Schistosomiasis

Schistosomiasis, also known as bilharzia, is a disease caused by parasitic flat-worms. Although the worms that cause schistosomiasis are not found in the United States, more than 200 million people are infected worldwide. In terms of impact this disease is second only to malaria as the most devastating parasitic disease. The parasites that cause schistosomiasis live in certain types of freshwater snails, and transmission generally occurs as a result of skin contact with a contaminated fresh-water source. The infectious form of the parasite, known as cercariae, emerges from the snail, hence contaminating water, or the water can be contaminated by the urine or feces of a diseased host. Most human infections are caused by //Schistosoma mansoni, S. haematobium//, or //S. japonicum//. The re-emergence of Schistosomiasis in China was the dirty work of S. Japonicum.

//http://www.cdc.gov/parastites/schistosomiasis///

Schistosomiasis reemerged in Sichuan province in late 2004. Intensive sureveillance of the region yielded the following statistics: Human infections were detected in 35 of the 53 villages surveyed (infection prevalence: 0 to 43%), including 17 of 28 villages with no prior evidence of reemergence; Bovine infections were detected in 23 villages (infection prevalence: 0 to 65%) and snail infections in one village.

//http://www.plosntds.org/article/info%3Adoi%2F10.1371%2Fjournal.pntd.0000987//

In the mid 1950s, when China 's population was approximately 600 million, an estimated 11.6 million people were infected with // Schistosoma japonicum //. Hence, a national control programme was launched, with an emphasis on intermediate host snail control by means of environmental management. Over the past 50 years, the national control programme has made great progress and praziquantel-based morbidity control became the mainstay of control. In 2000, the number of infected people had been reduced to an estimated 694,788, the snail-infested area has been abridged by over 75%, and the disease had been eliminated in five of the 12 previously endemic provinces.This progress was interrupted by the resurgence in 2004.

//http://www.sciencedirect.com/science/article/pii/S0001706X05001907//

Below are images displaying the provinces affected by schistosomiasis in 2008, along with the percentages of the rural population affected by schistosomiasis in each province.

Fig 7.18 http://www.unicef.cn/en/index.php?m=content&c=index&a=show&catid=202&id=867

Fig 7.19 http://www.unicef.cn/en/index.php?m=content&c=index&a=show&catid=202&id=868

@Structure - Schistosomiasis

@Transmission - Schistosomiasis

@Symptoms & Disease Progression - Schistosomiasis

@Pathogenesis - Schistosomiasis

@Treatment & Response - Schistosomiasis

@Contributing Factors - Schistosomiasis