15 May 2015
From 1 January to 12 May 2015, Niger’s Ministry of Public Health notified WHO of 6179 suspected cases of meningococcal meningitis, including 423 deaths. This is a rapidly growing outbreak with some unprecedented features.
Suspected cases have been increasing very quickly, tripling over the last two weeks (see previous notification from 29 April 2015). This is the first large-scale and fast spreading meningitis outbreak caused by Neisseria meningitides serogroup C to hit any country in Africa’s meningitis belt.
Eleven districts from the regions of Niger, which includes the capital city, have crossed the epidemic threshold. This includes all five districts in Niamey, where 4099 suspected cases, including 226 deaths, have been reported. The outbreak is of high concern because it affects a densely populated urban area of more than one million people, creating a high risk of rapid spread and a large caseload.
Laboratory tests have confirmed the predominance of Neisseria meningitidis (Nm) serogroup C in the affected areas, with Nm serogroup W also being identified in several patient samples. Although serogroup C has been the predominant cause of meningitis in wealthy countries, it has never been of high concern in Africa.
Over the past 40 years, serogroup C has caused only sporadic cases and a few localized outbreaks in Africa, generally of mixed serogroup A and C origin. In West Africa, these outbreaks occurred in Nigeria in 1975, in Niger in 1991, and in Nigeria in 2013–2014.
Viewed against this historical pattern, the outbreak in Niger is an alarming development. Since this is the first large outbreak of meningitis in Africa caused by serogroup C, vaccines against this form of the disease are in short supply.
Public health response: case fatality drops despite vaccine shortage
A national epidemic committee has been activated to manage the outbreak. An international team, composed of staff from WHO and the U.S. Centers for Disease Control and Prevention (CDC) was deployed to support the Ministry of Public Health’s investigation of the outbreak and reinforce the country’s surveillance capacity.
WHO and partners are providing support to the government of Niger for the implementation of mass vaccination campaigns and other emergency control measures. Instrumental in this effort is the International Coordinating Group on Vaccine Provision for Epidemic Meningitis Control (ICG). ICG is a partnership uniting WHO, UNICEF, the International Federation of Red Cross and Red Crescent Societies, and Médecins Sans Frontières (MSF) and works closely with vaccine manufacturers. It was established in 1997 following exceptionally large and deadly meningitis outbreaks in Africa.
To date, ICG has approved four vaccination requests. Vaccines released include 460 000 doses of the older polysaccharide vaccine, which protects against the A, C and W serogroups, and 200 000 doses of the newer conjugate vaccine, which protects against serogroups A, C, W, and Y.
The conjugate vaccine, which is produced in small quantities for use in the U.S. and European markets at prices that are not affordable in Africa were able to be obtained thanks to intervention by ICG and financial support from the GAVI Alliance. In addition, Niger’s government has obtained 200 000 doses of polysaccharide ACWY vaccine from the government of Mali.
In response to this emergency situation, WHO, on behalf of ICG, has negotiated with public sector vaccine manufacturers and the pharmaceutical industry to start the urgent production of multivalent polysaccharide vaccines. An additional 640 000 doses will be despatched to Niger in the coming weeks.
Vaccine campaigns targeting children aged 2 to 15 years are ongoing in eight of the 11 epidemic districts, including Niamey. MSF is supporting the Ministry of Public Health with teams of doctors and case management facilities; 18 500 vials of ceftriaxone, a highly effective antibiotic has been made available with ICG support. Thanks to these interventions, case fatality from meningitis has dropped in the past few weeks from 11% to 6.8%. WHO and partners are supporting the Ministry of Health in the outbreaks surveillance, population sensitization and preventive measures.
Meningitis vaccines: a problematic supply
Outbreaks of meningitis pose an enormous burden to the populations of African countries. The area known as the classic African meningitis belt, which stretches across the continent from Senegal to Ethiopia, affecting 21 countries is hyperendemic for this disease. Cases frequently recur, with periodic outbreaks during the dry season, which runs from December to June.
Large-scale outbreaks in 1996–1997 caused more than 200 000 cases, including 20 000 deaths. The most recent large outbreak occurred in 2009, causing more than 80 000 cases, mainly in Nigeria and Niger. The vast majority of these outbreaks were caused by serogroup A.
Since 2010 a new conjugate vaccine, MenAfriVac, which protects against serogroup A and costs less than US$ 1 per dose has been progressively introduced in preventive mass campaigns in countries of the African belt. The new vaccine was developed especially for Africa by the Meningitis Vaccine Project, coordinated by WHO and PATH.
Since introduction of the new vaccine, the number of meningitis A cases in Africa has decreased dramatically, with no outbreaks caused by this serogroup occurring in vaccinated areas (see WER 27 March 2015).
The meningitis A conjugate vaccine is the only vaccine currently available and affordable that can be used to prevent meningitis outbreaks in Africa, as it confers long-lasting immunity. All other vaccines used in Africa for other serogroups are the older polysaccharide vaccines, which confer immunity lasting only 3 to 5 years. These vaccines are now used only in the emergency response to outbreaks, and are not suitable for the preferred objective of prevention.
Following introduction of the meningitis A conjugate vaccine, the market for polysaccharide vaccines shrank considerably and is now largely limited to international travellers. The ICG, which manages an emergency vaccine stockpile, has been instrumental in maintaining an adequate supply of these older polysaccharide vaccines for use in emergencies.
To prepare for the 2015 epidemic season, WHO and its partners in ICG have sent a request to vaccine manufacturers for 1.5 million doses of multivalent polysaccharide vaccines and 1.5 million doses of the new meningitis A conjugate vaccine.
Due to production problems with one manufacturer, this request could not be fully met. To fill the gap in the stockpile supply, WHO asked two public sector manufacturers, the Instituto Finlay in Cuba and Bio-Manguinhos in Brazil, to supply 600 000 doses of polysaccharide vaccines. They generously agreed to do so.
This vaccine shortage highlights the importance of accelerating the development of a multivalent conjugate vaccine that is affordable for the people and governments of Africa. For now, WHO continues to work with ICG and other partners to ensure that the stockpile of polysaccharide vaccines is maintained at a level that is sufficiently able to manage future outbreaks in Africa’s meningitis belt.