Madagascar: Polio transmission reported across multiple locations through June 27

Event

Health officials have reported a total of 13 cases of circulating vaccine-derived poliovirus (cVDPV) in Madagascar Jan. 1-June 27. All cases identified this year were classified as cVDPV1. This caseload is compared to the five cases reported over a similar period in 2022. Most cases have been reported in the Analamanga and Atsinanana regions. This represents the most complete data available as of July 3.

Context

Madagascar reported 16 cases of cVDPV in 2022, 13 cases in 2021, and 2 cases in 2020. Cases of cVDPV are a rare result of widespread vaccination using oral polio vaccine (OPV), which contains a live but weakened strain of poliovirus. When a child is immunized with OPV, the weakened vaccine-virus replicates in the intestine for a limited time, leading to the development of antibodies. In areas of inadequate sanitation, vaccine-virus excreted by these children can spread in the community.

Polio is highly infectious and can spread rapidly through contact with infected fecal material, such as in contaminated food and water. Infections are generally mild, but one in 200 cases leads to irreversible paralysis. Among those victims, 5-10 percent die when respiratory muscles become affected. The risk of paralysis increases with age. There is no specific treatment for polio.

The risk of healthy individuals contracting polio from contaminated food or water remains negligible, but individuals with compromised immune systems or those suffering from long-term illness may be more susceptible.

Advice

Visit a doctor to receive a precautionary polio booster before traveling to Madagascar, as even mildly symptomatic or asymptomatic people are infectious. Practice basic food and water precautions: drink only boiled, bottled, or purified water, and ensure that food is properly prepared and served hot.