Seroprevalence of Toxoplasma gondii and Neospora caninum in Tarim Red Deer (Cervus elaphus yarkandensis) from Xinjiang Province, Northwest China

Epidemiologic and Public Health Significance of Toxoplasma gondii Infections in Venison: 2009-2020

Toxoplasma gondii infections are common in humans and animals worldwide. The ingestion of food or water contaminated with oocysts excreted by infected cats or ingestion of uncooked or undercooked meat containing tissue cysts of T. gondii are the 2 major modes of transmission of T. gondii. Deer are a popular game. Recently, outbreaks of clinical toxoplasmosis were reported in humans in North America linked to ingestion of undercooked venison. Here, we review prevalence, persistence of infection, clinical disease, epidemiology, and public health risks of T. gondii infections in deer and other cervids for the past decade. Estimates of worldwide serological prevalence are summarized individually for each species of deer, elk, moose, and caribou. Genetic diversity of 112 viable isolates of T. gondii from cervids is discussed, including its public health significance. Prevalence of T. gondii in deer is very high. Any part of a deer, including liver, spleen, and muscles, should be cooked thoroughly before human consumption.

Molecular detection and genetic characterization of Toxoplasma gondii infection in sika deer (Cervus nippon) in China

The objective of the present study was to investigate the prevalence and genetic characterization of Toxoplasma gondii infection in sika deer in China. During August 2014 to November 2014, a total of 450 tissue samples coming from 150 sika deer were collected to detect the T. gondii B1 gene using a nested PCR, and the positive samples were genotyped at 11 genetic markers (SAG1, 5'- and 3'-SAG2, alternative SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and Apico) using multilocus polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technology. Seventeen of 150 sika deer (11.33%) were tested positive by nested PCR. Six DNA samples from the 17 positive samples were completely typed, in which 4 samples from lung tissues, and 2 from muscular tissues, were identified as ToxoDB Genotype #9 (http://toxodb.org/toxo/). The results of the present study revealed the existence of T. gondii infection in sika deer in China, which provided the information of T. gondii genetic diversity in this host species. This study also indicated that ToxoDB Genotype #9 has a wide distribution in sika deer that could be potential reservoirs for T. gondii transmission, which may pose a threat to human health.

Seroprevalence and risk factors of Toxoplasma gondii infection in domestic sika deer (Cervus nippon) in northeastern China

Toxoplasmosis is a worldwide zoonosis caused by Toxoplasma gondii, which can infect warm-blooded animals and humans. A serological survey was undertaken to examine the seroprevalence and risk factors associated with T. gondii infection in sika deer in northeastern China. 114 (13.46%, 95% CI 11.16-15.76) out of 847 serum samples were positive to T. gondii by modified agglutination test (MAT) at a 1:25 cut-off, with titers of 1:25 in 44, 1:50 in 32, 1:100 in 17, 1:500 in 11, 1:1500 or higher in 10. These samples were collected between November 2012 and October 2013 from Inner Mongolia, Jilin and Heilongjiang provinces in China. However, statistically significant differences were not observed between T. gondii seroprevalence and genders or regions of sika deer in the logistic regression analysis (P>0.05) and left out of the final model. Seroprevalence of T. gondii infection in male sika deer was 14.07% (95% CI 11.14-17.01), slightly higher than that in the female (12.38%) (95% CI 8.69-16.06) and seroprevalence of T. gondii infection in Harbin, Changchun city, Jilin city and Chifeng city were 12.02% (95% CI 7.60-16.44), 15.51% (95% CI 11.52-19.50), 12.27% (95% CI 7.23-17.31) and 12.50% (95% CI 7.38-17.63), respectively. Seasons of sampling were considered as main risk factors associated with T. gondii infection, autumn (15.32%) were more than two times (OR=1.98, 95% CI=1.18-3.33, P=0.01) at risk of acquiring T. gondii infection compared to winter (8.37%). Our results indicated a widespread exposure to T. gondii among sika deer in China. To our knowledge, this is the first report of T. gondii seroprevalence in sika deer in China.

Neospora caninum and Wildlife

Bovine neosporosis caused by Neospora caninum is among the main causes of abortion in cattle nowadays. At present there is no effective treatment or vaccine. Serological evidence in domestic, wild, and zoo animals indicates that many species have been exposed to this parasite. However, many aspects of the life cycle of N. caninum are unknown and the role of wildlife in the life cycle of N. caninum is still not completely elucidated. In North America, there are data consistent with a sylvatic cycle involving white tailed-deer and canids and in Australia a plausible sylvatic cycle could be occurring between wild dogs and their macropod preys. In Europe, a similar sylvatic cycle has not been established but is very likely. The present review is a comprehensive and up to date summary of the current knowledge on the sylvatic cycle of N. caninum, species affected and their geographical distribution. These findings could have important implications in both sylvatic and domestic cycles since infected wildlife may influence the prevalence of infection in cattle farms in the same areas. Wildlife will need to be taken into account in the control measures to reduce the economical losses associated with this important disease in cattle farms.