Meningococcal meningitis

Meningococcal meningitis remains a major global public health challenge with high case fatality rate and leading to serious long-term complications. It occurs in small clusters throughout the world with seasonal variations. It accounts for a variable proportion of epidemic bacterial meningitis. Meningitis is an infection that affects the meninges—the membranes covering the brain and spinal cord.

The largest burden of meningococcal disease occurs in an area of sub-Saharan Africa known as the “meningitis belt”, which stretches from Senegal in the west to Ethiopia in the east.

Although meningitis outbreaks are decreasing in size and frequency with the increase in vaccinations, they still pose a significant risk. Fatality rate is 10— 15 per cent and up to 40 per cent in meningococcal meningitis with septicaemia. Without any treatment the fatality rate is close to 100 per cent. The most effective way to deliver long-lasting protection is vaccination.

The following are standard case definitions to allow national health authorities to interpret data in an international context. However, during an outbreak case definitions may be adapted to the local context and the Red Cross Red Crescent should use those agreed/established by national health authorities. NB: Consider that during community surveillance, volunteers should use broad (simplified) case definitions to recognize most or all possible cases and encourage them to seek care. Other actors such as healthcare workers or investigators studying the cause of a disease, on the other hand, can use more specific case definitions that may require laboratory confirmation.

Suspected case of acute meningitis:  sudden onset of fever (over 38.5 °C rectal or 38.0 °C axillary) and stiff neck, altered consciousness or other meningeal signs.

Probable case of meningococcal meningitis: suspect case WITH microscopic confirmation of N. meningitidis (in cerebrospinal fluid (CSF) or blood) OR with a CSF leukocyte count greater than 10 cells/mm3; or with bacteria identified by Gram stain in CSF; or antigen detected by immunochromatographic dipstick or latex agglutination.

Confirmed case: suspected or probable case as defined above that is laboratory confirmed.

WHO case definition source of information: https://www.who.int/immunization/monitoring_surveillance/burden/vpd/WHO_SurveillanceVaccinePreventable_12_Meningococcus_BW_R1.pdf?ua=1

Endemic areas: For areas of population between 30,000 and 100,000: an alert threshold of three cases per 100,000 inhabitants per week; and an epidemic threshold of 10 per 100,000 in one week.

For small populations: alert threshold is either two cases in one week or a higher incidence than in a non-epidemic year; and an epidemic threshold of five cases in one week or a doubling of incidence in a three-week period.

Special situations (mass gatherings, displaced persons camp settings, or closed institutions such as schools or barracks): one case of meningococcal disease is confirmed in one week.

Non-endemic areas: Increased incidence of clustered meningitis cases and causal N. meningitidis pathogen (N. meningitidis A, C, Y, W135) has been confirmed.

• Living in an area of sub-Saharan Africa known as the “meningitis belt”: During the dry season dust winds, cold nights and an increase in upper respiratory tract infections damage the nasopharyngeal mucosa, increasing the risk of meningococcal disease.
• Transmission may be facilitated by overcrowded housing and by large population displacements, e.g. pilgrimages, mass gatherings, refugee camps, student, military and other occupational settings and traditional markets.
• Inadequate sanitation and hygiene measures (including hand hygiene and coughing etiquette).
• Infants, adolescents and young adults are most at risk because the nasopharyngeal carriage of meningococci is higher in this age and  close gatherings are generally more common.

• Endemic disease occurs primarily in children and adolescents, with highest attack rate in infants aged 3—12 months, whereas in epidemics older children and young adults may be more involved.
• In the “meningitis belt”, major epidemics occur every 5 to 12 years with attack rates reaching 1,000 cases per 100,000 population. Other regions of the world experience lower overall rates of disease and occasional outbreaks. Annual attack rates in these regions average around 0.3 to 3 per 100,000 population.

• Infants and the elderly.
• Immunosuppressed persons such as those receiving chemotherapy,  transplant recipients or HIV carriers.
• People with chronic diseases such as renal disease, cancer, chronic lung or liver disease and diabetes.

There are different types of bacteria causing meningitis, including: Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis. Neisseria meningitidis (Nm) is the bacteria that causes meningococcal meningitis, which has the highest potential to produce large epidemics. 

Humans.

Droplet and airborne spread: Droplets of saliva/mucous and respiratory secretions from one person to another, mainly by kissing, coughing or sneezing or by sharing eating and drinking utensils.

People carrying N. meningitidis in their throat can sometimes have overwhelmed body defences, leading the infection to spread through the bloodstream to the brain.

Three to four days (range two to ten days).

It is believed that 10—20 per cent of the population carries N. meningitidis in their throat at any given time and can infect other people. Nasopharyngeal carriage of meningococci is most common among adolescents and young adults, less so among young children and relatively rare in the adult population. However, the carriage rate may be higher in epidemic situations.

• High fever, neck stiffness, sensitivity to light, confusion, headaches, rash, joint pains, cold hands and feet and vomiting.
• Common signs and symptoms for infants include a fever, difficulty breathing, neck rigidity, bulging soft spot on top of the head, excessive sleepiness, poor feeding, irritability, rash, convulsions, pale skin, vomiting.

Meningitis due to other causes (viral, bacterial, mycotic).

• Initial diagnosis of meningococcal meningitis can be made by clinical examination followed by performing a lumbar puncture showing a purulent cerebral spinal fluid.
• The bacteria may sometimes be seen in a microscopic examination and gram staining of the spinal fluid.
• The diagnosis is 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.

Please refer to the appropriate local or international guidelines for clinical management. All clinical management including the administration of a treatment or vaccine should be conducted by a health professional.

• Meningococcal disease is potentially fatal and should always be viewed as a medical emergency.
• Admission to a hospital or health centre is necessary without high-grade isolation of the patient (face mask for those coming close to the patient and private room, if possible, is enough).
• Appropriate antibiotic treatment must be started as soon as possible.
• Different vaccines for prevention and outbreak control are available for serotypes A,C,W,Y and B. Protection is usually group-specific and the chosen vaccine depends on the presented serotypes in the region, the age and the aim of the vaccine. Some vaccines also prevent carriage of N. menigitidis, thereby reducing transmission and leading to herd protection.

• A previous infection will not offer lifelong protection from future infections.
• Vaccine efficacy is estimated between 63 per cent and 97 per cent, but this decreases in many adolescents within five years.