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How serious?
Risk of death
Yes
Vaccine available?
Time to symptoms
Countries affected
Active outbreaks
Polio is nearly eradicated but remains endemic in Afghanistan and Pakistan. Some countries require proof of polio vaccination for entry if arriving from endemic/outbreak areas. Verify your vaccination is up to date. A booster dose may be required.
Infectious viral disease that can cause permanent paralysis. Globally on the verge of eradication — wild poliovirus type 1 remains endemic in Pakistan and Afghanistan.
Symptoms | Frequency | Severity | Onset |
|---|---|---|---|
| Fever | 85% | Mild | Early |
| Headache | 75% | Mild | Early |
| Malaise | 80% | Mild | Early |
| Irritability | 30% | Mild | Early |
| Loss of appetite | 45% | Mild | Early |
| Nausea | 40% | Mild | Early |
| Sore throat | 50% | Mild | Early |
| Vomiting | 35% | Mild | Early |
| Abdominal pain | 25% | Mild | Early |
| Diarrhea | 15% | Mild | Early |
| Paralysis | 1% | Critical | Peak |
| Back pain | 20% | Moderate | Peak |
| Dysphagia | 3% | Severe | Peak |
| Myalgia | 25% | Moderate | Peak |
| Neck stiffness | 15% | Moderate | Peak |
| Shortness of breath | 2% | Critical | Peak |
| Photophobia | 10% | Mild | Peak |
| Constipation | 20% | Mild | Peak |
| Tremor | 5% | Mild | Peak |
| Fatigue | 80% | Mild | Any phase |
Highly infectious viral disease that can cause permanent paralysis.
Poliomyelitis is caused by poliovirus (types 1, 2, 3), an enterovirus transmitted primarily via the fecal-oral route. Most infections are asymptomatic or cause mild illness; <1% progress to paralytic disease. The Global Polio Eradication Initiative has reduced wild poliovirus cases by >99.9% since 1988.
Seek emergency medical care immediately if:
Sudden weakness or paralysis of any limb — especially if asymmetric
Difficulty breathing or swallowing
Inability to raise the head against gravity
Sudden severe back or neck pain with muscle weakness
These symptoms in an unvaccinated child require urgent AFP reporting
Most common signs and symptoms
Asymptomatic infection: ~72% of cases
Abortive polio (minor illness, 3–5 days): Fever, sore throat, nausea, abdominal pain — resolves without sequelae.
Non-paralytic aseptic meningitis: Meningismus, muscle pain, stiffness — no paralysis.
Paralytic poliomyelitis (<1%): After an asymptomatic period following minor illness (biphasic fever), sudden onset of asymmetric flaccid paralysis, maximal within 2–5 days. Spinal type: limb weakness (legs > arms). Bulbar type: respiratory muscle and cranial nerve involvement — risk of respiratory failure. Post-polio syndrome can develop 15–40 years after recovery.
Knowing the symptoms is the first step to a quick response.
Typical disease course (paralytic polio):
Spinal vs. bulbar: Spinal polio (limb paralysis) is most common. Bulbar polio involves cranial nerves and respiratory center — medical emergency.
How this disease is identified
Suspect polio in any child <15 years with acute flaccid paralysis (AFP) or any age person with AFP in endemic/outbreak setting. Confirmation:
Stool culture: poliovirus isolation (gold standard) — two specimens 24 hours apart, within 14 days of paralysis onset
CSF analysis: lymphocytic pleocytosis, normal glucose, elevated protein
Serology: not routinely used
EMG: lower motor neuron pattern All AFP cases must be reported to national health authorities (polio-free zones) and WHO.
Available treatment methods
No specific antiviral treatment is available for poliomyelitis. Management is supportive:
Acute phase: analgesics, complete bed rest; hot packs for muscle spasm relief
Respiratory support: mechanical ventilation for bulbar or respiratory involvement
Physiotherapy: early passive range-of-motion exercises during acute phase; intensive rehabilitation during recovery phase
Long-term rehabilitation: orthotics, surgical correction of deformities, assistive devices
Post-polio syndrome: energy conservation, pain management, non-fatiguing exercise programs
Most cases are effectively treated with early diagnosis.
How to protect yourself
Two highly effective vaccines are available:
Inactivated Polio Vaccine (IPV): injectable
no risk of vaccine-derived polio
used in polio-free countries
Oral Polio Vaccine (OPV): live-attenuated
provides intestinal immunity
rare risk of vaccine-derived poliovirus (VDPV) — being phased out WHO recommended schedule: IPV at 2, 4, 6–18 months, and 4–6 years. Booster for travelers to endemic/outbreak areas. Travelers to Pakistan, Afghanistan, or areas with circulating vaccine-derived poliovirus should receive a booster IPV dose within 4 weeks to 12 months before departure (required by GPEI exit requirements for residents/long-term visitors of endemic countries).
Preparation is the best protection.
Check polio vaccination status before all international travel.
Travelers to Pakistan, Afghanistan, or cVDPV-affected areas: require proof of IPV vaccination (within 4 weeks to 12 months before departure from endemic country). Some countries require documentation on the International Certificate of Vaccination.
Travelers from endemic countries may be required to show proof of vaccination at borders.
Practice strict hand hygiene and food/water safety in areas with inadequate sanitation.
Statistics and geographic data
Since the Global Polio Eradication Initiative (1988), wild poliovirus cases fell from ~350,000/year to 6 (WPV1) reported in 2021. Wild poliovirus type 2 eradicated in 1999; type 3 in 2019. WPV1 remains endemic in Pakistan and Afghanistan. Circulating vaccine-derived poliovirus (cVDPV) outbreaks occur in areas with low OPV coverage, including parts of Africa, Middle East, and Asia. Over 200 countries have maintained polio-free status.
Who is most at risk
Host factors increasing risk of paralytic disease:
Age: Risk of paralysis increases with age at infection. Adults develop paralytic polio more frequently and with greater severity than children.
Immunodeficiency: Primary immunodeficiency (especially B-cell defects such as agammaglobulinemia) dramatically increases risk of paralytic disease and chronic infection. These individuals can excrete vaccine-derived poliovirus for years (immunodeficiency-associated VDPV, iVDPV).
Pregnancy: Pregnant women have a higher incidence of paralytic polio and higher case-fatality rates.
Tonsillectomy: Prior tonsillectomy increases risk of bulbar polio.
Intramuscular injections: Injections in the weeks before or during infection increase risk of paralysis in the injected limb ("provocation polio").
Strenuous physical exercise: Physical exertion during the incubation period or early illness is associated with increased severity of paralysis.
Environmental and geographic risk factors:
Lack of vaccination: Unvaccinated or under-vaccinated individuals in any country are at risk. Immunity gaps from missed routine immunization are the primary driver of cVDPV outbreaks.
Poor sanitation: Fecal contamination of water supplies facilitates transmission.
Conflict and displacement: Disruption of immunization programs in conflict zones (Afghanistan, Pakistan, parts of Africa) sustains transmission.
Overcrowding: Close living conditions in camps or urban slums increase exposure risk.
Travel-related risk factors:
Travel to endemic countries (Afghanistan, Pakistan) or countries with active cVDPV outbreaks
Extended stays in rural areas with poor sanitation infrastructure
Visiting friends and relatives (VFR) travelers may underestimate risk and delay vaccination
Potential complications
Permanent flaccid paralysis: asymmetric limb weakness, most commonly legs; occurs in <1% of infections but leaves lifelong disability
Respiratory failure: bulbar polio or high cervical spinal cord involvement; historically required iron lung
Post-polio syndrome (PPS): gradual onset of new muscle weakness, fatigue, pain 15–40 years after initial infection, affecting ~25–40% of paralytic polio survivors
Secondary musculoskeletal complications: scoliosis, joint deformities due to muscle imbalance
Psychological impact: chronic disability, depression, social isolation
Expected outcomes and recovery
Asymptomatic infection: 72% of cases. No sequelae.
Abortive polio (minor illness): 24%. Complete recovery.
Non-paralytic aseptic meningitis: 1–5%. Full recovery within 2–10 days.
Paralytic polio: 0.5–1% of infections.
CFR: 2–5% in children, 15–30% in adults (respiratory muscle involvement).
Bulbar polio (brainstem involvement): CFR 25–75%.
Partial or complete recovery of paralysis in 60% over 6–12 months. Residual paralysis is permanent.
Post-polio syndrome: 25–40% of paralytic polio survivors develop new weakness, fatigue, and muscle atrophy 15–40 years later.
This disease is vaccine-preventable. Effective protection is available through vaccination.
Talk to a travel health specialist about the recommended schedule before your trip.
Find a vaccination clinic →The content on this page is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment recommendations. If you have health concerns, consult a qualified healthcare professional. Medova is not a medical service provider.
Full terms of useGeographic distribution and active outbreaks
Recent epidemiological data from the World Health Organization Global Health Observatory.
Source: WHO GHO OData ↗
This data is provided for informational purposes. Please consult official WHO sources for the most current information.
View WHO data source →| Flag | Country | Risk level |
|---|---|---|
 | Pakistan | High risk |
 | Afghanistan | High risk |
 | Indonesia | High risk |
 | South Sudan | High risk |
 | Somalia | High risk |
 | Chad | High risk |
 | Malawi | High risk |
 | Sudan | High risk |
 | Myanmar | High risk |
 | Mozambique | High risk |
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