Immunization Focus - the GAVI quarterly

NEWS - October 2003

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Renewed attack on polio as cases spread to Nigeria's neighbors

©WHO

POLIO from Nigeria has spread to several nearby countries that had previously been free of the virus, in what WHO experts are describing as “a grave threat” to public health. A dozen children have been paralysed by wild polio in Ghana, Togo, Burkina Faso, Niger and, most recently, Chad. Among these countries only Niger has had any wild polio virus circulating in the past year.

Public health officials are also worried by the spread of infection within Nigeria, from its epicentre in the north of the country around Kano to Lagos, a city of some 10 million people. Nigeria, which has long been a reservoir for polio in West Africa, has now overtaken India as the country with the largest number of polio cases worldwide. As of late October, Nigeria had reported 193 confirmed cases for the year so far. India had so far reported 161 cases, compared with 1600 in last year’s outbreak.

The setback means that Benin, Burkina Faso, Ghana, Niger and Togo have had to launch another major polio immunization campaign, at a cost of $10 million, to protect some 15 million children and stop transmission of the virus. Further campaigns, in Chad and Cameroon, will follow in mid-November. A second round of campaigns will follow within weeks. The campaigns in previously polio-free areas will inevitably add to the burden on health services that are already stretched and attempting to improve their routine immunization services.

Genetic analyses of the viruses from the five affected countries indicate that they are closely related to strains currently circulating in northern Nigeria. They are clearly different from strains of the virus that were circulating in these countries before they stopped transmission a year or more ago.

"The spread of the virus is obviously extremely unfortunate, particularly since such tremendous progress has been made in West and Central Africa in 2001 and 2002,” said Mr Chris Maher of the Polio Eradication Initiative at WHO. He said the partners in the initiative are confident that transmission can be quickly stopped by effective campaigns in the affected countries. He said that the reasons for the spread of the virus in Nigeria were “very clear”: immunization had not reached enough children to stop wild polio from circulating. In at least one state, as few as 16% of children had been adequately immunized against polio.

“In order to improve the quality of activities, there must be a major improvement in the level of local government and community engagement, and a significant improvement in training and supervision,” said Mr Maher. Since the start of the Polio Eradication Initiative in 1988, the number of polio-endemic countries has fallen from 125 to seven.

Immunization Focus October 2003 - Contents