MENINGITIS VACCINATIONS: HOW IMPORTANT ARE THEY?

by Hospital Ceram
(Marbella)

The meningococcus or Neisseria meningitides is a gram-negative bacterium cause meningitis and other forms of meningococcal disease such as meningococcemia or sepsis.

The bacterium is referred to as a coccus because it is round, and more specifically, diplococcus because of its tendency to form pairs.

The meningococcus (Neisseria meningitides) is the one with the potential to cause large epidemics. There are 12 serogroups of N. meningitides 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 bacterial serogroups.

INCIDENCE & TRANSMISSION OF MENINGITIS

The bacteria are transmitted from person-to-person (is an exclusively human pathogen there is no animal reservoir) through droplets of respiratory or throat secretions from carriers. About 10% of adults are carriers of the bacteria in their nasopharynx. Close and prolonged contact such as kissing, sneezing or coughing on someone, or living in close quarters (dormitory, sharing eating or drinking utensils) with an infected person (a carrier) facilitates the spread of the disease. The average incubation period is 4 days, but can range between 2 and 10 days.

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 meningitides in their throat at any given time. However, the carriage rate may be higher in epidemic situations.

MENINGITIS SYMPTOMS

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 hemorrhagic rash and rapid circulatory collapse.

DIAGNOSIS OF MENINGITIS: WHAT YOU NEED TO KNOW

Initial diagnosis can be made by clinical examination followed by a lumbar puncture showing a purulent spinal fluid and the bacteria can sometimes be seen in microscopic examinations of the spinal fluid.

The diagnosis is supported or confirmed by:

• Blood or spinal cultures who shows the bacterial growing
• Agglutination tests
• PCR

The identification of the serogroups and susceptibility testing to antibiotics are important to define control measures.

TREATMENT OF MENINGITIS

Suspicion of meningitis is a medical emergency and immediate medical assessment is recommended. Current guidance in the United Kingdom is that if a case of meningococcal meningitis or septicaemia (infection of the blood) is suspected intravenous antibiotics should be given and the ill person admitted to the hospital. This means that laboratory tests may be less likely to confirm the presence of Neisseria meningitides as the antibiotics will dramatically lower the number of bacteria in the body. The UK guidance is based on the idea that the reduced ability to identify the bacteria is outweighed by reduced chance of death.

Appropriate antibiotic treatment must be started as soon as possible, ideally after the lumbar puncture has been carried. 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.

A range of antibiotics can treat the infection, including penicillin, ampicillin, chloramphenicol and ceftriaxone.

PREVENTION OF MENINGITIS

The most important form of prevention is a vaccine against N. meningitides. Different countries have different strains of the bacteria and therefore use different vaccines.

Five serogroups, A, B, C, Y and W135 are responsible for virtually all cases of the disease in humans. Vaccines are currently available against all five strains, including the newest vaccine against serogroups B. The first vaccine to prevent meningococcal serogroups B (meningitis B) disease was approved by the European Commission on 22 January 2013. The vaccine is manufactured by Novartis and sold under the trade name Bexsero. Bexsero is for use in all age groups from two months of age and older.

Serotype distribution varies markedly around the world. Among the 13 identified capsular types of N. meningitides, six (A, B, C, W135, X, and Y) account for most disease cases worldwide. Type A has been the most prevalent in Africa and Asia, but is rare/ practically absent in North America. In the United States, serogroups B is the predominant cause of disease and mortality, followed by serogroups C. The multiple subtypes have hindered development of a universal vaccine for meningococcal disease.

MENINGITIS VACCINES

Meningococcal vaccines are available in either bivalent (groups A and C), trivalent (groups A, C and W), or tetravalent (groups A, C, Y and W).

• Meningococcal vaccines for group B
• Meningococcal vaccines against group C. Tetravalent A, C, Y and W conjugate
• Meningococcal vaccines for group A

Written by Dr.Luzdivina Garcia Morales.

For more information Marbella Family Medical advice on vaccinations, contact Ceram Hospital.