New global consortium to fight meningitis in Africa
20 July 2009
The initiative has been made possible by donations of £2.25 million from the Wellcome Trust and £5 million from the Bill and Melinda Gates Foundation.
The African Meningococcal Carriage Consortium (MenAfriCar) will be the largest, most concerted effort to date to understand how meningococcal meningitis is spread in Africa.The Consortium will combine the expertise of leading scientists from eight centres in developed countries and nine African partners, working closely with the Meningitis Vaccine Project (MVP).
Meningococcal disease is a major problem in the countries of the African Sahel and sub-Sahel - the African meningitis belt - where major epidemics occur every few years.These epidemics are not only distressing for those affected, but they necessitate the setting up of emergency treatment centres, which can cause immense disruption to health services that are already under-resourced and overstretched.
The last major epidemic, in 1996, caused at least 200 000 cases and many thousands of deaths. Most cases are seen in older children and young adults, with mortality rates during epidemics usually in the range of 5-10 per cent.Many more people carry the infection in their throat than go on to develop serious disease - the ratio is usually in the range of one case to several hundred carriers, although this can increase during epidemics.Infection is spread from person to person through respiratory droplets, for example by sneezing.
In recent years, the impact of these epidemics has been mitigated to some extent by reactive vaccination with polysaccharide vaccines, but the widespread use of these has not reduced the frequency of epidemics. This is likely to be because these vaccines provide only short-term protection in young children, and do not prevent transmission of the infection.
It is known that conjugate vaccines, prepared by linking the capsular polysaccharide antigen of the bacterium to a protein, are much more effective, but these are expensive and have not been widely used in developing countries until now. This deficit is being remedied by the MVP, which is developing an affordable serogroup A meningococcal conjugate vaccine for use in Africa.The vaccine, which is being produced by Serum Institute of India Ltd, is now in clinical trials in Africa and India.If approved for licensure, it is set to be introduced in Burkina Faso towards the end of this year, before being rolled out more widely across the African meningitis belt in subsequent years.
MenAfriCar will seek to evaluate the impact of this new vaccine on the transmission of meningococcal infection in countries of the African meningitis belt.
Cross-sectional surveys will be undertaken in 2000 subjects in eight target countries across the meningitis belt, once during the dry season and once during the rainy season, and detailed studies of carriage will be undertaken in households where a carrier is found. These studies will determine patterns of transmission of the infection within households, risk factors for carriage and how long carriage persists, information of importance to the planning of vaccination strategies.In addition, pre- and post-vaccination surveys will be undertaken in three countries, Ethiopia, Mali and Niger, to determine the impact of vaccination on carriage.Meningococci isolated during these studies will be subjected to detailed molecular analysis to determine their relationship to each other and to meningococci found in other parts of the world.
Professor Brian Greenwood of the London School of Hygiene and Tropical Medicine, who is leading the Consortium, says: "Vaccination campaigns with conjugate vaccines have been very successful in reducing the impact of meningitis in developed countries.In the UK, for example, a campaign to vaccinate againstserogroup C meningococcal meningitis has had a dramatic impact on the incidence of the disease and it is highly likely that the ability of the vaccineto prevent pharyngeal carriage, and thus to interrupt transmission, played a role in its success.
"African countries, however, have yet to benefit from the advances that have been made in reducing the impact of this disease. The development of an effective serogroup A meningococcal conjugate vaccine, and the launch of support that this new Consortium will be able to give to the vaccination programme, looks set to change this, and offers these countries real hope of a future in which meningitis is no longer the scourge it is today."
Image: Schoolboys queue for meningitis vaccination in West Africa. Credit: teseum on Flickr