Cryptococcal meningitis is an infection of the meninges (the membranes covering the brain and spinal cord), caused by the fungus Cryptococcus neoformans.

Cryptococcus neoformans is found in soil around the world. Cryptococcal meningitis most often affects people with compromised immune systems. Risk factors include AIDS, lymphoma (a type of cancer), and diabetes. It occurs in 5 out of 1 million people.

• Headache
• Fever
• Nausea and vomiting
• Stiff neck
• Sensitivity to light (photophobia)
• Mental status change
• Hallucinations

In order to diagnose cryptococcal meningitis, a lumbar puncture (spinal tap) must be performed. This test involves taking a sample of fluid from the spinal column (called cerebrospinal fluid or CSF). The following tests on the CSF allow the diagnosis of cryptococcal meningitis:

• CSF stains may show the fungus
• CSF culture grows cryptococcus
• CSF may be positive for cryptococcus antigen

Also, a blood test, the serum cryptococcal antigen test, can be helpful in diagnosing cryptococcus infection, especially in AIDS patients.