Causes of meningitis
One of the major, some believe only, causes of meningitis is infection by the Nesseria meningitides bacteria and in upto 80% cases, strain 'B' of this bacteria is the cause of meningitis. The other strains of this bacteria are 'A', 'C', 'Y' and 'W-135'. According to a study carried out in 2000, almost 45% of humans carry the Nesseria meningitides bacteria in the throat and the nose, but we have developed a natural immunity to the bacteria and, so it does not infect us. Other organisms which have been implicated as causes of meningitis include enteroviruses, human immunodeficiency virus (HIV), mumps virus, Streptococcus pneumoniae, Group 'B' streptococci, Listeria monocytogenes and Haemophilus influenzae.
Causes of meningitis
Hedrich, in an article in 'Reviews of Infectious Diseases', has said that the prevalence of meningococcal infection is as common as the common cold in epidemics but that only about 0.1% of these infections may develop into the full-blown disease while Niklasson has estimated that only about 0.02% of carriers of the bacteria develop the disease.
It is common knowledge, and doctors agree, that the major causes of meningitis are overcrowding, poor diet, poverty, exposure to toxins like tobacco smoke and bad living conditions.
As has been studied by JM Stuart et al[1], the presence of active smokers in the house and exposure to tobacco smoke have a strong correlation with the increased risk of meningitis. Hence, it can even be said that smoking and exposure to tobacco smoke are also causes of meningitis.
Another one of the largely-ignored causes of meningitis is iron-deficiency anemia with a low pH (about 6.6) which magnifies the virulent nature of the meningitis infection by about 1200 times. This is to say that the 50% lethal dose (the dose which causes death in 50% of those infected) of 3600 bacteria is reduced to four bacteria[2].This risk is increased many-fold since the anemic child also suffers from vitamin B, vitamin C and Vitamin A deficiencies, that weaken the child.
The usual practice of administering paracetamol to control fever has also been found to increase the risk of the underlying infection developing into meningococcal meningitis since the paracetamol stops the body from fighting the infection; the fever is a sign that the body is fighting the infection since elevated body temperatures increase the action of the immune system.
In addition to the causes of meningitis discussed above, suppression of infections by the indiscriminate use of antibiotics, which produces resistant strains, is also a commonly found cause, especially in the developing countries.
References
1. Stuart JM, Cartwright KA, Robinson PM, Noah ND. Effect of smoking on meningococcal carriage. Lancet. 1989 Sep 23;2(8665): 723-5.
2. I W DeVoe, The meningococcus and mechanisms of pathogenicity. Microbiological Reviews, Volume 46, June 1982
