On Sunday, May 11, the World Health Organization reported the investigation of a possible wild poliovirus type 1 (WPV1) case in Somalia's Banadir region. A 32-month-old girl had become ill due to acute flaccid paralysis (AFP – essentially, muscle weakness or paralysis) on April 18, and preliminary lab tests indicate WPV1. While other diseases and conditions can cause AFP, they are rare (about 1 case per 100,000 children under 15). Therefore, surveillance of cases of AFP is an important tool in polio surveillance.
Somalia was declared polio-free in 2008 after a massive vaccination effort that mobilized over 10,000 volunteers and health workers to fully vaccinate 1.8 million children under that age of five in a country torn by civil war leading to frequent large scale population movement.
Since 2009, polio vaccination activities have decreased in several areas of Somalia. If this recent suspected case is confirmed, children from large swaths of Somalia may be highly vulnerable to an outbreak. A vaccination campaign for more than 350,000 children in the Banadir region has already been planned for May 14 – 16. WHO has advised countries in the WHO regions of Africa and the Eastern Mediterranean to heighten their poliovirus surveillance.
There are three types of wild poliovirus: types 1, 2, and 3. The last case of type 2 was in India in 1999. Of the 223 polio cases in 2012, 202 were WPV1 and 21 were WPV3, representing a decrease of over two-thirds from 2011. Despite that progress, wild poliovirus continues to circulate in Afghanistan, Nigeria and Pakistan. If Somalia joins that list, the Global Polio Eradication Initiative will need to mobilize a substantial effort to increase vaccination coverage against this terrible but preventable disease. WHO states that it will report on the investigation results as soon as possible.