Toxoplasma gondii infection in humans in China

Toxoplasmosis, a cosmopolitan disease in humans and most mammals, is caused by the opportunistic protozoan Toxoplasma gondii mainly through peroral infections, bloodstream infections and congenital acquired infections. It has been estimated that one third of the world population has been infected [1,2]. In most adults it does not cause serious illness, however, blindness and mental retardation can be caused in congenitally infected children and severe diseases in those with compromised immunity. A recent study indicated that infection with T. gondii is associated with abdominal hernia [3].Toxoplasma gondii needs both definitive hosts and intermediate hosts to complete its sexual and the asexual replication phases in life cycle. The sexual phase only occurs in the intestine of the definitive hosts, felids. All the warm-blooded animals, the intermediate hosts, become infected mainly by consuming food or drink contaminated by oocysts evacuated from felids and tissue cysts from other intermediate hosts [4]. Acute infection happens in the initial few days, with the rapidly growing replication of the tachyzoites. Tachyzoites switch to bradyzoites as time goes by and form tissue cysts parasitizing in host cells. It would be lethal in Toxoplasma infected immune-compromised patients if bradyzoites revert to tachyzoites. In addition to felids, intermediate hosts carried with tachyzoites or tissue cysts are also responsible for the spread of T. gondii. Peroral infection, congenital and blood infection are three major ways for the transmission of this parasite [5].The first human case of toxoplasmosis in China was report in 1964 in Jiangxi Province [6]. Many human cases were reported in China since the first epidemic survey on toxoplasmosis was carried out in Guangxi Province in 1978 [7]. However, toxoplasmosis cases in China are hardly recognized by western clinicians, for very little information from China was published in English. The rising prevalence of T. gondii infection