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.     

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.     

Seroprevalence of Toxoplasma gondii infection in dogs in Sichuan Province, southwestern China

There is a lack of information concerning the prevalence of Toxoplasma gondii infection in dogs from southwestern China. In the present study, serum samples from 314 household dogs were collected from Wenchuan, Heishui, and Jiuzhaigou in Sichuan Province, southwestern China, in May and June 201; sera were assayed for T. gondii antibodies using an indirect haemagglutination test (IHA). Antibodies to T. gondii were found in 11 of 314 (3.5%), with IHA titers of 1:64 in 4 dogs, 1:128 in 3, 1:256 in 2, 1:512 in 1, and 1:1024 in 1. No regional difference was observed among the 3 counties (P > 0.05). The results of the present study indicated that infection with T. gondii in dogs is common in China, including household dogs in Sichuan Province, and should be of public health concern.     

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.     

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 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 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 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.     

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 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.     

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.     

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.     

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.     

Seroprevalence of Toxoplasma gondii infection in female sterility patients in China

Toxoplasmosis is an important parasitic disease worldwide and is related to certain psychiatric disorders and sterility. In the present study, serum samples from 882 female sterility patients and 107 pregnant-puerperant women were assayed for anti- T. gondii IgG antibodies using ELISA. The overall T. gondii seroprevalence was 14.8%. In the female sterility patients, 15.9% (140/882) were seropositive and, in the pregnant-puerperant women, 5.6% (6/107) were positive for anti- T. gondii IgG antibodies. There was a significant difference between the 2 groups ( P < 0.05). The samples were further divided into 5 groups based on age, but no significant difference was found among the 5 groups (P > 0.05). Results of the present study argue for more attention to prevention of T. gondii infection in the female population and, in particular, women of childbearing age.     

Seroprevalence of Neospora caninum infection in dairy cattle of Southern China

A seroepidemiological survey of Neospora caninum infection in dairy cattle was carried out in China's southern Guangdong Province between July 2009 and March 2010. A total of 370 serum samples of dairy cattle was collected from 5 farms and examined for antibodies to N. caninum by enzyme-linked immunosorbent assay. The overall seroprevalence of N. caninum in dairy cattle was 18.9% (70/370). The seroprevalence of N. caninum in aborting cows (22.7%) was higher than that in nonaborting cows (16.3%), but the difference was not statistically significant (P > 0.05). Five-yr-old dairy cattle had the highest seroprevalence (27.8%), followed by those that were 6-yr-old (20.4%). Dairy cattle with 4 pregnancies had the highest seroprevalence (29.2%). There was no apparent association of N. caninum seropositivity with age or number of pregnancies (P > 0.05). The results of the present survey indicated that the infection with N. caninum is prevalent in dairy cattle of all ages in southern China, which may be one of the causes of bovine abortion. This is the first report of seroprevalence of N. caninum in dairy cattle in southern China.     

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.     

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.     

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.     

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.