This raised concern because the Americas had been free of wild poliovirus since 1991. All of the new polio cases were either unvaccinated or had not received the complete schedule of polio vaccine doses. To control the circulation of both wild and OPV-derived polioviruses, countries must ensure their populations receive high vaccination coverage. As PAHO has stated, the outbreak is a powerful reminder that even polio-free areas need to maintain high polio immunization coverage. The incubation period for poliomyelitis varies from 4 to 35 days.
Infected individuals can transmit the virus to others even though they exhibit no symptoms.
In the most severe cases, the brain and respiratory system are affected, which may lead to death. There is no specific treatment for polio. Severe cases require supportive care that may help the patient recover. The IPV is delivered by injection of killed virus, and is highly protective and extremely safe but not necessarily lifelong. The OPV vaccine is given orally and is formulated from live viruses of each of the polio serotypes.