Seroprevalence of polio antibodies in adult laboratory staff in South Africa, 2009 to 2013

Shelina Moonsamy,Melinda Suchard

doi:10.4102/sajid.v31i2.91

Abstract

The global eradication of polio has been a World Health Organization goal since May 1988 with the current target for global eradication set at 2018. A keystone of the eradication initiative is achieving and maintaining high immunisation coverage, producing high population immunity. Assessing infant vaccination coverage does not give a reliable indication of adult immunity levels as antibody titres decline with age. A requirement of the occupational health programme at the National Institute for Communicable Diseases is to test newly appointed personnel for immunity to polio. During the period 2009 to 2013, 352 sera were collected and tested by means of antibody neutralisation assays to determine immunity to all three polio serotypes. The objective of this study was to assess immunity to polio in personnel employed at the National Institute for Communicable Diseases as a proxy for the general adult South African population. The seroprevalence to polio serotypes 1, 2 and 3 were 85.5, 90.0 and 74.0%, respectively. Of the 352 samples tested, 2.3% were sero-negative for all three serotypes and 36.0% were sero-negative to at least one of the serotypes. The seroprevalence to polio serotype 3 falls below the target of 80.0%, and could pose a potential risk following importation or development of vaccine derived poliovirus type 3.

Highlights

In May 1988, the 41st World Health Assembly adopted a resolution to globally eradicate polio by the year 2000.1 This target was not achieved, nor the two subsequent targets of 2005 and 2010
Progressing towards polio eradication, only three countries globally remain endemic for wild poliovirus type 1: Nigeria, Pakistan and Afghanistan.[5]
No wild type cases have been identified in Nigeria since July 2014.6 In South Africa, the last wild-type polio case was identified in 1989.7 Those countries that have been certified as polio free remain vulnerable to importation from endemic countries

Summary

Introduction

In May 1988, the 41st World Health Assembly adopted a resolution to globally eradicate polio by the year 2000.1 This target was not achieved, nor the two subsequent targets of 2005 and 2010. The new target for global certification of eradication has been set for 2018.2 In 1988, polio occurred in more than 125 countries on five continents and paralysis was observed in more than 350 000 children.[1] Elimination strategies that proved successful included high routine immunisation coverage; national immunisation days that targeted all children under 5 years of age; enhanced and effective acute flaccid paralysis surveillance; and, mop-up immunisation campaigns.[1] The lack of cross protection between the three polio serotypes warranted the use of trivalent vaccines during national immunisation days and campaigns, but required monovalent vaccines to eliminate wild type poliovirus 1 from India.[3,4]. In 2009, South Africa introduced an inactivated polio vaccine (IPV) into its routine immunisation schedule, with an oral polio vaccine (OPV) given at birth and six weeks and IPV given at six, ten and fourteen weeks, as well as at eighteen months. 10,11

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Conclusion