Cause: Poliovirus, a member of the enterovirus subgroup, family Picornaviridae. Three serotypes, P1, P2, and P3 (and the related live oral vaccine strains), can cause disease.

Illness and treatment: Over 90% of infections are asymptomatic and 4-8% are minor illnesses. Nonparalytic aseptic meningitis with full recovery occurs in 1-2% of infections. Fewer than 1% of infections result in flaccid paralysis. Treatment is supportive.

Sources: Humans are the reservoir. Transmission is mainly through the fecal-oral route. Virus may be present in the stool of an infected person for 3-6 weeks.

Additional risks: Travel by susceptible persons to the few countries where polio is still endemic or to countries still routinely using oral polio vaccine can increase the risk of becoming infected.

Prevention: Universal immunization prevents infection. Only inactivated polio vaccine – which can prevent paralysis, but does not provide intestinal immunity – is now used in this country.

Recent Washington trends: The last naturally acquired infection with wild-type polio virus was in 1977. In 1993, a case of vaccine-associated paralytic polio occurred in a state resident after a family member received live oral polio vaccine, which is no longer used in the United States.

Purpose of Reporting and Surveillance

  • To identify cases of polio.
  • To prevent transmission of polio.
  • To distinguish between wild-type polio and vaccine-associated paralytic polio.

Legal Reporting Requirements

  • Health care providers and health care facilities: immediately notifiable to local health jurisdiction
  • Laboratories: Poliovirus, acute, by IgM positivity or PCR positivity immediately notifiable to local health jurisdiction; specimen submission is required – submission required – isolate or if no isolate available, specimen associated with positive result, within 2 business days 
  • Local health jurisdictions: immediately notifiable to the Washington State Department of Health (DOH) Communicable Disease Epidemiology (CDE): 1-877-539-4344

Paralytic polio is designated “immediately notifiable, extremely urgent”, requiring state and local health authorities to notify CDC within 4 hours of their notification.

Non-paralytic polio is designated “immediately notifiable and urgent” requiring state and local health authorities to notify CDC within 24 hours of their notification.