Toxoplasma gondii is a protozoan parasite that causes severe diseases in mammals, including humans, around the world. In China, pork is the main meat source; accordingly, T. gondii in pigs is considered an important source for human toxoplasmosis. Understanding the epidemiology of toxoplasmosis in pig farms is thus important for control of the disease in humans. The purpose of the present study was to investigate the epizootiology of T. gondii infections in pig farms in central China by assessing the seroprevalence and risk factors of this disease. In the present study, 3,558 sera samples were collected from pigs in 37 large-scale pig farms in this region and tested by AG-ELISA. The total seroprevalence was 24.5%, with the greatest prevalence in breeding pigs. The risk factors for toxoplasmosis suggest that high frequency of the contact of pigs with cats ( P ≤ 0.01; IC 95%), high density of pig breeding ( P ≤ 0.01; IC 95%), the presence of mosquitoes and flies ( P ≤ 0.01; IC 95%), semi-patency pens ( P ≤ 0.05; IC 95%), and low frequency of scavenging ( P ≤ 0.01; IC 95%) were all associated with seroprevalence. In addition, the use of sulfonamides ( P ≤ 0.01; IC 95%) significantly decreased seroprevalence. This is the first report of anti– T. gondii antibodies in pigs on large-scale pig farms in central China. The findings will provide useful information for designing control strategies of toxoplasmasis in pig farms.
Toxoplasma gondii genetic diversity varies in different geographical regions. In South America, T. gondii isolates are highly diverse, whereas in North America and Europe, the parasite is highly clonal, with 3 distinct lineage types (I, II, III). However, little is known of the T. gondii genotypes in the People's Republic of China. Because pork is considered the principal meat source for T. gondii infection in China, we conducted a survey to determine the prevalence and genetic diversity of this parasite in pigs from central China. In total, 434 DNA samples were extracted from the hilar lymph nodes of sick pigs in Hubei and Henan provinces in central China, and 34 were T. gondii B1 gene-positive. These T. gondii -positive DNA samples were typed at 10 genetic markers, including 9 nuclear loci, i.e., SAG1, SAG2, SAG3, BTUB, GRA6, L358, PK1, c22-8, c29-2, and an apicoplast locus Apico. Of these, 16 isolates could be genotyped with complete data for all loci. Two genotypes were present; one was the clonal type I lineage and the other was previously identified as a widespread lineage from many hosts in China. These results indicate that these 2 genotypes may be the major lineages in China. This is the first report of genetic typing of T. gondii isolates from pigs in central China. The results have implications for the prevention and control of T. gondii infections in humans and other animals.