| Toxoplasma gondii is a kind of intra-cellular parasite which can exist inside the nucleated cells of nearly all kind of warming blood vertebrates and cause toxoplasmosis for animals and human beings. Toxoplasmosis is a worldwide disease which can be a hazard to the health and safety of human beings. Toxoplasmosis is especially harmful to women that can bring infertility to reproductive women and abortion, abnormality of fetus,fetal death and thinking barrier to pregnant women. For the majority of healthy individuals, after the infection of T.gondii, no symptom can be observed, which is called inapparent infection and for the minority of infected individuals, an apparent symptom of multiple organ injury can be observed. However, for patients of immune deficiency, organ transplantation and tumor, toxoplasmosis can be lethal. On the other hand, T. gondii is harmful to swine industry. It can cause abortion for sows, bring abnormality, weakness and dysplasia for piglets, slow down the growing of commercial pigs, decrease the feed conversion ratio and speed up the process of death for the swinery at the inducement of other diseases. Especially with the development of intensive culture, it coincides with other diseases and can bring a great loss to breeding industry.There have been many epidemiological studies on toxoplasmosis at home and abroad. However, the studies on toxoplasmosis epidemiology in large scale pig farms have scarcely been documented. Sulfonamides are the commonly used drugs for current treatment of toxoplasmosis clinically. Long term and inappropriate clinical drug administration of sulfonamides can lead to drug resistance. This study was conducted to investigate the toxoplasmosis epidemiology in large scale pig farms in Hubei province and make a preliminary research on drug resistance of T.gondii so as to provide reference for the prevention and control of toxoplasmosis in large scale pig farms.According to the cross-sectional study of toxoplasmosis epidemiology in 15 large scale pig farms in Hubei province,the serological positive rate of toxoplasmosis is 24.2% (200/825 ) . According to the serological detection results of different swinery, the prevalance of toxoplasmosis falls into three categorie: highly prevalence, moderate prevalence and sporadic occurrence. Statistical analysis of T.gondii infection factors showed that the seropositive rate was related to the age of the swinery, the existance of cats and mice in the swinery, sweeping and sterilization frequency of swinery and the administration of anti T.gondii drugs. T.gondii infection rate rises as the age of the swinery and the contact with cats and mice increases and decreases as the sweeping and sterilization frequency of swinery increases. Administration of anti T.gondii drugs decreases the infection rate as well.The dynamic epidemiology investigation of T.gondii in 11 large scale pig farms in Hubei province showed that seropositive rate of Toxoplasma gondii in large scale pig farm was 23.2% (564/2531) . Statistical analysis of T.gondii infection factors showed that T.gondii infection was related to the age of swinery, seasons, existance of cats, mice, mosquitoes and flies, sweeping frequency and formation of swinery and the density of the pig population. T.gondii infection rate rises as the age of the swinery and the contact with cats, mice, mosquitos and flies increases and decreases as the temperature falls, the density of the pig population decreases and sweeping frequency of swinery increases. No apparent association with the topography of pigsty , water resources and the using of disinfectant were found.T.gondii drug resistant genes in 17 different regions were amplified by PCR and the sequencing results were compared using BLAST in NCBI. Although no mutation was detected in reported mutation gene locus, 1-6 base pair mutations in unreported conservative regions was detected in 7 strains from different regions and 1-6 mutations of amino acid in 5 strains from different regions were detected as well. Although no mutation was detected in reported mutation gene locus, drug-resistant strains of T.gondii might already exist in Hubei province.Through investigation of toxoplasmosis, the results of the study revealed the epidemic situation and the changing tendency of toxoplasmosis in large scale pig farms in Hubei province and related infection factors. The results of the drug-resistance study of T.gondii showed the existance of the risk of drug-resistance mutation of T.gondii in Hubei province. The study provides reference for the prevention and control of toxoplasmosis in large scale pig farms and theoretical support for clinical administration of anti T.gondii drugs.
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