Adventure Doc Meningitis

keeping you healthy for life's adventures

Erik McLaughlin MD, MPH

This is an infection or inflammation of the tissue that surround the brain. The meninges is a membrane of tissue that lies between the brain and the inside of the skull. If this layer becomes inflamed, you get meningitis. There are many causes of meningitis. The main two are viral or bacterial. The symptoms of both are very similar. Fever, stiffness of the neck, headache and photophobia (increased headache with bright light) are common. Meningitis is a medical emergency and needs prompt attention. The mortality rate (chance of dying) is low, but only with medical care.

All types of meningitis are diagnosed based on a lumbar puncture (spinal tap). The goal is to put a small needle into the spinal column and extract a small sample of CSF (cerebro-spinal fluid). This CSF is the fluid that surrounds the brain and spinal cord. This procedure is very safe and poses no risk of paralysis because the sample is taken from very low on the back. This is well below the spinal cord and does not interfere with the nerves.

Nisseria Meningitidis, Strep. Pneumo and H. Influenza account for approx 80% of bacterial meningitis. An acute illness characterized by headache, neck stiffness, photophobia, fever and nausea/vomiting. All three bacteria have vaccines. Long term effects after treatment occur approx 20% of the time and include mental retardation, deafness and limb paralysis.

Worldwide, especially at mass gatherings such as prisons, dormitories, religious gatherings and military barracks.

Transmission/ Incubation:

Spread via inhalation of respiratory droplets containing the bacteria. Incubation is generally 3-5 days but symptoms can occur as late as 2 weeks after exposure.

Vaccines exist for all three mentioned bacteria. The vaccine for N. Meningitis protects against serotypes A, C, Y and W-135. There is no protection against the B serotype. The HiB vaccine, commonly given in childhood, in developed countries, covers H. Influenza. S. Pneumo is prevented by the PCV vaccine, again, commonly given to children in developed nations. Prophylaxis is also given for those with known contact to an infected individual. Quarantine of known cases is also advised.

Diagnosis centers on analysis of CSF (cerebro-spinal fluid) taken during a lumbar puncture (spinal tap).

This is a medical emergency and treatment should be started as soon as possible. If this is suspected, do not wait for laboratory confirmation to begin antibiotics. 3 rd. generation cephalosporins are first line treatment, given intravenously. Penicillin, ampicillin and chloramphenicol can also be used. Reports of drug resistant bacteria are becoming more common. Once cultures and identification of the causative organism have been made, the treatment plan can be adapted.

Countries where Meningitis is endemic. Note the "African Meningitis Belt".

Bacterial Meningitis

Bacterial meningitis produces classic meningitis symptoms such as fever, neck pain, photophobia (worse headache with bright light), difficulty flexing and bending knees and sometimes a rash. There are a few main bacteria that cause meningitis. Depending on the patient’s age some of the culprits could be Nisseria Meningitidis, Streptococcus Pneumonia and H. Influenza. These all require prompt antibiotics and a doctor’s care. If you suspect you or somebody else has meningitis, go to the hospital. A vaccine exists for four of the main types of bacterial meningitis, but not the fifth.

Nisseria Meningitidis has several types (sero-groups) that cause infection in humans, groups A, B, C, Y and W-135. Group A is found primarily in Asia and Africa. Groups B and C are found mainly in Europe and South America. These account for 90% of all infections with this bacteria. The vaccine protects people against groups A, C, Y and W-135. Group B is not covered. In the last 25 years, group B has become much more common, unfortunately. This bacteria is spread by respiratory droplets and outbreaks are common. Good ventilation and reducing overcrowding are key to prevent this disease. If you have had contact with somebody who has a confirmed case of meningitis, you may need to be placed on antibiotics to make sure you don’t get the disease, too. A single dose of a quinolone, such as Cipro, is advised.

Haemophilus Influenza is a bacteria and it does not cause Influenza. This is a bad name for the bacteria because Influenza is caused by a virus. Most people born in America, Europe, Australia and developed nations have been vaccinated against this at a very young age. This bacteria effects people who have not been immunized, like those from developing nations and children ages 6-12 months old.

Strep. Pneumococcus is a bacterium that a vaccine exists for, as well. There are 7 main types that cause disease and all seven are included in the vaccine. Most children born in developed nations have received this vaccine, as well. This type of bacterial meningitis most commonly effects children 6months old to 5 years old and those who have not been immunized.

Most common types of bacterial meningitis based on age:

Neonates: Group B Strep, Listeria and E. Coli
Infants: Nisseria, Strep Pneumo, H. Influenza
Children: Nisseria, S. Pneumo
Adults: S. Pneumo, Nisseria, Mycobacteria, Cryptococci

Viral meningitis can be caused by a number of viruses. The patient will have the classic symptoms of meningitis such as headache, fever, neck stiffness (nuchal rigidity), difficulty touching their chin to their chest and photophobia. This condition can be acquired most anywhere but is more common in places where people gather, such a prisons, refugee camps, army barracks and school dormitories. Treatment for this is supportive (treat the symptoms) and include reducing the fever and adequate hydration. There is no role for antibiotics in treating viruses. Some of the most well know viruses in this category include coxsackie viruses, echo viruses and herpes viruses.

Interpretation of CSF for suspected meningitis is based on a few things. Glucose, gram stain and culture are the key things to know:

Viral-- increased protein, normal glucose and the absence of bacteria, presence of mononuclear cells

Bacterial-- decreased glucose, increased WBC (white blood cell count) and higher opening pressure.