The World Health Organisation (WHO) is launching an immunisation drive for more than half a million people in response to four confirmed new cases of yellow fever, one of them fatal, in southern Burkina Faso near the border with Cote d'Ivoire.
"It's important to carry out a vaccination campaign quickly so that the disease does not spread to other areas," WHO's yellow fever expert Sylvie Briand told IRIN from Geneva.
It is expected that 650,000 people will be immunised in the days ahead in Burkina Faso's regions of Batie, Gaoua and Banfora. The WHO will also undertake a drive in neighbouring Cote d'Ivoire as the lone fatality, a four year-old boy, had come from that country's Bouna region close to Burkina Faso.
Yellow fever is a virus generally transmitted to humans by mosquitoes. Its effects can range from mild flu-like symptoms to haemorrhagic fever and death. There is no treatment for the disease once contracted and the fatality rate in unprotected populations can exceed 50 per cent.
Briand said the risk of contagion was high because of the affected region's low vaccination rate despite recent immunisation campaigns. While 60 per cent of Burkina Faso's children were vaccinated between 2000 and 2004, that figure can drop to 20-30 per cent in rural areas. A rate of 80 per cent is needed for a population to be considered effectively covered.
The high number of people transiting through this border area compounds the danger. In order to avoid the spread of the disease into densely populated urban centres, both residents and travellers will be targeted by the vaccination campaign.
According to the WHO, urban epidemics are a growing concern because rural migration can lead to a lethal mix of low immunisation rates and high population densities.
Burkina Faso's most recent urban outbreak occurred last year in Bobo-Dioulasso, the country's second biggest city, but was quickly brought under control. In 2001, seven people died following an outbreak in Cote d'Ivoire's commercial capital Abidjan.
This article was produced by IRIN News while it was part of the United Nations Office for the Coordination of Humanitarian Affairs. Please send queries on copyright or liability to the UN. For more information: https://shop.un.org/rights-permissions