Migrant workers and schistosomiasis in the Gezira, Sudan

A cross sectional study of schistosomiasis in migrant laboureres in the Sudan Gezira is described. The people examined were of two ethnic groups: (i) those of local Arabic origin and (ii) those from Western Sudan, West Africa or west of longitude 27 degrees E. These two migrant groups were examined in one area treated with molluscicide and in another that was not. Almost all the schistosome infections were with Schistosoma mansoni, with a prevalence of 57% over-all and up to 89% in particular groups. The prevalence was lower in the treated than in the untreated area, and slightly lower in the Arab nomads than in the others, except that it was markedly lower in females from the West in the treated area. These results are consistent with the known water-contact habits of the two migrant groups. An association was observed between infection and liver and spleen enlargement, but not between infection and other symptoms. The potential importance of migrants in transmitting the infection is discussed.