Parasitic diseases of the small intestinal tract.

The epidemiology, clinical aspects, and treatment of human intestinal infections with Giardia, Cryptosporidium, coccidia and Strongyloides in industrialized countries are reviewed. In well-nourished and immunocompetent persons, inapparent infections or mild, transitory gastrointestinal upsets caused by these parasites are quite common. Some patients develop severe symptoms, such as profuse diarrhoea, dehydration, stool irregularities for weeks or months followed by weight loss and malabsorption of fat, vitamins and iron. In patients receiving immunosuppressive treatment or with lymphotropic viral infections, Cryptosporidium and Strongyloides can cause life-threatening or debilitating disease. By autoinfection or external reinfection these parasites can persist in the intestine for years. Clinicians should consider such infections in immigrants, travellers and former servicemen, even long after their stay in endemic areas, and also in the handicapped and children in day-care centres.