[Epidemiology, etiology and laboratory diagnosis of infectious diarrhea diseases in the tropics]

Diarrhoeal diseases belong to the leading causes of morbidity and mortality in tropical countries, especially in infants and small children. About one billion episodes are estimated for this group of age with 4.6 million fatalities. Many causes are discussed to explain the high incidence: bottle feeding of infants, protein malnutrition, unsafe drinking water and unsafe disposal of excrements and sewage, unsufficient consciousness of personal and domestic hygiene, lack of knowledge on the origin of disease, and inadequate food hygiene. Among the viral infectious agents rotavirus is isolated from 30-40% of enteritis cases in infants and small children; Norwalk virus, adenovirus and human calicivirus, too, appear to occur worldwide. Enteropathogenic (EPEC) and, especially, enterotoxigenic Escherichia coli (ETEC) are of primary importance as bacterial pathogens. Campylobacter jejuni and C. coli primarily cause disease in infants and small children. Shigellae are important whereas salmonellae are less frequently identified as a cause for diarrhoeal illness. Yersinia enterocolitica is rare in tropical countries. Cholera and infections with other vibrionaceae (V. cholerae non-01, V. mimicus, V. parahaemolyticus, aeromonas, Plesiomonas shigelloides) mainly occur in coastal areas. Clostridium perfringens type C is the causal agent of Enteritis necroticans in several countries, especially New Guinea. C. difficile appears to be of minor importance. Among the parasites Giardia lamblia and Entamoeba histolytica are the most important organisms causing diarrhoeal disease. Macroscopic (visible blood) and microscopic stool examination (faecal leukocytes) may be helpful in dysenteric disease to distinguish between shigella and E. histolytica infections; it is, however, of limited usefulness to discriminate between organisms causing watery diarrhoea.