What is cryptococcal meningitis?

Cryptococcus is a common fungus that is often found in soil and bird droppings. Cryptococcal meningitis is a serious infection of the lining of the brain and spinal cord caused by this fungus.

It is rare for a healthy person to develop cryptococcal meningitis. Most people who develop cryptococcal meningitis have a weakened immune system caused by an underlying illness, for example, HIV or cirrhosis of the liver.

Symptoms

Symptoms of cryptococcal meningitis often develop gradually, within a few days to weeks of exposure to the fungus.

A person with cryptococcal meningitis may develop the following symptoms:

• headache
• nausea and vomiting
• fatigue
• confusion or hallucinations
• personality changes
• sensitivity to light
• fever
• stiff neck
• blurred vision

It may be difficult for someone to tell if they have symptoms of cryptococcal meningitis. Many of the symptoms may be similar to the side effects of a medication they may be taking to treat an underlying condition.

If left untreated, cryptococcal meningitis can lead to more serious symptoms, including:

• fluid on the brain
• coma
• hearing loss

Cryptococcal meningitis can be fatal if not treated quickly, especially in people with HIV or AIDS.

Causes

Cryptococcal meningitis may be found in soil or bird droppings.

Two types of Cryptococcus fungi cause cryptococcal meningitis.

The fungus C. neoformans causes most cases of cryptococcal meningitis. This species is commonly found in soil and is spread via bird droppings.

The second fungus that causes cryptococcal meningitis is C. gatti. This variety is not found in the soil but is associated with several trees, including eucalyptus.

Not as many cases of cryptococcal meningitis are caused by C. gatti as by C. neoformans. However, C. gatti is more likely to cause cryptococcal meningitis in individuals who are healthy.

Risk factors

Cryptococcal meningitis is a relatively rare illness, and most healthy people are not at risk of developing cryptococcal meningitis. It is most common in people who have a weakened immune system.

People more at risk for developing cryptococcal meningitis will often have one of the following underlying conditions:

• HIV
• AIDS
• diabetes
• leukemia
• cirrhosis of the liver
• transplanted organs

Cryptococcal meningitis is most likely to occur in people who have a low CD4 count. CD4 cells, also known as T cells, are a type of white blood cell and vital to the immune system.

People with HIV and AIDS often have low CD4 counts, so they are much more likely than others to develop cryptococcal meningitis.