Pakistan: Poliovirus update for multiple provinces, Nov. 24

Event

Authorities reported the number of poliovirus cases in Pakistan Jan. 1-Nov. 24 as approximately 185 compared to roughly 100 cases reported over the same period in 2019. Officials identified 81 of the total cases as wild poliovirus (WPV); the remaining 104 cases are circulating vaccine-derived poliovirus (cVDPV). Polio eradication efforts in Pakistan resumed July 20 after a four-month suspension due to the coronavirus disease (COVID-19) pandemic. Khyber Pakhtunkhwa remains the most-affected area (64 cases) followed by Sindh (44 cases), Balochistan (25 cases), and Punjab (31 cases). This report represents the most recent information as of Dec. 2.

Context

Global polio eradication efforts were suspended due to the COVID-19 pandemic, but subsequently resumed July 20. Despite a significant improvement in the number of poliovirus cases over the past decade due to nationwide vaccination campaigns, this virus remains endemic to the Pakistan and Afghanistan regions. A surge in the number of cases was observed toward the end of 2019, continuing into 2020.

The increase in the amount of cVDPV cases is concerning. 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, infecting susceptible individuals. To date, 83 cases of cVDPV have been reported in 2020, compared to a total of 22 cases for the whole of 2019.

Similarly, WPV has seen an increase to 80 cases in 2020 compared to 80 cases in 2019 over the same time period. Since WPV remains endemic to the region, human reservoirs are likely to increase as a result of the previously suspended vaccination campaigns. 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.

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

Advice

Visit a doctor to receive a precautionary polio booster before traveling to Pakistan, 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.