Cause: Polioviruses belong to the family Picornaviridae and are classified under the genus Enterovirus, specifically within the species Enterovirus C. There are three serotypes of poliovirus: PV1, PV2, and PV3, all of which can cause the paralytic disease, polio.
Illness and treatment: Approximately 70% of all polio infections are asymptomatic. 4% to 8% of people infected with poliovirus develop a mild form of the disease, symptoms are similar to a mild flu-like illness or mild gastrointestinal symptoms. Nonparalytic aseptic meningitis occurs in 1% to 5% of cases after the flu-like symptoms, the symptoms include fever, stiff neck, muscle pain and severe headache. Fewer than 1% of people with a poliovirus infection develop paralysis. The most severe form of the disease typically includes paresthesia or paralysis of one arm or one leg. More severe symptoms include paralysis if the muscles involved in swallowing or breathing. In all cases, individuals shed the virus in nasopharyngeal secretions and in stool and can transmit the virus to others. Treatment for polio is primarily supportive, focusing on managing symptoms. Post-polio syndrome (PPS) is a non-contagious condition that can occur in polio survivors decades after the initial infection. Symptoms of PPS can include muscle weakness, fatigue, joint pain, and issues with breathing, swallowing, and speech. Management 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: Polio disease can be caused by two types of virus: naturally occurring (wild) polioviruses and vaccine-derived poliovirus. In rare circumstances, the attenuated virus in the oral polio vaccine (OPV) can revert to a form that can cause paralysis, potentially leading to paralytic disease in susceptible individuals. Because of this risk, many countries, including the United States, transitioned from using OPV to the inactivated polio vaccine (IPV). IPV contains an inactivated virus, it cannot revert to a virulent form or cause paralytic disease. Susceptible individuals traveling to countries where polio is still endemic or using the OPV increases their risk of infection.
Prevention: Vaccination with IPV is the most effective method for protecting against paralytic polio by eliciting an immune response without using a live virus vaccine. IPV is the only polio vaccine administered in the United States.
Purpose of Reporting and Surveillance
- To detect importation of wild poliovirus into the United States
- To detect the presence of vaccine-derived poliovirus
- To prevent transmission of poliovirus and to distinguish between wild-type polio and vaccine-associated paralytic polio, if a case of poliomyelitis occurs
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): 206-418-5500.
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.