Meningococcal Disease Medical Briefing

Meningitis is an infection of the ‘meninges’, the membrane that surrounds the brain and spinal cord. The infection can be caused by bacteria, viruses or occasionally fungal infections, and can affect anyone, but it is most common in babies, young children and young adults.

Meningococcal meningitis is the most serious bacterial form of meningitis. It is caused by the Neisseria meningitidis bacterium and typically presents with sudden onset of high fever, stiff neck, headache and sensitivity to light. Rapid diagnosis and treatment are essential since it can cause severe brain damage, proving to be fatal in up to 50% of cases if left untreated.

Treatment is with antibiotics given as soon as the meningitis is suspected, but the majority of infections can be prevented by routine vaccination in childhood.

Meningitis can occur all over the world, but studies indicate that epidemic meningitis has been present in Africa for about 100 years. The disease is most prevalent in the sub-Saharan meningitis belt, an area that stretches from Senegal and the Gambia in the west to Ethiopia in the east (26 countries) and has an at-risk population of about 430 million.

Meningococcal Belt

During the dry season between December to June, dust winds, cold nights and upper respiratory tract infections combine to damage the nasopharyngeal mucosa, increasing the risk of meningococcal disease. At the same time, transmission of Neisseria meningitides may be facilitated by overcrowded housing and by large population displacements at the regional level due to pilgrimages and traditional markets. This combination of factors explains the large epidemics that occur during the dry season in the meningitis belt.

There are 12 different types or ‘serogroups’ of N. meningitidis. Six of these – A, B, C, W, X and Y – can cause epidemics [defined as “the widespread occurrence of an infectious disease in a community at a particular time”]. Meningitis B, C, and Y cause the majority of disease in the developed world, while meningitis A is responsible for most of the infections in developing countries.

As a result of coordinated action, rates of the disease in the world have fallen dramatically since the 1990s when widespread childhood vaccination was introduced. During the 2014 epidemic season, 19 African countries implementing enhanced surveillance reported 11,908 suspected cases including 1,146 deaths, the lowest numbers since the implementation of enhanced surveillance through a functional network (2004).

Transmission

N. meningitidis is carried in the throat and nasal passages of between 10 to 20% of the population, and can suddenly overwhelm the body’s defences to spread to the bloodstream and then the brain.

The bacteria are transmitted from person-to-person through droplets of respiratory or throat secretions from carriers. Close or prolonged contact – such as kissing, sneezing or coughing on someone, living in close quarters, or sharing eating and drinking utensils with a carrier – facilitates the spread of the disease.

It should be noted that these bacteria are not as contagious as viruses that cause the common cold or the flu.  This particular bacterium only infects humans and cannot be carried by animals.

Risk Factors

Certain people are at increased risk for meningococcal disease. These risk factors include:

  • Age – meningococcal disease is more common among infants, adolescents and young adults. The highest incidence is in children younger than 1 year, followed by a second peak in adolescence, and then in 16 to 23 year olds
  • Communities – outbreaks are more common in group settings such as college campuses, schools and nurseries
  • Impaired immune system – people with diseases such as HIV/AIDS, or having chemotherapy, are more susceptible to infection
  • Travel – tourists or expatriates in regions such as the meningitis belt in sub-Saharan Africa are at much higher risk of meningococcal disease.

 Symptoms

Symptoms can develop within hours and escalate rapidly – they typically start 4 days after exposure, but this can range from anywhere between 2 to 10 days. The most common symptoms in children and adults are as follows:

  • Sudden onset of high fever
  • Stiff neck
  • Sensitivity to light
  • Headache
  • Confusion
  • Vomiting
  • Fitting, drowsiness and coma.

In newborns and infants, the classic symptoms of fever, headache, and neck stiffness may be absent or difficult to notice, but symptoms may include:

  • Fever while the hands and feet are cold
  • High pitched moaning or whimpering
  • Blank staring, inactivity, difficulty in waking up
  • Poor feeding
  • Neck retraction with arching of the back
  • Pale and blotchy complexion.

Septicaemia develops if the bacteria enter the bloodstream. A characteristic rash develops that may start as a cluster of pinprick blood spots under the skin, spreading to form bruises under the skin. The rash can appear anywhere on the body. It can be distinguished from other rashes by the fact that it does not fade when pressed under the bottom of a glass.

Diagnosis

Early diagnosis and treatment are major prognostic indicators for recovery.

Initial diagnosis of meningococcal meningitis should be simply made when a high degree of clinical suspicion is present. Samples of blood or cerebrospinal fluid (fluid near the spinal cord obtained by lumbar puncture) are then collected and sent to the laboratory for rapid testing.

The diagnosis is supported or confirmed by isolating the bacteria from specimens of spinal fluid or blood. Other tests performed at specialist labs can detect the DNA of the causative organism by using a PCR assay on samples of body fluids. The identification of the serogroups and susceptibility testing to antibiotics, are also important as they define control measures and the choice of the most appropriate antibiotics.

Treatment

Meningococcal meningitis is potentially fatal and should always be viewed as a medical emergency. All suspected cases should be admitted to hospital, although isolation of the patient is not usually necessary. Antibiotic treatment must be started as soon as possible, but 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 is more difficult to grow the bacteria from the spinal fluid in order to confirm the diagnosis.

A range of antibiotics are commonly used to treat the infection, including:

  • penicillin
  • ampicillin
  • chloramphenicol
  • cefrtriaxone.

During epidemics in Africa, where health infrastructure and resources can be limited, ceftriaxone is the drug of choice.

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, loss of limbs or a learning disability, in 10 – 20% of survivors.

Sometimes N. meningitidis bacteria spread to other people who have had close or lengthy contact with a patient with confirmed meningococcal disease. People in the same household, roommates, or anyone with direct contact with a patient’s oral secretions, such as an intimate partner, would be considered at increased risk of getting the infection. These people who qualify as close contacts of a person with meningococcal disease should receive ‘prophylactic’ (preventative) antibiotics to prevent them from becoming infected.

Prevention

The mainstay of prevention is through widespread childhood vaccination.

There are three types of vaccine available to control the disease worldwide:

  1. Meningococcal polysaccharide vaccines can be used for: groups A and C; for groups A, C and W; or for groups A, C, Y and W.
  2. Serogroup B meningococcal (Men B) vaccines that were only released in 2014are being rolled out across developed countries to help prevent meningococcal disease caused by serogroup B.
  3. Tetravalent conjugate vaccines against A, C, Y and W have been licensed since 2005 for use in children and adults in Canada, the US and Europe.

There is currently no single meningococcal vaccine that can help protect against all common serogroups that cause most meningococcal disease.

Like with any vaccine, meningococcal vaccines are not 100% effective. This means that even if you have been vaccinated, there is still a chance you can develop a meningococcal infection.

WHO promotes a strategy comprising: epidemic preparedness, prevention and response.

  1. Preparedness focuses on surveillance, from case detection to investigation and laboratory confirmation.
  2. Prevention consists of an integrated program to vaccinate all 1 to 29 year-olds in the African meningitis belt with the Men A conjugate vaccine. A new meningococcal A conjugate vaccine was introduced to the region in 2010. It has many advantages over the equivalent polysaccharide vaccines: it is cheaper; it does not need refrigeration; it is more effective in very young children; and it confers a more effective immune response against group A meningococcus.
  3. WHO regularly provides technical support at the field level to countries facing epidemics. Epidemic response consists of prompt and appropriate case management with reactive mass vaccination of populations not already protected through vaccination.

As of June 2015, over 220 million persons aged 1 to 29 years have received meningococcal A conjugate vaccine in 15 countries of the African belt. Following this successful rollout, epidemics due to meningitis A are disappearing. However, other meningococcal serogroups such as W, X and C still cause epidemics, albeit of smaller size and at a lower frequency.

Outbreak Management

Outbreaks usually occur in places such as schools, colleges or nurseries. An outbreak occurs when there are multiple cases of the same serogroup in an institution or community over a short period of time. This may be up to hundreds of cases or as few as two or three in a confined group.

The local health authority should take over responsibility for the outbreak in order to control the spread of disease. The following measures should be considered:

  • Vaccination program for those at risk – all those over 2 months old
  • If a Meningitis B outbreak, then vaccines are recommended for those identified at risk who are 10 years or older.
  • Prophylactic antibiotics for all close contacts of the index cases. This includes people in the same household, or anyone with direct intimate contact with the index case.

 

Key Facts

  • Meningococcal meningitis is a bacterial form of meningitis, a potentially fatal infection of the lining that surrounds the brain and spinal cord
  • The extended meningitis belt of sub-Saharan Africa, stretching from Senegal in the west to Ethiopia in the east, has the highest rates of the disease
  • Infection is most common in babies, adolescents and 16-23 year olds
  • Spread is through close or prolonged contact with secretions from a carrier – 10-20% of the population are asymptomatic carriers of the bacteria in their nasal passages
  • Symptoms range from high temperature, neck stiffness, headache, drowsiness, light sensitivity, confusion and vomiting
  • Diagnosis is by blood or cerebrospinal fluid analysis and treatment should be initiated as soon as possible with appropriate antibiotics
  • Effective vaccines are essential in preventing most infections.

Written by Dr. Adrian Hyzler