Seroprevalence of Toxoplasma gondii in swine from slaughterhouses in Lima, Peru, and Georgia, U.S.A

Toxoplasma gondii is an important pathogen transmitted by food, with raw or undercooked meat as the main foodborne source of toxoplasmosis. In Peru, 2-4 million people have antibodies to T. gondii. It is believed that more than 60 million people in the United States are infected with T. gondii. In this study, the prevalence of T. gondii in pigs from Peru and the United States was determined by Western blot. The presence of IgG antibodies to T. gondii from serum samples was determined. Blood samples were collected from 137 pigs at a slaughterhouse in Lima, Peru, and 152 pigs at a slaughterhouse in Georgia. Of the serum samples collected from swine, 27.7% (n = 38) from Peru and 16.4% (n = 25) from the United States were positive for T. gondii. Swine represent a significant source of human infection with T. gondii in Peru and the United States.     

Seroprevalence of Toxoplasma gondii and Neospora caninum in slaughtered pigs in the Czech Republic

In the Czech Republic, sera from 551 clinically healthy adult slaughtered pigs (females, 6-8 months old) were collected during the first half of June in 2010. Sera were tested for Toxoplasma gondii-specific IgG antibodies by an enzyme-linked immunosorbent assay; samples with more than 50% S/P were considered as positive. The same samples were also analysed for Neospora caninum antibodies using a commercial competitive-inhibition enzyme-linked immunosorbent assay; samples with more than 30% inhibition were considered as positive. Antibodies against T. gondii were found in 198 pigs (36%) in all districts with prevalences ranging from 18% to 75%. Antibodies against N. caninum were found in 16 pigs (3%); positive animals were found in 4 districts with prevalences ranging from 1% to 20%. Indication of mixed infections (concurrent presence of both N. caninum and T. gondii antibodies) was found in 8 (1·5%) pigs. The results of our study indicate that pigs in the Czech Republic have a relatively high seroprevalence for T. gondii, while they have only a low seroprevalence for N. caninum. Therefore, natural infection with T. gondii seems to be very common in Czech pigs. It is the first evidence of N. caninum antibodies in pigs in the Czech Republic. These results complete data about N. caninum infection in pigs in Europe.     

Anti-Toxoplasma gondii antibodies in cattle and pigs in a highly endemic area for human toxoplasmosis in Brazil

Sera from 77 cattle and 61 pigs from herds of Campos dos Goytacazes and neighborhood, north of Rio de Janeiro state, Brazil, were analyzed for the presence of antibodies anti-Toxoplasma gondii via ELISA. The seropositivity was confirmed at 49.4% (38 of 77) for cattle and at 11.5% (7 of 61) for pigs. Pigs bred under free-ranging systems presented with 20.6% (7 of 34) seropositivity and no pigs bred under indoor systems were positive (n = 27). The seropositivity verified for cattle and pigs confirmed the extensive distribution of the parasite in this region. In the face of these data, we discuss the potential risk for human infection by consumption of raw or undercooked meat in this geographic region of Brazil. This is the first report of seropositivity for anti-T. gondii antibodies in cattle in the north of Rio de Janeiro State, Brazil.     

Characterization of Toxoplasma gondii from domestic animals from Minas Gerais, Brazil

In an attempt to isolate and characterize Toxoplasma gondii from the State of Minas Gerais, Brazil, musculature samples from 72 pigs, 25 dogs, 28 free-range chickens and 50 chickens produced in industrialized farms were collected. Antibodies to T. gondii have not been detected in pigs, but were found in nine (40.9 %) out of 22 dogs, and in 15 (53.6 %) of 28 free range chickens. T. gondii was not isolated from pigs and industrialized chickens, but from eight dogs and 11 free range chickens. In order to determine T. gondii virulence, female BALB/c mice were inoculated with 10(3), 10(2), 10(1) and 10(0) tachyzoites of the 19 isolates. The strains RH (virulent) and ME49 (non-virulent) were used as references. Isolates were divided into three groups according to the virulence phenotype: five isolates were classified into virulent in mice, one into non-virulent and 13 into intermediate virulent. Nested-PCR of T. gondii SAG2 locus amplified DNA from 21 out of 22 DNA samples directly extracted from heart of free range chickens. These samples were genotyped through a PCR-RFLP assay. Seventeen (80.9 %) were classified into type I; one (4.8 %) into type III and three (14.3 %) into type I or II.     

Prevalence to Toxoplasma gondii and Sarcocystis spp. in a reintroduced fisher (Martes pennanti) population in Pennsylvania

Understanding the role of disease in population regulation is important to the conservation of wildlife. We evaluated the prevalence of Toxoplasma gondii exposure and Sarcocystis spp. infection in 46 road-killed and accidentally trapper-killed fisher (Martes pennanti) carcasses collected and stored at -20 C by the Pennsylvania Game Commission from February 2002 to October 2008. Blood samples were assayed for T. gondii antibodies using the modified agglutination test (MAT, 1 : 25) and an indirect immunofluorescent antibody test (IFAT, 1 : 128). For genetic analysis, DNA samples were extracted from thoracic and pelvic limb skeletal muscle from each carcass to test for Sarcocystis spp. using 18s-rRNA PCR primers. Antibodies to T. gondii were found in 100% (38 of 38) of the fishers tested by MAT and in 71% (32 of 45) of the fishers tested by IFAT. PCR analysis revealed that 83% (38 of 46) of the fishers were positive for Sarcocystis spp. Sequence analysis of 7 randomly chosen amplicons revealed the fisher sarcocysts had a 98.3% to 99.1% identity to several avian Sarcocystis spp. sequences in GenBank. Data from our study suggest that a high percentage of fishers in Pennsylvania have been exposed to T. gondii and are infected with Sarcocystis spp.     

National seroprevalence of Toxoplasma gondii in pigs

Serum samples from 11,842 commercial pigs killed in 1983-1984 throughout the United States were tested for anti-Toxoplasma gondii antibodies by the agglutination test in dilutions of 1:25, 1:50, and 1:500. Anti-T. gondii antibodies were found in 23.9% of pigs. At dilutions of 1:25, 1:50, and 1:500, 13.5%, 6.9%, and 3.5% were serologically positive, respectively. The prevalence of anti-T. gondii antibodies was higher in breeder pigs (42%) than in market pigs (23%). These results indicate that anti-T. gondii antibodies are widespread in the national swine herd.     

Toxoplasma gondii: detection by mouse bioassay, histopathology, and polymerase chain reaction in tissues from experimentally infected pigs

In the present study, we evaluated three techniques, mouse bioassay, histopathology, and polymerase chain reaction (PCR) to detect Toxoplasma gondii infection in tissues from experimentally infected pigs. Twelve mixed breed pigs, seronegative for T. gondii using an indirect immunofluorescent antibody test (IFAT), were used. Ten pigs were infected with 4 x 10(4) VEG strain oocysts, and two were maintained as uninfected controls. Animals were killed 60 days pos infection. Muscle (heart, tongue, diaphragm, and masseter) and brain samples were collected to investigate the presence of T. gondii tissue cysts by the different assay methods. For the bioassay, samples of brain (50 g) and pool of muscle samples (12.5 g of tongue, masseter, diaphragm, and heart) were used. PCR was performed using Tox4 and Tox5 primers which amplified a 529 bp fragment. The DNA extraction and PCR were performed three times, and all tissue samples were tested individually (brain, tongue, masseter, diaphragm, and heart). For histopathology, fragments of tissues were fixed in 10% of buffered formal saline and stained with HE. Histopathological results were all negative. PCR showed 25/150 (16.6%) positive samples, being 17/120 (14.1%) and 8/30 (26.6%) from muscle, and brain tissues, respectively. Tissue cysts of T. gondii were identified by mouse bioassay in 54/98 (55.1%) samples, being 31/48 (64.6%) from muscle samples, and 23/50 (46.0%) from brain samples. Toxoplasma gondii isolation in muscle samples by mouse bioassay was higher than in PCR (P<0.01). Results indicate that DNA from pig tissues interfered with 529-bp-PCR sensitivity, and mouse bioassay was better than PCR in detecting T. gondii in tissues from pigs.     

Molecular characterization of Toxoplasma gondii isolates from cats in Spain

Cats are important in the epidemiology of Toxoplasma gondii because felids are the only definitive hosts that can excrete environmentally resistant oocysts. Fresh samples of brain from 103 Spanish cats with antibodies to T. gondii were analyzed for T. gondii DNA using nested-PCR; 47 (45.5%) were found to be positive. Further characterization of DNA from 46 cats using RFLP-PCR at the 3' and 5' ends of the SAG2 locus revealed that 12 (26%) isolates were Type I and 34 (74%) were Type II; no Type III were found, and the 47th sample could not be classified to its genetic type. In addition, T. gondii was also isolated by bioassay in mice from 42 of 103 seropositive cats. This is the first report of T. gondii characterization from cats in Spain.     

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.     

A field trial of the effectiveness of a feline Toxoplasma gondii vaccine in reducing T. gondii exposure for swine

A 3-yr field trial was conducted on 8 commercial swine farms in Illinois to determine the effectiveness of a feline Toxoplasma gondii vaccine in reducing the exposure of swine to T. gondii. A vaccine consisting of live bradyzoites of the mutant T-263 strain, capable of preventing oocyst shedding by cats, was used in this study. Each farm was visited 3 times in 1994, 3 times in 1995, and once in 1996. Cats were trapped and inoculated with the T-263 oral vaccine during 1994 and 1995. On each visit, the following samples were collected: blood from pigs, cats, and mice for detection of serum antibodies to T. gondii, feces from cats to detect oocysts, and heart and brain tissues from rodents to determine the presence of T. gondii tissue cysts. The modified agglutination test (MAT), with a positive titer set at the 1:25 dilution, was used to determine serum antibodies. At first capture, 72.6% (61/84) of juvenile cats and 32.6% (31/95) of adult cats had no detectable antibodies (seronegative), indicating no prior exposure to T. gondii when they received their first vaccine. Of these first-time seronegative cats, 58.1% (18/31) of adult and 45.9% (28/61) of juvenile cats were recaptured and received a second dose of vaccine. Changes in the prevalence of T. gondii infection were evaluated from the prevaccination (1992, 1993) to the postvaccination (1996) period. Eleven cats (5%) were detected shedding oocysts between 1994 and 1996, of which 10 (90.1%) shed during 1994. The last detection of oocyst shedding by cats was during the first farm visit in 1995. There was a significant decrease in T. gondii seroprevalence for finishing pigs (P < 0.05, Wilcoxon sign rank test). There was a positive correlation (Spearman's p = 1.0, P < 0.0001) between the change in prevalence in juvenile cats and the change in prevalence in finishing pigs. The seropositivity rate (MAT > or = 1:25) in mice among all farms decreased from 4% in 1992-1993 to 0% in 1996. The mean prevalence of T. gondii tissue cyst isolation for mice on all farms decreased from 1.1% in 1994, to 0.8% in 1995, and to 0.5% in 1996. The results of this study suggest that the reduced exposure of pigs to T. gondii was due to the administration of the T. gondii vaccine to cats.     

Seroprevalence of Toxoplasma gondii antibodies in cats and pigs from rural Western Amazon, Brazil

Antibodies to Toxoplasma gondii were assayed in sera of 63 cats and 80 pigs from 71 farms located at Rond?nia State, Western Amazon, Brazil, by the modified agglutination test (MAT) and the indirect immunofluorescent antibody test (IFAT). Antibodies (MAT > or = 1: 25) were found in 55 of 63 cats (87.3%) with titers of 1:25 in 2, 1:50 in 2, 1:100 in 7, 1:200 in 1, 1:400 in 2, 1:800 in 9, 1:1,600 in 6, and 1:3,200 or higher in 26 cats. By IFAT, antibodies were found in 55 cats (87.3%) with titers of 1:25 in 2, 1:50 in 1, 1:100 in 4, 1:200 in 4, 1: 400 in 1, 1:800 in 13, 1:1,600 in 12, and 1:3,200 or higher in 18 cats. In pig sera, by MAT, antibodies were found in 30 of 80 pigs (37.5%) with titers of 1:25 in 2, 1:50 in 3, 1:100 in 2, 1:200 in 8, 1:400 in 3, 1:800 in 5, 1:1,600 in 3, and 1:3,200 or higher in 4 pigs. By using the IFAT (titers > or = 1:64), antibodies were found in 35 (43.7%) pigs. The ingestion of undercooked tissues of infected pigs can be a source of T. gondii infection for humans and cats. However, the high seroprevalence of T. gondii in cats from the Amazon seems most likely to be indicative of high contamination of the environment by oocysts.     

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.     

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.     

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.     

Seroprevalence of Toxoplasma gondii infection in slaughtered pigs and cattle in Liaoning Province, northeastern China

Toxoplasmosis is an important food-borne parasitic disease. In the present study, the seroprevalence of Toxoplasma gondii infection in slaughtered pigs and cattle was surveyed in Liaoning Province, northeastern China in May and June 2011. In total, 1,164 porcine serum samples and 646 bovine serum samples were collected from 5 counties and examined for T. gondii antibodies by an indirect hemagglutination test. Antibodies to T. gondii were found in 12.0% (140/1,164) of pigs, with some regional differences. The highest prevalence of 14.4% (47/326) was found in Fuxin followed by 12.5% (62/497) in Jinzhou; overall, 6.0% (39/646) was observed in cattle but with no regional difference (P > 0.05). Prevalence of T. gondii infection in pigs was also significantly higher compared to cattle (P < 0.05). The results of the present study indicate that infection with T. gondii in pigs and cattle is widely spread in China including Liaoning Province, northeastern China, and is, therefore, of public health concern.     

Prevalence of Toxoplasma gondii antibodies in sera of domestic pigs and some wild game species from Zimbabwe

Serum samples of domestic pigs (Sus scrofa), elands (Taurotragus oryx), sable antelopes (Hippotragus niger), warthogs (Phacochoerus aethiopicus), bushpigs (Koiropotamus [Potamochoerus] koiropotamus), white rhinos (Ceratotherium simus), African buffalos (Syncerus caffer), wildebeest (Connochaetas taurinus), and African elephants (Loxodonta africana) from Zimbabwe were tested for Toxoplasma gondii IgG antibodies by the modified agglutination test (MAT) with whole formalized tachyzoites and mercaptoethanol. Sera were diluted at 1:25, 1:50, and 1:500 for MAT testing. Sera with antibodies in a 1:25 dilution were considered to have T. gondii infection. Toxoplasma gondii antibodies were found in 9.3% of 97 domestic pigs, 36.8% of 19 elands, 11.9% of 67 sables, 0 of 3 warthogs, 0 of 3 bushpigs, 50% of 2 white rhinos, 5.6% of 18 buffalos, 14.5% of 69 wildebeest, and 10.5% of 19 elephants examined.     

Polymerase chain reaction for detection ofToxoplasma gondii in human biological samples

Using the polymerase chain reaction (PCR), Toxoplasma gondii from gene TGR1E with primers TGR1E-1, TGR1E-2 (standard PCR), and from B1 gene with primers TM1, TM2, TM3 (hemi-nested PCR) was detected in biological samples from 347 individuals (441 biological materials). Of the total of 441 biological materials, T. gondii DNA was detected in 5.2 %; it was positive in the following samples: blood (n = 6), blood from newborns (2), biopsies (2) and samples of progenitor cells (2) (from candidates for bone marrow transplantation). DNA of T. gondii was also revealed in 11 samples (8.3 %) of 120 cases of pregnant women during prenatal examinations. A positive result in the blood was also found in two cases of newborn babies from mothers who were infected in later pregnancy. The positive PCR examination was confirmed by serological methods (ELISA and complement fixation test). Agreement of PCR results and the detection of antibodies against toxoplasma was found in 83.3 %. Rapid PCR examination for the confirmation of acute parasitemia T. gondii is particularly important for the patients in whom the infection may cause serious consequences (e.g., for fetus in pregnant women or for patients suffering from imunosuppression).     

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.     

Real-time PCR-based quantification of Toxoplasma gondii in tissue samples of serologically positive outdoor chickens

This study aimed to quantify Toxoplasma gondii in tissue samples of serologically positive chickens using real-time polymerase chain reaction (PCR). Of 65 chickens evaluated, 28 were positive for T. gondii antibodies. Brain and heart samples were collected from 26 seropositive chickens and DNA was extracted using Trizol? and amplified using real-time PCR with SYBR? Green. Parasite DNA was detected in 24 of the 26 samples analyzed; the number of positive tissue samples and the parasite quantity did not differ between tissue types. The results confirmed the analytical sensitivity of parasite detection in chicken tissue samples and demonstrated the possibility of using other molecular systems for genotypic analysis.     

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.