Vertical transmission of Toxoplasma gondii in naturally infected ewes in the semiarid region of Brazil

Seroprevalence and molecular detection of Toxoplasma gondii and Neospora caninum in beef cattle and goats in Hunan province, China

BACKGROUND

Toxoplasma gondii and Neospora caninum are closely related protozoan parasites that are considered important causes of abortion in livestock, causing huge economic losses. Hunan Province ranks 12th in the production of beef and mutton in China. However, limited data are available on the seroprevalence, risk factors and molecular characterization of T. gondii and N. caninum in beef cattle and goats in Hunan province, China.

METHODS

Sera of 985 beef cattle and 1147 goats were examined for the presence of specific antibodies against T. gondii using indirect hemagglutination test (IHAT) and anti-N. caninum IgG using competitive-inhibition enzyme-linked immunoassay assay (cELISA). Statistical analysis of possible risk factors was performed using PASW Statistics. Muscle samples of 160 beef cattle and 160 goats were examined for the presence of T. gondii DNA (B1 gene) and N. caninum DNA (Nc-5 gene) by nested PCR. The B1 gene-positive samples were genotyped at 10 genetic markers using the multilocus nested PCR-RFLP (Mn-PCR-RFLP).

RESULTS

Specific IgG against T. gondii were detected in 8.3% (82/985) and 13.3% (153/1147) and against N. caninum in 2.1% (21/985) and 2.0% (23/1147) of the beef cattle and goats, respectively. Based on statistical analysis, the presence of cats, semi-intensive management mode and gender were identified as significant risk factors for T. gondii infection in beef cattle. Age was a significant risk factor for T. gondii infection in goats (P < 0.05), and age > 3 years was a significant risk factor for N. caninum infection in beef cattle (P < 0.05). PCR positivity for T. gondii was observed in three beef samples (1.9%; 3/160) and seven chevon samples (4.4%; 7/160). Genotyping of PCR positive samples identified one to be ToxoDB#10. The N. caninum DNA was observed in one beef sample (0.6%; 1/160) but was negative in all chevon samples.

CONCLUSIONS

To our knowledge, this is the first large-scale serological and molecular investigation of T. gondii and N. caninum and assessment of related risk factors in beef cattle and goats in Hunan Province, China. The findings provide baseline data for executing prevention and control of these two important parasites in beef cattle and goats in China.

Low Prevalence of Toxoplasma gondii in Sheep and Isolation of a Viable Strain from Edible Mutton from Central China

Sheep are highly susceptible to Toxoplasma gondii, and miscarriage is the main clinical feature. This study investigated 227 sheep samples (210 myocardial tissues from slaughterhouses, 6 ewe serum samples, 3 aborted fetuses, and 8 dead lambs from veterinary clinics) from central China for T. gondii infection. Antibodies against T. gondii were detected using the modified agglutination test (MAT). PCR was performed to detect T. gondii DNA in the tissue samples. The results showed that four samples were seropositive (MAT titer ≥ 1:100), with a seroprevalence of 1.8% (4/227). The seropositive samples included two myocardial samples from a slaughterhouse, one ewe and its aborted fetus from a veterinary clinic. The results revealed that 7 out of 207 (3.4%) sheep tissue samples were PCR-positive, including two myocardial tissue samples from slaughterhouses, three aborted fetuses, and two lambs from veterinary clinics. Toxoplasma gondii vertical transmission had occurred in two of three pairs of ewes and her pups. One viable T. gondii strain (TgSheepCHn14) was isolated from the myocardial tissues of sheep from a slaughterhouse. Tachyzoites were obtained from cell cultures at 70 days following seeding in the brains and lungs of mice. This strain was non-lethal to Swiss mice. The number of parasite brain cysts in mice decreased with time post-infection (p < 0.05). Overall, the prevalence of T. gondii in the sheep samples was low. Although the samples were scattered, and not from planned collections, the current study detected T. gondii antibodies and DNA in aborted fetuses, indicating that vertical transmission could occur and maintain the parasites in sheep herds without exogenous infection.

Toxoplasma gondii is not an important contributor to poor reproductive performance of primiparous ewes from southern Australia: a prospective cohort study

Background

Toxoplasma gondii causes reproductive losses in sheep worldwide, including Australia. The reproductive performance of primiparous ewes is typically lower than for mature, multiparous ewes, and younger ewes are more likely to be immunologically naïve and therefore more susceptible to reproductive disease if T. gondii infection occurs during pregnancy. The aim of this study was to assess the impact of infection with T. gondii on the reproductive performance of primiparous ewes in southern Australia using a prospective cohort study. This will inform the need for targeted control strategies for T. gondii in Australian sheep.

Results

Toxoplasma gondii seropositivity using indirect ELISA was detected at 16/28 farms located across southern Australia. Apparent seropositivity to T. gondii was lower in primiparous ewes (1.1, 95% confidence interval (CI) 0.6, 1.8) compared to mature, multiparous ewes (8.1, 95% CI 6.0, 10.5; P < 0.001). Toxoplasma gondii seroconversion during the gestation and lambing period was confirmed for 11/1097 (1.0, 95% CI 0.5, 1.7) of pregnant primiparous ewes that failed to raise a lamb, and 1/161 (0.6, 95% CI 0.1, 2.9) primiparous ewes with confirmed mid-pregnancy abortion.

Conclusions

Low frequency of detection of T. gondii seroconversion during gestation and low frequency of seropositivity to T. gondii suggests that toxoplasmosis was not an important contributor to reproductive losses in primiparous ewes on farms located over a wide geographical area in southern Australia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03211-w.

Seroprevalence and isolation of Toxoplasma gondii in sheep intended for human consumption in Paraíba, northeastern Brazil

Toxoplasma gondii is a zoonotic parasite capable of infecting almost all warm-blooded animals. Currently, studies assessing the viability of cysts present in sheep meat are still scarce, especially in the northeastern region of Brazil. Therefore, the aim of this study was to evaluate the seroprevalence of anti-Toxoplasma gondii antibodies, isolate the parasite from tissue samples, and determine factors associated with infection of sheep intended for human consumption in the state of Paraíba, northeastern Brazil. Serum samples from 205 sheep slaughtered in Paraíba were tested using the indirect fluorescence antibody test (IFAT ≥ 64) for the presence of anti-T. gondii antibodies. Among the animals sampled, 30.7% (63/205) were seropositive, with antibody titers ranging from 1:64 to 1:16384. Sixty-one bioassays were performed in mice, and an isolation rate of 47.5% (29/61) was obtained. The infection was lethal to at least one infected mouse in 24.1% (7/29) of the bioassays. The mean length of survival of infected mice was 36.4 days. Females (OR = 3.183; CI = [1.452-6.976]), extensive breeding system (OR = 2.612; CI = [1.120-6.094]), and purebred animals (OR = 2.157; CI = [1.009-4.612]) were considered to be factors associated with infection. These results revealed that the prevalence of anti-T. gondii antibodies and the percentage of viable cysts recovered from sheep destined for human consumption in Paraíba, northeastern Brazil, were high.

Prevalence and isolation of Toxoplasma gondii in goats slaughtered for human consumption in the semi-arid of northeastern Brazil

The aim of this study was to determine the seroprevalence of anti-Toxoplasma gondii antibodies and factors associated with infection in goats, and to isolate protozoan strains in tissue samples from seropositive goats that were destined for human consumption in the state of Paraíba, northeastern Brazil. Serum samples from 229 slaughtered goats were tested using the indirect fluorescence antibody test (IFAT), with a cutoff point of 1:64. Epidemiological questionnaires were applied to the producers, to acquire information about the sanitary management used in their herds. Tissue samples from the animals were collected during slaughter, in order to perform bioassays in mice. The seroprevalence found was 21.39% (49/229), with antibody titers ranging from 1:64 to 1:32,768. The municipalities of origin, Patos (OR: 3.047; CI: 1.384-6.706) and Sousa (OR: 3.355; CI: 1.536-7.327), were considered to be factors associated with infection by T. gondii. Thirty-eight bioassays were performed in mice, using tissues from seropositive goats, with an isolation rate of 50% (19/38). There was no correlation between isolation rate and antibody titers. Only one mouse died, at 30 days post-infection, which demonstrated that the strains isolated had low virulence towards mice. It was concluded that there is high seroprevalence in goats in northeastern Brazil, as well as a high percentage of viable tissue cysts in slaughtered animals destined for human consumption. These results demonstrate that there is an imminent one health problem relating to toxoplasmosis, especially in the most populous municipalities in the study (Patos and Sousa), which were identified as factors associated with T. gondii infection in goats.