Controlling disease – how China is turning the tables on a deadly parasite

Schistosomiasis – also known as Bilharzia – has been present in China for over 2000 years, causing millions of deaths, and destroying families and even entire villages. Caused by flatworms of the genus Schistosoma, the symptoms are extremely unpleasant, ranging from swelling of the abdomen and spleen, to physical underdevelopment and much more besides.

Thankfully though, it now looks like the tide is turning. A new review, published today in Infectious Diseases of Poverty, offers hope that occurrences of this disease have dramatically reduced since the introduction of  a national control program.

The worm Schistosoma japonicum is the culprit of schistosomiasis in China. The eggs of this parasite have been identified in ancient corpses, showing that the disease has a history in the country of more than 2100 years. In fact, symptoms relating to the late stages of schistosomiasis can be traced back as early as 2697 B.C.

Before a national control program was introduced in the 1950s, both morbidity and mortality from this disease was high. However, the success of this program has brought the disease under control, with major improvements to both incidence and death rates.

Professor Xiao-Nong Zhou, Director of the National Institute of Parasitic Diseases at the Chinese Center for Disease Control and Prevention and  Editor-in-Chief of Infectious Diseases of Poverty, commented: “[In his new review] Professor Chen traced back the morbidity of schistosomiasis before 1950 with his first-hand pictures, followed by presenting the facts of significant decreases both in the morbidity and prevalence of the disease after the national schistosomiasis control program was initiated and sustained during the last six decades.

Currently, transmission interruption of schistosomiasis has been reached in large areas, for instance, out of 12 endemic provinces in China, schistosomiasis has been eliminated in 5 provinces, and its transmission has been effectively controlled in 3 provinces, and the remained 4 provinces are at the low transmission status with its prevalence rate less than 5%.

However, Professor Chen has warned that for a small number of formerly infected and cured individuals, clinical disease can still develop even after the schistosomiasis transmission has stopped and no living worms remain in the hosts’ bodies. Therefore, the control efforts on post-transmission schistosomiasis should be sustained even if the disease reaches the criteria of elimination.”

So it seems that China are well on the way to escaping the threat of this horrible disease, but there is still need for caution and control to ensure that schistosomiasis is eliminated once and for all.

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