Africa faces new meningitis threat. (Emerging Infections).

A previously rare, vaccine-resistant strain of a deadly bacterium caused an epidemic of meningitis last year in western Africa and seems to have spread around the world, researchers report.

Three years ago, people from more than a dozen countries in Africa, Asia, Europe, and North America became infected with the W-135 strain of Neisseria meningitidis after Muslim pilgrims unknowingly carried it home from the annual Hajj in Mecca, Saudi Arabia.

Seasonal outbreaks of other strains of N. meningitidis often strike Africa's so-called meningitis belt, which stretches from Senegal to Ethiopia. Anticipating that W-135 might cause an outbreak, Joshua Jones of the CDC in Atlanta and his colleagues closely monitored three meningitisbelt nations for 6 months last year. Sure enough, they detected an outbreak of the rare strain as it moved through Burkina Faso.

A relatively inexpensive vaccine can stop outbreaks of the two most common strains of N. meningitidis. The emerging strain, which can be blocked only by a much pricier vaccine, could hamper meningitis-control efforts in Africa, says Jones. Public health officials are now working with vaccine manufacturers to develop a cheaper vaccine that's effective against W-135.--B.H.