International Journal of Vaccines and Immunity

International Journal of Vaccines and Immunity Vol. 2 (2), pp. 084-096, February, 2015.© International Scholars Journals

Case Study

The function of vaccine derived polioviruses in the global suppression of polio: The Nigeria experience as a case study

Osazuwa Austine

Department of Virology, Faculty of Medical Sciences, University of Benin, Edo State, Nigeria.

E.mail:aust-osas@yahoo.com

Accepted 25 January, 2015

Abstract

This review reports the role of vaccine derived poliovirus (VDPV) in the global eradication of poliomyelitis. A vaccine derived poliovirus (VDPV) is a rare strain of poliovirus, genetically mutated from the strain contained in OPV. The OPV contains a weakened or attenuated version of poliovirus, activating an immune response in the body. A vaccinated person transmits the weakened virus to others, who also develop antibodies to polio, ultimately stopping transmission of poliovirus in a community. The World Health Assembly in 1988, resolved to eradicate poliomyelitis from the world by the year 2000 and since then, the Global Polio Eradication Initiative (PEI) of the World Health Organization (WHO) has led to a decline in global polio incidence, from an estimated 350,000 cases in 1988 to under 3,500 in the year 2000, with the last remaining global poliovirus reservoirs confined to parts of Southeast Asia and Sub-Saharan Africa. In the African Region (AFRO) of the WHO, eradication strategies were accelerated following supporting resolutions by WHO’s Regional Committee for African in 1995 and the organization for African Unity in 1996. Despite the reported success in National Immunization days (NIDs), establishment of acute flaccid paralysis (AFP) surveillance and accelerated efforts to meet the year 2000 targets including “mopping- up” executed in 1999 and subsequent years, Nigeria, the most populous country in Africa, remains one of the major reservoirs for wild poliovirus transmission. Conversely, American region (AMRO) of the WHO was certified as polio-free in 1994 as was the Western Pacific Region (WPRO) in 2000. Recommendations have therefore being presented on ways of evaluating vaccine administration to boost its output in checkmating the increasing waves of paralytic poliomyelitis (including vaccine associated paralytic poliomyelitis-VPP) and prevalence of wild poliovirus in the country. However, there are obstacles to the global eradication which involve among others, vaccine derived polioviruses (VDPVs) in areas with low oral poliovirus vaccine (OPV) coverage. In addition, long term excretion of neurovirulent immunodeficiency-associated vaccine derived polioviruses (iVDPVs) can lead to poliovirus spread to contacts. Overcoming these obstacles is challenging.

Key Words: Global eradication, Poliovirus, poliomyelitis, vaccine administration, vaccine derived poliovirus (VDPV).