A case of vaccine-associated paralytic poliomyelitis.

Vaccine-associated paralytic poliomyelitis (VAPP) is a very rare complication of oral polio vaccine (OPV), seen predominantly with first exposure to OPV. Reversion of vaccine strain poliovirus to a more neurovirulent strain of the virus is thought to be necessary for paralytic disease to occur. Vaccine-associated poliomyelitis can occur in either recipients of the vaccine or in susceptible contacts. We describe an episode of VAPP in an infant in whom paralysis became evident at age 124 days, 14 days after administration of the second dose of OPV vaccine. The second dose of diphtheria-tetanus-pertussis- Haemophilus (DTPH) type-b vaccine had been given at the time of OPV administration, and the hepatitis B vaccine had been administered in the opposite leg. Paralysis was localized to the limb in which the DTPH had been injected.