Oxylog studies of energy expenditure and schistosomiasis in the Sudan.

The effects of varying intensities of S. mansoni infection on physical work performance in agricultural tasks were studied in 269 male farmers living in the highly endemic Gezira area of the Sudan. The subjects were in the age range 18-50 years, and they were subdivided into four infection groups: non-infected (passing no S. mansoni eggs in their faeces), lightly infected (egg excretion 1-499), moderately infected (egg excretion 500-999), and heavily infected (egg excretion 1000+ eggs g-1 faeces). The Oxylog, a portable oxygen analyser, was used to measure energy expenditure throughout the field studies. The investigations showed that heavy S. mansoni infection significantly lowered oxygen intake by 20-30% during agricultural work tasks. There was a clear relationship between the intensity of S. mansoni infection and both the aerobic power output and morbidity in those populations. Anti-schistosomal treatment (praziquantel) given over a period of 1 year produced a marked improvement in working capacity and reduced morbidity.