Chronic schistosomiasis is an infection caused by a parasitic worm. More than 200 million people are affected worldwide, most of them live in sub-Saharan Africa. Allocation of health-care resources relies on the accurate estimates of the death and disability of health conditions. Current estimates suggest the effect of infection is quite small. But many health workers believe the disabling effects of schistosomiasis have not been adequately quantified.
Charles King and colleagues reviewed 135 published and unpublished reports from March 1921 to July 2002 on disability-associated outcomes for all forms of schistosomiasis. They found that human schistosome infection was significantly linked to anaemia, diarrhoea, chronic pain, fatigue, exercise intolerance, and malnutrition, and concluded that the resulting disability was substantially higher than the World Health Organisation's current estimates. The authors also found that the loss of performance in a person with schistosomiasis can be improved through intervention with specific treatment.
Dr King comments: "Although in most cases schistosomiasis is unlikely to progress to a lethal outcome, it is a prominent, chronic, recurring infection in endemic areas, and its effect on health status of infected individuals is clearly not negligible."
In an accompanying comment Lorenzo Savioli (WHO) and colleagues state: "King's results should trigger a better quantification of the development impact of schistosomiasis. Beyond this, King and colleagues' analysis should encourage a comprehensive re-evaluation of the burden on human and economic development of a group of highly prevalent but still concealed communicable diseases of the poor."