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

Toxoplasma gondii Investigation of Home-Reared Pigs through Real-Time PCR and Digital Droplet PCR: A Very Low Prevalence

Toxoplasma gondii is a widespread protozoon that can infect both animals and humans. The main route of human infection is the consumption of the raw or undercooked meat of several animal species, including pigs. Although T. gondii represents a public health concern, control during slaughter is not mandatory, leading to a lack of information on the impact on human contagion as well as poor data availability in domestic animals intended for human consumption. We studied the presence of T. gondii in home-reared pigs, an unconventional type of farming subjected to stringent breeding conditions dictated by Italian regulation. Thus, the diaphragms, livers and masseter muscles from 480 pigs in Napoli Province (Italy) were analyzed using real-time PCR and digital droplet PCR. The results showed four matrices that tested positive for T. gondii with very low protozoan loads (0.62%), belonging to three different animals. The low density of the animals (the maximum was four animals per farm) and the biosafety farming features decisively contributed to the bioexclusion of this pathogen. Comparing these results to intensive and extensive farm data, lower exposure to the parasite was revealed, suggesting that this farming method might mitigate the risk of human exposure through meat consumption.

A serological survey of Toxoplasma gondii in polish pigs from organic farms, other housing systems and in pigs of different age groups

Background

The consumption of raw or undercooked meat, especially pork, and offal containing infective tissue cysts is suspected to be a significant route of infection with Toxoplasma gondii. Although the use of “animal-friendly pig production systems” ensuring direct contact with the natural environment offers ethical benefits, it limits the ability to ensure animal health; it may also increase the probability of infections by pathogens such as T. gondii, and thus their entry into the food chain. This study determines the seroprevalence of T. gondii in pigs from different housing systems and farms with different hygiene standards in Poland, as well as among pigs of different age groups from farms with high hygiene standards. In total 760 pig serum samples were examined for the presence of specific antibodies using the PrioCHECK^® Toxoplasma Ab porcine commercial ELISA test (Prionics, Switzerland).

Results

Test results with PP ≥ 20% were regarded as positive, as indicated by the manufacturer. Antibodies to T. gondii were found in 193 of 760 (25.4%) tested sera. Regarding different housing systems, antibodies were found in 117 pigs: of these, 52.6% (61/116) were from organic farms, 40.9% (47/115) from farms with low hygiene standards, 5.4% (9/167) from farms with high hygiene standards and 0% (0/40) from a farm with a high level of biosecurity. Regarding age groups, antibodies were found in 76 animals on farms with high hygiene standards: 11.1% (7/63) were pigs younger than 3 months, 0% (0/60) aged 3–4 months, 12.3% (7/57) aged 5–6 months (final fattening stage) and 43.7% (62/142) were sows aged 9 months and older.

Conclusions

Antibodies to T. gondii were most often found in pigs from organic and low-hygiene farms, as well as in pigs aged 9 months and older. Meat derived from seropositive animals can pose a potential source of infection for humans. As maternal antibodies to T. gondii can be present in the blood of piglets aged up to 3–4 months, serological examination is unjustified in piglets up to this age.

High level of infection by Toxoplasma gondii in pigs slaughtered in the city of São Luís, Maranhão

A serological, molecular and histopathological study was carried out in order to investigate occurrences of Toxoplasma gondii in pigs slaughtered with and without inspection service. Serum samples were collected from 60 pigs to detect anti-T. gondii antibody by indirect fluorescent antibody (IFAT). Tongue, masseter and diaphragm fragments were also collected for parasite DNA detection by means of the polymerase chain reaction (PCR) and histopathological analysis. The serological results showed that 77% (44/60) of the pigs were positive. Regarding PCR, 66.67% (40/60) were positive for T. gondii. Among the tissues evaluated, the diaphragm was the one with the highest frequency of positivity (40%; 24/60), followed by the masseter (38.33%; 23/60) and tongue (33.3%; 20/60). Histopathological changes were only observed in the diaphragm, which presented inflammatory infiltrates of lymphohistiocytic and neutrophilic types. These results not only show the potential threat of T. gondii to human health, but also demonstrate the dynamic epidemiological situation of toxoplasmosis in pigs in the city of São Luís, providing support for food security regarding pigs and for T. gondii control programs in Brazil.

The first seroepidemiological study on Toxoplasma gondii in backyard pigs in Myanmar

A cross-sectional study of Toxoplasma gondii infection in pigs was carried out in backyard farms in three townships, within Nay Pyi Taw area from June 2014 to August 2014. Blood samples were randomly collected from 256 pigs in 129 farms. Using commercial Latex Agglutination Test kits, specific antibodies to T. gondii were analyzed. Based on LAT results, among 256 serum samples examined, 47 samples (18.4%) were found positive to T. gondii. The numbers of samples showing specific antibody titres from 47 positive pig sera were 20 at 1:64, 2 samples at 1:128, 9 samples at 1:256, 3 samples at 1:512 and 13 samples at 1:1024. Among the hypothesized risk factors, roaming of cats around the farm was found associated to T. gondii seropositivity in pigs (OR = 3.13; 95% CI = 1.33–7.34). This study provides information on seroepidemiology study of T. gondii in backyard pigs for the first time in Myanmar. This information will be useful in developing strategies for the control of T. gondii infection in pigs.

All about Toxoplasma gondii infections in pigs: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasma gondii infection in pigs continues to be of public health concern. Pigs are important for the economy of many countries, particularly, USA, China, and European countries. Among the many food animals, pigs are considered the most important for T. gondii transmission in USA and China because viable parasites have rarely been isolated from beef or indoor raised chickens. Besides public health issues, T. gondii causes outbreaks of clinical toxoplasmosis in pigs in China, associated with a unique genotype of T. gondii (ToxoDB genotype #9 or Chinese 1), rarely found in other countries. The safety of ready to eat pork products with respect to T. gondii infection is a matter of recent debate. Here, we review in detail seroprevalence, prevalence of viable and nonviable T. gondii, epidemiology, risk assessment, diagnosis, and curing of pork products containing T. gondii for the past decade. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.