Multiple anthropogenic environmental stressors with reinforcing effects to the deterioration of ecosystem stability can obscure links between ecosystem change and the prevalence of infectious diseases. Incomplete understanding may lead to ineffective public health and disease control strategies, as appears to be the case with increased urogenital schistosomiasis in humans around Lake Malawi over recent decades. Sedimentation and eutrophication help explain historical changes in intermediate host range and parasite transmission. Hence, control strategies should account for abiotic changes.