Nigeria: Polio activity reported in additional Nigerian states; Jigawa State is most affected. Confirm vaccination.

Event

Health authorities have reported 68 cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) in Nigeria Jan. 1-Aug. 11. This is compared to one case reported over a similar period in 2020 and eight total cases reported during 2020. Officials have observed cases of cVDPV2 during 2021 in at least 16 states, with Jigawa, Kebbi, and Yobe reporting the most cases. This represents the most complete data available as of Aug. 18.

Context

Officials reported sporadic cases of circulating vaccine-derived poliovirus (cVDPV) in Nigeria, with 8 cases in 2020, 18 in 2019, and 34 in 2018. Nigeria was declared free of wild poliovirus in 2020; however, fluctuating levels of vaccine coverage against polio may cause flare-ups of cVDPV in susceptible communities. Cases of cVDPV are a rare result of widespread vaccination using oral polio vaccine (OPV), which contains a live but weakened poliovirus strain. When a child is immunized with OPV, the weakened vaccine-virus replicates in the intestine for a limited time, leading to antibodies' development. 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 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. Still, 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 Tajikistan, 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.