Molecular Detection of Toxoplasma gondii in the Slaughter Sheep and Goats from Shandong Province, Eastern China

Detection of Toxoplasma gondii Infection in Small Ruminants: Old Problems, and Current Solutions

Toxoplasmosis is a parasitic zoonosis of veterinary importance, with implications for public health. Toxoplasma gondii infection causes abortion or congenital disease in small ruminants. Moreover, the consumption of infected meat, cured meat products, or unpasteurized milk and dairy products can facilitate zoonotic transmission. Serological studies conducted in various European countries have shown the high seroprevalence of specific anti-T. gondii antibodies in sheep and goats related to the presence of oocysts in the environment, as well as climatic conditions. This article presents the current status of the detection possibilities for T. gondii infection in small ruminants and their milk. Serological testing is considered the most practical method for diagnosing toxoplasmosis; therefore, many studies have shown that recombinant antigens as single proteins, mixtures of various antigens, or chimeric proteins can be successfully used as an alternative to Toxoplasma lysate antigens (TLA). Several assays based on DNA amplification have been developed as alternative diagnostic methods, which are especially useful when serodiagnosis is not possible, e.g., the detection of intrauterine T. gondii infection when the fetus is not immunocompetent. These techniques employ multicopy sequences highly conserved among different strains of T. gondii in conventional, nested, competitive, and quantitative reverse transcriptase-PCR.

Toxoplasma gondii infection in sheep from Romania

BACKGROUND

Toxoplasmosis is a widespread zoonosis caused by the intracellular protozoan parasite Toxoplasma gondii. Limited epidemiological information is available about the prevalence of T. gondii in sheep in Romania, and a high incidence would have implications for both the economy and public health. To our knowledge, no studies are available about the T. gondii strains circulating in lambs. The objective of this study was to assess the prevalence of T. gondii in sheep (serology), lambs (serology, bioassay, PCR) and sheep abortions (PCR) in Romania. Moreover, the study aimed to perform the genetic characterization of T. gondii isolates from lambs.

METHODS

Serum samples collected from 2650 sheep (2067 adults and 583 lambs) were tested for anti-T. gondii antibodies (IgG) using a commercial ELISA kit. Likewise, 328 pairs of diaphragmatic muscle-serum samples were collected from lambs aged between 2 and 4 months. Lamb serum samples were analyzed using MAT for anti-T. gondii antibody detection. The diaphragm tissue samples from MAT-positive lambs (at a dilution ≥ 1:25) were bioassayed in mice. The T. gondii strains were genotyped using 15 microsatellites markers. Additionally, brain and heart samples from 76 sheep abortions were analyzed for T. gondii DNA by polymerase chain reaction (PCR) targeting the 529-bp repeat region (REP529).

RESULTS

The results showed that more than half of the tested sheep were T. gondii seropositive (53.5%). The seroprevalence was significantly higher in adults (61.1%) than in lambs (26.4%). The seroprevalence of T. gondii infection in slaughtered lambs, by MAT, was 37.5% (123/328). There were bioassayed in mice 56 diaphragmatic tissues from 123 seropositive lambs. Toxoplasma gondii strains were isolated from 18 (32.1%) lambs intended for human consumption. All T. gondii strains were confirmed by PCR. Six strains were genotyped using 15 microsatellite markers and belonged to genotype II. Toxoplasma gondii DNA was detected in 11.8% (9/76) of sheep abortions.

CONCLUSIONS

The present study showed the presence of T. gondii in sheep in all the regions considered in the study. The high prevalence of T. gondii infection in sheep and lambs, demonstrated by serology, molecular analysis and bioassay, highlighted that there is an important risk of human infection in consuming raw or undercooked sheep/lamb meat.

Prevalence of Toxoplasmosis in Sheep and Goats in Pakistan: A Systematic Review and Meta-Analysis

Toxoplasmosis, a parasitic disease caused by Toxoplasma gondii, results in congenital disorders and miscarriages among livestock and humans worldwide. This systematic review and meta-analysis were conducted to determine the prevalence of T. gondii infection in sheep and goats in Pakistan from 2000 to 2020. We searched the PubMed, Scopus, EMBASE, and Google Scholar databases and selected 17 publications that fulfilled our inclusion criteria. Eight studies were conducted in Southern Punjab, six in Khyber Pakhtunkhwa, two in Northern Punjab, and one in Central Punjab. The diagnostic tests used in the included articles to confirm toxoplasmosis were the latex agglutination test in 56% of the studies, the enzyme-linked immunosorbent assay in 38%, and the indirect hemagglutination assay in 6%. The infection rates were substantially higher among sheep > 1 year of age (37%) than among sheep ≤ 1 year old (19%). Statistically significant differences in infection rates were found between male and female sheep and goats. The overall infection rate by age was also significant among sheep and goats. Sex and age variability between sheep investigations were significant, and sex heterogeneity and age homogeneity were significant among goats. Hence, robust infection control protocols should be implemented to prevent infection in animals and humans.

Seroprevalence of Toxoplasma gondii infection in sheep and goats from different geographical regions of the world: Systematic review and meta-analysis

The Toxoplasma gondii is an obligate intracellular protozoan parasite which significantly impact small ruminant productivity, international animal trade and transboundary movement of animal across the globe. The seroprevalence of T. gondii infection (toxoplasmosis) in sheep and goats is widely studied in many parts of the world and there is a lack of comprehensive information on prevalence estimates considering the global and regional perspectives. The aim of the study was to use systematic review and meta-analysis methods to estimate the global and regional pooled seroprevalence of T. gondii infection in sheep and goats, as well as factors that influence prevalence estimations. Relevant articles reporting the seroprevalence of toxoplasmosis in sheep and/goats were searched in five electronic databases, including PubMed, Web of Science, Scopus, Embase and ProQuest. After the publications were checked to verify they fit the inclusion criteria, a total of 225 articles were included in the systematic review and meta-analysis, reflecting data from 70 countries/regions. The pooled prevalence was estimated using a random effect meta-analysis model. Overall, the seroprevalence of T. gondii infection was 33.86% (95% CI: 30.47-37.25%) in sheep and 31.78% (95% CI: 28.99-34.58%) in goats, with significant variation in prevalence estimates across geographical locations (p < .001). Substantial heterogeneity (I²  > 75%) was observed in most pooled seroprevalence estimates. The T. gondii infection in global sheep and goat population showed uptrend over the period. This information would be useful for epidemiologist, health authorities and farmers in order to plan future T. gondii survey and infection management strategies both locally and internationally.

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.

The prevalence of Toxoplasma gondii in sheep in China: A systematic review and meta-analysis

Toxoplasmosis is a zoonotic disease caused by Toxoplasma gondii, which is widespread in warm-blooded animals and humans. Currently, many studies regarding T. gondii infection in sheep have been published worldwide. However, there is no meta-analysis of sheep infection in China. In this study, five databases were used to retrieve articles related to T. gondii in China. A total of 59 studies from 1987 to June 30, 2020, have been included. We estimated that the combined prevalence of T. gondii in the selected period was 8.5% (3197/28,099). In the analysis of publication year, the lowest positive rate after 2010 was 7.4% (1883/17,313). Geographically, the highest prevalence of T. gondii in sheep was recorded in Southwest China 19.2% (490/2080). Analysis according to age showed that the prevalence of infection in sheep older than 12 months was significantly (P < 0.05) higher than that in younger animals. The prevalence of T. gondii in sheep farmed by farmers was 7.2% (566/6336), which was higher than 5.3% (660/3121) of large-scale farming, suggesting a role for the feeding and husbandry. We also analyzed the impact of different geographic and climatic factors on the prevalence of T. gondii infection in sheep. The results showed that the prevalence was higher in low altitude, warm, humid, and high rainfall areas. We suggest that appropriate control programs should be formulated according to the differences in reproduction patterns and geographical conditions in different regions to reduce the prevalence of T. gondii among sheep in China.

Molecular Detection of Toxoplasma gondii and Neospora caninum in Domestic Ducks in Hunan Province, China

Toxoplasma gondii and Neospora caninum are protozoan parasites that infect warm-blooded animals, and cause major economic losses in livestock industries worldwide. However, little is known about the genotypes of T. gondii and N. caninum in domestic ducks in China. Herein, brain samples from 588 domestic ducks from Hunan province in China were examined for the presence of T. gondii and N. caninum. Polymerase chain reaction (PCR) was used to detect T. gondii B1 gene and N. caninum NC-5 gene. Forty-five DNA samples (7.7%; 95% CI: 5.5–9.9) were positive for B1 gene, and two (0.3%; 95% CI: 0–0.7) were positive for NC-5 gene. The risk factors significantly associated with T. gondii infection were age and sex. The 45 samples positive for T. gondii were genotyped using multi-locus PCR-RFLP analysis and only one sample was fully genotyped as ToxoDB#9 (Chinese I). These results provide new information about the epidemiology of T. gondii and N. caninum in ducks in Hunan province in China. The data also highlight the importance of a “One Health” approach to dealing with toxoplasmosis.

Toxoplasma gondii in Sheep and Goats from Central Iran

OBJECTIVE

Toxoplasmosis, caused by Toxoplasma gondii, infects humans by consuming infected raw or undercooked meat and foods harboring mature oocysts. In this study, we assessed the prevalence of T. gondii in sheep and goats coming from central Iran. After completing the questionnaire, about one gram of liver or diaphragm tissue was taken as a sample from 90 sheep and 90 goats slaughtered in Yazd Province and stored at - 20 ºC. DNA extraction was done, and then T. gondii was detected using nested PCR.

RESULTS

This study indicated that the prevalence of T. gondii in all slaughtered animals was 11.6% (21 of 180), including 14.4% (13/90) in sheep and 8.8% (8/90) in goats. The infection rates in liver and diaphragm samples were 12.2% (11/90) and 11.1% (10/90), respectively (p = 0.8163). The infection rate in animals older than one was 16.3% (15/92), and it was 6.8% (6/88) in animals under one year of age. Therefore, no significant differences were found (p = 0.475). Infection rates were 19.5% (18/92) in males and 3.4% (3/88) in females (p = 0.0007). In conclusion, the infection rates of toxoplasmosis in livestock in this area are almost high, and therefore, it is necessary to design appropriate prevention programs to control the disease.

Economic and public health importance of Toxoplasma gondii infections in sheep: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, control, and genetic diversity of T. gondii in sheep in the past decade. There is debate and uncertainty concerning repeat congenital infection as evidenced by finding T. gondii DNA in progeny of chronically infected sheep. However, there is no concrete evidence that T. gondii is the cause of repeated abortions in sheep. Recent data concerning pathogenesis of abortion in acutely infected sheep are reviewed. PCR-RFLP typing of T. gondii DNA derived from viable T. gondii isolates or tissues of infected sheep revealed low genetic diversity in sheep in Europe, Africa, Asia and North America but high diversity in South America. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Public health and economic importance of Toxoplasma gondii infections in goats: The last decade

Toxoplasma gondii infections are common in humans and animals worldwide. Toxoplasmosis in goats continues to be of public health and economic concern. The present review summarizes worldwide information on the prevalence of clinical and subclinical infections, epidemiology, diagnosis, treatment, and genetic diversity of T. gondii in goats in the past decade. There is debate and uncertainty regarding excretion of T. gondii in milk and the ingestion of raw milk as sources of T. gondii infection for humans. Toxoplasmosis can cause abortion and deaths even in adult goats. PCR-RFLP typing of T. gondii DNA derived from viable T. gondii isolates has revealed genetic diversity in goats in North and South America. The significance of T. gondii isolates in domestic goats usually associated with wildlife in USA is discussed. This review will be of interest to biologists, parasitologists, veterinarians, and public health workers.

Seroprevalence of Toxoplasma gondii infection in sheep in Inner Mongolia Province, China

Toxoplasma gondii is an important zoonotic parasite that can infect almost all warm-blooded animals, including humans, and infection may result in many adverse effects on animal husbandry production. Animal husbandry in Inner Mongolia is well developed, but data on T. gondii infection in sheep are lacking. In this study, we determined the seroprevalence and risk factors associated with the seroprevalence of T. gondii using an indirect enzyme-linked immunosorbent assay (ELISA) test. A total of 1853 serum samples were collected from 29 counties of Xilin Gol League (n = 624), Hohhot City (n = 225), Ordos City (n = 158), Wulanchabu City (n = 144), Bayan Nur City (n = 114) and Hulunbeir City (n = 588). The overall seroprevalence of T. gondii was 15.43%. Risk factor analysis showed that seroprevalence was higher in sheep ≥12 months of age (21.85%) than that in sheep <12 months of age (10.20%) (p < 0.01). Seroprevalence was higher in male sheep (18.76%) than females (12.80%) (p < 0.01). Barn-feeding sheep (23.13%) had higher prevalence than grazing sheep (10.94%) (p < 0.01). The seroprevalence was significantly different in different districts (p < 0.01). This study shows that sheep are exposed to T. gondii in Inner Mongolia, and provides a data reference for public health and disease control.