A case of paralytic poliomyelitis due to an imported type 1 poliovirus has been reported in Botswana, a country which had been polio-free since 1991. The virus has been closely linked genetically to poliovirus endemic to northern Nigeria. The case - a seven year old boy from the Ngami district of north-western Botswana - had onset of paralysis on 8 February 2004.
In the past 18 months, wild polioviruses genetically linked to northern Nigeria have caused new cases of polio in the previously polio-free countries of Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Côte d'Ivoire, Ghana and Togo. The importations are associated with an extensive outbreak of polio in Nigeria, which resulted following the suspension of polio immunization campaigns in some northern states of the country in August 2003. As of March 2004, all states in Nigeria, with the exception of Kano, had resumed mass polio immunization activities.
The polio case in Botswana underlines the magnitude of the risk posed to polio-free areas by the ongoing polio outbreaks in west and central Africa, and is compounded by the growing vulnerability of populations to polio globally, following the cessation of preventive polio immunization campaigns in most polio-free countries in 2002/03. Children across Africa will continue to be at risk of polio from such importations until the disease is eradicated everywhere.
The Government of Botswana, WHO, UNICEF and partners are currently preparing an emergency response to the importation, including heightened disease surveillance throughout the country and a nationwide immunization campaign to ensure that any transmission of wild poliovirus in Botswana is stopped rapidly. Neighbouring countries are being notified of the importation, and urged to further strengthen their surveillance for polio and routine immunization coverage.
The Global Polio Eradication Initiative is spearheaded by WHO, Rotary International, the US Centers for Disease Control and Prevention and UNICEF. The poliovirus is now endemic in only six countries, down from over 125 when the Global Polio Eradication Initiative was launched in 1988. The six countries with indigenous wild poliovirus are: Nigeria, India, Pakistan, Niger, Afghanistan and Egypt.