Soil contamination of Toxoplasma gondii oocysts in pig farms in central China.

Toxoplasmosis in pigs is a large threat to pig industry as well as pork consumers. Most pigs become infected by ingestion of oocysts from contaminated environment (soil, water and feed) or infected animal tissues postnatally. In the present study, field studies were conducted to evaluate the relationship between soil contamination status of Toxoplasma gondii oocysts and T. gondii infection in pigs in 12 pig farms with different density of cats in central China. The presence of T. gondii oocysts in soil were determined by PCR and loop-mediated isothermal amplification (LAMP). T. gondii DNA was found in 11 farms with different cat density excepting one farm exposed to low cat density. Twenty (21.1%) and 36 (37.9%) of 95 soil samples were T. gondii positive by PCR and LAMP, respectively (0.01<P<0.05). Soil contamination was found with significant difference in statistics between farms with high and low cat density by PCR (0.01<P<0.05), and highly significant differences by LAMP (P<0.01). Additionally, a total of 2277 sera were collected to determine the presence of IgG antibodies against T. gondii using AG-ELISA. Antibodies were found in 453 of 1238 (36.6%) samples from pig farms with high cat density and 220 of 1039 (21.2%) samples from pig farms with low cat density (P<0.01). The results indicated that a high seroprevalence of T. gondii in pigs was found in the pig farms with high soil contamination by T. gondii oocysts in Hubei Province. The soil contamination status of pig farms was significantly influenced by cat density and may be an indicator of T. gondii infection in pigs.