Vaccine-derived polio virus suspected in Minnesota death

Health officials are monitoring health care workers who came into contact with a Minnesota resident who died last month with symptoms including paralytic poliomyelitis.

The Minnesota Department of Health emphasized that the patient had multiple health conditions and a weakened immune system. Although officials are unable to corroborate to what extent polio contributed to the patient’s death, they have confirmed that the infecting virus strain was identical to a strain in the oral poliovirus vaccine.

“This is a very rare occurrence and does not signal a resurgence of polio,” Ruth Lynfield, MD, Minnesota State Epidemiologist said in a press release. Health officials have not yet released details on the patient.

Live-virus oral poliovirus vaccine administration was discontinued in the U.S. nine years ago, due to concerns that vaccine-derived polio strains could spread in rare instances when an unvaccinated or immunodeficient person comes in contact with a vaccinated individual who is shedding the virus.

The injected polio vaccine currently in use contains only inactivated virus.

Since 2000, this is the second polio infection caused by a vaccine strain in the United States, and one of 45 cases reported worldwide since 1961. The last U.S. case of naturally occurring paralytic polio disease occurred in 1979.

“Only unvaccinated people or people with deficient immune systems who have had direct, ungloved contact with the patient’s bodily secretions are at any risk for disease,” Aaron DeVries, MD, medical epidemiologist with the Minnesota Department of Health said. – by Nicole Blazek

This brief report raises a multitude of questions. One wonders first what the vaccination status of this patient was. Other reports indicate that Minnesota public health officials are still trying to determine that. It is well known that vaccine-type poliovirus can persist in immunocompromised patients for years, and may from time to time provide the virus to infect contacts who may be susceptible. Did this patient acquire the virus from such a contact, or could this be some rare kind of autoinfection?

Curiously, the only other vaccine-derived case of polio in the United States since the use of live virus vaccine was discontinued in 2000 also occurred in Minnesota. Coincidence? Perhaps, but a close relationship between public health and clinical medicine, an excellent clinical laboratory network and a first rate public health laboratory might also be factors. One wonders how many other vaccine-related polio illnesses might have occurred that, for one reason or another, simply escaped detection.

– Theodore C. Eickhoff, MD

Infectious Diseases in Children