Cooperative studies on diarrheal diseases

Abstract

Enteric infection still causes the highest global morbidity and mortality in children under 5 years old. While there have been impressive developments in the early treatment of diarrhea, adequate diagnostic techniques are not yet available. An international collaboration was conducted with the National Institute of Cholera and Enteric Diseases, Calcutta on the rapid diagnosis and prevention of diarrheal diseases. Forty to fifty per cent of the 780-bed Infectious Diseases Hospital is occupied by cases of diarrhea. Vibrio cholerae OI continues to occupy a prominent position, and the prevalence in children up to 2 years is 30.9%. Accordingly, immuno-enzymatic detection of cholera toxin in stool was achieved. Bead enzyme-linked immunosorbent assay (ELISA) could successfully detect 40 pg/mL toxin within 4 h, but the detection rate of culture, bead ELISA and polymerase chain reaction (PCR) method was 72.2, 71.1 and 95.9%, respectively, indicating that PCR provides the most sensitive and specific assay for diagnosis of cholera directly from the stool of patients. Heat-stable enterotoxin (STa) is another virulence factor of gastroenteritis. Various monoclonal antibodies were established against it, and developed a competitive ELISA for the detection of STa producing strains. A DNA probe was also prepared, and genus vibrio was monitored. V. mimicus were found to be the reservoirs of STa among clinical vibrios. Various monoclonal antibodies against STa were also useful for the epitope mapping, providing information on the topology of the toxin-host interaction.