Poliomyelitis

Poliomyelitis, or polio, is an infection transmitted via the fecal-oral and oral-oral routes by the poliovirus. Today, polio primarily affects children younger than 5 in countries with poor water, sanitation, and hygiene infrastructure. While extremely rare outside these areas, polio presents a risk to populations with low vaccination rates, including in industrialized nations. The 2014 declaration deeming the global spread of polioviruses a public health emergency of international concern under the International Health Regulations remains in place.[WHO. Vaccine Position]

Previously one of the most feared diseases in the world, polio caused widespread morbidity and mortality in children during multiple epidemics between the 1900s and 1960s. The incidence of polio began to decline following the development of the injectable polio vaccine (IPV) and oral polio vaccine (OPV). Intensified worldwide vaccination efforts starting in the 1980s by the World Health Organization (WHO) and partners under the Global Polio Eradication Initiative (GPEI) have almost completely eradicated the disease. Vaccination protocols worldwide now recommend administering at least 3 doses of IPV (IPV-only schedule) or at least 3 doses of bivalent OPV plus at least 2 doses of IPV (combined OPV-IPV schedule). The latter is recommended in countries where poliovirus incidence rates remain unchanged or are at risk of increasing. See StatPearls' companion article "Polio Vaccine" for more information on polio vaccinations.

Healthcare professionals must maintain a high index of suspicion to diagnose acute poliomyelitis in patients who present with new-onset paralysis following a viral prodrome and are living in an endemic region or under-vaccinated population. The presentation of polio is highly variable, ranging from asymptomatic to a transient flu-like viral illness to paralysis, quadriplegia, and even respiratory failure and death. Many polio survivors experience a poor quality of life. Alternate diagnoses must be considered as polio is rare, and other more common diseases and conditions can present similarly. In particular, acute flaccid myelitis (AFM) presents with a polio-like syndrome. This condition is caused by epidemic enteroviral infections, most commonly enterovirus D68.

As no antiviral treatment for acute poliomyelitis exists, prevention is critical. Paralytic deficits are often permanent, resulting in chronic pain, deformities, weakness, and eventual osteoporosis and fragility fracture. Between 25% and 40% of the estimated 12 to 20 million polio survivors worldwide will also develop postpolio syndrome (PPS). A diagnosis of PPS requires new-onset, progressive muscle weakness or fatiguability, mental fatigue, or pain in a patient diagnosed with poliomyelitis up to 40 years prior. PPS is not contagious and is rarely life-threatening, but it often affects patients' independence and quality of life.

While the near eradication of polio represents a tremendous achievement for global public health, multiple challenges and delays remain. Vaccine-derived polioviruses (VDPVs) revert or recombine to wild-type neurovirulence and transmissibility, causing outbreaks and distrust in vaccination programs. Poliovirus typically escapes early detection; most infections are asymptomatic, and the characteristic paralysis occurs in a small minority of those it infects.[CDC. Polio_HCP] Delays in detecting circulating wild poliovirus (WPV) and VDPVs pose a significant risk to eradication efforts. Political unrest or indecision and declining or competing interests threaten efforts to eradicate the disease. Recent polio cases and the discovery of poliovirus in wastewater in industrialized nations emphasize that, until completely eradicated, polio remains a global risk.[GPEI. Polio Eradication]

All suspected cases of poliomyelitis in the United States should be immediately reported to the United States Centers for Disease Control and Prevention (CDC). Clinicians should suspect polio in patients with acute-onset flaccid paralysis, decreased or absent tendon reflexes, and without sensory or cognitive deficits. Contact the CDC Emergency Operations Center within 4 hours of the suspected diagnosis to ensure appropriate diagnostic testing, surveillance, and public health follow-up at 770-488-7100.[CDC. Polio_Clinical]