Meningitis is an infection and inflammation of the meninges. Your meninges are the membranes that cover your spinal cord and your brain. Meningitis can be caused by many different germs, including bacteria, fungi, and viruses.
Most cases of meningitis are caused by viruses. Cryptococcal meningitis (CM) is one of the exceptions. It is caused by two types of fungus: Cryptococcus neoformans and Cryptococcus gattii. This disease is rare in normally healthy people. It is more common in people who have compromised immune systems, such as AIDS patients.
Most cases of CM are caused by a fungus called Cryptococcus neoformans. This fungus is found in soil all over the world. It is usually found in soil that contains bird droppings.
Cryptococcus gattii, the other fungus that causes CM, is not found in bird droppings. Instead, it is associated with trees, most commonly eucalyptus trees. It grows in the debris around the trees’ bases.
Cryptococcal meningitis usually occurs in people who have a compromised immune system. It rarely occurs in someone who has a normal immune system. Of the two fungi that can cause the condition, gattii is the one more likely to infect someone with a normal immune system.
Symptoms of CM usually come on slowly. Within a few days to a few weeks of contact, an infected person may develop the following symptoms:
- mental changes such as: confusion, hallucinations, and/or personality changes
- sensitivity to light
In some cases, the infected person may experience a stiff neck and fever.
If left untreated, cryptococcal meningitis may lead to more serious symptoms such as:
- brain damage
- hearing loss
- hydrocephalus (“water on the brain”)
Eventually, untreated CM is fatal, especially in a person with HIV/AIDS. According to the British Medical Bulletin, 10 to 30 percent of HIV-related cryptococcal meningitis patients die from the illness (Bicanic and Harrison, 2005).
If your doctor suspects you might have CM, he or she will perform a spinal tap. You will lie on your side with your knees close to your chest. Your doctor will clean a spot over your spine, and then inject numbing medication. Finally, the doctor will insert a needle and collect a sample of your spinal fluid. This fluid will be tested to find out if you have the disease. Your blood may also be tested.
Your doctor might also perform a physical examination when trying to figure out if you have CM. He or she will look for the symptoms associated with this disease.
If you have CM, you will be given antifungal drugs. The most common choice is amphotericin B. You will need to take the drug daily. Your doctor will monitor you closely while you are on this drug to watch for nephrotoxicity (meaning the drug is toxic to your kidneys). Amphotericin B is typically administered intravenously. This means that it is administered directly into your veins.
You will probably also take flucytosine, another antifungal medication, while you are taking the amphotericin B. The combination helps treat the condition more quickly than amphotericin B alone.
You will need to have your spinal fluid tested repeatedly during treatment. After your tests have come back negative for CM for two weeks, you will generally stop taking amphotericin B and flucytosine. You will typically switch to taking only fluconazole, which you will generally keep taking for about eight weeks.
Most people who develop this form of meningitis already have severely compromised immune systems. Prior to about 1979, cryptococcal meningitis was very rare worldwide (Berger, 2011). It became much more common after the beginning of the AIDS epidemic starting in about 1980. According to the U.S. Centers for Disease Control and Prevention, in the general healthy population, infections by Cryptococcus neoformans occurs yearly in about 0.4 to 1.3 cases per 100,000 people. However, in patients with HIV/AIDS, the yearly incidence rate is between 2 and 7 cases per 1,000 people. It is far more common in HIV/AIDS patients in sub-Saharan Africa, where these patients have a mortality rate that is estimated to be 50 to 70 percent (CDC, 2012).
In many cases, patients will need to continue taking fluconazole indefinitely. This is especially true in patients with AIDS. This helps prevent a relapse.