Tuesday, 26 July 2011

Meningitis

Published in City Times



Is Meningitis Preventible?


Meningitis is an infection of the meningis, the membranes surrounding the central nervous system - the brain and the spinal cord. The disease is usually bacterial or viral, and occasionally is due to fungal infections. Viral meningitis, the most common form of the disease presents with fever and severe headache. It has no specific treatment since it is a self-limiting condition, that is, it resolves by itself and is almost never life threatening and most people recover fully from it, explains Dr.Robert Erasmus, Specialist Family Medicine, Welcare Hospital, Dubai. While the exact manner in which the disease spreads is not really known, hand to hand contact is believed to contribute to the spread of viral meningitis.

The secret, however, says Dr.Erasmus, “is to distinguish viral meningitis from the more dangerous bacterial one which may be caused by any of several bacteria. Almost 80% of bacterial meningitis are caused by three of the commonest bacteria, Hemophilus Influenzae type B (HIB), Neisseria Meningitidis (meningococcus) and Streptococcus Pneumoniae (pneumococcus).

Meningococcus Meningitis is the more dangerous one because it could result in pus around the brain. The brain floats in a water bag and meningitis is an infection of this area. The pus blocks the circulation of this fluid which is constantly being produced and drained. When the pus cannot be drained, there is increased pressure in the brain. This is seen particularly in babies as a bulge on the head, in the fontanelle. These patients present with fever, severe headaches, skin rash and very stiff neck. The stiff neck is the predominant symptom of this form of meningitis though it is perceived in the other bacterial meningitis as well.”

Meningococcal Meningitis mostly affects adults and children above the age of 5 years, being most predominant in school and college going students and adults in military camps, explains Dr.Erasmus.

Most cases of pneumococcal meningitis are in children under two years old and adults with specific problems like head injuries, diseases of the blood or circulation, or immune deficiency. Hib meningitis is caused by bacteria called Haemophilus influenzae type b. It affects mainly the under fives, though nowadays, it is rare in all age groups, and is extremely unusual in adults. However, both these forms can be dangerous, particularly HIB meningitis, opines Dr.Erasmus.

Certain strains of E Coli bacteria can cause meningitis, especially in newborn babies, thoug
Tubercular Meningitis is a rare form of meningitis due to the tuberculosis bacteria. Dr.Erasmus assures, “It is less common now because of the BCG vaccine which is given to newborns. The vaccine is a protection against TB meningitis and it is a disease which the under-two-year olds get; very seldom you see the condition in older children or adults.”

Explaining the spread of the bacterial meningitis, Dr.Erasmus continues, “The high risk groups are persons living in close communities as in schools and universities, hostels, military camps because the spread of infection is by droplets from sneezing and coughing. These bacteria are often carried harmlessly in the upper airways of human beings and so spread from person to person through sneezing and coughing. The disease therefore, often takes an epidemic form and spreads like forest fires.”

Meningitis due to fungus is invariably associated with HIV and AIDS infection and it is a less acute disease; it is more sub acute and goes on a bit longer than meningococcal meningitis. These patients become ill more gradually and the treatment is a long term one with a bad prognosis, usually, explains Dr.Erasmus.

The incubation period varies for the different kinds of meningitis. Viral meningitis has a short incubation period of 2-3 days, Meningococcal type, 10 days and the others vary, depending on when there were exposed to the particular organism.

In terms of symptoms, Dr.Erasmus explains, “The most important symptom of bacterial meningitis is stiff neck and it is one of the earlier signs. The severity of the headache, is again, more than what one would expect. While these patients don’t usually get high fevers, the headache is terrible and is very short lasting. Severe headache with stiffness of neck is the predominant feature of meningitis unless otherwise proven. There are, of course, other non-specific symptoms, commonly found in so many other disorders, like nausea, vomiting and dizziness.”

What about head injury contributing to meningitis, especially in babies which fall from their cots? Dr.Erasmus explains, “You can get meningitis only if there is a direct connection between the outside world and the subdural skull. It is very unlikely that from a hit or bump on the head you get the disease. Usually when you have facial fractures that leads to a connection with the cerebrospinal fluid or a skull base injury, this may be possible. Even here, it requires severe trauma to get affected with meningitis. But sometimes, when you play contact sport and you get a blow on the face, very often you have a fracture that connects, especially the nose, to the cerebrospinal fluid. These bacteria and viruses are usually harbored in the upper airways of the sinuses and nerves and they can infect the cerebrospinal fluid, thus contributing to meningitis.

How is diagnosis of meningitis made? Apart from the clinical examination, it is necessary to do a lumbar puncture to rule out bacterial meningitis. This is a routine procedure to confirm bacterial meningitis and is done under local anesthesia. A needle is inserted between two of the bones of the spine to extract a small sample of the spinal fluid. A culture test is done to identify the particular strain of bacteria causing the disease so that treatment is undertaken accordingly, explains Dr.Erasmus.

How safe is the lumbar puncture itself? Dr.Erasmus assures, “It is like any other medical procedure and should normally take about 5 minutes. However, it does have its risks and complications but these are extremely rare. The major risk is that if the pressure in the cerebrospinal space is so high and you put a needle in and reduce the pressure too quickly, you can have a part of the brain stem bulging down into the spinal column and the patient can die from that. But, I emphasize that this is a very remote possibility when the procedure is done by a capable doctor. Also, if the patient has got such a high pressure already, the chances of his survival, anyway, are very slim. Having said that, we do measure the pressure while we do the lumbar puncture.”

What about damage to surrounding nerves during a lumbar puncture? Dr.Erasmus explains, “Sometimes, it is very difficult to find the disc space where you go through to get into the required area. And of course though extremely rare again, there is the possibility of such a damage.”

Once diagnosis is confirmed, what is the treatment modality? Dr.Erasmus is emphatic, “Even before diagnosis of bacterial meningitis is confirmed through the lumbar puncture, we start the patient on Penicillin and one or two broad spectrum antibiotics, depending upon the severity of symptoms. Once diagnosis is confirmed, we give high doses antibiotics, usually intravenously, specific to the strain of bacteria. It all depends on the response of the patient to the medication. Some respond very quickly and are fine within a few hours; other take longer and some patients develop complications.”

What are the possible complication from meningitis? Complication in the young, the newborns – upto 2 years, is fairly high, explains Dr.Erasmus. “They can get permanent brain damage because their brain is still in a developmental stage. Then, if you get a blockage with pus in the whole space surrounding the brain, it gives rise to hydrocephalus. In the young child, the head becomes big; in the older patients, this pressure will compress the brain, leading to complications in terms of cerebral functions. It is difficult to say what percentage of people will have these complications from meningitis. This is because the complications depend on a host of factors including the organism involved, duration of the disease, vaccination status, nutritional status, facilities available for treatment, nursing care, follow up, rehabilitation, etc”.

What are the possibilities of a recurrent attack of meningitis during another epidemic? ‘Yes, this is possible in the fungal meningitis and Tubercular meningitis, but a recurrence is very rare.”

Is Meningitis preventable? Most often it is with vaccination, says Dr.Erasmus. Earlier we had the AC vaccine and now we have the newer one, the ACWY135, the quadrivalent or four-in-one vaccine which provides immunity against most of the strains of bacteria commonly causing meningitis. The vaccines provide immunity for 3 years and hence have to be repeated once every three years especially for people living in high risk areas.”

What about Post exposure Prophylaxis? “Yes, if there are people who have come into contact with meningitis cases, if even one student in a school has been identified as being sick with meningitis, if one member of a family has come down with the disease, the rest of the members should be given a single dose of antibiotic to prevent getting the disease, since they may be carriers of the bacteria,” explains Dr.Erasmus.

*****

No comments:

Post a Comment