Risk of acute non-specific upper respiratory tract infections in healthy men taking dapsone-pyrimethamine for prophylaxis against malaria.

The relative risks of non-specific upper respiratory tract infections were studied in two well matched groups of military recruits to see whether dapsone-pyrimethamine (Maloprim) given as antimalarial prophylaxis was associated with immunosuppression. Mean risks of upper respiratory tract infection were 64% higher in the study group than in the controls, the largest monthly differences being recorded in the months of harder training. These findings were unlikely to have been due solely to harder training in the study group, as concurrently measured sprains (arguably more likely to have been affected) were increased by only 19%. A more likely explanation was some degree of immunosuppression, physical stress possibly having a synergistic effect. These findings suggest that travellers taking dapsone-pyrimethamine as antimalarial prophylaxis may be rendered more susceptible to commoner infections, especially when engaged in increased physical activity.