Prevalence, molecular detection and risk factors investigation for the occurrence of Toxoplasma gondii in slaughter pigs in North India

Seroepidemological investigation of Toxoplasma gondii and Trichinella spp. in pigs reared by tribal communities and small-holder livestock farmers in Northeastern India

Toxoplasma gondii and Trichinella spp. are critical tissue-dwelling foodborne zoonotic parasites associated with pork consumption and pig rearing. Despite being a major pig-rearing region in the country, Northeastern India has not undergone any investigation regarding the presence of T. gondii and Trichinella spp. in pigs. Therefore, this study aims to determine the seroprevalence of T. gondii and Trichinella spp. and identify associated risk factors in pigs reared by tribal communities and small-holder livestock farmers in the northeastern region of India. In a cross-sectional serological survey, 400 pigs from 400 households across five northeastern states of India underwent testing for the seroprevalence of porcine toxoplasmosis and trichinellosis. Serum samples (80 from each state) were analyzed using commercially available ELISA assays. Data on backyard farm characteristics and various management aspects were collected, and risk factors linked with prevalence were analyzed through univariate and multivariate logistic regression analysis. The findings revealed that the apparent and true prevalence of anti-T. gondii antibodies were 45% (40.12-49.88, 95% CI) and 45.7% (40.7-50.69, 95% CI), respectively. As for anti- Trichinella antibodies, both the apparent and true prevalence were 0.75% (-0.1-1.6, 95% CI). The univariate and multivariate analyses indicated that age above 24 months (OR 7.20, 95% CI 2.45-23.71), exposure to cats (OR = 5.87, 95% CI 2.55-14.05), and farms operating for breeding purposes (OR = 5.60, 95% CI 3.01-11.04) were significant risk factors associated with the seroprevalence of T. gondii. This study marks the initial documentation of the seroprevalence of T. gondii and Trichinella spp. in pigs reared by tribal communities in Northeastern India. The results emphasize the significance of these parasites as foodborne zoonotic threats in the region, potentially posing substantial public health risks, especially within tribal and rural communities. The insights derived from this research could be valuable in formulating targeted preventive and control strategies against T. gondii and Trichinella spp. in pigs, not only in this region but also in areas with similar rearing practices.

Serological and Molecular Detection of Toxoplasma gondii in Domestic Pigs Intended for Human Consumption and Potential Occupational Hazard to Pig Farmers in India

Toxoplasma gondii, an important food-borne zoonotic parasite, poses a worldwide public health hazard. Domestic pigs are considered one of the main intermediate hosts in the zoonotic transmission of T. gondii. To date, seroepidemiological information on T. gondii in domestic pigs in India is very scarce, and there are no reports of occupational hazards to pig farmers in this country. Here, we aimed at estimating the occurrence of T. gondii (antibodies and parasite DNA) in slaughtered pigs and pig farmers in Central India. Seroprevalence was determined in 410 serum samples from slaughtered pigs and 103 sera from pig farmers using an in-house prepared antigen-based modified agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA), and indirect-fluorescent antibody test (IFAT). Anti-T. gondii IgG antibodies were detected in 200 pigs (up to 48.8%, confidence interval [95% CI]: 40.4-52.2) and 44 pig farmers (up to 42.7%, 95% CI: 35.6-47.3) using MAT, ELISA, and IFAT. Inter-rater agreement showed an excellent agreement (kappa κ = 0.9) among the different serological tests suggesting similar detection potential of these tests. Recently acquired infections in all seropositive subjects were determined using IgG avidity testing and polymerase chain reaction (PCR). IgG avidity showed that 20 (10.3%) of slaughtered pigs and 8 (19.5%) pig farmers had a recently acquired infection. PCR for B1 and 529 repeats was performed in the heart tissues of slaughtered pigs and the blood cells of pig farmers. T. gondii DNA was detected in 14 (7.2%) slaughtered pigs and 5 (12.2%) pig farmers. Univariate analysis revealed that adult animals (>1 year), cats and rodents on the farm, and outdoor access are common factors (p ≤ 0.05) associated with T. gondii infection in pigs. Our results indicate that T. gondii is widely distributed in slaughtered pigs and pig farmers at risk of infection, highlighting a potential zoonotic transmission and health risk to consumers.

Impact of global trade agreements on agricultural producer prices in Asian countries

Following global trade agreements, Asian countries have been highly aggressive in implementing free trade. These conditions will impact all sectors, including agriculture. This study aims to examine the impact of the General Agreement on Tariffs and Trade (GATT), World Trade Organization membership (WTO), and the Doha Round implementations on agricultural producer prices in Asian countries (PPI). The study was conducted using secondary data from 1991 to 2020. The data for 28 Asian countries were analyzed using the first difference General Method of Moments (GMM). The results show that implementing the GATT raises the PPI, but implementing the WTO has the reverse impact. PPI is unaffected by the Doha Round. Inflation, exchange rate, value-added, human capital, and land area equipped for irrigation are all positive contributors to PPI. Several recommendations are made to increase PPI in Asian countries: increasing commitment to agricultural fair trade, increasing agricultural value-added, improving educational opportunities for agricultural business players, and prioritizing agricultural infrastructure investment.

Molecular Detection and Genotyping of Toxoplasma gondii from Pigs for Human Consumption in Zhejiang and Jiangsu Provinces, Eastern China

Toxoplasma gondii infections are common in humans and animals worldwide. Ingestion of raw or undercooked meat containing tissue cysts of T. gondii is one major source of transmission of this parasite. It is important to guarantee the meat quality of China since our pork industry produces about half of the world's pork. In this study, a total of 746 pig samples were collected from Zhejiang and Jiangsu provinces in eastern China, and examined for T. gondii infection by PCR amplification targeting B1 gene. In this study, we found that 57 of 746 (7.6%) pigs were positive for B1 gene, with 8.5% (48/562) in Zhejiang province and 4.9% (9/184) in Jiangsu province, respectively. The positive DNA samples were further genotyped at 11 genetic markers, including SAG1, 5'-and 3'-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico through PCR-restriction fragment length polymorphism (PCR-RFLP) technology. Two genotypes (ToxoDB 9 and ToxoDB 10) of T. gondii were identified by PCR-RFLP in Zhejiang province. However, both genotypes were not determined from Jiangsu province, which is speculated on the low DNA concentration and the small number of samples. These results indicate that T. gondii infection is endemic in pigs in eastern China and may raise public food safety concerns, suggesting more interventions for T. gondii-related risks are needed in the future.

Pseudorabies in pig industry of China: Epidemiology in pigs and practitioner awareness

Pseudorabies virus (PRV) is widely prevalent in China, which can transmit from pigs to other mammals. Moreover, a PRV variant isolated from an acute human encephalitis case was documented recently. It is imperative to investigate PRV epidemiology in pigs, the knowledge regarding pseudorabies (PR) and self-protection behaviors upon working among relevant practitioners including pig farmers, pig cutters, and pork salesman. In the present study, 18,812 pig serum samples and 1,634 tissue samples were collected from Hunan Province during the period of 2020 to 2021 for detecting the presence of PRV gE-special antibody and nucleic acids, respectively. Meanwhile, we conducted a questionnaire survey about PR among these practitioners in China. The results showed that nearly 9% (1,840/20,192) pigs from 161 collected sites (20.17%, 161/797) were seropositive for PRV-gE antibody. Though only 2.33% tissue samples were positive for PRV nucleic acids, all the representative PRV strains were variant. It was learned that most practitioners were frequently injured when working, the injured sites mainly included hand and foot. Among the three transmission routes of PRV, the aerosol transmission route was often overlooked. Moreover, the workers lacked self-protection awareness and were poor conscious about PRV and its potential threat to humans. All the results demonstrate that PRV remains widely spread in pig populations, while the potential threats of PRV in pig industry receive less attention, suggesting that targeted educational programs to these people should be performed.

Toxoplasma gondii in Foods: Prevalence, Control, and Safety

Toxoplasma gondii is an obligate intracellular parasite that causes toxoplasmosis, with approximately one third of the population around the world seropositive. The consumption of contaminated food is the main source of infection. These include meat products with T. gondii tissue cysts, and dairy products with tachyzoites. Recently, contamination has been detected in fresh products with oocysts and marine products. Despite the great health problems that are caused by T. gondii, currently there are no standardized methods for its detection in the food industry. In this review, we analyze the current detection methods, the prevalence of T. gondii in different food products, and the control measures. The main detection methods are bioassays, cell culture, molecular and microscopic techniques, and serological methods, but some of these do not have applicability in the food industry. As a result, emerging techniques are being developed that are aimed at the detection of multiple parasites simultaneously that would make their application more efficient in the industry. Since the prevalence of this parasite is high in many products (meat and milk, marine products, and vegetables), it is necessary to standardize detection methods, as well as implement control measures.

Molecular occurrence and risk factors for Toxoplasma gondii infection in equids in Jilin, China

Toxoplasma gondii, one of the important zoonotic parasites, has been detected in lots of hosts including humans, with a widespread prevalence. The products of equids, such as meat and milk, have been closely related to humans’ life. As the intermediate hosts, little is known about equids toxoplasmosis in Jilin province. Therefore, the present study aimed to evaluate the occurrence and risk factors of Toxoplasma gondii infections in equids from Jilin, northeastern China. In this study, a total of 245 blood samples of equids (192 horses, 25 donkeys and 28 mules) were collected from six localities in Jilin Province from March 2018 to August 2020 and detected by PCR. The occurrence rate of T. gondii B1 gene was analyzed using multivariable logistic regression to evaluate risk factors associated with the positive rates in equids. Among 245equids, T. gondii molecular occurrence was 9.0% (22/245). The highest positive rate was observed in equids from Dongfeng (16.3%) followed by Taonan (10.0%), Wangqing (8.3%), Antu (8.0%), Tonghua (8.0%) and Shulan (2.3%). Statistical analysis revealed that farming model and region may be two main risk factors. Data analysis indicated that the positive rate in captive farm (3.2%, 95% CI: 0.0–6.7%) was significantly lower than those in cage-free farm (P < 0.05), and the region of Shulan was protective factor (OR: 0.063, 95% CI: 0.007–0.559).The results of our study alert people to be aware that the present of equids T. gondii infection in this region, and contribute to a prevention and treatment program for toxoplasmosis in Jilin, China.

Seroprevalence and risk factor investigation for the exposure of Toxoplasma gondii among veterinary personnel in Punjab, India

Toxoplasma gondii, a globally important food borne zoonotic parasite, infects most of the warm-blooded animals as well as people. Veterinarians and para vets are considered at risk of T. gondii exposure. We determined the seroprevalence of T. gondii in veterinary personnel and investigated the associated risk factors in Punjab, India. Two hundred and five blood samples collected from veterinary personnel were tested for the presence of Toxoplasma IgG and IgM antibodies using ELISA. The apparent and true seroprevalence of T. gondii with 95% confidence interval (CI) were estimated. Information about participant demographics, and possible routes of exposure was collected using a self-completed questionnaire at the time of blood collection. For risk factor investigation, a veterinary person was considered Toxoplasma seropositive using a combination of tests in parallel, i.e. if it was positive in either IgG or IgM ELISA. A mixed effects logistic regression model was constructed to evaluate the association of demography, occupational and non-occupational factors with Toxoplasma seropositive status. The apparent and estimated true seroprevalence of T. gondii antibodies using Toxoplasma IgG ELISA was 8.78% (95% CI 5.63-13.45%) and 7.36% (95% CI 4.04-12.29%), respectively. The apparent and estimated true seroprevalence using Toxoplasma IgM ELISA was 0.49% (95% CI inestimable - 2.71%) and 0.51% (95% CI inestimable - 2.83%), respectively. After adjusting other variables in the final model, consuming mutton and owning a cat were associated with large odds of being Toxoplasma seropositive. In this study occupational exposure does not seem to play an important role for the exposure of T. gondii in veterinary personnel in Punjab state of India. The seroprevalence of toxoplasmosis in veterinary personnel is comparatively low in occupationally exposed veterinary personnel in Punjab, India.

Toxoplasma gondii Infection in Swine: Implications for Public Health

Toxoplasmosis, due to Toxoplasma gondii, is a parasitic disease with global importance. Among livestock, chronic T. gondii infection has been reported in higher rates in pigs and small ruminants, but with subclinical infections in case commonly encountered in pigs. Seroprevalence in the global pig population ranges according to the age or species of pigs, geographical distribution, production programs, and systems. Generally, T. gondii infections are noticed in low prevalence rates in conventional pig farms with high hygiene standards. In contrast, higher prevalence is common on free-ranging farms, outdoor or backyard small pig fams, as well as in farmed or hunted wild boars. The T. gondii average worldwide seroprevalence in pigs is reported to be 13% in Europe, 21% in Africa, 25% in North America, 21% in Asia, and 23% in South America. Human toxoplasmosis outbreaks have been correlated with the consumption of raw or undercooked meat, especially from infected pigs or wild boars, as well as of contaminated drinking water. The risk of infection in processed pork products is lower compared with fresh pork, as meat processing can reduce or inactivate T. gondii tissue cysts. Hence, the prevalence of T. gondii in the pig population may be a useful indicator of the risk of human toxoplasmosis associated with the consumption of pork products. The lack of obligatory screening methods at farm level for the detection of antibodies in farmed animals or the viable T. gondii in carcasses at slaughterhouse level increases the risk of contaminated pork or meat products. For this reason, the application of biosecurity and surveillance programs at farm level is very important to prevent a T. gondii infection.

Seroprevalence and risk factors of Toxoplasma gondii infection among veterinary personnel and abattoir workers in Central India

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important zoonotic infection. Veterinary personnel and abattoir workers are considered to be at a high risk of T. gondii infection owing to their occupational exposure. However, the association of T. gondii infection with occupational exposure to animals has not been determined in India. Hence, we analysed 139 and 126 blood samples of veterinary personnel and abattoir workers, respectively, for anti-T. gondii antibodies using enzyme-linked immunosorbent assay (ELISA), modified agglutination test (MAT) and indirect fluorescent antibody test (IFAT). The association of seroprevalence with sociodemographic profiles, work activities and dietary habits was determined in the study population. MAT, ELISA and IFAT results demonstrated nearly 46%, 48% and 47% seropositivity, respectively. MAT (kappa = 0.924) and IFAT (kappa = 0.962) results showed good agreement with ELISA results. Of the ELISA positive samples, 46% was copositive for IgG antibody, 1.5% for IgM antibody and 1.5% for both IgG and IgM antibodies. High IgG avidity was observed only in IgG+ IgM- and IgG+ IgM+ samples and not in IgM+ IgG- samples, indicating chronic T. gondii infection in most of the cases. Furthermore, multivariate analysis revealed that T. gondii seropositivity was associated with age > 30 years (odds ration [OR] = 1.992), cat at home (OR = 1.991), not wearing gloves (OR = 1.886), not wearing safety glasses (OR = 1.985) and contact with soil (OR = 1.695). These findings support the presence of a potentially significant association between T. gondii seropositivity and occupational exposure to animals.

Designing and developing of high-resolution melting technique for separating different types of Toxoplasma gondii by analysis of B1 and ROP8 gene regions

BACKGROUND

Determination of Toxoplasma gondii genotypes plays an important role in the health management and epidemiology of toxoplasmosis. We developed HRM analysis to differentiate genotypes of T. gondii using the B1 and ROP8 genes, through comparing the sensitivity and specificity of both genes and methods used for the detection of T. gondii.

METHODS

A total of 96 DNA samples of muscle tissue of livestock and poultry brain tissue with three standard strains RH (type I), PRU (type II) and VEG (type III) were prepared and analyzed. Three methods of nested PCR, PCR-PCR and nested-qPCR-HRM were used. Specific new primers were designed and synthesized for developing HRM. Thirty positive samples obtained from nested-qPCR-HRM were sequenced (18 B1 and 12 ROP8).

RESULTS

Overall, 87 infected samples were identified using both genes. Through the B1 gene, we could separate type I (T_m = 84.8 °C) from II/III types (T_m = 84.6 °C). Also, the ROP8 gene could separate type II (T_m = 84.5 °C) from I/III types (T_m = 84.12 °C). Highest sensitivity (100%) and specificity (78.72%) were observed by nested-qPCR-HRM assays of the B1 and ROP8 genes than by other methods, respectively. Thus, the B1 gene can be used to most accurately detect T. gondii, while the ROP8 gene was more appropriate for T. gondii genotyping. PCR-sequencing results were consistent with HRM results in most selected samples.

CONCLUSION

HRM analysis is a powerful diagnostic tool for rapid detection and determination of main clonal lineages, and even unusual T. gondii genotypes.

Toxoplasma gondii in Chickens (Gallus domesticus) from North India

PURPOSE

Toxoplasma gondii, an important food-borne parasite has been reported in a wide range of food animals globally. Poultry meat production is on rise in several developing nations including India. Several studies on status of T. gondii conducted globally had shown substantial risk of this parasite through poultry meat. Such information is lacking in the north India, where poultry meat is a preferred non-vegetarian food over other meats; therefore, this study determined the seroprevalence (based on detection of antibodies) and tissue prevalence (based on detection of DNA) of T. gondii in poultry meat intended for human consumption in north India.

METHODS

Samples (skeletal muscle and/heart as well as blood) were collected from slaughter poultry intended for human consumption reared in Punjab state (n = 366), Himachal Pradesh (n = 44) state, and Chandigarh union territory (n = 112) in North India. Serum samples were tested using commercially available Chicken T. gondii IgG ELISA kit to determine the serostatus. The DNA of T. gondii was detected by nested PCR. To determine the agreement between ELISA and PCR, Kappa value was estimated.

RESULTS

Overall, study reports 2.3% (95% CI 1.3%-4.1%) tissue prevalence and 6.5% (95% CI 4.6%-9.1%) seroprevalence from chickens reared in north India. Backyard poultry had significantly higher proportion of T. gondii (24.4%, 10/41; p < 0.001) than caged (0%, 0/284) and deep litter poultry (16.2%, 32/197). The sequence alignment score of three sequences obtained in this study showed 97-100% nucleotide identity with Type I RH strain and VEG type III strain. The agreement between ELISA and PCR was poor (Kappa = 0.145; 95% CI 0.07-0.22). Thus, a combination of serological and molecular tests can improve the diagnosis of T. gondii.

CONCLUSION

A low prevalence indicates that T. gondii in poultry presents a lower food safety risk for public health in north India; however, this study recommend cooking of poultry meat before consumption. Further studies are required to check the viability of T. gondii in poultry meat intended for human consumption, and to determine the risk factors associated and the genotypes circulating in poultry in north India.

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.

Seroprevalence and B1 gene Phylogeny of Toxoplasma gondii of Dogs and Cats in Republic of Korea

The outbreak of human toxoplasmosis can be attributed to ingestion of food contaminated with Toxoplasma gondii. Toxoplasmosis recently increased in domestic and stray dogs and cats. It prompted studies on the zoonotic infectious diseases transmitted via these animals. Sero- and antigen prevalences of T. gondii in dogs and cats were surveyed using ELISA and PCR, and B1 gene phylogeny was analyzed in this study. Toxoplasmosis antibodies were measured on sera of 403 stray cats, 947 stray dogs, 909 domestic cats, and 2,412 domestic dogs collected at nationwide regions, Korea from 2017 to 2019. In addition, whole blood, feces, and tissue samples were also collected from stray cats (1,392), stray dogs (686), domestic cats (3,040), and domestic dogs (1,974), and T. gondii-specific B1 gene PCR was performed. Antibody prevalence of stray cats, stray dogs, domestic cats, and domestic dogs were 14.1%, 5.6%, 2.3%, and 0.04%, respectively. Antigen prevalence of these animals was 0.5%, 0.2%, 0.1%, and 0.4%, respectively. Stray cats revealed the highest infection rate of toxoplasmosis, followed by stray dogs, domestic cats, and domestic dogs. B1 gene positives were 5 of stray cats, and identified to high/moderate pathogenic Type I/III group. These findings enforce that preventive hygienic measure should be strengthened at One Health level in dogs and cats, domestic and stray, to minimize human toxoplasmosis infections.