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The Global Polio Eradication Initiative --- Progress and Challenges

By M. Puister

Abstract

Poliovirus is a non-enveloped single stranded positive sense RNA virus arranged in an icosahedral capsid. The virus infects humans and primates through the fecal-oral route. Although most infections pass unapparent with minor illness, 1% of the infections lead to paralytic poliomyelitis. There are two available polio vaccines; the inactivated polio vaccine (IPV) and the live attenuated oral polio vaccine (OPV). Both vaccines have played an important role in polio eradication. The global polio eradication initiative (GPEI) was launched in 1988. The initiative significantly increased oral polio vaccine (OPV) coverage and has reduced polio incidence from 350.000 cases in 1988 to 1315 cases in 2007. Currently there are four endemic countries left: Nigeria, India, Afghanistan and Pakistan. While the problems in Nigeria, Afghanistan and Pakistan are mainly associated with OPV delivery the main problem in India is lack of OPV efficacy. In a large wild poliovirus type 3 (WPV3) outbreak in India most of the identified cases occurred in children who had been vaccinated multiple times. OPV has been used as the vaccine of choice in the GPEI, because of its low costs, ease of administration and ability to produce intestinal immunity. However, a major disadvantage of OPV is its genetic instability and its ability to be transmitted. This causes vaccine-associated paralytic poliomyelitis (VAPP) and leads to the emergence of circulating vaccine-derived polioviruses (cVDPVs). Most of these VDPVs are recombinants with the closely related human enteroviruses C, which also replicate in the gut. Several outbreaks of VDPVs have shown that cVDPVs have the ability to circulate in the population and cause poliomyelitis. With the eradication of wild poliovirus coming closer, it is time to analyze the risks that are associated with the cease of OPV. Mishandled poliovirus and poliovirus materials or a circulating VDPV can be a major threat in an increasingly susceptible population

Topics: Geneeskunde, Polio, Poliomyelitis, WHO, eradication, IPV, OPV, VDPVs, VAPP
Year: 2009
OAI identifier: oai:dspace.library.uu.nl:1874/35207
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