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 domestic sheep in Durango State, Mexico

The seroprevalence of Toxoplasma gondii infection in sheep (Ovis aries) in northern Mexico is largely unknown. Antibodies to T. gondii were determined in serum samples from 511 sheep from 8 farms in Durango State, Mexico, using the modified agglutination test (MAT). Sheep were raised in 3 geographical regions, i.e., mountainous (n = 68), semi-desert (n = 132), and valley (n = 311). Overall, T. gondii antibodies were found in 77 (15.1%) of 511 sheep, with MAT titers of 1∶25 in 27, 1∶50 in 10, 1∶100 in 11, 1∶200 in 11, 1∶400 in 8, 1∶800 in 3, 1∶1,600 in 4, and 1∶3,200 in 3. The seroprevalence of T. gondii infection increased significantly with age, indicating post-natal transmission. In contrast, gender, breed, flock size, and geographic region did not significantly influence the seroprevalence. Seropositive sheep were found in 7 of 8 farms sampled. This is the first report of T. gondii infection in sheep in Durango State, Mexico. Results indicate that infected sheep are probably an important source of T. gondii infection for humans in Durango State.     

Prevalence of Toxoplasma gondii infection in wild birds in Durango, Mexico

There is a lack of information concerning the prevalence of Toxoplasma gondii infection in wild birds in Mexico. In the present study, serum samples and tissues from 653 birds from Durango State, Mexico, were evaluated for T. gondii infection. Antibodies to T. gondii (modified agglutination test, titer 1∶25 or higher) were found in 17 (2.6%) of the 653 birds, including 1 of 2 curve-billed thrashers (Toxostoma curvirostre), 2 (1 Anas platyrhynchos, 1 Anas diazi) of 4 ducks, 1 of 2 eagles (Aquila sp.), 5 (27.8%) of 18 great-tailed grackles (Quiscalus mexicanus), 7 (1.3%) of 521 rock pigeons (Columba livia), and 1 (14.3%) of 7 quail (Coturnix coturnix). The seroprevalence of T. gondii infection in birds captured in a park outside the city zoo (11.6%, 8/69) was significantly higher than that found in birds from other regions (1.5%, 9/584, OR = 8.38; 95% CI: 2.82-24.77; P = 0.0001). Brains and hearts of 23 birds (17 seropositive, 6 seronegative) were bioassayed in mice for the isolation of T. gondii . Viable T. gondii was isolated from 1 of 7 seropositive pigeons. The DNA obtained from the T. gondii isolate from the pigeon was genotyped using the PCR-RFLP typing using 11 markers (B1, SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico) and revealed an atypical genotype. This is the first report of T. gondii infection in great-tailed grackles, the Mexican duck, and curved-billed thrashers and the first survey of wild birds in Mexico.     

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.     

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 infection in dogs in Jiangsu Province, eastern China

There is a lack of epidemiological data on Toxoplasma gondii infection in dogs from eastern China. In the present study, serum samples from 288 dogs were collected from Xuzhou, Huaiyin, and Yianchen in Jiangsu Province, eastern China, in August 2010; T. gondii antibodies were assayed by a modified agglutination test (MAT). Antibodies to T. gondii were found in 62 of 288 (21.5%) with MAT titers of 1∶25 in 21 dogs, 1∶50 in 15, 1∶100 in 11, 1∶200 in 6, and 1∶400 and above in 3 dogs. The seroprevalence in ≥3-yr-old dogs was significantly higher (P < 0.05) than that in dogs less than 3-yr-old. The results of the present study indicated that infection with T. gondii in household dogs in Jiangsu Province is a public health concern.     

Prevalence of Toxoplasma gondii in chickens from an area in southern Brazil highly endemic to humans

The prevalence of Toxoplasma gondii in free-range chickens from Campos dos Goytacazes, Rio de Janeiro State, Brazil, was examined to evaluate environmental contamination by oocysts. Antibodies against T. gondii were assayed by the modified agglutination test (MAT) in sera of chickens. Antibodies against the parasite were found in 129 of 198 chickens with MAT titers > or = 1:25. Brains and hearts of 86 of the 198 chickens were bioassayed in mice for the presence of T. gondii. Viable parasites were isolated from 61 (70.9%) of the 86 chickens. Importantly, viable T. gondii were recovered even from seronegative chickens (MAT titer < or = 1:10). The distribution of parasite-positive chickens by MAT titer was 4 of 17 (titer < or = 1:10), 3 of 4 (titer of 1:20), 2 of 6 (titer of 1:40), and 52 of 59 (titer > or = 1:80). Thus, the high recovery rate of T. gondii observed in mice is indicative of high levels of environmental contamination of free-range chickens by T. gondii oocysts in this area that is endemic to humans.     

Seroprevalence of Toxoplasma gondii antibodies in cats from Durango City, Mexico

The prevalence of antibodies to Toxoplasma gondii was determined in sera from 105 domestic cats from Durango City, Mexico. Using a modified agglutination test, antibodies to this parasite were found in 21% of the 105 cats, with titers of 1:25 in 3 cats, 1:50 in 4 cats, 1:200 in 5 cats, 1:400 in 2 cats, 1:800 in 2 cats, 1:1,600 in 4 cats, and 1:3,200 or higher in 2 cats. Cats older than 1 yr had a significantly higher frequency of infection than that found in cats younger than 0.5 yr (41 vs. 13.2%, respectively; odds ratio = 4.55; 95% CI = 1.24-17.18; P = 0.01). Overall, the seroprevalence of T. gondii antibodies in cats in Durango, Mexico, is much lower compared with those reported in other countries.     

Toxoplasma gondii isolates from free-range chickens from the northeast region of Brazil

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 152 free-range chickens (Gallus domesticus) from 22 municipalities in 7 northeastern states (Pernambuco, Rio Grande do Norte, Maranh?o, Bahia, Ceará, Sergipe, and Alagoas) of Brazil was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT); 81 (53.3 %) chickens had titers of 1:5 in 26, 1:10 in 9, 1:20 in 4, 1:40 in 1, 1:80 in 6, 1:160 in 6, 1:320 in 13, 1:640 in 6, 1:1,280 in 3, 1:2,560 in 6, and 1:5,120 or higher in 1. Hearts and brains of 81 seropositive chickens were bioassayed individually in mice. Toxoplasma gondii was isolated from 23 chickens with MAT titers of 1:5 or higher; the isolates were designated TgCKBr165-187. Five isolates killed all infected mice. Results indicate widespread contamination of rural environment in Brazil with T. gondii oocysts.     

Isolation and genotyping of Toxoplasma gondii from free-ranging chickens from Argentina

The prevalence of Toxoplasma gondii in free-ranging chickens can be considered a good indicator of the prevalence of T. gondii oocysts in the environment because chickens feed from the ground. In the present study, prevalence of T. gondii in 29 free-range chickens (Gallus domesticus) from Argentina was investigated. Blood, heart, and brain from each chicken were examined for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (MAT), were found in 19 of 29 (65.5%) chickens. Hearts and brains of seropositive (MAT > or = 1:5) chickens were bioassayed in mice. Toxoplasma gondii was isolated from 9 of 19 seropositive chickens. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 1 was type I, 1 was type II, and 7 were type III. This is the first report of isolation of T. gondii from chickens from Argentina.     

Seroprevalence of Toxoplasma gondii in pigs, sheep, goats, and cattle from Grenada and Carriacou, West Indies

Prevalence of Toxoplasma gondii infection in pregnant women in Grenada is considered high. Little is known of the epidemiology of T. gondii infection in Caribbean Islands. Serum samples of 750 food animals in Grenada and Carriacou were tested for antibodies to T. gondii by the modified agglutination test (MAT). Antibodies to T. gondii (MAT, 1∶25 or higher) were found in 23.1% of 247 pigs, 44.1% of 204 sheep, 42.8% of 180 goats, and 8.4% of 119 cattle. Seroprevalence increased with age, indicating postnatal acquisition of T. gondii. Antibody titers of 1∶200 or higher were present in 65 of 90 seropositive sheep, 61 of 77 seropositive goats, and 23 of 57 seropositive pigs. However, none of the cattle had a MAT titer of 1∶200, suggesting that bovines are a poor host for T. gondii. Results indicate that pigs, sheep, and goats could be important sources of T. gondii infection if their meat is consumed undercooked.     

Isolation of Toxoplasma gondii from animals in Durango, Mexico

Little is known concerning the epidemiology of Toxoplasma gondii infection in people and animals in rural Mexico. Serum samples and tissues from 150 dogs (Canis familaris), 150 cats (Felis catus), 65 opossums (Didelphis virginianus), 249 rats (Rattus spp.), 127 mice (Mus musculus), and 69 squirrels (Spermophilus variegatus) from the Durango area were evaluated for T. gondii infection. Using a modified agglutination test and a serum dilution of 1:25, antibodies to this parasite were found in 68 (45.3%) of 150 dogs, 14 (9.3%) of 150 cats, 11 (16.6%) of 66 opossums, 2 (0.8%) of 249 rats, 4 (3.1%) of 127 mice, and 0 of 69 squirrels. Tissues (brain and heart) of dogs, cats, opossums, rats, mice, and squirrels were bioassayed in mice for the presence of T. gondii. Viable T. gondii was isolated in tissues from 3 of 28 seropositive dogs and 5 of 8 seropositive cats, but not from the other animals. The DNA obtained from the 3 T. gondii isolates from dogs, 6 isolates from 5 cats, and 4 isolates from free-range chickens from Mexico, previously isolated, were genotyped. The PCR-RFLP typing, which used 11 markers (B 1, SAGI, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico), identified 5 genotypes. One genotype (the 4 chicken isolates) belongs to the clonal Type III lineage, three genotypes were reported in previous reports, and 1 genotype is unique.     

Isolation and genotyping of Toxoplasma gondii from free-ranging chickens from Mexico

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the presence of T. gondii oocysts in the environment because chickens feed from the soil. In the present study, prevalence of T. gondii in 208 free-range chickens (Gallus domesticus) from Mexico was investigated. Blood, heart, and brain from each animal were obtained to test for T. gondii infection. Antibodies to T. gondii, assayed with the modified agglutination test (1:10 or higher), were found in 13 (6.2%) chickens. Hearts and brains of 13 seropositive chickens were bioassayed in mice, and T. gondii was isolated from 6 chickens. All 6 isolates were avirulent for mice. Genotyping of chicken isolates of T. gondii using the SAG2 locus indicated that 5 were type III and 1 was type I. This is the first report of isolation of T. gondii from chickens from Mexico.     

Characterization of Toxoplasma gondii isolates in free-range chickens from Argentina

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 61 free-range chickens (Gallus domesticus) from provinces of Santiago del Estero and Entre Rios, Argentina was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and were found in 25 chickens; titers were 1:5 in 6 chickens, 1:10 in 1 chicken, 1:20 in 2 chickens, 1:40 in 1 chicken, 1:80 in 2 chickens, 1:60 in 4 chickens, 1:120 in 2 chickens, 1:640 in 3 chickens, and 1: 1,280 or higher in 4 chickens. Hearts, pectoral muscles, and brains of 22 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 39 chickens with titers of 1:5 or less were pooled and fed to 3 T. gondii-free cats. Feces of cats were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 17 of 22 chickens with MAT titers of 1:10 or higher. Genotyping of these 17 isolates using polymorphisms at the SAG2 locus indicated that 4 were Type I, 3 were Type II, and 10 were Type III. Toxoplasma gondii isolates (2 Type I and I Type III) from 3 chickens were virulent for mice and 1 Type I was not mouse virulent. Prevalence of T. gondii antibodies in chickens varied among regions, being 3 times greater in the humid Pampeana region (61.2%) than in the semiarid plain of Santiago del Estero (20%).     

Characterization of Toxoplasma gondii isolates in free-range chickens from Portugal

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 225 free-range chickens (Gallus domesticus) from Portugal was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT) and found in 61 chickens with titers of 1:5 in 8, 1:10 in 6, 1:20 in 3, 1:40 in 23, 1:80 in 5, 1:160 in 4, 1:320 in 8, and 1:640 or higher in 4. Hearts, leg muscles, and brains of 15 seropositive (MAT 1:10 or higher) chickens were bioassayed individually in mice. Tissue from 38 chickens with titers of 1:5 or less were pooled and fed to a T. gondii-free cat. Feces of the cat were examined for oocysts, but none was found. Toxoplasma gondii was isolated from 16 of 19 chickens with MAT titers of 1:10 or higher. Genotyping of 12 of these 16 isolates with polymorphisms at the SAG2 locus indicated that 4 were type III, and 8 were type II. None of the isolates was lethal for mice. Phenotypically, T. gondii isolates from chickens from Portugal were different from those of T. gondii isolates from chickens from Brazil.     

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.     

Toxoplasma gondii isolates from free-ranging chickens from the United States

Prevalence of Toxoplasma gondii infection in chickens is a good indicator of the strains prevalent in their environment because they feed from ground. The prevalence of T. gondii was determined in 118 free-range chickens from 14 counties in Ohio and in 11 chickens from a pig farm in Massachusetts. Toxoplasma gondii antibodies (> or = 1: 5) were found using the modified agglutination test (MAT) in 20 of 118 chickens from Ohio. Viable T. gondii was recovered from 11 of 20 seropositive chickens by bioassay of their hearts and brains into mice. The parasite was not isolated from tissues of 63 seronegative (< or = 1:5) chickens by bioassay in cats. Hearts, brains, and muscles from legs and breast of the 11 chickens from the pig farm in Massachusetts were fed each to a T. gondii-negative cat. Eight cats fed chicken tissues shed oocysts; the 3 cats that did not shed oocysts were fed tissues of chickens with MAT titers of 1:5 or less. Tachyzoites of 19 isolates of T. gondii from Ohio and Massachusetts were considered avirulent for mice. Of 19 isolates genotyped, 5 isolates were type II and 14 were type III; mixed types and type I isolates were not found.     

Toxoplasma gondii infections in chickens from Venezuela: isolation, tissue distribution, and molecular characterization

The prevalence of Toxoplasma gondii, in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 46 free-range chickens (Gallus domesticus) from Venezuela was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 16 (32%) chickens with titers of 1:5 in 1, 1:10 in 2, 1:40 in 2, 1:80 in 2, 1:160 in 2, 1:320 in 3, 1: 640 in 2, and 1:1,280 or higher in 2. Hearts, pectoral muscles, and brains of 13 chickens with MAT titers of 1:40 or more were bioassayed individually in mice. Tissues of each of 3 chickens with titers of 1:5 or 1:10 were pooled and bioassayed in mice. Tissues from the remaining 30 seronegative chickens were pooled and fed to 1 T. gondii-free cat. Feces of the cat were examined for oocysts; it did not shed oocysts. Toxoplasma gondii was isolated from 12 of 13 chickens with MAT titers of 1:40 or more. Toxoplasma gondii was isolated from pooled tissues of 1 of 2 chickens with titers of 1:10. Eight of these 13 isolates were virulent for mice. Genotyping of 13 of these isolates using the SAG2 locus indicated that 10 were type III, and 3 were type II. Phenotypically and genetically these isolates were different from T. gondii isolates from North America and Brazil. This is the first report of isolation of T. gondii from chickens from Venezuela.     

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.     

Seroprevalence of Toxoplasma gondii in rats in southern China

Toxoplasma gondii is widely distributed in humans and other animals, including wild rats throughout the world, but little is known of the prevalence of T. gondii in rats in China. The seroprevalence of T. gondii in rats ( Rattus norvegicus and Rattus flavipectus ) was investigated in Guangzhou, southern China, between November 2009 and January 2010. In total, 217 rat serum samples were collected; antibodies to T. gondii were detected by the modified agglutination test (MAT), and 7 (3.2%) were found positive (titers ≥ 1:40). The seroprevalence was higher (3.4%) in R. norvegicus than in R. flavipectus (3.0%), but the difference was not statistically significant (P > 0.05). All 7 positive rats were female; no T. gondii antibodies were detected in males. This is the first extensive survey of T. gondii infection in rats in southern China, and the results have public health implications in this region.