Seroprevalence and correlates of Toxoplasma gondii infection in domestic pigs in Veracruz State, Mexico

Seroepidemiology of Neospora caninum in Cattle of Pastoral Production System in Teltelle District of Borana Zone, Southern Ethiopia

Background

Neosporosis is a major cause of abortion in smallholder dairy farms in Ethiopia. However, its status and impact in pastoral cattle production settings were uncovered. This study was performed with the aims of estimating the seroprevalence and associated potential risk factors for Neospora caninum in Boran cattle in Teltelle district of Borana zone, Ethiopia.

Methods

180 blood samples were collected from 48 randomly selected pastoral herds using a multistage sampling technique and subjected to an indirect enzyme-linked immunosorbent assay (ELISA) test to detect antibodies specific to N. caninum. A questionnaire survey was also used to identify the potential risk factors of N. caninum in the study area. Evaluation of the associated risk factors was conducted using a multivariable logistic regression model.

Results

Antibodies against N. caninum exposure were detected in 5% of cattle (95% CI: 1.816–8.184) from 180 animals tested. Similarly, the seroprevalence of N. caninum in herds with at least one positive animal was 14.6% (95% CI: 4.598–24.567) from 48 herds examined. A multivariable logistic regression model identified the following as significant risk factors: a history of abortion (AOR = 23; 95% CI: 2.354–188.702; P = 0.006), dystocia (AOR = 11; 95% CI = 22.275–55.860; P = 0.003), wells water sources (AOR = 9; 95% CI: 1.599–47.568; P = 0.012), and dogs fed with raw animal products (AOR = 6; 95% CI: 11.213–27.222; P = 0.028).

Conclusion

This study revealed the first serological evidence of N. caninum exposure in cattle reared under pastoral production system. Our findings suggest N. caninum is likely to be an important cause of abortion and dystocia in cattle in Ethiopia. Management practices, such as provision of hygienic water and restriction of dogs fed with raw animal products, are likely to reduce the risk of infection. Thus, maximizing community awareness about these disease management practices is suggested.

Molecular detection and genetic characterization of Toxoplasma gondii in pork from Chongqing, southwest China

Raw or undercooked meat is an important source of Toxoplasma gondii infection in China, but there is little research data on these infections in Chongqing. This study determined the prevalence of T. gondii, and its genotypes, in pork. A total of 1,223 diaphragm muscle samples were collected from eight slaughterhouses and 79 markets and detected by PCR amplification of the ITS gene. All of the positive samples were used for genotype identification by PCR-RFLP with 11 genetic markers. The total positive rate of T. gondii in Chongqing pork was 8.7%, and differences in T. gondii infection rates were found between different districts (0%-23.3%), seasons (e.g., 4.3% from Spring, 7.3% from Summer, 11.4% from Autumn, 12.0% from Winter) and years (2.7%-14.3%). Six samples were successfully genotyped, of which one was identified as ToxoDB#9 and five were ToxoDB#9-like. This was the first continuous study about the prevalence of T. gondii in pork in Chongqing for several years. Slaughterhouses in different districts, pork source, farm scale, season and year were potential risk factors for T. gondii contamination by the univariate logistic regression, and using multivariate logistic regression districts, pork source and year were the independent risk factor. These data may help reducing the levels of toxoplasmosis in pigs and humans in Chongqing.

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 Public Health Significance of Toxoplasmosis in Small Ruminants of Pastoral Community in Yabello District, Borana Zone, Southern Ethiopia

Toxoplasmosis is a zoonotic protozoan disease. Data on seroepidemiology of toxoplasmosis in Ethiopia is scarce, almost null in the pastoral area of the Borana zone. The study was carried out to determine the seroprevalence, to identify risk factors of toxoplasmosis in sheep and goats, and to assess the awareness level of pastoralists about toxoplasmosis in the Yabello district of Borana zone, Southern Ethiopia. A cross-sectional study was conducted from November 2016 to April 2017 in six peasant associations of the Yabello district of Borana zone, Southern Ethiopia. A total of 400 serum samples of randomly selected small ruminants owned by pastoralists were examined to detect antibodies specific to Toxoplasma gondii using Latex Agglutination Test (SPINREACT, Girona, Spain). A semistructured questionnaire survey was used to conduct a face-to-face interview with owners (n = 100) of sampled flocks. Logistic regression analysis was used to determine the association of hypothesized risk factors. The overall seroprevalence was 52.8% of which 57.8 and 47.8% were sheep and goats, respectively. Univariate logistic regression analysis revealed a higher seroprevalence ratio of T. gondii infection in sheep than goats (COR: 1.95, 95% CI: 1.226-3.112; P = 0.005). Multivariate logistic regression analysis indicated significantly higher odds of acquiring T. gondii infection in adult animals (sheep: (AOR = 2.26, 95% CI: 1.323-3.874; P = 0.003), goats: (AOR = 2.15; 95% CI: 1.009-4.579; P = 0.047)), female sheep (AOR = 2.45; CI: 1.313-4.568; P = 0.005), animals from lowland areas (sheep: (AOR = 2.28; CI: 1.190-4.356; P = 0.013), goat: (AOR = 3.27; CI: 1.386-7.723; P = 0.007)), animal drinking lake water (sheep: (AOR = 1.93; CI: 1.011-3.698; P = 0.046), goat: (AOR = 2.96; CI: 1.297-6.771; P = 0.010)), and goats with history of abortion (AOR = 2.42; CI: 1.242-4.711; P = 0.009) than young animals, male (sheep), animals from midland areas, animals drinking wells water, and flock with no history of abortion (goat), respectively. Among respondents, 97.0% had no knowledge about toxoplasmosis and 75.0% drink raw milk and consume the meat of sheep and goats. 80.0% of respondents had no knowledge about the risk of cats to human and animal health while 70.0% of them had domestic cats and practice improper fetal body handling. Highly prevailing toxoplasmosis in small ruminants of the Yabello district might pose a serious economic loss and be a potential public health threat to the extremely vulnerable pastoralists. Therefore, awareness and further studies are warranted to tackle the economic and public health consequences of T. gondii infection.

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 of Toxoplasma gondii infection in slaughter pigs in Shanghai, China

Toxoplasma gondii is a pathogen that seriously threatens the health of humans and animals. However, the current infection status of T. gondii in slaughter pigs in Shanghai is still not clear. To investigate the seroprevalence of T. gondii infection and analyze the prevalence factors associated with the parasite infection, 1158 serum samples were collected from five slaughterhouses in three districts between 2015 and 2018. Serum antibodies against T. gondii were detected in 160 pigs (13.8%) by enzyme-linked immunosorbent assay (ELISA). Additionally, seroprevalence rates differed among different districts (ranging from 4.0% in JD-2 to 17.6% in JD-1), seasons (ranging from 6.7% in winter to 17.8% in autumn), and years (ranging from 8.0% in 2016 to 26.8% in 2015). Region, season, and year were the main factors affecting T. gondii infection in these pigs. There were few reports on serological monitoring of T. gondii in Shanghai slaughterhouses between 2015 and 2018, and the number of infections had steadily increased over the past several consecutive years. Therefore, our data are helpful to understand the epidemic status of T. gondii in Shanghai, which will strengthen the prevention and treatment of swine toxoplasmosis.

Antibodies anti-Toxoplasma gondii and anti-Neospora caninum in backyard pigs from the state of Mato Grosso, Brazil

To estimate the seroprevalence of Toxoplasma gondii and Neospora caninum, using an indirect immunofluorescent assay (IFA), and identify the risk factors associated, serum samples were collected from 1,070 pigs from 320 backyard pig farming in the of Mato Grosso state. The animal-level seroprevalence of T. gondii and N. caninum was 32.48% and 13.49%, respectively, with a herd seroprevalence of 55.63% for T. gondii and 27.81% for N. caninum. Feeding the animals with leftovers increases the probability of the presence of anti-T. gondii antibodies in pigs by 1.09-fold. Unlike to T. gondii, feeding with leftovers was found to be negatively associated with N. caninum seropositivity in farm-level analysis and in the animal-level model, so decreasing the chances of positivity. Yet, age was considered a risk factor for N. caninum seropositivity. Further studies are necessary to evaluate the impact of T. gondii infection on backyard pig farming production, and its importance as a source of toxoplasmosis infection in humans in the Mato Grosso state, as well as, the role of domestic pigs in the epidemiology of neosporosis.

Toxoplasma gondii infection and toxoplasmosis in farm animals: Risk factors and economic impact

The protozoan parasite Toxoplasma gondii is a zoonotic parasite that can be transmitted from animals to humans. Felids, including domestic cats, are definitive hosts that can shed oocysts with their feces. In addition to infections that occur by accidental oral uptake of food or water contaminated with oocysts, it is assumed that a large proportion of affected humans may have become infected by consuming meat or other animal products that contained infective parasitic stages of T. gondii. Since farm animals represent a direct source of infection for humans, but also a possible reservoir for the parasite, it is important to control T. gondii infections in livestock. Moreover, T. gondii may also be pathogenic to livestock where it could be responsible for considerable economic losses in some regions and particular farming systems, e.g. in areas where the small ruminant industry is relevant. This review aims to summarize actual knowledge on the prevalence and effects of infections with T. gondii in the most important livestock species and on the effects of toxoplasmosis on livestock. It also provides an overview on potential risk factors favoring infections of livestock with T. gondii. Knowledge on potential risk factors is prerequisite to implement effective biosecurity measures on farms to prevent T. gondii infections. Risk factors identified by many studies are cat-related, but also those associated with a potential contamination of fodder or water, and with access to a potentially contaminated environment. Published information on the costs T. gondii infections cause in livestock production, is scarce. The most recent peer reviewed reports from Great Britain and Uruguay suggest annual cost of about 5-15 million US $ per country. Since these estimates are outdated, future studies are needed to estimate the present costs due to toxoplasmosis in livestock. Further, the fact that T. gondii infections in livestock may affect human health needs to be considered and the respective costs should also be estimated, but this is beyond the scope of this article.

The global seroprevalence of Toxoplasma gondii in pigs: A systematic review and meta-analysis

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is an important disease with worldwide distribution. Infection can occur from ingesting raw or undercooked infected meat, and among food animal species, pork is known to be one of the main sources of meat-borne infection. Here, we present results of the first systematic review and meta-analysis on the global T. gondii seroprevalence in pigs. PubMed/MEDLINE, Scopus, and EMBASE databases were comprehensively searched for relevant studies published between January 1, 1990 and October 25, 2018. We used a random effects model to calculate pooled seroprevalence estimates with 95% confidence intervals (CI) and analyzed data from five continents. We also conducted subgroup and meta-regression analyses to evaluate the effects of geographical and climate variables on pooled seroprevalence rates. Among 1542 publications identified, 148 studies containing 150 datasets were included in the meta-analysis, and comprised 148,092 pigs from 47 countries. The pooled global T. gondii seroprevalence in pigs was estimated to be 19% (95%CI, 17-22%; 23,696/148,092), with the lowest seroprevalence in Europe (13%; 10-15%) and highest seroprevalence in Africa (25%; 17-34%) and North America (25%; 19-33%). The seropositivity rates in Asia and South America regions were (21%, 16-26%) and (23%; 17-30%), respectively. A significantly higher T. gondii seroprevalence was associated with higher mean annual temperature and lower geographical latitude. The presence of cats on farms was identified as a potential risk factor for T. gondii seropositivity (OR, 1.41; 95%CI, 1.00-2.02). Our findings highlight the importance of pigs as a possible source of human T. gondii infections.

Experimental Porcine Toxoplasma gondii Infection as a Representative Model for Human Toxoplasmosis

Porcine infections are currently not the state-of-the-art model to study human diseases. Nevertheless, the course of human and porcine toxoplasmosis is much more comparable than that of human and murine toxoplasmosis. For example, severity of infection, transplacental transmission, and interferon-gamma-induced antiparasitic effector mechanisms are similar in pigs and humans. In addition, the severe immunosuppression during acute infection described in mice does not occur in the experimentally infected ones. Thus, we hypothesise that porcine Toxoplasma gondii infection data are more representative for human toxoplasmosis. We therefore suggest that the animal model chosen must be critically evaluated for its assignability to human diseases.

Toxoplasma gondii, a Foodborne Pathogen in the Swine Production Chain from a European Perspective

Toxoplasmosis is a foodborne zoonosis transmitted by Toxoplasma gondii, a cosmopolitan protozoan that infects humans through exposure to different parasite stages, in particular by ingestion of tissue cysts or tachyzoites contained in meat, primary offal (viscera), and meat-derived products or ingestion of environmental sporulated oocysts in contaminated food or water. The pig is an important species for infection: raw or undercooked pork consumption not subject to treatment able to inactivate the parasite represents a risk to consumers' health. Broadening knowledge of transmission ways and prevalence concerning this important pathogen in swine, together with a thorough acquaintance with hazard management are key elements to avoid T. gondii spreading within the swine production chain. This review aims to illustrate why toxoplasmosis should be regarded as a veterinary public health issue through a careful description of the parasite, routes of infection, and inactivation treatments, highlighting the main prevention lines from pig breeding to pork consumption.

Cross-Sectional Study of Toxoplasma gondii Infection in Pig Farms in England

Ingestion of undercooked meat has been proposed as an important source of human Toxoplasma gondii infection. To ascertain the contribution of meat consumption to the risk of human infection, estimates of the prevalence of infection in meat-producing animals are required. A cross-sectional study was conducted to assess T. gondii infection in pigs raised in England, to identify risk factors for infection, and to compare performance of two serological tests: modified agglutination test (MAT) and enzyme-linked immunosorbent assay (ELISA). Blood samples from 2071 slaughter pigs originating from 131 farms were collected and 75 (3.6%) were found to be positive by MAT. Positive pigs originated from 24 farms. A subset of samples (n = 492) were tested using ELISA, and a significant disagreement (p < 0.001) was found between the two tests. An empirical Bayes approach was used to estimate the farm-level prevalence and the probability of each individual farm having at least one positive animal, considering the uncertainty arising from the sampling strategy and the imperfect test performance. The adjusted farm-level prevalence was 11.5% (95% credible interval of positive farms 8.4-16.0%). Two different criteria were used for classifying farms as infected: (1) ≥50% probability of having at least one infected pig (n = 5, 6.8%) and (2) ≥10% probability (n = 15, 20.5%). Data on putative risk factors were obtained for 73 farms. Using a 10% cutoff, the relative risk (RR) of infection was higher in farms where cats have direct access to pigs' food (RR = 2.6; p = 0.04), pigs have outdoor access (RR = 3.0; p = 0.04), and farms keeping ≤200 pigs (RR = 3.9; p = 0.02), with strong collinearity between the three variables. The findings suggest a low level of T. gondii infection in the farms studied, most of which are likely to send to slaughter batches comprising 100% uninfected pigs. These results provide key inputs to quantitatively assess the T. gondii risk posed by pork to consumers.

Toxoplasma gondii infection in pork produced in France

The aim of this study was to assess the seroprevalence of the Toxoplasma gondii parasite in pork produced in France, and to determine infection risk factors. An innovative survey was designed based on annual numbers of slaughtered pigs from intensive and outdoor farms in France. A total of 1549 samples of cardiac fluids were collected from pig hearts to determine seroprevalence using a Modified Agglutination Test. Of those, 160 hearts were bio-assayed in mice to isolate live parasites. The overall seroprevalence among fattening pigs was 2·9%. The adjusted seroprevalence in pigs from intensive farms was 3·0%; the highest in sows (13·4%); 2·9% in fattening pigs and 2·6% in piglets. Adjusted seroprevalence in fattening animals from outdoor farms was 6·3%. Strains were isolated from 41 animals and all were genotyped by Restriction Fragment Length Polymorphism as type II. Risk-factor analysis showed that the risk of infection was more than three times higher for outdoor pigs, and that sows' risk was almost five times higher than that of fattening animals. This study provides further evidence of extensive pork infection with T. gondii regardless of breeding systems, indicating that farm conditions are still insufficient to guarantee 'Toxoplasma-free pork'.

Prevalence of infection with Toxoplasma gondii in landrace and mixed breed pigs slaughtered in Baja California Sur State, Mexico

We performed a cross-sectional study to determine the seroprevalence of Toxoplasma gondii infection in 308 domestic pigs slaughtered in La Paz, Baja California Sur State, Mexico using the modified agglutination test (MAT, cut off 1:25). Forty (13%) of the 308 pigs were seropositive with MAT titers of 1:25 in 16, 1:50 in 5, 1:100 in 4, 1:200 in 5, 1:400 in 3, 1:800 in 3, 1:1600 in 2, and 1:3200 in 2. Multivariate analysis of pigs' characteristics showed that seropositivity to T. gondii was negatively associated with mixed breed (OR = 0.02; 95% CI: 0.003-0.26; P = 0.001). Other variables including sex, type of raising, and municipality did not show an association with T. gondii seropositivity by multivariate analysis. The frequency of high antibody titers (≥1:400) was significantly higher (P < 0.001) in Landrace pigs than mixed breed pigs. The seroprevalence of T. gondii infection in pigs for slaughter in Baja California Sur State is low compared with seroprevalences reported in pigs in other Mexican states. Landrace pigs demonstrated higher seroprevalence rates and antibody levels than mixed breed pigs. This is the first report of T. gondii infection in pigs raised in a desert climate.

Prevalence and risk factors for Toxoplasma gondii infection in meat animals and meat products destined for human consumption

Toxoplasma gondii is a protozoan parasite that is responsible for approximately 24% of all estimated deaths attributed to foodborne pathogens in the United States. Human infection results from accidental ingestion of oocysts from the environment, in water, or on insufficiently washed produce or from consumption of raw or undercooked meat products that contain T. gondii tissue cysts. This review focused on studies of T. gondii in meat because many human T. gondii infections are acquired through consumption of raw or undercooked meat. Prevalence of T. gondii is higher in conventionally reared pigs, sheep, and poultry than in cattle and is greater in meat products from organic than from conventionally reared meat animals because of outdoor access, which poses substantially greater opportunities for exposure to infected rodents, wildlife, and oocyst-contaminated feed, water, or environmental surfaces. Risk factors related to T. gondii exposure for livestock include farm type, feed source, presence of cats, methods of rodent and bird control, methods of carcass handling, and water quality. This review serves as a useful resource and information repository for informing quantitative risk assessment studies for T. gondii infection in humans through meat consumption.

Seroprevalence of Toxoplasma gondii infection and associated risk factors in Huicholes in Mexico

Background

Very little is known about the seroepidemiology of Toxoplasma gondii infection in ethnic groups in Mexico. Huicholes are an indigenous ethnic group living in a remote mountainous region in Mexico. We sought to determine the prevalence of anti-Toxoplasma IgG and IgM antibodies in Huicholes; and to determine the association of Toxoplasma seropositivity with socio-demographic, behavioral, and clinical characteristics of Huicholes.

Methods

We performed a cross sectional survey in Huicholes from September 2013 to January 2014. A convenience sampling method was used. We investigated the prevalence of anti-Toxoplasma IgG and IgM antibodies in 214 Huicholes using enzyme-linked immunoassays. A standardized questionnaire was used to obtain the characteristics of the Huicholes. Bivariate and multivariate analyses were used to assess the association of Toxoplasma exposure and Huicholes’ characteristics.

Results

Of the 214 Huicholes studied (mean age: 37.98 ± 15.80 years), 71 (33.2%) were positive for anti-T. gondii IgG antibodies and 47 (66.2%) of them were also positive for anti-T. gondii IgM antibodies. Seroprevalence of T. gondii infection did not vary with age, sex, or occupation. However, seroprevalence of anti-T. gondii IgM antibodies was significantly higher in female than in male Huicholes. Multivariate analysis of socio-demographic and behavioral characteristics showed that T. gondii exposure was associated with consumption of turkey meat (OR = 2.28; 95% CI: 1.16-4.46; P = 0.01). In addition, seroprevalence of T. gondii infection was significantly higher in Huicholes suffering from dizziness and memory impairment than those without such clinical characteristics.

Conclusions

Our results demonstrate serological evidence of T. gondii exposure among Huicholes which may be impacting their health. Results of this first study of T. gondii infection in Huicholes may be useful for the design of optimal preventive measures against infection with T. gondii.