Cryptococcosis is a fungal disorder or an infection that is caused by the intake of fungus Cryptococcus neoformans, which is mostly found in soils enriched with pigeon droppings. In moist or desiccated pigeon dropping, Cryptococcus neoformans may remain viable for 2 years or longer.
Two types of Cryptococcus neoformans are present which are known as neoformans and gattii. Cryptococcus neoformans var neoformans is the most common variety of this infection and it mainly affects immunosuppressed patients like those with HIV and AIDS.
Cryptococcus neoformans var gattii is much less common type of infection but it mainly affects immunocompetent (normal immune function) individuals. This variety of infection is restricted to subtropical and tropical areas and the fungus found on eucalyptus trees and the surrounding air.
What are the causes and risk factors for cryptococcosis?
The most common cryptococcosis infections affect people who are suffering with immunodeficiency, e.g. patients who are on high doses of corticosteroids, cancer chemotherapy patients, organ transplantation patients, and patients with acquired immune deficiency (AIDS) and human immunodeficiency virus infection (HIV).
With the global emergence of acquired immune deficiency (AIDS), cryptococcosis is now one of the most common life-threatening fungal infections in these patients.
Infection is basically through the intake of Cryptococcus spores released from soil and bird droppings. It occurs in both humans and animals, but animal-to-human and human-to-human transmission by respiratory droplets has not been documented.
Transmission by organ transplantation has been reported when infected donor organs were used. Infection via cuts through the skin is not common but may occur.
How is cryptococcosis diagnosed?
The following laboratory and radiology tests are performed in the diagnosis of cryptococcal disease.
- Sputum culture and stain
- Lung biopsy
- CSF culture and stain
- Chest x-ray
- Skin biopsy shows characteristic histopathology
What is the treatment for cryptococcosis?
Treatment of cryptococcal disease relies on the patient’s immunological status and the site of infection. It is based on the following categories of infection.
- Pulmonary cryptococcosis in an immunocompetent patient
- Pulmonary cryptococcosis in an immunosuppressed patient
- CNS cryptococcosis
- Disseminated non-pulmonary, non-CNS cryptococcosis
Usually immunocompetent patients with asymptomatic pulmonary disease do not require any treatment. If the disease does not resolve very early then the antifungal fluconazole can be given for 3-6 months.
Treatment goals for categories 2, 3 and 4 differ on whether the patient is suffering from HIV/AIDS or not. The goal in infected patients with HIV/AIDS is to first control the infection that is followed by life-long treatment to suppress Cryptococcus neoformans.
For patients who are suffering with cryptococcal disease and not complicated by HIV/AIDS then the treatment goal is to eradicate the fungi and achieve a permanent cure.
Several antifungal medications are used.
- Intravenous Amphotericin B is the drug of choice for the initial therapy of disseminated, pulmonary and CNS cryptococcosis.
- Flucytosine should be used in combination with amphotericin B.
- Oral fluconazole can be given in less major infections and is used for life-long treatment to prevent relapses.