What is meningitis?

Meningitis is a term used to describe inflammation of the tissues covering the brain and spinal cord.

I read in the newspapers about the horrifying meningitis deaths in the US. To recap, there has been an outbreak of meningitis in several states because some vials of an injectable steroid have been contaminated by a fungus. How did the fungus get into the vials?

Yes, this is very unfortunate. The steroids were used for good purposes - to treat back and joint pain. Unfortunately, the sealed vials of the steroid called methylprednisolone acetate, which are made by the New England Compounding Center, contained a fungus found in soil and plants. This fungus is called Exserohilum rostratum. The investigations show that the floor mats around the supposedly sterile drug-mixing areas were soiled, so it is possible the fungus might have got in that way.

What is meningitis?

Meningitis is an inflammation of the meninges surrounding your brain and spinal cord. This inflammation is usually caused by an infection - most often with a virus, followed by bacteria, and then a fungus.

To understand what the meninges are, you have to picture three layers of thin material covering your brain and spinal cord as the meninges are divided into three layers:

1. Dura mater: the tough layer that is closest to your skull. It contains blood vessels.

2. Arachnoid mater: the thin, transparent middle layer which provides a cushioning effect.

3. Pia mater: the very thin, fragile layer that covers your brain and spinal cord. This layer will follow the undulations of your brain.

How would I know if I have meningitis? It sounds dangerous.

Meningitis is certainly a disease you cannot treat at home by yourself. Be careful. Meningitis can also commonly occur in infants, and this may be missed because infants cannot complain about what is bothering them. They usually just fret and cry.

Meningitis is often mistaken for the flu. Its symptoms may occur over a few hours or even one to two days.

You can get:

Fever - usually high A severe headache A stiff neck Nausea and vomiting Difficulty concentrating Confusion Fits Sleepiness or difficulty in waking up Inability to stand bright light Loss of appetite Skin rash (sometimes) In babies, all these can be difficult to spot. But any baby who has high fever, excessive sleepiness, irritability (and when you pick them up, they cry even more and refuse to be comforted), stiffness in the neck and body, fits or a general refusal to feed should immediately be brought to the doctor.

OK, so we know about the fact that viruses, bacteria and fungus cause meningitis. But how do these get into the meninges?

In a lot of cases, the viruses, bacteria and fungus enter through the nose. Bacterial infections are the most dangerous. These pathogens (agents causing disease) can enter during an upper respiratory tract infection, or a sinus or ear infection. They then get into the bloodstream and may be "carried up" to your meninges and brain.

Sometimes, you can get meningitis as a result of a skull fracture and the pathogen directly invades your brain.

What types of virus, bacteria and fungus cause meningitis? Are they the types which cause the flu or common cold?

The flu and common cold are caused by viruses. Most of the cases of viral meningitis never have a certain type of virus attributed to them. The good thing about viral meningitis is that it's usually mild and it can clear up on its own within two weeks.

However, 30 per cent of viral meningitis are caused by a group called the Enteroviruses (entero = gut), not so much the cold viruses. Enteroviruses tend to give you sore throat, a rash, diarrhoea and joint aches in addition to your meningitis.

Bacterial meningitis is by far the more dangerous one. The bacteria that cause this type of meningitis are usually the ones which can also cause pneumonia. They include Streptococcus pneumoniae, Neisseria meningitidis, which affects mostly teenagers and young adults and can cause epidemics in boarding schools and college dorms, and Haemophilus influenza.

Fungal meningitis is relatively rare. It usually causes chronic meningitis, which develops over weeks rather than days - but with the same signs and symptoms. It usually affects people with AIDS or other diseases which can suppress the immune system.

Meningitis will be treated with antivirals, antibiotics and antifungals, depending on the isolated cause.