Environmental Factors Associated with the Seroprevalence of Toxoplasma gondii in Wild Boars (Sus scrofa), France

Toxoplasma gondii is a protozoan parasite infecting humans and animals. Wild boars Sus scrofa are a potential source of human infection and an appropriate biological model for analyzing T. gondii dynamics in the environment. Here, we aimed to identify environmental factors explaining the seroprevalence of toxoplasmosis in French wild boar populations. Considering 938 individuals sampled from 377 'communes', overall seroprevalence was 23% (95% confidence interval: [22-24]). Using a Poisson regression, we found that the number of seropositive wild boars detected per 'commune' was positively associated with the presence of European wildcats (Felis silvestris) and moderate winter temperatures.     

Toxoplasma gondii infection and schizophrenia: a case control study in a low Toxoplasma seroprevalence Mexican population

There are conflicting reports concerning the association of Toxoplasma gondii infection and schizophrenia in humans. Therefore, we determined such association in a Mexican population of Mestizo ethnicity. Through a case-control study design, 50 schizophrenic patients and 150 control subjects matched by gender, age, residence place, and ethnicity were examined with enzyme-linked immunoassays for the presence and levels of T. gondii IgG antibodies and for the presence of T. gondii IgM antibodies. Schizophrenic patients attended a public psychiatric hospital in Durango City, Mexico, and the control group consisted of individuals of the general population of the same city. Socio-demographic, clinical and behavioral characteristics from the study subjects were also obtained. Both the seroprevalence and the level of T.gondii IgG antibodies were higher in schizophrenic patients (10/50; 20%) than in control subjects (8/150; 5.3%) (OR=4.44; 95% CI: 1.49-13.37; P=0.003). The IgG T. gondii levels higher than 150 IU/ml were more frequently observed in patients than in controls (10% versus 2%, respectively; P=0.02). One (50%) of the two patients with recently diagnosed schizophrenia and none of the controls had T. gondii IgM antibodies (P=0.01). T. gondii seropositivity was significantly higher in patients with a history of cleaning cat excrement (P=0.005), and suffering from simple schizophrenia (ICD-10 classification: F20.6) (P=0.03) than patients without these characteristics. Toxoplasma seroprevalence was also significantly higher in patients with simple schizophrenia (F20.6) than in those with paranoid schizophrenia (F20.0) (P=0.02). This study provides elements to clarify the controversial information on the association of T. gondii infection and schizophrenia.     

Seroprevalence and risk factors for Toxoplasma gondii infection on pig farms in central China

Toxoplasma gondii is a protozoan parasite that causes severe diseases in mammals, including humans, around the world. In China, pork is the main meat source; accordingly, T. gondii in pigs is considered an important source for human toxoplasmosis. Understanding the epidemiology of toxoplasmosis in pig farms is thus important for control of the disease in humans. The purpose of the present study was to investigate the epizootiology of T. gondii infections in pig farms in central China by assessing the seroprevalence and risk factors of this disease. In the present study, 3,558 sera samples were collected from pigs in 37 large-scale pig farms in this region and tested by AG-ELISA. The total seroprevalence was 24.5%, with the greatest prevalence in breeding pigs. The risk factors for toxoplasmosis suggest that high frequency of the contact of pigs with cats (P ≤ 0.01; IC 95%), high density of pig breeding (P ≤ 0.01; IC 95%), the presence of mosquitoes and flies (P ≤ 0.01; IC 95%), semi-patency pens (P ≤ 0.05; IC 95%), and low frequency of scavenging (P ≤ 0.01; IC 95%) were all associated with seroprevalence. In addition, the use of sulfonamides (P ≤ 0.01; IC 95%) significantly decreased seroprevalence. This is the first report of anti- T. gondii antibodies in pigs on large-scale pig farms in central China. The findings will provide useful information for designing control strategies of toxoplasmasis in pig farms.     

Seroepidemiology of Toxoplasma gondii infection in general population in a northern Mexican city

There is a lack of information about the seroepidemiology of T. gondii infection in the general population of Durango City, Mexico. Anti- Toxoplasma gondii IgG and IgM antibodies were sought in 974 inhabitants in Durango City, Mexico with the use of enzyme-linked immunoassays. in total, 59 (6.1%) of 974 participants (mean age 37 ± 16.1 yr) had IgG anti- T. gondii antibodies. Twenty (2.1%) of them also had IgM anti- T. gondii antibodies. IgG levels of 13-99, 100-150, and >150 International Units (IU)/ml were found in 14 (23.7%), 3 (5.1%), and 42 (71.2%) anti- T. gondii IgG-positive participants, respectively. Prevalence of infection increased with age (P < 0.05), and was significantly lower in participants born in Durango State than those born in other Mexican states (P < 0.01). Toxoplasma gondii infection was significantly associated with consumption of boar meat (adjusted odds ratio [OR] = 3.02; 95% confidence interval [CI]: 1.49-6.13), and squirrel meat (adjusted OR = 2.18; 95% CI: 1.17-4.09). in addition, infection was negatively associated with travel abroad (adjusted OR = 0.42; 95% CI: 0.23-0.77), and salami consumption (adjusted OR = 0.57; 95% CI: 0.32-0.99). This is the first report of seroprevalence and contributing factors for T. gondii infection in general population in Durango City, and of an association of the consumption of boar meat with T. gondii infection. This study provides a basis for the design of successful preventive measures against T. gondii infection.     

Prevalence of antibodies to Toxoplasma gondii in horses in Riyadh Province, Saudi Arabia

The aim of the present study was to determine the seroprevalence of Toxoplasma gondii in horses used for sporting purposes in the Province of Riyadh, Saudi Arabia. In total, 266 serum samples from clinically healthy horses were analyzed for anti- T. gondii antibodies using the Sabin-Feldman dye test. Antibodies to T. gondii were found in 84 (31.6%) horses, with specific titers of 1∶16 (78 with a prevalence of 29.3%), 1∶64 (4 with a prevalence of 1.5%), and 1∶256 (2 with a prevalence of 0.8%). The number of seropositive horses in Shaqra (43.7%) was considerably higher than in other regions, with the lowest occurring in Al-Majmaah (11.0%). However, the differences in seroprevalence between the 6 locations were not statistically significant (P > 0.05). In contrast, the overall seroprevalence in Riyadh province was higher than that reported in other countries. Horses are not a direct source of infection for human toxoplasmosis in this region. Usually human infection is facilitated via cats, which are the reservoir hosts for this parasite.     

Performance of a Western immunoblot assay to detect specific anti-Toxoplasma gondii IgG antibodies in human saliva

Toxoplasma gondii represents the most prominent infectious parasitic organism found in humans. While normally asymptomatic in healthy individuals, toxoplasmosis can cause abortion in patients during pregnancy, or can be fatal in immunosupressed individuals such as persons suffering from acquired immunodeficiency syndrom (AIDS). Toxoplasma gondii infection in humans is routinely assesssed by serological means. Here, we show that detection of anti-T. gondii IgG is also possible using a non-invasive methodology employing saliva. Sera and saliva of 201 healthy volunteers were investigated for the presence of anti-T. gondii-IgG antibodies by immunoblotting. The sera of 59 (29.4%) individuals showed IgG antibodies against T. gondii by ELISA, Vidas, and immunoblotting; 58 (98.3%) of these were also positive for anti-T. gondii IgG in the saliva immunoblot, with diagnostic relevant bands of Mr of 32-35 kDa and 40-45 kDa. The saliva immunoblot test exhibits a specificity of 100% and a sensitivity of 98.5%. Thus, saliva could be used as an alternative, non-invasive means for the detection of specific anti-T. gondii IgG in humans.     

Prevalence of Toxoplasma gondii antibodies and DNA in dogs in Shanghai, China

The aim of this study was to estimate the prevalence of Toxoplasma gondii infection in dogs in Shanghai, China. A total of 1,736 sera (1,178 from the city center and 558 from the outskirts) was collected from healthy dogs and tested for T. gondii infection by indirect hemagglutination; 56 sera (3.2%) were considered positive, with titers > 1∶64. The seroprevalence in dogs from the outskirts of the city (town dogs, 6.0%; countryside dogs, 9.8%) was significantly higher (P > 0.05) than that in city center dogs (1.3%). The age of the dog has an apparent association with T. gondii infection; that is, the seroprevalence ranged from 1.9% (in dogs ≤ 1 year old) to 3.6% (in dogs > 5 years old). There was no significant difference in gender (P ≥ 0.05), that is, 1.4% versus 1.1% for male and female dogs in the city center, 6.2% versus 5.9% in town dogs, and 8.4% versus 11.5% in country dogs, respectively. These results suggest that T. gondii infections are common in dogs from the city center and outskirts of Shanghai, but the T. gondii seroprevalence in dogs is considerably lower than in other regions in PR China. The presence of T. gondii DNA was investigated by nested PCR on 110 blood samples from city center dogs, but no positive samples were found, which may suggest that there were no acute infections of T. gondii in the city center samples. Our results indicate that the control and treatment of toxoplasmosis in Shanghai has been effective. However, it is still essential to further implement integrated strategies to prevent and control T. gondii infection in dogs in both the city center and the outskirts.     

Toxoplasmosis in pregnant women in Crete

In Greece there are no official recommendations concerning the management of pregnant women for the prevention of congenital toxoplasmosis. A protocol for monitoring pregnant women was designed in order to differentiate between acute and latent toxoplasmosis and was tested successfully for 7 years. The maternofetal transmission rate in Crete was assessed and a map showing seroprevalence of pregnant women in all prefectures of Greece was prepared. The high seroprevalence of Toxoplasma gondii in Greece (up to 46% in some areas) may be explained by: (a) the presence of a great number of stray cats; (b) the Greek diet consisting of large amounts of raw, wild vegetables and salads that could easily be contaminated with oocysts; (c) the high consumption of meat, smoked pork and sausages, well-documented sources of T. gondii infection. T. gondii genotypes were characterized, directly from clinical samples, after PCR-RFLP on the SAG2 gene and sequence analysis at the restriction sites. They belonged to all 3 clonal lineages.     

Seroepidemiology of Toxoplasma gondii infection in pregnant women in rural Durango, Mexico

The epidemiology of Toxoplasma gondii infection in pregnant women in rural Mexico is largely unknown. The seroepidemiology of T. gondii infection in 439 pregnant women from 9 communities in rural Durango State, Mexico was investigated. Using commercial enzyme-linked immunoassays, sera were tested for T. gondii IgG, IgM, and avidity antibodies. Prevalences of T. gondii IgG antibodies in the communities varied from 0% to 20%. Overall, 36 (8.2%) of the 439 women had IgG T. gondii antibodies. Ten (2.3%) women had also T. gondii IgM antibodies; IgG avidity was high in all IgM-positive women, suggesting chronic infection. None of the women, however, had delivered a known T. gondii-infected child. The seroprevalence was significantly higher (P < 0.05) in women from low socio-economic conditions (14%) than in those with higher socio-economic status (6.6%). Multivariate analysis showed that T. gondii infection was associated with soil floors at home (adjusted OR = 2.89; 95% CI: 1.12-7.49). This is the first epidemiological study of T. gondii infection in pregnant women in rural Mexico.     

Seroprevalence of Toxoplasma gondii in equids from Southern Spain

Antibodies to Toxoplasma gondii were determined in serum samples from 616 equids (454 horses, 80 mules and 82 donkeys) in a cross-sectional study of 420 herds in Andalusia (Southern Spain), the region with the highest number of equids in Spain. Antibodies to T. gondii were found in 10.8% horses, 15.0% mules and 25.6% donkeys by using the modified agglutination test (MAT) at a cut-off of 1:25. Herd seroprevalence for horses, mules and donkeys was 14.7% (48/327), 23.9% (11/46) and 34.0% (16/47), respectively, and 75 herds (17.8%) had at least one seropositive animal. Significant differences in T. gondii seroprevalence were observed among species, with donkeys having the highest seroprevalence and horses the lowest (P=0.04). Seroprevalence was significantly higher in herds with presence of domestic ruminants. This study is the first report of the presence of T. gondii antibodies in equine species in Spain and the first reporting T. gondii infection in donkeys in Europe. The presence of antibodies is indication of contact with the parasite and therefore, consumption of equine meat could be a potential source of human infection in Spain.     

Seroepidemiology of Toxoplasma gondii infection among Chinese aboriginal and Han people residing in mountainous areas of northern Thailand

A seroepidemiological survey of Toxoplasma gondii infection among Chinese refugees, including Akka and Yau aborigines and Han people living in mountainous areas at elevations of 1,100-1,400 m in Chiang-Rai Province of northern Thailand, was conducted during January 2003 using the latex agglutination test. The overall seroprevalence of T. gondii infection was 9.1% for Akka aborigines, 37.9% for Yau aborigines, and 7.9% for Han people, respectively. No significant gender difference in seroprevalence was found among any of the groups (P > 0.05). The results of a multiple logistic regression analysis for Yau aborigines and Han people showed that the older the age, the higher the odds ratios (OR) of being seropositive (OR = 3.0, 95% confidence interval [CI] = 0.5 to 16.9, P < 0.001 and OR = 1.5, 95% CI = 0.3 to 8.0, P = 0.06 for the elderly group vs. the child group for the Yau aborigines and Han people, respectively). In contrast, the OR was lower among older Akka aboriginal populations (OR = 0.1, 95% CI = 0.0 to 0.4, P < 0.001). Ethnically, Yau aboriginal populations had a significantly higher seroprevalence than did the Akka aborigines and Han people (P < 0.001).     

Lacrimal secretory IgA in active posterior uveitis induced by Toxoplasma gondii

It is quite difficult to diagnose active toxoplasmosis in patients with ocular toxoplasmosis. Active posterior uveitis presumably due to Toxoplasma gondii infection (APUPT) is seldom produced during a prime-infection; hence most patients do not show high IgM antibodies. High levels of IgA have been described in active toxoplasmosis. The purpose of this study was to investigate possible association between APUPT and the specific anti-parasite sIgA in tears. The study was carried out as case-control. Tears of 25 clinically confirmed APUPT patients and 50 healthy control subjects were analyzed. All were IgG seropositive. Specific sIgA was determined by ELISA assay using T. gondii RH strain crude extract. Anti-T. gondii sIgA was found in 84% of the cases and in 22% of the control subjects. The intensity of the reaction was higher in APUPT cases (P = 0.007). There was strong association between APUPT patients and lacrimal sIgA (odds-ratio 18.61, P = 0.0001). ELISA test sensitivity was 84% and specificity 78%. Our data suggest that anti-T.gondii secretory IgA found in tears may become an important marker for active ocular toxoplasmosis.     

Age-related Toxoplasma gondii seroprevalence in Dutch wild boar inconsistent with lifelong persistence of antibodies

Toxoplasma gondii is an important zoonotic pathogen that is best known as a cause of abortion or abnormalities in the newborn after primary infection during pregnancy. Our aim was to determine the prevalence of T. gondii in wild boar to investigate the possible role of their meat in human infection and to get an indication of the environmental contamination with T. gondii. The presence of anti-T. gondii antibodies was determined by in-house ELISA in 509 wild boar shot in 2002/2003 and 464 wild boar shot in 2007. Most of the boar originated from the "Roerstreek" (n = 673) or the "Veluwe" (n = 241). A binormal mixture model was fitted to the log-transformed optical density values for wild boar up to 20 months old to estimate the optimal cut-off value (-0.685) and accompanying sensitivity (90.6%) and specificity (93.6%). The overall seroprevalence was estimated at 24.4% (95% CI: 21.1-27.7%). The prevalence did not show variation between sampling years or regions, indicating a stable and homogeneous infection pressure from the environment. The relation between age and seroprevalence was studied in two stages. Firstly, seroprevalence by age group was determined by fitting the binary mixture model to 200 animals per age category. The prevalence showed a steep increase until approximately 10 months of age but stabilized at approximately 35% thereafter. Secondly, we fitted the age-dependent seroprevalence data to several SIR-type models, with seropositives as infected (I) and seronegatives as either susceptible (S) or resistant (R). A model with a recovery rate (SIS) was superior to a model without a recovery rate (SI). This finding is not consistent with the traditional view of lifelong persistence of T. gondii infections. The high seroprevalence suggests that eating undercooked wild boar meat may pose a risk of infection with T. gondii.     

Prevalence and co-infection of Toxoplasma gondii and Neospora caninum in Apodemus sylvaticus in an area relatively free of cats

The protozoan parasite Toxoplasma gondii is prevalent worldwide and can infect a remarkably wide range of hosts despite felids being the only definitive host. As cats play a major role in transmission to secondary mammalian hosts, the interaction between cats and these hosts should be a major factor determining final prevalence in the secondary host. This study investigates the prevalence of T. gondii in a natural population of Apodemus sylvaticus collected from an area with low cat density (<2·5 cats/km2). A surprisingly high prevalence of 40·78% (95% CI: 34·07%-47·79%) was observed despite this. A comparable level of prevalence was observed in a previously published study using the same approaches where a prevalence of 59% (95% CI: 50·13%-67·87%) was observed in a natural population of Mus domesticus from an area with high cat density (>500 cats/km2). Detection of infected foetuses from pregnant dams in both populations suggests that congenital transmission may enable persistence of infection in the absence of cats. The prevalences of the related parasite, Neospora caninum were found to be low in both populations (A. sylvaticus: 3·39% (95% CI: 0·12%-6·66%); M. domesticus: 3·08% (95% CI: 0·11%-6·05%)). These results suggest that cat density may have a lower than expected effect on final prevalence in these ecosystems.     

Molecular cloning of ribosomal P protein in Toxoplasma gondii and the availability to detect antibody against recombinant protein in toxoplasmosis patients

Among the panel of monoclonal antibodies (mAb) against Toxoplasma gondii, mAb of Tg621 (Tg621) clone blotted 38 kDa protein which localized in the cytoplasm of tachyzoites by immunofluorescence microscopy. The protein was not released into the parasitophorous vacuole during or after invasion. The cDNA fragment encoding the protein was obtained by screening a T. gondii cDNA expression library with Tg621. The full length cDNA sequence was completed with 5'-RACE as 1,592 bp, which contained open reading frame of 942 bp. The deduced amino acid sequence of Tg621 consisted of a polypeptide of 313 amino acids, with significant homology to ribosomal P proteins (RPP) of other organisms especially high to those of apicomplexan species. The expressed and purified TgRPP was assayed in western blot with the sera of toxoplasmosis patients and normal sera, which resulted in the 74.0% of positive reactions in toxoplasmosis patients whereas 8.3% in normal group. Therefore, the antibody formation against TgRPP in toxoplasmosis patients was regarded as specific for T. gondii infection and suggested a potential autoantibody.     

Seroprevalence of Toxoplasma gondii infection in Tibetan sheep in northwestern China

The seroprevalence of Toxoplasma gondii infection in Tibetan sheep was surveyed in Qinghai Province, northwestern China, in May and June 2010. In total, 580 serum samples was collected from 6 counties, and antibodies to T. gondii were detected by indirect hemagglutination (IHA) test. Antibodies to T. gondii were found in 29.8% (173/580); regional differences showed the highest prevalences in Nangqian County (39.4%) and Zaduo County (48.7%). The results of the present study indicate that infection with T. gondii in sheep is widely spread in China, including Tibetan sheep in Qinghai Province, and is a potential public health concern.     

Seroepidemiology of Toxoplasma gondii Infection among Healthy Blood Donors in Taiwan

Toxoplasma gondii is an opportunistic, zoonotic pathogen with a worldwide distribution. There are large variations in the seroprevalence of T. gondii infection in different regions of the world. Although toxoplasmosis became a notifiable communicable disease in Taiwan in 2007, little is known about its epidemiology among the general population. This cross-sectional study aimed to survey the seroprevalence of T. gondii infection and its risk factors among healthy blood donors in Taiwan. Through collaborating with the Taiwan Blood Services Foundation, a total of 1,783 healthy blood donors from all six-branch blood service centers participated in this study. The blood samples were tested for the presence of T. gondii antibodies and DNA using enzyme immunoassays and real-time PCR, respectively. Structured questionnaires were used to gather information on risk factors for T. gondii infection. Of the 1,783 participants, 166 (9.3%) tested positive for anti-Toxoplasma IgG, while 5 (0.28%) tested positive for anti-Toxoplasma IgM. The five IgM positive donors had high avidity antibodies suggestive of past infection. No active parasitemia was detected by real-time PCR assays. Multivariate logistic regression showed that undercooked pork meat consumption (adjusted odds ratio [OR] = 2.9; 95% confidence interval [CI]: 1.3–6.5), raw mussels consumption (adjusted OR = 5.3; 95% CI: 1.5–19.1), having a cat in the household (adjusted OR = 2.0; 95% CI: 1.2–3.2), a lower education level (adjusted OR = 1.6; 95% CI: 1.1–2.3), and donation place in eastern Taiwan (adjusted OR = 2.5; 95% CI: 1.6–3.9) were independent risk factors for Toxoplasma seropositivity. These findings provide information on the seroprevalence and epidemiology of T. gondii infection among healthy blood donors in Taiwan.     

Oocyst ingestion as an important transmission route of Toxoplasma gondii in Brazilian urban children

Toxoplasmosis is a cosmopolitan protozoan infection. Data regarding risk factors for the post-natal acquisition of Toxoplasma gondii infection in childhood are limited. We conducted a serological survey for T. gondii IgG antibodies and associated risk factors in 1,217 children 4-11-yr-old from Salvador, Brazil, using a commercial ELISA kit; antibodies were found in 17.5% of the children. Age (OR = 2.18; 95% CI: 1.50-3.17) and maternal schooling level (OR = 0.62; 95% CI: 0.42-0.92) were negatively associated with infection. A greater number of siblings (OR = 1.53; 95% CI: 1.12-2.09), cat at home (OR = 1.54; 95% CI: 1.06-2.24), house with non-treated piped water (OR = 2.54; 95% CI: 1.22-5.31), and the absence of a flush toilet at home (OR = 1.45; 95% CI: 1.04-2.01) were positively associated with T. gondii infection. Our data suggest that low socioeconomic levels and poor hygiene habits are important factors in favoring T. gondii infection.     

Serological survey of caprine toxoplasmosis in Ethiopia: prevalence and risk factors

The study was conducted to determine the prevalence and risk factors of toxoplasmosis in goats in Southern and central Ethiopia between October 2005 and May 2006. A total of 641 goats sera were tested using Modified Direct Agglutination Test (MAT), of which 480 (74.8% CI: 71.3, 78.2) were found to be positive. The highest prevalence was recorded in South Omo zone (82%) while the lowest was observed in East Shewa zone (62.2%). The study revealed that goats raised in southern Ethiopia are at a greater risk of acquiring T. gondii infection (OR = 2.55, CI: 1.726, 3.776; p = 0.000) than those which are raised in central Ethiopia. The prevalence of anti T. gondii antibody was significantly higher in older goats than in kids (OR = 2.33, CI: 1.490, 3.655; p < 0.0002) and in females than in males (p < 0.0007; OR = 0.68, CI: 0.542, 0.849). No significant difference was observed among goats kept under various husbandry practices. The high prevalence of toxoplasmosis in Ethiopian goats suggests a high risk of human infections. Further epidemiological investigation, isolation and genotyping of T. gondii are planned.     

Seroepidemiology of Toxoplasma gondii infection in human adults from three rural communities in Durango State, Mexico

There is scarce information concerning the epidemiology of Toxoplasma gondii infection in people of rural Mexico. Anti-T. gondii immunoglobulin (Ig)G and IgM antibodies were sought in 462 adult inhabitants from 3 rural communities of Durango, Mexico, using enzyme-linked immunoassays. In total, 110 (23.8%) of 463 persons had IgG anti-T. gondii antibodies. Ten (2.2%) of them also had IgM anti-T. gondii antibodies. Prevalences of T. gondii IgG antibodies in the 3 communities varied from 14.8 to 35.8%. The highest prevalence of infection was observed in participants older than 70 yr and in those with good housing conditions. Toxoplasma gondii infection was significantly associated with consumption of squirrel (adjusted odds ratio [OR] = 4.22; 95% confidence interval [CI] = 1.11-16.05) and turkey meat (adjusted OR = 4.58; 95% CI = 1.14-18.44). This is the first epidemiological study of T. gondii prevalence in rural Mexico.