Cryptococcosis is an infection caused by inhaling the fungus Cryptococcusneoformans. It is one of the diseases most often affecting AIDS patients.Cryptococcosis may be limited to the lungs, but frequently spreads throughout the body. Although almost any organ can be infected, the fungus is often fatal if it infects the nervous system, where it causes inflammation of the membranes covering the brain and spinal cord (meningitis).
The fungus causing cryptococcus, C. neoformans, is found in soil contaminated with pigeon or other bird droppings. It has also been found on unwashed raw fruit. Cryptococcosis is rare in healthy individuals, but is the mostcommon fungal infection affecting people with AIDS.
People with Hodgkin's disease or who are taking large doses of drugs that suppress the immune system (corticosteroids, chemotherapy drugs) are more susceptible to cryptococcal infection.
Once the cryptococcal fungus reaches the lungs, three things can happen. Theimmune system can heal the body without medical intervention, the disease canstay localized in the lungs, or it can spread throughout the body. In healthy people, the body usually heals itself and the infected person notices no symptoms and has no complications.
If the body does not heal itself, the fungus begins to grow in the lungs andforms nodules that can be seen on chest x rays. In the early stages of infection, an individual usually only exhibits symptoms of a respiratory infection,such as a dry cough, so the disease is rarely diagnosed.
The fungus can remain dormant in the lungs and produce an active infection later if the immune system is weakened. If the disease becomes active, it can cause cryptococcal pneumonia in the lungs. Unfortunately, cryptococcal pneumonia has symptoms similar to other pneumonias (cough, chest pain, difficulty breathing), making it difficult to accurately diagnose.
Most patients are not diagnosed as having cryptococcosis until they show signs of cryptococcal meningitis. Fever and headache, nausea, vomiting, unwantedweight loss, and fatigue are common symptoms. Others may include blurred vision, stiff neck, aversion to light, and seizures.
Cryptococcal infection can spread to the kidneys, bone marrow, heart, adrenalglands, lymph nodes, urinary tract, blood, and skin. Painless rashes and lesions that mimic other skin diseases may develop.
Physicians who regularly work with AIDS patients have the most experience indiagnosing cryptococcosis. The preferred methods of diagnosis use simple andvery accurate blood and cerebrospinal fluid (CSF) tests. CSF is collected during a procedure called a lumbar puncture, during which an anesthetic is applied near the spine and a needle withdraws fluid from the space between the vertebrae and the spinal cord. Chest x rays are useful in assessing lung damage,but the x ray alone does not lead to a definitive diagnosis of cryptococcosis.
Once cryptococcosis is diagnosed, treatment begins with amphotericin B (Fungizone), sometimes in combination with 5-flucytosine (Ancobon). Amphotericin Bis a powerful drug with potentially toxic side effects, such as kidney toxicity and lower concentrations of an important blood component called hemoglobin. This medication can also cause fever, chills, nausea and vomiting, diarrhea, headache, and muscle aches. Patients may receive other medication to minimize the side effects from these drugs.
Amphotericin B, with or without 5-flucytosine, is given for several weeks until the patient is stable, after which the patient receives oral fluconazole (Diflucan). Patients with AIDS must continue taking fluconazole for the rest of their lives to prevent a relapse of cryptococcosis. Sometimes fluconazole is given to patients with advanced AIDS as a preventative measure.
Untreated cryptococcosis is always fatal. For AIDS patients who do not receive continued fluconazole, the relapse rate is 50-60% within six months. Once cryptococcosis infection has been successfully treated, individuals may be left with a variety of neurologic symptoms, such as weakness, headache, and hearing or visual loss. In addition, fluid may accumulate around the brain (hydrocephalus).
The best way to prevent cryptococcosis is to stay free of HIV infection. People with suppressed immune systems should stay away from areas contaminated with pigeon or other bird droppings.