taenIaSIS/cyStIcercoSIS In chIna

This review concerning the status of taeniasis/cysticercosis in China has been compiled from various reports of studies conducted over the past 30 years, most of which have appeared in national publications in Chinese. Previous hospital reports and epidemiologic surveys have indicated that taeniasis/ cysticercosis has been distributed throughout 671 counties in 29 provinces or prefectures of China. There are an estimated three million cysticercosis cases nationwide, while Taenia asiatica has presently been confirmed by DNA typing as occurring in Sichuan, Yunnan, and Guizhou Provinces. Although efforts to reduce transmission of taeniasis/cysticercosis have occurred in most endemic areas over the last 30 years, reports conducted over the past 15 years in southwest China have indicated that cysticercosis is emerging as a serious public health problem in this area. The most recent available information on this food-borne parasitic disease, from a Tibetan population in Sichuan, is presented in this review. In addition, recommendations for a national surveillance program for cysticercosis are discussed. Correspondence: Tiaoying li, Institute of Parasitic Diseases, Sichuan Centers for Disease Control and Prevention, 6 Middle School road, Chengdu 610041, Sichuan Province, People’s republic of China. Tel: +86 28 85589512; Fax: +86 28 85589563 E-mail: [email protected] INTroDUCTIoN Human taeniasis refers to food-borne infections with adult tapeworms: Taenia solium, Taenia asiatica (from pigs), or Taenia saginata (from bovids). Cysticercosis is a tissue infection with the larval cysticercus or metacestode stage of tapeworms, and occurs most commonly in pigs and cattle. The larval stage of Taenia solium can also infect humans and cause cysticercosis/neurocysticercosis, which is considered widespread in the developing countries of latin America, Africa, and Asia (Del Brutto, 1999; Murrell, 2005). T. solium taeniasis/cysticercosis is particularly prevalent in rural areas and is associated with poverty and poor sanitation; where raw or undercooked pork is consumed, and scavenging pigs have access to human feces (Sarti et al, 1992; Pawlowski and Murrell, 2001; Burneo and garcia, 2002). In endemic areas, neurocysticercosis is an important contributor to neurological morbidity (garcia et al, 1991), and the major cause of acquired epilepsy in the world (Commission on Tropical Diseases, 1994). It is accepted that human taeniasis and cysticercosis are present in Asia and the AsianPacific region (Ito et al, 2006). T. solium occurs in several Asian countries, including China, India, Indonesia, Thailand, lao PDr, Cambodia, Nepal, Philippines, Myanmar, Vietnam, and korea, where local people consume undercooked/raw pork (Singh et al, 2002). In China, the emergence of cysticercosis as a serious public health problem was recognized by the Chinese government. Therefore, intervention measures for taeniasis/ cysticercosis control have been carried out since the 1970s in some endemic areas, such as Heliongjiang, Jilin, Henan, and Fujian Provinces, where mass screening and treatment for taeniasis carriers, treatment of cysticercosis patients and pigs, enhancement of meat inspection, and population education programs were conducted. Consequently, infection of taeniasis and prevalence of cysticercosis in humans and swine in these endemic areas were reported to be REVIEW SoUTHEAST ASIAN J TroP MED PUBlIC HEAlTH 132 Vol 38 (suppl 1) 2007 Table 1 The status of taeniasis/cysticercosis in some endemic areas of China. Province Year Taeniasis Cysticercosis % reference % Seropositivity Prevalence Heliongjiang 1993-1994 2.3-4.3 li et al, 1996 liaoning 1995-1997 0.05 0.03 li et al, 1998 Jilin 1993 0.008 Sun, 1995 Shandong 2000 0.05 0.06 liu et al, 2002 Qinghai 1997-1998 0.4 14.7 Wu et al, 2001 Inner Mongolia 1996-1998 0.8 10.8 0.1 Zhang et al, 2000 greatly reduced (Table 1) (Sun et al, 1984; Sun, 1995; Xu et al, 1998). Since the open-market policy was implemented nationwide after 1989, there have been great increases in the numbers of small private butchers and slaughterhouses without strict meat inspection. Since then, more and more cases of taeniasis/cysticercosis have been recorded in provincial hospitals. For example, 4,504 cases of cysticercosis that originated from Jilin Province were identified in local hospitals during 1987-1994, while about 2,528 cysticercosis patients were reported from the Affiliated Hospital of Shandong Province during 1991-2002 (liu et al, 1997; li et al, 2004). The purpose of this review is to make national authorities, scientists, and the international community aware of the emerging situation concerning human cysticercosis and other zoonotic Taenia infections in China. Furthermore, the most recent information available on taeniasis/ cysticercosis in Tibetan populations in Sichuan Province, southwest of China, is presented.