Health Science: Could Polio Cross the Bridge From West to East Africa?

The East African (Nairobi)
ANALYSIS
April 26, 2004

By Dagi Kimani, Special Correspondent
Nairobi

Kenya, Tanzania and Uganda are at risk of a recurrence of polio following its flare-up in West Africa, and children below five years may have to undergo extra rounds of immunisation.

The risk to East Africa has arisen following the emergence of Nairobi as the transport hub for West Africans travelling to the Middle East and Far East, as well as East Africans travelling to West Africa on business or UN duty, including with the peacekeeping missions in Sierra Leone and Liberia.

Currently, several airlines fly directly between various West African capitals and Nairobi, establishing an air corridor that the polio virus could exploit to reach East Africa. Kenya Airways, the leading carrier between the two regions, operates at least 11 flights per week from cities such as Abidjan in Ivory Coast, Lagos in Nigeria, Yaunde in Cameroon and Accra in Ghana.

"The current interaction between West and East Africa, especially the use of Nairobi by West African travellers as a transit point to Asia, raises the possibility that polio could spread from there to here," Dr Samuel Gathere, a Nairobi-based medic told The EastAfrican last week. "Whether that will actually happen only time will tell but epidemiologically, it is very possible," he added.

Although precise figures are not available, sources in the airline industry estimate that the air bridge between the two regions is used by over 2,000 passengers every week.

A fortnight ago, in what public health experts fear could be a reproducible event, the Southern African state of Botswana reported its first polio case in 13 years, which the World Health Organisation (WHO) said probably originated in Nigeria.

According to the UN health agency, studies on the genetic structure of the polio virus isolated in Botswana from a seven-year-old boy, had established that it was closely linked to the polio strain endemic to Nigeria's north, where Muslim leaders have resisted a WHO vaccination campaign.

Although it is not yet clear how the virus reached Botswana's north-western Ngami district, where the boy lives, the results of the genetic mapping studies all but established that it had reached Botswana through travel, the UN agency said.

The fact that the infected boy had not been to Nigeria also meant that the polio virus was spreading secondarily into Botswana, meaning that the country will have to re-vaccinate all its children below the age of five years to ensure its eradication.

According to the WHO, the risk of a possible spread of the polio virus from West Africa to other African countries, including those in East Africa, is heightened by the fact that there is currently no convenient test that can be used by public health authorities to screen travellers. The virus usually lies dormant in most carriers.

Already, the UN agency says, the Nigerian polio virus has spread to eight neighbouring countries that were previously free of the disease, including Cameroon, Ivory Coast and Ghana, which are all served by direct flights to Nairobi.

Other than Nigeria, polio is also endemic in India, Pakistan, Afghanistan, Niger and Egypt. In 2003, Nigeria had the highest number of polio cases anywhere in the world (302 as of January 13, 2004), and accounted for 45 per cent of all confirmed cases globally.

The current crisis in Nigeria erupted last August when clerics and other Islamic leaders in the north of the country decreed that people there should not take their children for immunisation against polio, alleging that the vaccine being used in the region was harmful.

According to the leaders, tests conducted by local scientists last year had shown the vaccines to be contaminated with a variant of the female hormone oestrogen, which they said could affect ovulation in girls. Some clerics also argued that the vaccine spread Aids, citing "evidence" obtained from the Internet.

Although most of the states have since reversed their decrees, the populous state of Kano continues to insist that the polio vaccine is dangerous. The state's Supreme Council for Sharia said last month that it would continue with an "enlightenment campaign for our people to jettison the vaccines" despite a federal government decision to pursue the immunisation drive.

Significantly, similar allegations have dogged the polio immunisation campaign in other African countries, including Kenya and Tanzania, where public health authorities had to enlist the help of religious and local leaders to convince people that the polio vaccine was harmless.

In Kenya, the allegations two years ago almost derailed immunisation campaigns in the Central Province.

Just last week, President Mamadou Tandja of Niger urged parents to vaccinate their children against polio, underlining the scale of suspicion that has been attached to the polio immunisation across much of sub-Saharan Africa.

"I want again to send out a vibrant call for the vaccination of our children and to ask you to relay this call to your respective communities so we can finish with polio," President Tandja told about 100 traditional chiefs and religious leaders in Mamadi, a town near the border with Nigeria.

Copyright © 2004 The East African. All rights reserved.

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