Seroepidemiology of Toxoplasma gondii in dogs in Trinidad and Tobago

Cumulative incidence and spatial distribution of dogs exposed to Toxoplasma gondii

Toxoplasma gondii is one of the most important protozoa parasites worldwide. Although many seroprevalence studies have been performed in domestic and wild species, data on the cumulative incidence and the spatial distribution of T. gondii in animals are extremely scarce. In the present study, dogs from Botucatu municipality, São Paulo state, were followed for one year and their blood samples were collected on three moments: days 1, 180, and 360. The sera were submitted to the immunofluorescence antibody test (IFAT) to detect IgG antibodies to T. gondii. Age and sex were compared with IFAT results through statistical tests. Spatial analysis was used to detect clusters of seropositive dogs. Among the 350 dogs that were seronegative on day 1, 53 became seropositive in subsequent samplings; thus, cumulative incidence was 15.1% exposed dogs/year. Age and sex were not associated with serological results. The spatial analysis revealed that seropositive dogs were distributed in all the studied areas, with a significant cluster in a zone with poor sanitary conditions and low socioeconomic status. T. gondii is frequent and widely distributed in the urban area of Botucatu, and impoverished areas are possibly associated with high levels of environmental contamination by this parasite.

Seroprevalence of anti-Toxoplasma gondii antibodies in wild boars (Sus scrofa), hunting dogs, and hunters of Brazil

Seroprevalence of Toxoplasma gondii has been extensively studied in wild boars worldwide due to the emerging risk for human infection through meat consumption. However, this is the first study that reports toxoplasmosis seroprevalence in wild boars, wild boar hunters and their hunting dogs. The aim of the present study was to evaluate the seroprevalence of anti-T. gondii antibodies in the complex wild boars, hunting dogs and hunters, and to determine the risk factors associated with seropositivity in southern and central-western Brazil. Overall, anti-T. gondii seropositivity was observed in 15/71 (21.1%) wild boars by modified agglutination test (MAT); and 49/157 (31.2%) hunting dogs and 15/49 (32.7%) hunters by indirect immunofluorescent antibody test (IFAT). Seroprevalence of toxoplasmosis in Brazilian wild boars was within the national and international range, posting wild boars as potential environmental sentinels for T. gondii presence. In addition, the findings have comparatively shown that wild boars have been less exposed to infection than hunting dogs or hunters in both Brazilian regions. Seropositivity for T. gondii was statistically higher in 12/14 (85.7%) captured wild boars when compared to 5/57 (7.0%) free-range wild boars (p = 0.000001). Similarly, captured wild boars from anthropized areas were more likely to be seropositive than of natural regions (p = 0.000255). When in multiple regression model, dogs with the habit of wild boar hunting had significant more chance to be positive (adjusted-OR 4.62 CI 95% 1.16–18.42). Despite potential as sentinels of environmental toxoplasmosis, seroprevalence in wild boars alone may provide a biased basis for public health concerns; thus, hunters and hunting dogs should be always be included in such studies. Although hunters should be aware of potential T. gondii infection, wild boars from natural and agricultural areas may present lower protozoa load when compared to wild boars from anthropized areas, likely by the higher presence of domestic cats as definitive hosts.

Serosurvey for Infectious Agents Associated with Subfertility and Abortion in Dairy Cattle in Trinidad and Tobago, West Indies

Despite frequent reports of subfertility and abortion in dairy cattle in Trinidad and Tobago (T&T), little is known about the potential infectious and non-infectious causes. This study set out to investigate possible infectious causes of reproductive problems by measuring the seroprevalence of four of the most significant reproductive pathogens in dairy cattle worldwide: Brucella abortus (B. abortus); Neospora caninum (N. caninum), Bovine Viral Diarrhoea virus (BVDV), and Infectious Bovine Rhinotracheitis virus (IBRV). These four reproductive pathogens have been suspected to be present in dairy cattle in T&T for some time but, previously, studies have not been carried out to confirm their presence. Bulk milk samples were collected from 92 dairy farms across Trinidad, representing a total of 1177 dairy cattle. Four dairy farms were selected for individual milk sampling to assess in-farm seroprevalence levels. Milk samples were tested for antibodies to the four pathogens by commercial ELISA kits. The overall farm seroprevalence was 62% for N. caninium and 23% for IBRV, and no antibodies were detected in any of the bulk milk samples for B. abortus or BVDV. Mixed infections for IBRV and N. caninum were common. Seroprevalence levels were between 8% and 65% for N. caninum and between 3% and 53% IBRV on the four individual farms. These results reveal the presence of IBRV and N. caninum for the first time on the island of Trinidad and importantly reveal no evidence for the circulation of BVDV or B. abortus in dairy cattle in Trinidad.

SEROEPIDEMIOLOGY OF TOXOPLASMOSIS IN HUMANS AND DOGS FROM A SMALL MUNICIPALITY IN PARANA, BRAZIL

Abstract Toxoplasmosis is a worldwide zoonosis with important public health implications. The aims of this study were to determine and identify factors associated to the seroprevalence of anti-Toxoplasma gondii antibodies in humans and dogs from Jataizinho, Parana State, Brazil. Serum samples from 280 humans and 766 dogs, from rural and urban areas, were tested by indirect immunofluorescent antibody test. Positive dilutions were ≥ 1:16. Epidemiological informations were obtained through an individual questionnaire and data tabulation was performed using EpiInfo 3.5.3 (CDC, Atlanta). Statistical significance was evaluated by chi-square (ᵪ2) or Fisher's exact tests with a 5.0 % significance level. The seroprevalence in humans was 70.00% (196/280), as follows: 69.08% (143/207) in rural and 72.60% (53/73) in a slum urban community. The seroprevalence in dogs was 52.35% (401/766), as follows: 71.74% (99/138) in rural and 48.08% (302/628) in urban area. In rural areas, there was no factor associated to risk of infection. In urban slum community, visualizing more than four rats at home was a factor statistically associated to seropositivity for human toxoplamosis. Infection of urban dogs was associated to age, contact with stray dogs or rodents, and free access to street. The results indicated a similar possibility of contact with Toxoplasma gondii between dogs and humans living in rural or slum urban areas of small municipalities.

Toxoplasma gondii, Neospora caninum and Leishmania spp. serology and Leishmania spp. PCR in dogs from Pirassununga, SP

Abstract We examined the presence of antibodies against the parasites Toxoplasma gondii, Neospora caninum, and Leishmania spp., as well the presence of DNA from Leishmania spp., in dogs from Pirassununga - SP. The seropositivity rate was compared with the animals’ originating location. Three hundred seventy-three blood samples from the county’s kennel and local veterinary clinics were collected and analyzed. A total of 300 samples were tested for T. gondii and N. caninum using an indirect immunofluorescence antibody test (IFAT); 45% (135/300) were positive for T. gondii and 24.3% (73/300) were positive for N. caninum. Three hundred seventy-three samples were tested for Leishmania spp. using the IFAT. Of these, 4.6% (17/373) were positive. Additionally, 145 samples were tested using a polymerase chain reaction (PCR); of these samples, 0.7% (1/145) was positive. Considering the results, we conclude that these parasites are present in the city of Pirassununga - SP and that the animals have contact with the protozoan. It is therefore necessary to create methods for disease prevention to maintain both animal and human health in regard to leishmaniasis and toxoplasmosis.

Seroprevalence of Toxoplasma gondii infection in domestic dogs in an area from northwest of Iran: a cross-sectional study using immunodominant surface antigen 1 (SAG1)

Toxoplasma gondii is an obligate intracellular protozoan parasite that infects humans and animals. T. gondii surface antigen 1 (SAG1) is an appropriate antigen with high specificity and sensitivity for the detection of T. gondii infection in humans and animal hosts. The aim of this study was to determine the seroprevalence of T. gondii infection using SAG1 antigen (P30) in ownership dogs in Meshkin-Shahr district in the northwestern Iran. The sera samples were collected from 171 domestic dogs and tested using indirect ELISA (SAG1 antigen). The data were analyzed using SPSS software version 13. From a total of 171 dogs, 82 (48 %) of them were sero-positive. No statistical significant difference was seen between T. gondii infection and gender (P = 0.995). The highest sero-prevalence of rate was observed in >5 years animals; but no statistical significant difference was seen between T. gondii infection and age (P = 0.589). Our findings indicate that Toxoplasma seropositivity rate is high in ownership dogs in northwest of Iran. This is probably due to high exposure to contaminated food, soil, or water sources with sporulated Toxoplasma oocysts.

Prevalence of antibodies against Toxoplasma gondii and Neospora caninum in dogs

Toxoplasmosis and neosporosis are parasitic diseases of global importance. The present study had the objective to determine the influence of age, sex and breed in the prevalence of antibodies against both diseases in dogs from Brotas city, São Paulo State, Brazil. Blood samples of 342 dogs were collected, and the age, sex and breed of each animal were recorded. The serological diagnosis for toxoplasmosis and neosporosis were performed using the immunofluorescent antibody test (IFAT). The Fischer's test was used to calculate the association probability of the variables, with α = 5%. For toxoplasmosis the prevalence of antibodies was 26.9% (CI 95% 22.4-31.8%), and for neosporosis 4.97% (CI 95% 3.1-7.8%). The statistical analysis revealed a higher risk of infection for T. gondii in dogs with more than five years.

Frequency of Toxoplasmosis in Water Buffalo (Bubalus bubalis) in Trinidad

Toxoplasmosis has been reported to occur in several animals and humans causing different clinical manifestations. The study was conducted to determine the frequency of Toxoplasma gondii antibodies (IgG) in water buffalo (Bubalus bubalis) across farms in Trinidad using a latex agglutination test. Of a total of 333 water buffalo tested, 26 (7.8%) were seropositive for T. gondii antibodies. Seropositivity for toxoplasmosis was statistically significantly (P < 0.05; χ²) higher in adult water buffalo, 12.4% (14 of 113) compared with young water buffalo, 4.2% (6 of 143). Seropositivity for toxoplasmosis across the seven farms ranged from 0.0% (0 of 20) in Farm G compared with 20.0% (10 of 50) detected in Farm B. The differences in seropositivity by management system, free-ranging 6.7% (14 of 213) and semi-intensive 10.0% (12 of 120) and by sex, in male 6.7% (7 of 104) and female 8.3% (19 of 229) water buffalo, were not statistically significant (P > 0.05; χ²). This is the first documentation of toxoplasmosis in water buffalo in Trinidad.

Risk factors associated with Toxoplasma gondii infection in dairy cattle, state of Rio de Janeiro

Toxoplasmosis is one of the most common parasitic zoonoses throughout the world. Infection in man and animals varies in different geographical areas influenced by many environmental conditions. Seroprevalence of Toxoplasma gondii infection in cattle in Brazil ranges from 1.03 to 71%. A cross-sectional survey was carried out in 58 out of 453 farms in the South Fluminense Paraiba Valley, State of Rio de Janeiro, Brazil. Over 3-year-old cattle (n=589) from dairy herds were selected for blood collection and detection of anti-T. gondii antibodies by indirect immunofluorescence reaction (IFA) with initial titration of 1:16; titers > 64 were considered positive. Univariate analysis of risk factors showed that cats in contact with cattle, cats in contact with drinking water, and number of cats were associated with T. gondii seroprevalence. Logistic regression revealed a two-fold increased risk for infection of cattle (p=0.0138) through larger number of cats (>3) compared with low numbers of cats (1-2) on the farm. In contrast, the presence of chickens was considered a protective factor (p=0.025).

Antibodies to Toxoplasma gondii in stray and household dogs in Guangzhou, China

The frequency of Toxoplasma gondii antibodies in stray and household dogs in Guangzhou, China was examined by ELISA on serum samples from 150 animals (36 strays and 114 from households) and the overall prevalence was 21.3%. The extent of infection in stray dogs (33.3%) was significantly higher (P < 0.05) than in household dogs (17.5%). Infection in male and female dogs of both groups was not significantly different (P >or= 0.05), i.e., 31.8% versus 35.7% for male and female in stray dogs, and 14.5% versus 22.2% in household dogs. The results of the present investigation indicate that the seroprevalence of T. gondii infection in dogs was high in Guangzhou, especially in strays. Therefore, it is essential to implement integrated strategies to prevent and control T. gondii infection in both stray and household dogs.

Prevalence of Neospora caninum and Toxoplasma gondii in sheep and dogs from Guarapuava farms, Paraná State, Brazil

Sheep and dog blood samples were collected from nine farms in the county of Guarapuava, Paraná, Brazil. The indirect fluorescent antibody test (IFAT) was used to detect Neospora caninum and Toxoplasma gondii antibodies. Herein, serum samples from 305 sheep were evaluated, being 29 (9.5%) and 157 (51.5%) seropositives to N. caninum and T. gondii, respectively. Seven (29.1%) and five (20.8%) out of 24 dogs were seropositives to N. caninum and T. gondii, respectively. There were no differences among the sheep serology for N. caninum and reproductive problems, management and animal feeding variables, neurological problems and presence of other animals species on the farm (P>or=0.05). The simultaneous frequency of antibodies between N. caninum and T. gondii was 5.2% in the herds. Age, breed, farm size, semi-intensive activity, mineral salt supplementation, water origin, stage of the pregnancy when reproduction problems occurred, neurological problems in lambs, presence of rodents in the food room and pasture cat access were identified as associated factors for the occurrence of toxoplasmosis in sheep (P<0.05). There were no differences among the seropositivity in dogs for N. caninum and T. gondii and breed, age and sex (P>or=0.05). The present work is the first report on serum prevalence of N. caninum in sheep from the state of Paraná, Brazil.

Seroprevalence of Toxoplasma gondii antibodies in stray cats and dogs in the Bangkok metropolitan area, Thailand

Cats and dogs are the most popular pet animals worldwide. Cats are the natural reservoir of Toxoplasma gondii and excrete the resistant oocyst to environments. On the other hands, dogs play a role in the mechanical transmission of the parasite. Stray cats and dogs in the Bangkok metropolitan area are becoming a public concern because there is a considerable increase in their number annually. These facts indicate the risk of mechanically spreading zoonoses including toxoplasmosis to humans since human acquire the infection from infected mammals, either directly or indirectly. In the present study, the presence of T. gondii antibodies was examined in 592 cats and 427 dogs from October 2001 to September 2002 by using a latex agglutination test. T. gondii antibodies were detected in 65 (11.0%) of the 592 cats and 40 (9.4%) of the 427 dogs. The antibody titers in the positive animals ranged from 1:64 to 1:2048. Seroprevalence was significantly higher in female cats than in male cats. The present study suggested that T. gondii was widespread in the stray animals in the Bangkok metropolitan area; therefore, it is essential to control the number of stray cats and dogs in order to reduce the transmission of toxoplasmosis to animals and humans.

Toxoplasma gondii and Chlamydophila abortus in Caprine Abortions in Tobago: a Sero-Epidemiological Study

A sero-epidemiological study was conducted on a goat farm that experienced an abortion epidemic in the 2005 breeding season in Tobago. Serum samples of goats (aborting and non-aborting) and cats were collected, in addition to the use of stored sera from the farm sampled in 2003 and 2004. Farm records on the reproductive and mortality rates for year 2003, 2004 and 2005 were also reviewed. The sera were screened for Toxoplasma gondii antibodies using the latex agglutination test (LAT), Chlamydophila abortus with an enzyme-linked immunosorbent assay (ELISA) and Brucella abortus using the buffered plate agglutination test (BPAT). Farm records revealed that for the period 2003-2005, the average kid per doe rate decreased from 2.1 to 1.5, the mortality rate increased from 6.3% in 2002 to 19.4% in 2004 and the fertility rate decreased from 98-99% (2002-2004) to 89% (2005). There was a dramatic increase in the abortion rate from <1% (2002, 2003 and 2004) to 29.2% (2005). Of a total of 161 sera tested comprising 12 from 2003, 89 from 2004 and 70 from 2005, 0 (0.0%), 21 (23.6%) and 45 (64.3%) were positive for T. gondii agglutinins (i.e. titres > or =1 : 64) and the differences were statistically significant (P < 0.05; chi(2)). Of all serum samples tested, only 1 (1.1%) of 89 from 2004 was positive for C. abortus while all the sera tested were negative for B. abortus. Amongst the 24 does which aborted in 2005 and were available for testing in mid-2005, 15 (62.5%) had reciprocal titres of > or =1 : 2048, three (12.5%) each had titres of 1 : 1024, 1 : 256 and < or =1 : 16 i.e. negative. The seroprevalence and titres of does that aborted, 20 (87.0%) of 23, all with titres > or =1 : 256 suggesting current infection, were statistically significantly (P < 0.05; chi(2)) higher than was detected amongst does that delivered normal kids, 25 (53.25) of 47 with 22 (48.8%) having titres of > or =1 : 256. One (50.0%) of two cats caught and tested was seropositive with a reciprocal titre of 128. This is considered the first documentation of T. gondii agglutinins in caprine abortion as well the detection of C. abortus antibodies from livestock in Trinidad. It is concluded that of the three zoonotic abortifacient pathogens tested for, T. gondii appeared to have played some aetiological role in the abortion epidemic investigated.

Molecular epidemiology: A multidisciplinary approach to understanding parasitic zoonoses

Sound application of molecular epidemiological principles requires working knowledge of both molecular biological and epidemiological methods. Molecular tools have become an increasingly important part of studying the epidemiology of infectious agents. Molecular tools have allowed the aetiological agent within a population to be diagnosed with a greater degree of efficiency and accuracy than conventional diagnostic tools. They have increased the understanding of the pathogenicity, virulence, and host-parasite relationships of the aetiological agent, provided information on the genetic structure and taxonomy of the parasite and allowed the zoonotic potential of previously unidentified agents to be determined. This review describes the concept of epidemiology and proper study design, describes the array of currently available molecular biological tools and provides examples of studies that have integrated both disciplines to successfully unravel zoonotic relationships that would otherwise be impossible utilising conventional diagnostic tools. The current limitations of applying these tools, including cautions that need to be addressed during their application are also discussed.

Seroepidemiology of Toxoplasma gondii and Neospora caninum in dogs from the state of Paraíba, Northeast region of Brazil

A cross-sectional study was conducted to determine the seroprevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies and to investigate the risk factors related to antibodies against T. gondii and N. caninum in dogs of the city of Campina Grande, state of Paraiba, Northeast region of Brazil. For this purpose, 286 blood samples were collected from dogs during the rabies vaccination campaign, in September 2003, and on this occasion questionnaires addressing epidemiological aspects of the infections were given to each dog owner. The sera were analyzed for anti-T. gondii and anti-N. caninum antibodies by indirect fluorescent antibody tests. Of the total of 286 dogs, 129 were positive for T. gondii (titer16) with a prevalence value of 45.1% (95% CI=39.24-51.07%). For N. caninum, 24 dogs were positive (titer50), with a prevalence value of 8.4% (95% CI=5.45-12.23%). Antibodies to T. gondii and N. caninum were found simultaneously in 14 dogs (4.9%; 95% CI=2.7-8.08%). For T. gondii infection, the risk factors associated with seroprevalence was the age of the animals, with dogs older than one year presenting higher values of odds ratio, and co-habitation of cats in the household. For N. caninum infection, dogs that have street contact had higher odds of seropositivity than dogs that remained exclusively in a domestic environment.

Toxoplasma gondii spreading in an urban area evaluated by seroprevalence in free-living cats and dogs

Infection by the protozoan parasite, Toxoplasma gondii is widely prevalent in humans and animals throughout the world. Transmission takes place mainly by ingestion of raw or undercooked meat that contains parasite cysts or by ingestion of oocysts excreted in cat faeces, which can contaminate water and raw vegetables. The incidence of toxoplasmosis in urban areas can thus be also related to environmental contamination with oocysts. A direct measure of this environmental contamination by oocyst counting is unfeasible for technical reasons. An interesting alternative for measuring T. gondii urban spreading is the seroprevalence in free-living urban animals, used as sentinels, once they are exposed to similar risks of Toxoplasma infection-like humans. With this aim, we tested serum samples from stray cats and dogs for antibodies to T. gondii by indirect haemagglutination assay (IHA) and enzyme-linked immunosorbent assay (ELISA). Antibodies to T. gondii were found in 40% (40 of 100) of the cats, less than the 50.5% (101 of 200) found in dogs by ELISA (P < 0.05). Haemagglutination showed low resolution and concordance, precluding their use for diagnosis of T. gondii infection compared with ELISA. The prevalence of T. gondii was lower among stray cats probably due to their selective alimentary habits and lower water and food intake. Toxoplasma gondii seroprevalence in stray dogs and cats could be an indirect indicator of the parasite spreading in urban areas.