National seroprevalence of Toxoplasma gondii in India

This article reports the first national serological prevalence of Toxoplasma gondii in India. In total, 23,094 serum samples were tested for T. gondii IgG and IgM antibodies with the use of a solid-phase immunocapture ELISA. Antibodies (IgG) were found in 24.3%; IgM antibodies were detected in 2% of the samples. The lowest seroprevalences were in the northern parts of India, with the highest in the south. These data probably reflect the effects of significantly drier conditions and, therefore, a negative impact on the survivability of T. gondii oocysts.     

Seroprevalence of Toxoplasma gondii in pigs from Vietnam

Pigs are considered an important source of Toxoplasma gondii infection for humans. Antibodies to T. gondii were determined in serum samples from 587 pigs from Vietnam using the modified agglutination test (MAT) and found in 160 of 587 (27.2%) pigs, with MAT titers of 1:25 in 32 pigs, 1:50 in 34 pigs, 1:100 in 33 pigs, 1:200 in 24 pigs, 1:400 in 21 pigs, 1:800 in 14 pigs, and 1:3,200 in 2 pigs. Antibodies (MAT 1:20 or higher) were found in 75 of 325 (23%) finishers, 63 of 207 (32.3%) sows, and 22 of 55 (40%) boars. Results indicate high prevalence of T. gondii infection in pigs in Vietnam. This is the first report of prevalence of T. gondii in pigs from Vietnam.     

Toxoplasma gondii seroprevalence in goats,cats and humans in Russia

Toxoplasmosis, a most common zoonosis, is caused by the protozoan parasite Toxoplasma gondii. However, there is little epidemiological information on T. gondii infections in humans and livestock animals in Russia. Therefore, in this study, the seroprevalence of T. gondii in goats in Russia was investigated. A total of 216 goats from 32 farms were investigated and 95 of them were seropositive for T. gondii. The difference in seroprevalence between the examined regions was not statistically significant. We next collected serum samples from 99 cats and 181 humans in Kazan city, the state capital of the Republic of Tatarstan, Russia, and examined their T. gondii seroprevalences. Thirty-nine of the 99 cat samples and 56 of the 181 human samples showed seropositivity. Logistical regression analysis revealed that the cat breeding history of the human subjects, but not their sex or age is a significant risk factor for T. gondii seropositivity. These findings suggest that the natural environment in Russia may be widely polluted with T. gondii oocysts shed by cats, and ingestion of these oocysts provides a major route for human infection with this parasite.     

Pathogenicity of selected Toxoplasma gondii isolates in young pigs

The pathogenicity in 7-week-old pigs to five different Toxoplasma gondii strains of various host species origin was compared after i.v. inoculation of 10(4) tachyzoites. Additionally, one group of pigs was inoculated i.v. with 10(6) tachyzoites of the reference strain, SSI 119. In response to the infection a significant effect of T. gondii tachyzoite inoculation dose as well as differences among strains could be observed in several parameters. The 10(6)-dose inoculated pigs showed variable degrees of clinical illness and recurrent episodes of fever 4-17 days p.i., while pigs of four of the 10(4) tachyzoite inoculated groups experienced a short-lived rise in body temperature from day 6-8 p.i. without any apparent illness or inappetence. Control pigs and pigs infected with the least pathogenic strain had normal body temperature throughout the experiment. In all inoculated pigs, T. gondii-specific IgM and IgG antibodies appeared from day 8-10 and 10-17 p.i., respectively. Serum levels of alkaline phosphatase and the acute phase protein haptoglobin were decreased or increased, respectively, in response to the infection. Differential leukocyte count on peripheral blood revealed a significant lymphocytopenia on day 6 p.i. equal to both CD4+ and CD8+ T-cells, but shifting towards a reduced ratio of CD4+/CD8+ T-cells from day 8-14 p.i. In the 10(6)-dose inoculated pigs a considerable increase in zymosan induced and spontaneous oxidative burst capacity of peripheral blood leukocytes was observed from 6 days p.i. compared with control pigs. Oxidative burst capacity was not examined for other pigs. In conclusion, several useful parameters to identify differences in T. gondii pathogenicity other than mortality were identified. Furthermore, even at low doses, significant differences between recently collected Danish T. gondii field isolates were demonstrated after i.v. inoculation in young pigs.     

Seroprevalence of Toxoplasma gondii in pigs from slaughterhouses in Taiwan

From May 2003 to April 2004, blood samples from 395 feeder pigs in Taiwan were examined for antibodies to Toxoplasma gondii using the latex agglutination test; antibodies (titer 1:32 or higher) were found in 10.1% of 395 pigs. The results indicate a high prevalence of infection in pigs in Taiwan destined for human consumption.     

A seroprevalence survey of Toxoplasma gondii in common wombats (Vombatus ursinus)

Serum was collected from 23 wild common wombats (Vombatus ursinus) on a pastoral property in the Southern Tablelands of New South Wales, Australia (231N 616E) between 3rd August 2001 and 25th March 2002. The serum was tested using three serological methods for antibodies to Toxoplasma gondii. Six animals (26.1%) were shown to have antibodies to T. gondii. The latex agglutination test proved to be less sensitive than the direct agglutination test or the modified agglutination test. This is the first serological survey of T. gondii in wombats. This is the first recorded use of the latex agglutination test on wombat serum. This study demonstrated the highest percentage of seropositive animals in any serological survey for T. gondii in marsupials.     

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.     

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.     

Genetic characterization of Toxoplasma gondii isolates from pigs in southwestern China

The genetic diversity of Toxoplasma gondii varies in different geographical regions. Isolates of T. gondii in South America, for example, are genetically and biologically divergent from those in North America and Europe, where the population structure is highly clonal and composed mainly of 3 distinct lineages, i.e., Types I, II, and III. However, little is known of the T. gondii genotypes in the People's Republic of China. Toxoplasma gondii infection in pigs causes significant economic loss and presents a risk for human infection. We conducted a survey to determine the genetic diversity of this parasite in slaughtered pigs from Yunnan Province, southwestern China. In total, 412 DNA samples were extracted from hilar lymph nodes and livers of pigs from slaughterhouses in Yunnan Province in southwest China, 56 of which were found to be positive for the T. gondii SAG3 gene. These positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci, i.e., SAG1, SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico. Of these, 5 isolates were genotyped with complete data for all loci. Only 1 genotype (ToxoDB 9) was identified, previously reported as a widespread lineage from pigs, cats, and human patients in China. The results indicate that this genotype may be the major T. gondii lineage in China and possibly all of eastern Asia. This is the first report of genetic typing of T. gondii isolates from pigs in China's southwestern Yunnan Province, the results of which have implications for the prevention and control of T. gondii infections in humans and other animals.     

Low predictive value of seroprevalence of Toxoplasma gondii in cattle for detection of parasite DNA

The role of beef in human infections with Toxoplasma gondii is not clear. To get a better understanding of the value of seroprevalence as an indication of the role of beef in human infections with T. gondii we studied the seroprevalence of T. gondii in Dutch cattle and analysed the correlation between detection of antibodies and parasitic DNA. An indirect ELISA was developed and used to test a sample of the Dutch cattle population. Since validation of the ELISA was hampered by a lack of sufficient bovine reference sera, the results were analysed in two different ways: using a cut-off value that was based on the course of the OD in 27 calves followed from birth until 16 months of age, and by fitting a mixture of two normal distributions (binormal mixture model) to the log-transformed ODs observed for the different groups of cattle in the study population. Using the cut-off value, the seroprevalence was estimated at 0.5% for white veal, 6.4% for rosé veal and 25.0% for cattle. However, using the frequency distributions the prevalences were higher: 1.9% for white veal, 15.6% for rosé veal and 54.5% for cattle. Next, for 100 cattle the results with two different serological assays (ELISA and Toxo-Screen DA) were compared with detection of parasites by our recently developed sensitive magnetic capture PCR. Toxoplasma gondii DNA was detected in only two seronegative cattle. This discordance demonstrates that seroprevalence cannot be used as an indicator of the number of cattle carrying infectious parasites. Demonstrating parasitic DNA in seronegative cattle and not in seropositive cattle suggests that only recent infections are detectable. Whether beef from these PCR-positive cattle is infectious to humans remains to be studied.     

Seroprevalence of Toxoplasma gondii infection in slaughter pigs in Shanghai,China

Toxoplasma gondii is a pathogen that seriously threatens the health of humans and animals. However, the current infection status of T. gondii in slaughter pigs in Shanghai is still not clear. To investigate the seroprevalence of T. gondii infection and analyze the prevalence factors associated with the parasite infection, 1158 serum samples were collected from five slaughterhouses in three districts between 2015 and 2018. Serum antibodies against T. gondii were detected in 160 pigs (13.8%) by enzyme-linked immunosorbent assay (ELISA). Additionally, seroprevalence rates differed among different districts (ranging from 4.0% in JD-2 to 17.6% in JD-1), seasons (ranging from 6.7% in winter to 17.8% in autumn), and years (ranging from 8.0% in 2016 to 26.8% in 2015). Region, season, and year were the main factors affecting T. gondii infection in these pigs. There were few reports on serological monitoring of T. gondii in Shanghai slaughterhouses between 2015 and 2018, and the number of infections had steadily increased over the past several consecutive years. Therefore, our data are helpful to understand the epidemic status of T. gondii in Shanghai, which will strengthen the prevention and treatment of swine toxoplasmosis.     

Serological survey of Toxoplasma gondii infection among slaughtered pigs in northwestern Taiwan

A serological survey of Toxoplasma gondii infection among slaughtered pigs in the largest slaughterhouse located in Taoyuan County of northwestern Taiwan was conducted using the latex agglutination (LA) test during 1998. The overall seroprevalence of T. gondii infection was 28.8% (32/111) with LA titers of 1:32 (6, 18.8%), 1:64 (10, 31.2%), 1:128 (9, 28.1%), 1:256 (6, 18.8%), and 1:512 (1, 3.1%). No significant difference (P > 0.05) in seroprevalence between male (28.6%, 20/70) and female (29.7%, 12/41) slaughtered pigs was observed. A decreasing trend in the seroprevalence among slaughtered pigs examined in the same slaughterhouse was observed because of a lower seroprevalence (P < 0.05) than that (44.4%, 128/288) previously reported about 10 yr ago using the LA test. Nevertheless, it is important to avoid eating raw or undercooked pork in order to prevent the acquisition of T. gondii infection among people in Taiwan.     

Spatio-temporal variations and age effect on Toxoplasma gondii seroprevalence in seals from the Canadian Arctic

Toxoplasmosis is a significant public health threat for Inuit in the Canadian Arctic. This study aimed to investigate arctic seals as a possible food-borne source of infection. Blood samples collected from 828 seals in 7 Canadian Arctic communities from 1999 to 2006 were tested for Toxoplasma gondii antibodies using a direct agglutination test. Polymerase chain reaction (PCR) was used to detect T. gondii DNA in tissues of a subsample of seals. Associations between seal age, sex, species, diet, community and year of capture, and serological test results were investigated by logistic regression. Overall seroprevalence was 10·4% (86/828). All tissues tested were negative by PCR. In ringed seals, seroprevalence was significantly higher in juveniles than in adults (odds ratio=2·44). Overall, seroprevalence varied amongst communities (P=0·0119) and by capture year (P=0·0001). Our study supports the hypothesis that consumption of raw seal meat is a significant source of infection for Inuit. This work raises many questions about the mechanism of transfer of this terrestrial parasite to the marine environment, the preponderance of infection in younger animals and the natural course of infection in seals. Further studies to address these questions are essential to fully understand the health risks for Inuit communities.     

Seroprevalence of Toxoplasma gondii infection in domestic pigs in Durango State, Mexico

Little is known concerning the prevalence of Toxoplasma gondii infection in pigs in Mexico. Accordingly, antibodies to T. gondii were determined in 1,074 domestic pigs in Durango, Mexico using the modified agglutination test. Two groups (A, B) of pigs were sampled: Group A pigs (n = 555) were raised in 3 geographical regions in Durango State and Group B pigs (n = 519) were from Sonora State but slaughtered in Durango City. Overall, antibodies to T. gondii were found in 136 (12.7%) of 1,074 pigs with titers of 1∶25 in 29, 1∶50 in 23, 1∶100 in 18, 1∶200 in 22, 1∶400 in 12, 1∶800 in 8, 1∶1,600 in 2, and 1∶3,200 or higher in 22. Of the pigs raised in Durango State, seroprevalence varied with age, management, and the geographic region; pigs raised in backyards in the mountainous region had a significantly higher seroprevalence (32.1%) than those raised in the valley (13.0%) and the semi-desert regions (14.0%). In Group A pigs from Durango, seroprevalence of T. gondii infection was significantly higher in pigs older than 8 mo (19.5%) than in younger pigs (10.9%). In the whole pig population (Groups A and B together), seroprevalence was higher in pigs raised in Durango (16.0%) than in those raised in Sonora (9.1%) and higher in mixed-breed pigs (15.7%) than in pure-bred pigs (10.3%). This is the first, in-depth study on the seroprevalence of T. gondii infection of pigs in Mexico and the first report on pigs from Durango State, Mexico. Results indicate that infected pork is likely an important source of T. gondii infection for humans in Durango State.     

Seroprevalence of Toxoplasma gondii infection in pigs, in Zhejiang Province, China

Seroprevalence of Toxoplasma gondii infection in pigs in 10 regions of Zhejiang Province, China, was obtained by enzyme-linked immunosorbent assay (ELISA). Anti- T. gondii antibodies were found in 53.4% (434/813) of pigs. Results were analyzed by a chi-square (χ(2)) test. Differences were observed according to farm size, animal age, and sampling regions. Seroprevalences in pigs raised on small farms (71.4%) were significantly higher than that (42.7%) on large farms (P < 0.05), and seroprevalence increased progressively with age. The seroprevalence ranged from 28.1% to 66.0% in different regions, with Jiaxing having the lowest level (28.1%), followed by Hangzhou (36.0%) and Taizhou (42.0%). This is the first study on seroprevalence of T. gondii infection in pigs in Zhejiang Province.     

Prevalence of Toxoplasma gondii in slaughtered pigs in the state of Pernambuco, Brazil

The object of this study was to investigate Toxoplasma gondii antibodies and parasite DNA in pigs in the state of Pernambuco, Brazil. Blood samples were collected from 305 slaughtered pigs in 11 municipalities, and their sera were tested for T. gondii antibodies using the indirect fluorescent antibody test (IFAT, cutoff 1:64); 38 (12.5%) samples were positive. Attempts were made to detect T. gondii DNA in the heart tissue of seropositive pigs using the B 1 gene and PCR; 21 (55.2%) of the 38 hearts were positive. This is the first detection of T. gondii DNA in tissues of serologically positive swine in the State of Pernambuco, Brazil.     

Seroprevalence and risk factors associated with Toxoplasma gondii in domestic pigs from Spain

Serum samples from 2970 (1400 sows, 1570 fattening) pigs, from 100 farms in the 10 main swine production regions in Spain were tested for antibodies against T. gondii by the modified agglutination test (MAT). Antibodies to T. gondii (MAT 1:25 or higher) were detected in 492 pigs (16.6%, 9.7% in fattening pigs and 24.2% in sows). The herd prevalence was 85.0% (95% CI: 78–92) and within-farm prevalence ranged from 2.9% to 92.8% (median = 17.6%). Statistically significant differences were observed among sampling regions with seroprevalence significantly higher in pigs from Valencia Community (27.3%), Extremadura (23.3%) and Catalonia (21.2%). A generalized estimating equations model indicated that the risk factors associated with T. gondii seroprevalence were: age, sows compared to fattening pigs (OR = 2.9; 95% CI = 1.83–4.53), lack of rodent control (OR = 1.9; 95% CI = 1.04–3.60) and presence of cats (OR = 1.6; 95% CI = 1.12–2.34). The seroprevalence observed in the present study indicates a widespread, although variable, exposure to T. gondii among domestic pigs in Spain, which might have important implications for public health. Management measures including control of rodents and cats on the farms could help to reduce the observed prevalence levels in Spain.