NEW YORK (Reuters Health) – An investigation prompted by the discovery of vaccine-derived poliovirus (VDPV) infection in a hospitalized immunodeficient infant from an Amish community in Minnesota uncovered other such cases, researchers report in the February 1st issue of Clinical Infectious Diseases.

“Undervaccinated communities such as the Amish, even in societies that have high rates of immunization, are susceptible to infections with and outbreaks from polioviruses, whether wild or vaccine-derived,” lead investigator Dr. James P. Alexander told Reuters Health.”

Dr. Alexander of the Centers for Disease Control and Prevention, Atlanta and colleagues note that the infected infant was born in 2005 and oral poliovirus vaccine (OPV) has not been used in the US since 2000 or in Canada since 1996.

The investigation, which covered Amish communities in Minnesota, neighboring states and in Canada, failed to identify a source for the VDPV infection. However, 8 of the 23 children tested in the index community had evidence of type 1 poliovirus or VDPV infection.

Phylogenic analysis indicated that the VDPV had circulated in the community for about 2 months before the infant’s infection was detected. The researchers suggest that the original source of the outbreak was someone who was immunodeficient and had been exposed to OPV outside of the United States.

No paralytic disease was found in the community, and no poliovirus infections were found in other Amish communities investigated.

“Global travel allows rapid and far-reaching transmission of infectious agents,” Dr. Alexander commented. “This event is a reminder that well-immunized societies need to be on guard until polio eradication is achieved world-wide.”

He added, “This event and outbreaks of VDPVs also point out the necessity for OPV cessation following wild poliovirus eradication.”

Reference:
Clin Infect Dis 2009;199:391-397.