cryptococcosis

Cryptococcosis is an infection caused by encapsulated yeasts of the genus Cryptococcus, most commonly Cryptococcus neoformans and Cryptococcus gattii. The organisms are environmental and typically reach humans by inhalation, often from soil or bird droppings. After inhalation, infection may remain confined to the lungs or disseminate, most notably to the central nervous system, causing meningitis or meningoencephalitis.

C. neoformans is found worldwide and tends to affect individuals with weakened immune systems, particularly those with HIV/AIDS or on immunosuppressive therapy. C. gattii has a more restricted geographic distribution and can infect immunocompetent people as well. Environmental reservoirs include soil, bird droppings, and certain trees.

Clinical manifestations vary by site. Pulmonary cryptococcosis can be asymptomatic or present as a pneumonia-like illness. CNS involvement commonly presents as meningitis with headache, fever, neck stiffness, and altered mental status; cryptococcomas may appear as focal brain lesions on imaging. Disseminated disease can involve skin, bones, and other organs, particularly in advanced immunosuppression.

Diagnosis relies on laboratory testing of serum and cerebrospinal fluid. Cryptococcal antigen (CrAg) testing is highly sensitive; CSF culture and microscopy (including India ink staining) support confirmation. Imaging aids evaluation of the chest or brain. A positive CrAg in CSF or serum with compatible symptoms supports CNS involvement.

Treatment depends on disease severity and site. Meningitis is treated with induction therapy using amphotericin B plus flucytosine, followed by consolidation with fluconazole. HIV-infected patients require antiretroviral therapy and may need IRIS management. Mild to moderate pulmonary disease can be treated with fluconazole.

Prognosis improves with early diagnosis and appropriate antifungal therapy but remains guarded in CNS disease, especially with advanced immunosuppression. No widely available vaccine exists; preventive strategies focus on reducing environmental exposure in high-risk individuals.