Emergencies preparedness, response

Meningococcal meningitis

A new strain of meningitis expanding in Africa: urgent action needed

A new strain of meningococcal meningitis serogroup C emerged in North-West Nigeria in 2013. Between 2013 and 2017, the strain has expanded to Niger and to Northern States of Nigeria causing more than 2500 deaths. Meningitis epidemics could affect 34 million people in the next two years and 10 million doses of vaccines would be needed in addition to the stock available in the international emergency stockpile in order to provide a sufficient response. Urgent action is needed to minimize the impact of such a devastating scenario.

Introductory-level online course on meningitis

This interactive online course on meningitis is part of a comprehensive pandemic and epidemic-prone disease course package, which offers the most relevant scientific, technical and operational knowledge on managing infectious hazards through video lectures, presentations and self-tests. The module on meningitis focuses on the bacteria Neisseria meningitidis, as it can cause large-scale epidemics, and takes an hour to complete.

A group of children holding up their treatment record.
WHO

Meningitis is an inflammation of the meninges, the membranes covering the brain and spinal cord. It can be caused by a variety of organisms that include bacteria, fungi or viruses. It is a serious condition that can be life threatening.

Meningococcal meningitis is an acute form of bacterial meningitis caused by Neisseria meningitidis. Meningococcal meningitis is of particular importance as it has the potential to cause large epidemics.

Several different bacteria can cause meningitis. Neisseria meningitidis is the one with the potential to cause large epidemics. There are 12 serogroups of N. meningitidis that have been identified, 6 of which (A, B, C, W, X and Y) can cause epidemics. Geographic distribution and epidemic potential differ according to serogroup.

The most common symptoms are a stiff neck, high fever, sensitivity to light, confusion, headaches and vomiting. Even when the disease is diagnosed early and adequate treatment is started, 5% to 10% of patients die, typically within 24 to 48 hours after the onset of symptoms. Bacterial meningitis may result in brain damage, hearing loss or a learning disability in 10% to 20% of survivors. A less common but even more severe (often fatal) form of meningococcal disease is meningococcal septicaemia, which is characterized by a haemorrhagic rash and rapid circulatory collapse.

The bacteria are transmitted from person-to-person through droplets of respiratory or throat secretions from carriers. Close and prolonged contact – such as kissing, sneezing or coughing on someone, or living in close quarters (such as a dormitory, sharing eating or drinking utensils) with an infected person facilitates the spread of the disease. The average incubation period is 4 days, but can range between 2 and 10 days.

Neisseria meningitidis only infects humans; there is no animal reservoir. The bacteria can be carried in the throat and sometimes, for reasons not fully understood, can overwhelm the body's defenses allowing infection to spread through the bloodstream to the brain. It is believed that 10% to 20% of the population carries Neisseria meningitidis in their throat at any given time. However, the carriage rate may be higher in epidemic situations.

Initial diagnosis of meningococcal meningitis can be made by clinical examination followed by a lumbar puncture showing a purulent spinal fluid. The bacteria can sometimes be seen in microscopic examinations of the spinal fluid. The diagnosis is supported or confirmed by growing the bacteria from specimens of spinal fluid or blood, by agglutination tests or by polymerase chain reaction (PCR). The identification of the serogroups and susceptibility testing to antibiotics are important to define control measures.

Rapid diagnosis is essential, not only for individual patient management, but also for management of epidemics, in particular in the African meningitis belt. At the beginning of meningitis outbreaks, confirmation of the responsible pathogen is essential to enable the launch of an appropriate response. The development and promotion of heat-stable rapid diagnostic tests which detect a range of common bacterial-causing pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis) has been recommended as a priority by a group of WHO-convened experts.

Surveillance, from case detection to investigation and laboratory confirmation is essential to the control of meningococcal meningitis. Main objectives include: detect and confirm outbreaks; monitor the incidence trends, including the distribution and evolution of meningococcal serogroups; estimate the disease burden; monitor the antibiotic resistance profile; monitor the circulation, distribution and evolution of specific meningococcal strains (clones) as well as estimate the impact of meningitis control strategies, particularly preventive vaccination programmes.

Meningococcal disease is potentially fatal and should always be viewed as a medical emergency. Admission to a hospital or health centre is necessary, although isolation of the patient is not necessary. Appropriate antibiotic treatment must be started as soon as possible, ideally after the lumbar puncture has been carried out if such a puncture can be performed immediately. If treatment is started prior to the lumbar puncture it may be difficult to grow the bacteria from the spinal fluid and confirm the diagnosis. However confirmation of the diagnosis should not delay treatment.

A range of antibiotics can treat the infection, including penicillin, ampicillin, chloramphenicol and ceftriaxone. Under epidemic conditions in Africa in areas with limited health infrastructure and resources, ceftriaxone is the drug of choice.

Vaccines and immunization

Licensed vaccines against meningococcal disease have been available for more than 40 years. Over time, there have been major improvements in strain coverage and vaccine availability, but to date no universal vaccine against meningococcal disease exists. Vaccines are serogroup specific and confer varying degrees of duration of protection. There are three types of meningococcal vaccines available:

Polysaccharide vaccines are used during a response to outbreaks, mainly in Africa:
• They are either bivalent (serogroups A and C), trivalent (A, C and W), or tetravalent (A, C, Y and W)
• They are not effective before 2 years of age
• They offer a 3 year protection but do not induce herd immunity.

Conjugate vaccines are used in prevention (into routine immunization schedules and preventive campaigns) and outbreak response:
• They confer longer-lasting immunity (5 years and more), prevent carriage and induce herd immunity.
• They can be used as soon as of one year of age
•Available vaccines include:
Monovalent C
Monovalent A
Tetravalent (serogroups A, C, Y, W)

Protein based vaccine, against N. meningitidis B. It has been introduced into the routine immunization schedule (one country as of 2017) and used in outbreak response.

Chemoprophylaxis

Antibiotic prophylaxis for close contacts, when given promptly, decreases the risk of transmission.

• Outside the African meningitis belt, chemoprophylaxis is recommended for close contacts within the household.
• In the African meningitis belt, chemoprophylaxis for close contacts is recommended in non-epidemic situations.

Ciprofloxacin antibiotic is the antibiotic of choice, and ceftriaxone an alternative.

Technical information

Useful references and resources