Causes of Meningitis
Meningitis is caused by two main types of pathogens.
• Bacteria: Examples include meningococcal bacteria, haemophilus influenzae bacteria and pneumococcal bacteria. Bacterial meningitis is a particularly serious disease that requires timely treatment.
• Viruses: Examples include enterovirus and herpes simplex virus.
• Both viral and bacterial meningitis can be transmitted through direct exposure to droplets or oral/nasal secretions from carriers. Healthy persons, who have no signs of illness, can carry these bacteria in their nose or throat. 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 (a carrier), facilitates the spread of the disease.
Symptoms of Meningitis
There are no distinctive symptoms in the first 4-6 hours, but conditions deteriorate quickly and the symptoms can be severe, which begin suddenly with fever, headache and stiff neck accompanied by other symptoms such as decreased appetite, nausea, vomiting, sensitivity to light, confusion and sleepiness. The disease, which can result in brain damage, is fatal in serious cases.
For children, the symptoms include high fever, fits, sleepiness, dull expressions and occasionally vomiting, headache or even stiffness in the neck. Without proper treatment or rest, meningitis can lead to complications such as hydrocephalus, deafness, epilepsy, paralysis of hands/legs and mental retardation. Therefore, when a child is found to have high fever or fever with fits, the conditions should be explained in detail to the doctor to aid diagnosis.
Diagnosis of Meningitis
Initial diagnosis can be made by clinical examination followed by a lumbar puncture at the back of the patient to extract spinal fluid for testing. The bacteria can sometimes be seen in microscopic examination of the spinal fluid. The diagnosis can be 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.
Treatment of Meningitis
Meningococcal meningitis is a serious, potentially fatal infectious disease which should be viewed as a medical emergency, although isolation of the patient is not necessary. Patients should be treated immediately with suitable antibiotics. Close contacts need to be placed under surveillance and may be given preventive medications.
Prevention of Meningitis
- The following vaccines are available:
1. Meningococcal Bacteria
Presently there are two preparations on the market - the bivalent and the quadrivalent. The bivalent vaccine is intended for the prevention of meningitis caused by meningococci serogroups A and C. The quadrivalent vaccine can afford additional protection against meningococci serogroups W135 and Y. The vaccination, suitable from the age of 18 months only, comprises a single injection. It gives 3 years of post-vaccine immunity. In children it only gives 2 years of immunity. The vaccine confers protection after 7 to 14 days.
Besides, vaccination is recommended for:
- Travellers to Mecca in Saudi Arabia during the Hajj pilgrimage (quadrivalent vaccine). In 2002, the Saudi Arabian government requires all pilgrims on entry to produce a certificate of vaccination against the meningococcal disease using the quadrivalent vaccine. The certificate should be issued not more than 3 years and not less than 10 days before arrival.
- Travellers to sub-Saharan Africa during the dry season, i.e. December to June (bivalent or quadrivalent vaccine) with regard to local ad hoc epidemic situations and risk of exposure.
- Travellers to areas that are known to experience epidemic meningococcal meningitis as announced by authorities, e.g. World Health Organization; United States Centers for Disease Control and Prevention; and Health Canada.
This vaccine should not be administered to patients with acute infectious diseases. It is also not recommended for individuals suffering from ongoing progressive diseases or people who have severe reactions to the vaccine or its components.
2. Haemophilus Influenzae Type B (Hib) Vaccine/Combination vaccine containing Hib Vaccine
The Hib vaccine is given in four injections at 2 months, 4 months, 6 months and 1.5 years of age.
5-in-1 acellular combination vaccine covers diphtheria, tetanus, acellular pertussis, Hib and poliomyelitis. 6-in-1 acellular combination vaccine covers diphtheria, tetanus, acellular pertussis, Hib, poliomyelitis and hepatitis B. Please consult the doctor for the vaccination schedule.
3. Pneumococcal Conjugate Vaccines
13-valent Pneumococcal Conjugate Vaccine (PCV13)
PCV13 covers 13 serotypes and is suitable for all above 6 weeks of age. Only one injection is required for those aged 2 or above. Infants below age 2 have to receive four injections at 2 months, 4 months, 6 months and 12-15 months. This vaccine is included under the Childhood Immunisation Programme of the Department of Health. Please refer to relevant sources for details.
23-valent Pneumococcal Polysaccharide Vaccine (PPV23)
PPV23 covers 23 serotypes and is suitable for high-risk groups aged 2 or above, such as elderly people aged 65 or above, chronic disease patients or immunocompromised individuals. Only one injection is required for those aged 2 or above.
Maintain personal hygiene; keep the hands clean; cover the nose and mouth while sneezing or coughing, hold the spit with tissue and dispose of it in lidded rubbish bins.