Description

Cryptococcosis is a fungal disease caused by Cryptococcus neoformans that affects both dogs and humans. It is a rare disease in dogs, with cats seven to ten times more likely to be infected. The disease in dogs can affect the lungs and skin, but more commonly the eye and central nervous system.

Etiology and Incidence

Cryptococcosis is a defining opportunistic infection for AIDS. Other conditions which pose an increased risk include certain lymphomas (e.g. Hodgkin's lymphoma), sarcoidosis, and patients on long-term corticosteroid therapy.

Distribution is worldwide. The prevalence of cryptococcosis has been increasing over the past 20 years for many reasons, including the increase in incidence of AIDS and the expanded use of immunosuppressive drugs.

In humans, C. neoformans causes three types of infections:

• Wound or cutaneous cryptococcosis
• Pulmonary cryptococcosis, and
• Cryptococcal meningitis.

Cryptococcal meningitis (infection of the meninges, the tissue covering the brain) is believed to result from dissemination of the fungus from either an observed or unappreciated pulmonary infection. Cryptococcus gattii causes infections in immunocompetent people (those having a functioning immune system), but C. neoformans v. grubii, and v. neoformans usually only cause clinically evident infections in persons who have some form of defect in their immune systems (immunocompromised persons). People who have defects in their cell-mediated immunity, for example, people with AIDS, are especially susceptible to disseminated cryptococcosis. Cryptococcosis is often fatal, especially if untreated.

Diagnosis

Symptoms include fever, fatigue, chest pain, dry cough, swelling of abdomen, headache, blurred vision and confusion.

Detection of cryptococcal antigen (capsular material) by culture of CSF, sputum and urine provides definitive diagnosis. Blood cultures may be positive in heavy infections.

Cryptococcosis can rarely occur in the immunocompetent person without HIV, when it usually goes undiagnosed. Less than 250 cases in all are reported in the medical literature, the majority diagnosed postmortem.

Treatment

Treatment options in non-AIDS patients who have reduced immune-system function is not well studied. Intravenous Amphotericin B combined with oral flucytosine may be effective. Every attempt should be made to reduce the amount of immunosuppressive medication until the infection is resolved.

AIDS patients often have a reduced response to Amphotericin B and flucytosine, therefore after initial treatment as above, oral fluconazole can be used.

Veterinary cases

Cryptococcosis is also seen in cats and occasionally dogs. It is the most common deep fungal disease in cats, usually leading to chronic infection of the nose and sinuses, and skin ulcers. Cats may develop a bump over the bridge of the nose from local tissue inflammation. It can be associated with FeLV infection in cats.

Wikipedia and GNU

The content of this entry is from the Wikipedia article "Cryptococcosis" licensed under the GNU Free Documentation License.