Meningitis is a condition characterized by inflammation of the meninges, the membranes surrounding the spinal cord and brain. This inflammation may be produced by a number of different agents, including bacteria, viruses, fungi, and protozoa, and occurs in both acute and chronic forms.

The most dangerous varieties of meningitis are of bacterial origin, some being capable of causing death within only a few hours of the onset of symptoms. The first sign of the disease is often vomiting, which is usually followed by an excruciatingly intense headache that develops from escalated cerebrospinal fluid pressure. Other symptoms may include confusion, drowsiness, fever, sensitivity to light, and a skin rash. Eventually, as the nerves along the spine become increasingly irritated, the neck stiffens, and, in some cases, the patient may experience convulsions, especially if the individual is very young. If acute bacterial meningitis is left untreated, the inflammation may lead to fluid build up in the ventricles of the brain, which can result in a loss of consciousness or even death.

Transmitted most commonly by sneezing, coughing, or other means of exposure to respiratory fluids, meningococcal meningitis is more common in colder climates and in areas where many people live in close contact, such as dormitories. In fact, statistics provided by the Centers for Disease Control and Prevention indicate that between 1991 and 1997, the incidence of the disease doubled among individuals 15 to 24 years of age. Consequently, the federal agency began recommending that college students be vaccinated for meningococcal meningitis, particularly if they live in university housing. The vaccines that are currently available are considered effective for up to five years and provide at least some protection from four of the five strains of bacteria that cause the disease.

The primary agent that causes acute bacterial meningitis is Haemophilus influenzae b (Hib), but use of the Hib vaccine in the United States has helped decrease its incidence. The misleading name of the bacterium is indicative of the fact that when it was first discovered, it was believed to be an influenza virus. The bacterium Neisseria meningitidis is responsible for the second largest number of cases of the disease. Oftentimes this pathological agent will occur in epidemics. Between 1974 and 1975, an outbreak of meningococcal meningitis in the poverty stricken areas of Brazil resulted in the deaths of more than 11,000 inhabitants and the neurological damage of approximately 75,000 others. Also, in the mid-1990s, the spread of N. meningitidis killed approximately 16,000 people in West Africa.

Due to the rapid progression of many forms of meningitis, a quick and efficacious diagnosis is essential to the patient’s chances of survival and avoidance of serious complications. In some cases, a doctor may administer a general antibiotic to the patient immediately in an attempt to minimize the severity of the illness even before the specific cause is determined. Many people wait so long after symptoms begin to seek medical attention that the disease is already in an advanced state by the time they see a doctor. This mistake is very easy to make since many of the earliest signs of meningitis (vomiting, fever, headache, and lethargy) are remarkably similar to symptoms of the flu. Approximately 1 in 10 people with meningitis die from the disease.

Meningitis at 10x Magnification - When someone refers to an outbreak of meningitis, they are typically referring to meningococcal meningitis, a contagious bacterial form of the disease caused by Neisseria meningitidis.

Meningitis at 20x Magnification - In the United States, the number of deaths each year from meningococcal meningitis is estimated to only be a few hundred, but many more people experience serious long-term effects of the disease.

Meningitis at 40x Magnification - A medical history and physical exam may help clearly indicate that a patient has meningitis, but definitive diagnosis is generally made through the analysis of cerebrospinal fluid obtained via a spinal tap.