On October 5, the World Meningitis Day. The WHO has drawn up an ambitious roadmap to defeat meningitis by 2030. This disease constitutes a major public health problem that affects no less than 2.5 million people around the world each year.
The disease consists of inflammation of the meninges, which are the tissues that surround the brain and spinal cord. It can be caused by non-infectious processes (autoimmune disorders, cancer, drug reactions) or infectious processes (bacteria, viruses, fungi and, less frequently, parasites). And it affects all ages.
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most of Infections that cause meningitis can be transmitted from person to person. This is why mass gatherings, crowds and overcrowded environments, such as refugee camps, are places of risk.
Although the viral meningitis They are relatively common, the really dangerous ones are those of bacterial origin, which can cause death in just 24 hours. About one in ten people who contract bacterial meningitis die.
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The four main causes of acute bacterial meningitis are due to Neisseria meningitidis (meningococcus), Streptococcus pneumoniae (neumococcus), Haemophilus influenzae and Streptococcus agalactiae (group B streptococcus). Other bacteria such as Streptococcus suisin Southeast Asia, Listeria monocytogenes, Streptococcus pyogenes, Klebsiella pneumoniae, Mycobacterium tuberculosis (meningeal tuberculosis), and even the popular Escherichia coli, can cause meningitis in specific groups, including newborns, pregnant women, transplant recipients, and older adults. Some viruses such as enteroviruses and the paramyxovirus that causes mumps, various fungi, especially Cryptococcusand parasites such as amoebas are also important causes of meningitis.
Most bacteria that cause meningitis are carried in the nose and throat, and are spread from person to person through respiratory droplets or throat secretions.
It is estimated that each year they are produced all over the world more than 1.2 million cases of bacterial meningitis and that, without treatment, the fatality rate can reach up to 70%. To make matters worse, one in five survivors may suffer permanent complications such as hearing loss, neurological disability or loss of a limb.
In meningitis, the first symptoms can be nonspecific and confused with those of the flu, such as fever and general malaise. However, signs soon appear that should put us on alert: high fever, severe headache, photophobia, vomiting, altered consciousness and stiffness in the neck muscles.
Symptoms can appear suddenly and worsen quickly, leading to seizures, coma, and death.
The gold standard for diagnosing meningitis is examination of cerebrospinal fluid – the fluid that circulates through the hollow spaces of the brain and spinal cord – and lumbar puncture.
Moving towards “a world without meningitis”, as the WHO has proposed, involves achieving three main objectives. On the one hand, eliminate epidemics of bacterial meningitis. Secondly, reduce the number of cases of preventable bacterial meningitis by 50%, and deaths by 70%, through vaccination. Finally, efforts will have to be made to reduce disability and improve quality of life after meningitis.
Currently, most of the meningitis caused by bacteria in childhoodl can be prevented by vaccination. Available vaccines include the meningococcal conjugate vaccine (MenACWY) (e.g. MenQuadfi®, Menveo® and Nimenrix®) – which protects against serogroups A, C, W and Y of the bacteria. Neisseria meningitidis–, the meningococcal conjugate vaccine (MenB) (for example, Bexsero® and Trumenba®) – which protects against serogroup B of the same bacteria–, the meningococcal conjugate vaccine (MenC) (for example, Menjugate®, Meningitec® and NeisVac -C®) –which protects against serogroup C of Neisseria meningitidis–, the vaccine against Haemophilus Influenzae type B (HiB) (for example, hexavalent vaccines Hexavac® and Infanrix Hexa®) or pneumococcus vaccine Streptococcus pneumoniae (for example, Pneumovax 23®, Synflorix® and Prevenar 13®). The MMR vaccine (for example, Priorix®), included in the childhood vaccination schedule, protects against measles, rubella and mumps, which can cause some types of viral meningitis. In the last 30 years, more than 500 million doses of the MMR vaccine have been administered in more than 90 countries.
In Europe, serogroups B and C of the bacteria predominate Neisseria meningitidis, but cases have decreased greatly since vaccination was included in the children’s calendar. Two vaccines against serogroup B of the bacteria have been available in Europe for several years. Neisseria meningitidisBexsero, since 2013, and Trumenba, since 2017, which can be purchased with a prescription in pharmacies.
Bacterial meningitis is present worldwide, but the greatest burden of disease is seen in a region of sub-Saharan Africa known as the African Meningitis Belt. In this area, meningococcus serogroup A accounted for 80% to 85% of meningitis epidemics before the introduction of a conjugate vaccine against meningococcus A in mass preventive campaigns (since 2010) and in routine vaccination programs (since 2016).
It is evident that, to contain the disease and to avoid new epidemics that may emerge anywhere, it is essential to maintain high vaccination coverage.
*Raúl Rivas González is a professor of Microbiology. Member of the Spanish Society of Microbiology, University of Salamanca