Polio in Botswana Traced to Nigeria

The case of wild polio virus transmission from Nigeria reported last week in a village in Botswana has continued to generate concerns as epidemiologists warn of the globalization of disease and the World Heath Organization saying the development is a graphic illustration of the importance of immunization.

A seven-year-old boy was infected in the Ngami district of northwestern Botswana -- a country with good surveillance for polio -- developed paralysis in early February. Health workers in the country recognized that he might have the virus even though the disease was eradicated there in 1991.

Lab results confirmed in March through genetic sequencing of the strain of the virus that it came from northern Nigeria, one of six countries where polio is still endemic, and which UN health agencies are targeting in a final push to eradicate the disease.

A team of epidemiologists that visited the district shortly thereafter, questioned the infected boy's family and neighbours. They investigated patterns of travel in and out of the region and established the boy did not travel, nor did he have any contact with anyone who had. Thus the source of the infection remains a mystery.

In a similar case last year, a strain of polio that originated in India turned up in Lebanon, which had been polio-free for 10 years. Polio doesn't need a passport as long as transmission is ongoing, then all children are at risk.

Botswana is now working to increase health workers' knowledge about the disease and to boost the immunity of its children. So far there are no other cases of polio in the country.

According to sources, the Nigerian strain of the wild polio virus has spread with astounding speed. In the past 18 months, viruses shown by genetic analysis to have originated in northern Nigeria have caused new cases of the disease in eight previously polio-free countries.

A second round of vaccinations was held in February and March in all states except Kano. WHO is hoping that the next rounds of vaccinations scheduled for early May and later on in the year will be allowed to proceed in the resistant state.(source: Sola Ogundipe, Allafrica.com 20 April 2004)