Infectious diarrhoea is one leading cause of infantile mortality in developing countries. Rotaviruses and other enteroviruses have an important role in diarrhoea but, currently, there are no vaccines available to immunize infants. The use of oral poliovirus vaccine (OPV) over two decades has shown that, besides protecting effectively against poliomyelitis, it can interfere with intestinal infection by other enteroviruses. This interference by the vaccine viruses could explain two epidemiological observations showing that repeated and massive administration of OPV was followed by a statistically significant decrease of infantile diarrhoea mortality. OPV administration could have two objectives: to prevent poliomyelitis and to reduce infantile diarrhoea of viral aetiology.
PIP: Acute infectious diarrheal illness caused the deaths of 934 children under 5 per 100,000 in 1978 in Latin American countries, thus vaccination against rotaviruses has been stressed. Immunization with oral poliovirus vaccine (OPV) succeeded in preventing poliomyelitis, but the concurrent administration of OPV with rotavirus vaccine (RIT-4237) produced a significantly lower seroconversion rate for rotavirus. OPV strains replaced pathogenic flora of enteroviruses in the intestinal tract in several weeks. Nonspecific intestinal interference from the vaccine strains reduced diarrheal mortality. A poliomyelitis epidemic was controlled in Chile in 1961 with significant reduction of mortality between 1961 and 1963 as compared to the pre-OPV period of 1955-1960 and the post-OPV period of 1964-67. A massive immunization drive commenced in Brazil in 1980: OPV was administered in 1 day throughout the country and again 8 weeks later to children under 4 resulting in the reduction of poliomyelitis. Ill-defined gastrointestinal (GI) infection accounted for 98% of GI deaths of children 1 year of age during 1977-84 in Brazil. Infantile diarrhea deaths dropped 11,000 annually for 5 years when the OPV campaign reached its height. The prevention of poliomyelitis and reduction of clinical diarrhea of viral etiology are the goals of the OPV program. 2 OPV doses administered 2 months apart are sufficient for 4 months during period pathogenic enteroviruses are replaced by vaccine strains.