important protozoan diseases with a global impact on the health of domestic cats and with zoonotic significance. The aims of this study were to determine the prevalence of seropositivity for Toxoplasma gondii in different populations of cats in Greece and to assess risk factors for seropositivity. A total of 457 cats were prospectively enrolled, and a commercially available indirect immunofluorescence antibody testing (IFAT) kit was used for the detection of anti-T. gondii immunoglobulin G (IgG) in serum. Overall, 95 (20.8%) of the 457 cats were seropositive for T. gondii. Based on multivariate analysis, factors associated with seropositivity included older age [Odds ratio (OR), 1.33; p < 0.001]; a history of cat-fight trauma (OR, 3.88; p = 0.004); and lack of vaccination against calicivirus, herpesvirus-1, panleukopenia, and rabies (OR, 10; p = 0.002). This study shows a high prevalence of seropositivity for T. gondii in cats in Greece. This implies that toxoplasmosis is still a major public health concern and that optimal strategies for the prevention of infection with T. gondii in cats should be established.

Systematic Review and Modelling of Age-Dependent Prevalence of Toxoplasma gondii in Livestock, Wildlife and Felids in Europe

Toxoplasma gondii is a zoonotic parasite of importance to both human and animal health. The parasite has various transmission routes, and the meat of infected animals appears to be a major source of human infections in Europe. We aimed to estimate T. gondii prevalence in a selection of animal host species. A systematic literature review resulting in 226 eligible publications was carried out, and serological data were analyzed using an age-dependent Bayesian hierarchical model to obtain estimates for the regional T. gondii seroprevalence in livestock, wildlife, and felids. Prevalence estimates varied between species, regions, indoor/outdoor rearing, and types of detection methods applied. The lowest estimated seroprevalence was observed for indoor-kept lagomorphs at 4.8% (95% CI: 1.8-7.5%) and the highest for outdoor-kept sheep at 63.3% (95% CI: 53.0-79.3%). Overall, T. gondii seroprevalence estimates were highest within Eastern Europe, whilst being lowest in Northern Europe. Prevalence data based on direct detection methods were scarce and were not modelled but rather directly summarized by species. The outcomes of the meta-analysis can be used to extrapolate data to areas with a lack of data and provide valuable inputs for future source attribution approaches aiming to estimate the relative contribution of different sources of T. gondii human infection.

Toxoplasmosis Infection during Pregnancy

This literature review aims to give an overview of the current knowledge concerning how a toxoplasmosis infection affects the mother and her fetus. A thorough search of PubMed and a complimentary search of Google Scholar databases were used to identify relevant studies for this review. Although a Toxoplasma gondii infection is preventable, this infection is contracted by consuming contaminated food and water and by exposure to environmental sources of infection such as contaminated soil. Maternal-to-fetal transmission of this infection can result in devastating ophthalmic and neurological consequences for the fetus. Although a toxoplasmosis infection can result in long-term effects on the fetus, chronic disease is also associated with mental illness in mothers. Effective treatment can reduce the risk of congenital toxoplasmosis and the long-term consequences of infection in the fetus. Without appropriate screening and education programs, this infection will remain largely undiagnosed.

Feline Toxoplasmosis in Greece: A Countrywide Seroprevalence Study and Associated Risk Factors

Toxoplasma gondii is a ubiquitous zoonotic parasite, with felines being the only definitive hosts. Cats shed oocysts with their faeces, and seroprevalence studies can be used to indirectly assess the environmental contamination. The current study aimed to evaluate T. gondii seroprevalence in Greek cats and identify possible risk factors. In total, 1554 blood samples were analyzed from different cats across all nine geographic regions of Greece, and a short questionnaire was completed for each cat. A rapid immunochromatographic test was used to detect anti-T. gondii antibodies, IgG type, and 21.8% of cats were seropositive. Regarding risk factors, when chi-square tests were applied, seropositivity was significantly higher (p < 0.05) in rural cats, cats with outdoor access, and hunting cats. Gender, age, ownership, and raw feeding were not significant risk factors, although female, adult, stray, and raw-feeding cats had a higher seroprevalence than their counterparts. Binary logistic regression models were developed to adjust for the confounding effects of the initially recognized risk factors, and only hunting in urban areas remained a significant risk factor. Greek cats had lower seropositivity than the average European value, and the present research highlights the importance of updated seroprevalence and risk factor studies within the context of One-Health.

Role of landscape context in Toxoplasma gondii infection of invasive definitive and intermediate hosts on a World Heritage Island

Free-ranging cats are invasive species threatening biodiversity worldwide. They may also impose an environmental risk to humans and livestock through the transmission of zoonotic diseases. We investigated antibody levels against Toxoplasma gondii in free-ranging cats and black rats (definitive and representative intermediate hosts) by ELISA and determined their relationships with landscape environmental factors on Tokunoshima Island, Japan, the Natural World Heritage site. We found a higher seroprevalence (>70%) in both cats and black rats in landscapes where the cattle barn density was high. This was consistent with higher density of rats revealed in our trapping survey. The spatial scale of landscape factors affecting infection was broader in cats (1 km buffer radius) than in black rats (100 m buffer radius). Both cats and rats showed an increasing trend in optical density (OD) values with increasing body weight and landscape cattle barn density, suggesting that the antibody concentration increases as the chance of exposure to T. gondii in the environment increases. Thus, management actions to stop humans from feeding cats and to control rat populations without using cats are both necessary to reduce the human health risk as well as to conserve endangered species on the island.

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High seroprevalence of T. gondii was found in cats and black rats on an island.

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Seroprevalence was high (>70%) in landscapes where there were many cattle barns.

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Antibody level in cats was lower in forests and higher around residential areas.

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Spatial scale of environmental factors affecting infection was broader in cats.

Molecular detection and dense granule antigen 6 genotyping of feline Toxoplasma gondii in Phayao, Thailand

Background and Aim:

Globally, toxoplasmosis is an important zoonotic parasite infection of many warm-blooded animals (including humans). Toxoplasma gondii oocysts are widespread, and their contamination can be primarily attributed to the members of the Felidae family. This study aimed to estimate the prevalence and determine the dense granule antigen 6 (GRA6) genotype of T. gondii among domestic cats in the Phayao Province, Thailand.

Materials and Methods:

A total of 124 fecal samples were collected from owned cats in the Muang district, Phayao, Thailand, from January to December 2020. Fecal samples were tested for the presence of T. gondii DNA using targeted B1 gene polymerase chain reaction (PCR) amplification, and positive samples were subsequently analyzed for their T. gondii genotype through PCR-restriction fragment length polymorphism (RFLP) analysis and sequencing of the GRA6 gene.

Results:

Among the 124 samples, 46 (37.1%) were tested positive for T. gondii. Only 10 positive DNA samples were successfully amplified for the GRA6 marker. Subsequent PCR-RFLP and sequence analyses indicated that all T. gondii isolates from cats in Phayao belonged to GRA6 genotype I.

Conclusion:

Data revealed that toxoplasmosis is remarkably distributed among (studied) domestic cats in Phayao, Thailand. Moreover, the virulent GRA6 allele was found to be circulated among domestic cats in this area. However, no significant correlation was observed between infection rates and different risk factors, which indicated that pet cats of any age, gender, or breed have similar risks of being infected with T. gondii. Our results further suggested that infective oocysts of T. gondii are widely distributed and that environmental contamination with these oocysts will introduce more risks of disease transmission to humans and other animals.

Conditional associations between childhood cat ownership and psychotic experiences in adulthood: A retrospective study

Ownership of cats in childhood has been inconsistently associated with psychosis in adulthood. Parasitic exposure, the putative mechanism of this association, may be more common with rodent-hunting cats, and its association with psychosis may depend on other environmental exposures. We examined the conditional associations between childhood cat ownership and the frequency of psychotic experiences in adulthood. Adults (n = 2206) were recruited in downtown Montreal to complete a survey about childhood cat ownership (non-hunting or rodent-hunting), winter birth, residential moves in childhood, head trauma history, and tobacco smoking. The frequency of psychotic experiences (PE) was measured with the 15-item positive subscale of the Community Assessment of Psychic Experiences. Associations between exposures and PE were examined in linear regressions adjusted for age and sex. Interactions among variables were explored using a conditional inference tree. Rodent-hunting cat ownership was associated with higher PE scores in male participants (vs. non-hunting or no cat ownership: SMD = 0.57; 95% CI: 0.27, 0.86), but not in female participants (SMD = 0.10; 95% CI: -0.18, 0.38). In the conditional inference tree, the highest mean PE score was in the class comprised of non-smokers with >1 residential move, head trauma history, and rodent-hunting cat ownership (n = 22; mean standard score = 0.96). The interaction between rodent-hunting cat ownership and head trauma history was supported by a post-hoc linear regression model. Our findings suggest childhood cat ownership has conditional associations with psychotic experiences in adulthood.

Comparative Evaluation of Re 529-Bp Sequence and B1 Gene in the Detection of Toxoplasma gondii Through PCR in Water Samples of Denizli, Turkey

Purpose

While Toxoplasma gondii (T. gondii) infection is asymptomatic in immunocompetent individuals, it is a life-threatening protozoan in immunocompromised individuals. Its water-borne transmission to humans poses a serious public health concern. Polymerase Chain Reaction (PCR) has a considerable potential for the sensitive and specific detection of T. gondii oocysts in waters.

Methods

Comparative evaluation of RE 529-bp sequence and B1 gene to detect T. gondii tachyzoites and oocysts via PCR in agricultural irrigation water taken from downtown Denizli, Turkey and water samples collected from neighborhood fountains was performed for the first time in Turkish context.

Results

Based on real-time PCR targeting the B1 genetic markers and RE 529-bp sequence, T. gondii DNA was identified in 6 (16.7%) out of 48 samples collected from agricultural irrigation water. Besides, our PCR analysis did not establish any presence of T. gondii in drinking water samples.

Conclusion

T. gondii showed lower sensitivity in B1-based PCR than in PCR targeting RE 529-bp sequence.

Prevalence of Toxoplasma gondii Measured by Western Blot, ELISA and DNA Analysis, by PCR, in Cats of Western Mexico

Toxoplasma gondii is the causative agent of toxoplasmosis in humans and animals. The sexual reproductive cycle of Toxoplasma takes place in the small intestine of felines, the definitive hosts. In the final part of the sexual cycle, T. gondii forms oocysts in infected cats. Oocysts transferred via the faeces to the environment are highly infectious to both animals and humans. This study aimed to determine the prevalence and risk factors associated with T. gondii infection in cats from the metropolitan region of Guadalajara in western Mexico. Western blotting and ELISA for anti-Toxoplasma IgG antibodies was performed, and Toxoplasma DNA was identified using polymerase chain reaction. Prevalence of anti-T. gondii antibodies was 14.8% (44/297), and only 2/297 cases were positive for PCR. Cats older than one year were at an increased risk of infection (OR = 3.9, 95% CI 1.844-8.362). Sex, raw meat feeding, hunting habits, vaccination status, and body condition were not associated with positivity. The prevalence of T. gondii infection determined with Western blot in cats in the metropolitan area of Guadalajara, Jalisco, Mexico, was lower than that reported in previous studies.

Seroprevalence of Toxoplasma gondii in Cats from Cyprus

Toxoplasma gondii is a cosmopolitan protozoon parasite, and the causative agent of toxoplasmosis, one of the most prevalent zoonotic parasitic diseases. Cats, as definitive hosts, spread the parasite via their faeces, but this occurs only for a very short period in their life. Seropositivity in cats, although not associated with current shedding of the parasite, is indicative of the infection in a cat population and can be used to assess the infection risk for definitive and intermediate hosts in that area. In order to assess the prevalence of infection in cats living in Cyprus, 155 cats, originating from all districts of the country, were examined for the presence of T. gondii antibodies. Additionally, parameters such as age, sex, health status, lifestyle and concomitant infections were statistically assessed as potential risk factors for T. gondii seropositivity. Specific anti-T. gondii antibodies were detected in 50 (32.3%) cats, while the presence of feline immunodeficiency virus antibodies and a history of never having been vaccinated were statistically associated with T. gondii seropositivity on multivariate logistic regression analysis. This is the first report of T. gondii seroprevalence in cats in Cyprus and indicates that raised public awareness should be considered to prevent infection of animals and humans.

Bayesian Binary Mixture Models as a Flexible Alternative to Cut-Off Analysis of ELISA Results, a Case Study of Seoul Orthohantavirus

Serological assays, such as the enzyme-linked immunosorbent assay (ELISA), are popular tools for establishing the seroprevalence of various infectious diseases in humans and animals. In the ELISA, the optical density is measured and gives an indication of the antibody level. However, there is variability in optical density values for individuals that have been exposed to the pathogen of interest, as well as individuals that have not been exposed. In general, the distribution of values that can be expected for these two categories partly overlap. Often, a cut-off value is determined to decide which individuals should be considered seropositive or seronegative. However, the classical cut-off approach based on a putative threshold ignores heterogeneity in immune response in the population and is thus not the optimal solution for the analysis of serological data. A binary mixture model does include this heterogeneity, offers measures of uncertainty and the direct estimation of seroprevalence without the need for correction based on sensitivity and specificity. Furthermore, the probability of being seropositive can be estimated for individual samples, and both continuous and categorical covariates (risk-factors) can be included in the analysis. Using ELISA results from rats tested for the Seoul orthohantavirus, we compared the classical cut-off method with a binary mixture model set in a Bayesian framework. We show that it performs similarly or better than cut-off methods, by comparing with real-time quantitative polymerase chain reaction (RT-qPCR) results. We therefore recommend binary mixture models as an analysis tool over classical cut-off methods. An example code is included to facilitate the practical use of binary mixture models in everyday practice.

Systemic toxoplasmosis in a cat under cyclosporine therapy

Toxoplasma gondii, an obligatory intracellular protozoan parasite infecting warm-blooded animals, can cause toxoplasmosis, a major zoonosis. A male neutered, domestic cat was referred to the Hebrew University Veterinary Teaching Hospital due to dyspnea after long term treatment with cyclosporine for obsessive self-grooming and pruritis. After thorough diagnostics, including non - invasive imaging, broncho-alveolar lavage, blood serology, hematology and biochemistry, and evaluation of the aspirated fluid components, a severe pneumonia and abdominal effusion were detected with observation of free tachyzoites under light microscopy from lavage fluids. PCR and DNA sequencing of broncho-alveolar lavage was positive for T. gondii. Despite aggressive treatment with antibiotics, oxygen supplementation and T. gondii specific antimicrobials, the cat died. It is suggested that potential candidates for cyclosporine be screened for T. gondii antibodies, kept entirely indoors and not fed uncooked meat in order to prevent exposure to T. gondii infection.

Antibody kinetics and exposure to Toxoplasma gondii in cats: a seroepidemiological study

Domestic cats are the most important definitive hosts for Toxoplasma gondii, the agent of an important global zoonosis. Serial sera from cats orally inoculated either withT. gondii tissue cysts (n = 3) or sporulated oocysts (n = 3) and from 65 client-owned cats, plus sera from 1,757 client-owned cats presented to veterinarians in Switzerland were analysed for an antibody response to T. gondii by ELISA. Risk factors for seropositivity and prevalence were estimated with a generalised linear and beta regression model. The first model examined the association of an OD₄₀₅ value as the dependent variable, with gender, age, and outside access as possible independent variables. In the second model, we first analysed the data assuming a bimodal distribution representing two overlapping distributions of OD₄₀₅ values from positive and negative cats, enabling the assignment of a probability of true infection status to each cat. Mean probabilities of true infection status across groups represent an estimate of true prevalence. These probabilities were then regressed against age, gender and outside access. Antibody kinetics in cats orally inoculated with tissue cysts, shedding oocysts, did not differ significantly from those of cats inoculated with sporulated oocysts without detectable oocyst excretion, suggesting extraintestinal parasite invasion and exposure to tachyzoites in both situations at an early stage of infection. Analysis of serial serum samples suggested a persisting long-term humoral immune response. Of the client-owned cats, 42.4% (95% confidence interval (CI): 40.1-44.6) had a positive true infection status. This was higher (56.3% (95% CI: 53.2-59.6)) in cats with outside access than in those without (22.1% (95% CI: 18.9-25.4)). In the first model, the factors age (P < 0.0001), gender (male: P = 0.046), and outside access (P < 0.0001) were independently associated with significantly higher OD₄₀₅ values. In the second model, the probability of having a positive true infection status increased with age (P < 0.0001), was higher with outside access (P < 0.0001) and in outdoor male cats (P = 0.0006).

Seroprevalence of Toxoplasma gondii in household cats in Myanmar and molecular identification of parasites using feline faecal oocysts

Felids play an important role in the transmission of Toxoplasma gondii to humans and other animals since they can excrete millions of oocysts into the environment as definitive hosts. In the present study, seroprevalence and risk factors of feline Toxoplasma infection were investigated, and molecular identification was conducted for T. gondii oocysts isolated from faecal samples of seropositive cats. A total of 276 cat serum samples collected from the Yangon, Myanmar were tested for T. gondii antibodies by ELISA. The overall seroprevalence of T. gondii infection was 41.30% (114 seropositive cats). Age between 1 and 6 years (OR = 3.284; 95% CI = 1.462-7.375), age > 6 years (OR = 4.560; 95% CI = 1.588-13.100) and sex (OR = 1.725; 95% CI = 1.026-2.899) were found to be significant (P < 0.05) factors associated with T. gondii infection. DNA samples extracted from a single oocyst of seropositive cats were employed in three PCR assays amplifying parasite TOX-element and mitochondrial COI, and SAG2 locus. The obtained sequences of TOX-elements (n = 6) and COI (n = 5) were identical to those of T. gondii previously deposited in Genbank. SAG2 PCR yielded three different sequences, all of which were clustered with Type I T. gondii isolates in a phylogenetic tree. This study reported the seroprevalence and risk factors for T. gondii infection in cats and provided the molecular information on the parasite in Myanmar.

All about toxoplasmosis in cats: the last decade

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasmosis continues to be of public health concern. Cats (domestic and wild felids) are the most important host in the epidemiology of toxoplasmosis because they are the only species that can excrete the environmentally resistant oocysts in feces. Cats can excrete millions of oocysts and a single cat can spread infection to many hosts. The present paper summarizes information on prevalence, persistence of infection, clinical signs, and diagnosis of T. gondii infections in domestic and wild cats for the past decade. Special emphasis is paid to genetic diversity of T. gondii isolates from cats. Review of literature indicates that a unique genotype (ToxoDB genotype #9 or Chinese 1) is widely prevalent in cats in China and it has been epidemiologically linked to outbreaks of clinical toxoplasmosis in pigs and deaths in humans in China; this genotype has rarely been detected in other countries. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Species-specific differences in Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti seroprevalence in Namibian wildlife

Background

Knowledge about parasitic infections is crucial information for animal health, particularly of free-ranging species that might come into contact with livestock and humans.

Methods

We investigated the seroprevalence of three tissue-cyst-forming apicomplexan parasites (Toxoplasma gondii, Neospora caninum and Besnoitia besnoiti) in 506 individuals of 12 wildlife species in Namibia using in-house enzyme linked immunosorbent assays (indirect ELISAs applying purified antigens) for screening and immunoblots as confirmatory tests. We included six species of the suborder Feliformia, four species of the suborder Caniformia and two species of the suborder Ruminantia. For the two species for which we had most samples and life-history information, i.e. cheetahs (Acinonyx jubatus, n = 250) and leopards (Panthera pardus, n = 58), we investigated T. gondii seroprevalence in relation to age class, sex, sociality (solitary, mother-offspring group, independent sibling group, coalition group) and site (natural habitat vs farmland).

Results

All but one carnivore species (bat-eared fox Otocyon megalotis, n = 4) were seropositive to T. gondii, with a seroprevalence ranging from 52.4% (131/250) in cheetahs to 93.2% (55/59) in African lions (Panthera leo). We also detected antibodies to T. gondii in 10.0% (2/20) of blue wildebeest (Connochaetes taurinus). Adult cheetahs and leopards were more likely to be seropositive to T. gondii than subadult conspecifics, whereas seroprevalence did not vary with sex, sociality and site. Furthermore, we measured antibodies to N. caninum in 15.4% (2/13) of brown hyenas (Hyaena brunnea) and 2.6% (1/39) of black-backed jackals (Canis mesomelas). Antibodies to B. besnoiti were detected in 3.4% (2/59) of African lions and 20.0% (4/20) of blue wildebeest.

Conclusions

Our results demonstrate that Namibian wildlife species were exposed to apicomplexan parasites at different prevalences, depending on parasite and host species. In addition to serological work, molecular work is also needed to better understand the sylvatic cycle and the clear role of wildlife in the epidemiology of these parasites in southern Africa.

Who let the cats out? A global meta-analysis on risk of parasitic infection in indoor versus outdoor domestic cats ( Felis catus)

Parasitic infection risks in domestic animals may increase as a result of outdoor activities, often leading to transmission events to and from owners, other domestic animals and wildlife. Furthermore, outdoor access has not been quantified in domestic animals as a risk factor with respect to latitude or parasite transmission pathway. Cats are an ideal model to test parasitic infection risk in outdoor animals because there have been many studies analysing this risk factor in this species; and there is a useful dichotomy in cat ownership between indoor-only cats and those with outdoor access. Thus, we used meta-analysis to determine whether outdoor access is a significant risk factor for parasitic infection in domestic pet cats across 19 different pathogens including many relevant to human, domestic animal and wildlife health, such as Toxoplasma gondii and Toxocara cati. Cats with outdoor access were 2.77 times more likely to be infected with parasites than indoor-only cats. Furthermore, absolute latitude trended towards significance such that each degree increase in absolute latitude increased infection likelihood by 4%. Thus, restricting outdoor access can reduce the risk of parasitic infection in cats and reduce the risk of zoonotic parasite transmission, spillover to sympatric wildlife and negative impacts on feline health.

Toxoplasma gondii Seroprevalence in Horses from Ukraine: an Investigation Using Two Serological Methods

BACKGROUND

Horses are recognized as important hosts for the zoonotic parasite Toxoplasma gondii, mainly because meat of infected horses can be a source of human T. gondii infections. However, the baseline knowledge on equine T. gondii infections is limited and lacking from many countries. This seroepidemiological study was set in Ukraine, a country where little is known about T. gondii prevalence in any host species.

METHODS

We investigated 78 serum samples from horses, collected from Kyiv and Lviv regions of Ukraine, using a commercial enzyme-linked immunosorbent assay (ELISA) and a commercial modified direct agglutination test (DAT). The ELISA is intended to detect the presence of total antibodies against T. gondii, and the DAT detects specific anti-T. gondii immunoglobulin G antibodies. The cutoff titer for DAT seropositivity was a titer of 40.

RESULTS

Two horses were omitted from statistical analyses due to disagreeing ELISA results. Altogether 16 of the remaining 76 horses were seropositive with the ELISA, yielding an apparent seroprevalence estimate of 21.1% (95% confidence interval 13.0-31.3). Five horses tested positive with both ELISA and DAT, 11 horses tested positive with ELISA only, and one with DAT only. For 64 of the 76 horses, the results of ELISA and DAT agreed; the percent agreement was 84.2 and the Kappa statistic was - 1.5208, indicating poor agreement.

CONCLUSION

Our results add to the knowledge on the global epidemiology of T. gondii and exposure level of horses to the major zoonotic parasite, as well as to the discussion of challenges of applying serology to estimate exposure to T. gondii in horses.

Seroprevalence and associated risk factors of Toxoplasma gondii infection in domestic animals in southeastern South Africa

Toxoplasma gondii is a major neglected parasitic infection occurring in settings of extreme poverty in Africa. Apart from causing reproductive failure in animals it is also a significant zoonotic concern. The objective of this study was to determine the seroprevalence and associated risk factors of T. gondii infection in cats, chickens, goats, sheep and pigs in the southeast of South Africa, of which little is known. Sera was obtained from 601 domestic animals including 109 cats, 137 chickens, 128 goats, 121 sheep and 106 pigs managed under different production systems in different agro-ecological regions and evaluated by the Toxoreagent, a latex agglutination test for T. gondii antibody detection. Household-level and animal-level data were collected by interviewing animal owners and/or herders using a closed-ended questionnaire. The study revealed an overall farm seroprevalence of 83.33% (125/150 farms) with the highest rate of infection for the parasite found in sheep with 64.46% (78/121), followed by goats with 53.91% (69/128), pigs with 33.96% (36/106), cats with 32.11% (35/109 cats) and chickens with 33.58% (46/137). The risk factors that were found to be statistically significant (p 0.05) to different species of seropositivites were age, location, climate, animal production system, rodent control, seropositive cat, cat-feed access and cat faecal disposal. The relatively high seroprevalence of T. gondii detected in this region suggests that domestic animals may pose a substantial public health risk through the consumption of T. gondii-infected raw meat as well as via contact with cat faeces.

Toxoplasma gondii in small exotic felids from zoos in Europe and the Middle East: serological prevalence and risk factors

BACKGROUND

Toxoplasma gondii infections and cases of clinical toxoplasmosis have been recorded in zoo animals. Wild felids in human care can serve as definitive hosts that shed oocysts, but also as intermediate hosts for the parasite. Some felid species, such as the Pallas's cat (Otocolobus manul) or sand cat (Felis margarita), may suffer from clinically apparent toxoplasmosis. In the present study, our main aim was to assess risk factors for T. gondii infections in small exotic felids.

METHODS

A seroepidemiological study was conducted using the reduviid bug Dipetalogaster maxima for blood sample collection, a method previously evaluated on domestic cats. A total of 336 samples from 17 felid species were collected in 51 institutions, 48 of which were within Europe and the remaining three in the Middle East (United Arabic Emirates and Qatar). These samples were analyzed for T. gondii antibodies by immunoblotting and an immunofluorescent antibody test. Potential risk factors in zoos for seropositivity regarding T. gondii among members of the European Association of Zoos and Aquaria (EAZA) were evaluated using a questionnaire and individual data from the Zoological Information Management System (ZIMS).

RESULTS

The sampled felids showed an overall seroprevalence for T. gondii of 63%. The risk factor study including data of 311 small exotic cats of 10 species resulted in a final generalized linear mixed model comprised of five variables: the likelihood of seropositivity increased statistically significantly with "Age", while feeding "Cattle: frozen" relative to "Cattle: fresh", "Outdoor housing fenced in on all sides", "Mesh size 2-5 cm" relative to "Mesh size > 5 cm" and "Wearing gloves: yes" had statistically significant protective effects.

CONCLUSIONS

Wild felids, including endangered species, kept in human care in European and Middle Eastern institutions, are widely exposed to T. gondii. Risk factor analysis revealed that feeding previously frozen tissues, keeping animals in enclosures that are fenced on all sides using fences with small mesh sizes, and wearing gloves when working inside enclosures seem to be the most relevant protective measures to prevent T. gondii infections in these animals .

Endemicity of Toxoplasma infection and its associated risk factors in Cebu, Philippines

Toxoplasma gondii is a single-celled intracellular apicomplexan parasite that causes toxoplasmosis. It is capable of infecting humans and nearly all warm-blooded animals including pigs, but cats are the only known definitive host. This ubiquitous zoonotic pathogen can cause abortion, stillbirth and fetal abnormalities, and has been associated with mental and behavioral changes in humans. Acute infection is potentially fatal in immunocompromised individuals. The present study aimed to assess the Toxoplasma seroprevalence in pigs, humans and cats after its initial reported detection in pigs about three decades ago in Cebu, Philippines. A total of 924 humans, 104 cats and 514 slaughter pigs were tested for antibodies against T. gondii using a commercial latex agglutination test. The results revealed positive detection rates of 26.3% (244/924) for humans, 42.3% (44/104) for cats and 13.4% (69/514) for slaughter pigs. Statistical analyses revealed that the area (P = 0.004), cat ownership (P = 0.020), the frequency of contact with cats (P < 0.0001) and consumption of street foods (P = 0.043) were significantly associated with seropositivity for T. gondii in humans. Meanwhile, the use of litter trays (P = 0.001) and contact with other animals (P = 0.007) were significantly associated with seropositivity in cats. The odds ratio for selected significant factors revealed that living in suburban areas (OR 1.66, 95% CI: 1.20–2.31), owning a cat (OR 1.482, 95% CI: 1.07–2.07) and eating street foods (OR 1.585, 95% CI: 1.01–2.48) were associated with an increased risk of T. gondii exposure in humans. In cats, the use of a litter tray (OR 4.5, 95% CI: 1.73–11.71) was associated with an increased risk of exposure. None of the profile parameters were found to be significantly associated with seropositivity in slaughter pigs (P > 0.05). This study is the first report of the serological detection of T. gondii in humans and cats in Cebu, Philippines, and the first assessment of the prevalence of the parasite in pigs in the area since its initial detection in 1982. This is also the first report documenting the seropositivity of T. gondii in pregnant women in the country. The confirmed seropositivity of T. gondii in Cebu, Philippines, in the present study implies the endemicity of toxoplasmosis in this area and highlights the need for routine testing and increased public awareness.

Seroprevalence of Toxoplasma gondii in free-ranging and feral cats on Amami Oshima Island, Japan

On Amami Oshima Island, free-ranging and feral cats are harmful to wildlife populations. In this study, the seroprevalence of Toxoplasma gondii in these cats was examined using a newly developed Gaussia luciferase immunoprecipitation system assay. Of 1,363 cats, 123 cats (9.0%) was positive for T. gondii. The prevalence was significantly different in different areas; among cats in the rural area, where many wild animals live, including endangered species, T. gondii infection was more prevalent than in the urban area of the island. This finding indicates a possible risk to wildlife of infection from free-ranging and feral cats. Therefore, management of cats is important for wildlife conservation.

Seroprevalence of Toxoplasma gondii infection in feral cats in Qatar

BACKGROUND

Cats are essential in the life cycle of Toxoplasma gondii as they can shed the environmentally resistant oocysts after acquiring infection. Human populations living in cities with high densities of feral cats are therefore likely to be at risk of infection. The current study is the first to estimate the seroprevalence of T. gondii in the feral cat population in Qatar. We investigated the seroprevalence of T. gondii among 495 adult cats from urban and suburban districts in Qatar. Using results from the Modified Agglutination Test, we fitted statistical models with host sex, area and season as explanatory factors and seropositivity as the outcome.

RESULTS

The analysis revealed an overall seroprevalence of 82%. Seroprevalence was significantly higher in the summer season (P = 0.006). No significant difference was detected (P > 0.05) between seroprevalence in female and male cats and in cats from urban and suburban districts of Qatar.

CONCLUSIONS

Despite the seasonal difference, the observed seroprevalence of T. gondii suggests high environmental contamination throughout the year, with some female cats generating more intense responses compared to males. Both findings merit further investigations.

Toxoplasma gondii seroprevalence in pet cats in Norway and risk factors for seropositivity

OBJECTIVES

The aims of the study were to estimate Toxoplasma gondii seroprevalence in pet cats in Norway and to evaluate risk factors for seropositivity. Additionally, serum biochemistry and haematological variables for T gondii seropositive and seronegative cats were compared.

METHODS

A convenience sample of surplus sera submitted to the Central Laboratory, Norwegian University of Life Sciences, was collected. The samples were from healthy cats and cats with a variety of diseases. Analyses for IgG antibodies to T gondii were performed with a commercial direct agglutination test, with 1:40 as the threshold value. For risk factor analysis a logistic regression model of the relationship between predictors and the outcome was applied.

RESULTS

One hundred and ninety-six of 478 cats were seropositive for T gondii, and the estimated seroprevalence in the study sample was 41.0% (95% confidence interval 36.6-45.4). Compared with domestic cats, pedigree cats had reduced risk for Toxoplasma seropositivity (odds ratio [OR] 0.42). Males had increased risk (OR 1.63) compared with females. The effect of age was highly significant, and an increase in the cats' age across the interquartile range (IQR; 52-160 months/4-13 years of age) doubled the risk of Toxoplasma seropositivity (OR 2.11). The risk for Toxoplasma seropositivity among cats living in Oslo was significantly reduced (OR 0.51) when compared with the rest of Norway.

CONCLUSIONS AND RELEVANCE

Pet cats in Norway appear to be commonly exposed to T gondii. Signalment and geographical region influenced the odds of Toxoplasma seropositivity, whereas health status did not.

Seroprevalence of and Risk Factors for Toxoplasma gondii Infection in Cats in Estonia

In Estonia, northeastern Europe, Toxoplasma gondii seroprevalence in humans has not declined, in contrast to many other countries. The reasons for this are unknown. Domestic cats are important hosts in the epidemiology of the parasite, but information on local feline T. gondii infections has been lacking. An epidemiological cross-sectional study was conducted to estimate the seroprevalence of T. gondii and the risk factors associated with seropositivity in cats in Estonia. Surplus from blood samples that had been collected for unrelated diagnostic purposes from 306 pet cats and 184 shelter cats were analyzed for anti-T. gondii immunoglobulin G antibodies by using a direct agglutination test. Two questionnaires were designed to reveal relevant risk factors for seropositivity. The overall seroprevalence of T. gondii in cats in Estonia was 60.8%. Older age, outdoor access, hunting, living outside the city in the countryside, and not being a purebred cat were among the risk factors associated with seropositivity. T. gondii is highly prevalent in domestic cats in Estonia. This suggests that the environment has been contaminated with T. gondii. Seropositivity indicates previous oocyst shedding, and most of the cats had outdoor access. The increase in T. gondii seroprevalence with age indicates acquired infections, and most of the risk factors were lifestyle-related. Cat owners could diminish the risk of T. gondii infection and also limit the spread of the parasite by not allowing their cats to roam free.

Comparison of Toxoplasma gondii Seroprevalence in Shelter Cats and Dogs during 1999-2001 and 2009-2011 in Tokyo, Japan

Toxoplasma gondii is an important human health concern with respect to abortion, congenital hydrocephalus, and encephalitis in immunocompromised people. Cats and dogs both are potential sources of T. gondii because they have close contact with humans. However, no epidemiological surveys have been conducted in Tokyo over the past decade. Therefore, the present study investigated and compared the seroprevalence of T. gondii infection in shelter cats and dogs during 1999–2001 and 2009–2011 in Tokyo, Japan. Serum samples were collected from 337 shelter cats and 325 shelter dogs in urban and suburban areas of Tokyo, during 1999–2001 (233 cats and 219 dogs) and 2009–2011 (104 cats and 106 dogs). T. gondii antibodies were measured in the serum samples using a commercial latex agglutination test. Data were compared using the Fisher’s exact test, and significance was indicated at P < 0.05. The overall seroprevalence of T. gondii infection in cats was 5.6% (13 of 233) in 1999–2001 and 6.7% (7 of 104) in 2009–2011, and that in dogs was 1.8% (4 of 219) and 1.9% (2 of 106), respectively. Significantly higher seroprevalence was observed in cats from suburban areas compared with cats in urban areas during both periods (P < 0.05). These results reveal that there has been little change in the feline and canine seroprevalence over the past decade, indicating that the risk of T. gondii exposure for cats and dogs in Tokyo is considerably low as the seroprevalence has reached a steady state.

Seroprevalence of Toxoplasma gondii in White-Tailed Deer (Odocoileus virginianus) and Free-Roaming Cats (Felis catus) Across a Suburban to Urban Gradient in Northeastern Ohio

Felids serve as the definitive host of Toxoplasma gondii contaminating environments with oocysts. White-tailed deer (WTD; Odocoileus virginianus) are used as sentinel species for contaminated environments as well as a potential source for human foodborne infection with T. gondii. Here we determine the seroprevalence of T. gondii in a WTD and felid population, and examine those risk factors that increase exposure to the parasite. Serum samples from 444 WTD and 200 free-roaming cats (Felis catus) from urban and suburban reservations were tested for T. gondii antibodies using the modified agglutination test (MAT, cut-off 1:25). Antibodies to T. gondii were found in 261 (58.8%) of 444 WTD, with 164 (66.1%) of 248 from urban and 97 (49.5%) of 196 from suburban regions. Significant risk factors for seroprevalence included increasing age (P < 0.0001), reservation type (P < 0.0001), and household densities within reservation (P < 0.0001). Antibodies to T. gondii were found in 103 (51.5%) of 200 cats, with seroprevalences of 79 (51%) of 155 and 24 (53.3%) of 45 from areas surrounding urban and suburban reservations, respectively. Seroprevalence did not differ by age, gender, or reservation among the cats' sample. Results indicate WTD are exposed by horizontal transmission, and this occurs more frequently in urban environments. The difference between urban and suburban cat densities is the most likely the reason for an increased seroprevalence in urban WTD. These data have public health implications for individuals living near or visiting urban areas where outdoor cats are abundant as well as those individuals who may consume WTD venison.

Epidemiological review of toxoplasmosis in humans and animals in Romania

Infections by the protozoan parasite Toxoplasma gondii are widely prevalent in humans and other animals worldwide. However, information from eastern European countries is sketchy. In many eastern European countries, including Romania, it has been assumed that chronic T. gondii infection is a common cause of infertility and abortion. For this reason, many women in Romania with these problems were needlessly tested for T. gondii infection. Most papers on toxoplasmosis in Romania were published in Romanian in local journals and often not available to scientists in other countries. Currently, the rate of congenital infection in Romania is largely unknown. In addition, there is little information on genetic characteristics of T. gondii or prevalence in animals and humans in Romania. In the present paper we review prevalence, clinical spectrum and epidemiology of T. gondii in humans and animals in Romania. This knowledge should be useful to biologists, public health workers, veterinarians and physicians.

Intervention strategies to reduce human Toxoplasma gondii disease burden

Infection with Toxoplasma gondii is acquired through consumption of undercooked infected meat, or by uptake of cat-shed oocysts. Although congenital toxoplasmosis is generally considered to contribute most to the disease burden of T. gondii, ocular disease from acquired infection was recently shown to add substantially to the burden. In addition, toxoplasmosis in immune-compromised individuals usually results from reactivation of an infection acquired earlier in life. Nevertheless, prevention of toxoplasmosis commonly targets mainly pregnant women. We summarize current prevention strategies of congenital toxoplasmosis and evaluate options to improve protection of the general population (including pregnant women). To protect the general population, freezing of meat destined for raw or undercooked consumption is the most readily applicable option, especially when limited to meat from animals originating from nonbiosecure husbandry systems. In the long term, more health benefits are expected from cat vaccination; therefore, development of a cat vaccine and evaluation of its implementation is a research priority.

Serotyping of Toxoplasma gondii in cats (Felis domesticus) reveals predominance of type II infections in Germany

Background

Cats are definitive hosts of Toxoplasma gondii and play an essential role in the epidemiology of this parasite. The study aims at clarifying whether cats are able to develop specific antibodies against different clonal types of T. gondii and to determine by serotyping the T. gondii clonal types prevailing in cats as intermediate hosts in Germany.

Methodology

To establish a peptide-microarray serotyping test, we identified 24 suitable peptides using serological T. gondii positive (n=21) and negative cat sera (n=52). To determine the clonal type-specific antibody response of cats in Germany, 86 field sera from T. gondii seropositive naturally infected cats were tested. In addition, we analyzed the antibody response in cats experimentally infected with non-canonical T. gondii types (n=7).

Findings

Positive cat reference sera reacted predominantly with peptides harbouring amino acid sequences specific for the clonal T. gondii type the cats were infected with. When the array was applied to field sera from Germany, 98.8% (85/86) of naturally-infected cats recognized similar peptide patterns as T. gondii type II reference sera and showed the strongest reaction intensities with clonal type II-specific peptides. In addition, naturally infected cats recognized type II-specific peptides significantly more frequently than peptides of other type-specificities. Cats infected with non-canonical types showed the strongest reactivity with peptides presenting amino-acid sequences specific for both, type I and type III.

Conclusions

Cats are able to mount a clonal type-specific antibody response against T. gondii. Serotyping revealed for most seropositive field sera patterns resembling those observed after clonal type II-T. gondii infection. This finding is in accord with our previous results on the occurrence of T. gondii clonal types in oocysts shed by cats in Germany.

Food- and water-borne disease: using case control studies to estimate the force of infection that accounts for primary, sporadic cases

Disease models which take explicit account of heterogeneities in the risk of infection offer significant advantages over models in which the risk of infection is assumed to be uniform across all hosts. However, estimating the incidence rate (force of infection) in the different at-risk (exposure) groups is no easy matter. Classically, epidemiologists differentiate groups of hosts with different infection-risks according to their exposure to putative explanatory risk factors. The importance of these risk factors is assessed by case-control studies, in which the measure of effect (the difference in disease occurrence between one population and another) is the odds ratio. This paper describes for the first time how - and under what circumstances - the incidence in these different exposure groups can be estimated from odds ratios derived from case control studies in which controls have been selected by density sampling. This new estimation technique can be applied to any transmission modality but is especially useful in the case of models of food- and water-borne disease for which the case control literature represents a vast and, as yet, untapped resource. The paper finishes with a worked example using one of the most common of all food- and water-borne pathogens, Toxoplasma gondii.