Polio Outbreak Investigation and Response in The Horn of Africa: 2013-2016

Background: There has been civil strife, spanning more than two decades in some countries and recurrent natural disasters in the Horn of Africa (HoA). This has consistently maintained these countries in chronic humanitarian conditions. More important however is the fact that these crises have also denied populations of these countries access to access to lifesaving health services. Children in the difficult terrains and security compromised areas are not given the required immunization services to build their immunity against infectious diseases like the poliovirus. This was the situation in 2013 when the large outbreaks of poliovirus occurred in the HoA. This article reviews the epidemiology, risk, and programme response to what is now famed as the 2013-204 poliovirus outbreaks in the HoA and highlights the challenges that the programme faced in interrupting poliovirus transmission here. Methods: A case of acute flaccid paralysis (AFP) was defined as a child <15 years of age with sudden onset of fever and paralysis. Polio cases were defined as AFP cases with stool specimens positive for WPV. Results: Between 2013 and 2016, when transmission was interrupted 20,266 polio viruses were in the Horn of Africa region. In response to the outbreak, several supplementary immunization activities were conducted with oral polio vaccine (OPV) The trivalent OPV was used initially, followed subsequently by bivalent OPV, and targeting various age groups, including children aged <5 years, children aged <10 years, and individuals of any age. Other response activities were undertaken to supplement the immunization in controlling the outbreak. Some of these activities included the use of various communication strategies to create awareness, sensitize and mobilize the populations against poliovirus transmission. Conclusions: The outbreaks were attributed to the existence of clusters of unvaccinated children due to inaccessibility to them by the health system, caused by poor geographical terrain and conflicts. The key lesson therefore is that the existence of populations with low immunity to infections will necessary constitutes breeding grounds for disease outbreak and of course reservoirs to the vectors. Though brought under reasonable control, the outbreaks indicate that the threat of large polio outbreaks resulting from poliovirus importation will remain constant unless polio transmission is interrupted in the remaining polio-endemic countries of the world.