Viruses that multiply in the gut and cause endemic and epidemic gastroenteritis.
BACKGROUND
Acute infectious diarrhea in young children is a leading cause of morbidity and mortality in developing countries. Even in developed countries, infectious enteritis is second only to respiratory infections as a cause of morbidity in early childhood.


OBJECTIVE
To nominate the various viral agents that cause enteritis, discuss the pathogenesis, clinical features, epidemiology and diagnostic procedures employed.


METHODS
Pertinent literature was reviewed and the findings of investigations carried out on viral enteritis by various colleagues recalled.


RESULTS
The viruses causing gastroenteritis include: Rotaviruses; Adenoviruses-especially Ad 31, Ad 40 and Ad 41; members of the Caliciviridae, e.g. Norwalk virus, Hawaii virus, Snow Mountain virus, Taunton virus, Southampton virus, Toronto virus (formerly mini-reovirus) and others; Astrovirus; Coronavirus; Torovirus; Cytomegalovirus (CMV) and possibly Picobirnavirus. Enteritis-producing viruses replicate in columar epithelial cells in the distal parts of villi of the small intestine. Two mechanisms are addressed to explain why diarrhea occurs. Clinically, the main expression of illness is a watery diarrhea that lasts 24 h to about 7 days. Vomiting is of shorter duration and may not always accompany the diarrhea. Fever is generally 38.5 degrees C. Virus is shed in the stool for about 3-7 days. Diagnostic procedures employ electron microscopy (EM), immune electron microscopy (IEM), enzyme-linked immunosorbent assay (ELISA), time-resolved fluoroimmunoassay (TR-FIA), latex agglutination, polyacrylamide gel electrophoresis (PAGE) and the polymerase chain reaction (PCR).


CONCLUSIONS
In developed countries viral enteritis among young children may be up to three times more common than bacterial gut disease. With the exception of CMV enteric involvement, the stool is characteristically not bloody and white blood cells are not found. Patient management may involve the employment of IV replacement therapy to counter dehydration and electrolyte imbalance. Milder cases may be managed with oral rehydration.
Middleton
P J
PJ
Provincial Laboratory, B.C. Centre for Disease Control, 828 West 10th Avenue, Vancouver, B.C., Canada V5Z 1L8.