Cryptococcosis: Current status

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      Cryptococcosis is a cosmopolitan infectious disease of man which begins as a primary infection of the lungs and which may spread to the central nervous system in susceptible subjects. The disease is encountered more frequently in patients with Hodgkin's disease, lymphosarcoma, leukemia and diabetes, and in those receiving prolonged therapy with steroids. Although the incidence of the disease in the United States is low, it is second to histoplasmosis as a cause of death by mycotic agents. The drug of choice for treatment of cryptococcal meningitis remains amphotericin B, the use of which has reduced mortality considerably. Specific toxic effects on the kidneys may be lessened by alternate day intravenous therapy and monitored more accurately by the creatinine clearance. The presence of the etiologic agent in the sputum in the absence of overt evidence of disease, indicates the existence of a carrier state in men. Circulating cryptococcal antigens are present in the serum and spinal fluid in the active phase of the disease and decline during the recovery phase when circulating antibodies appear. Although skin testing antigens have been improved, an adequate antigen is still unavailable. Since normal human serum inhibits the etiologic agent, changes in the anticryptococcal activity of the serum which appear as sequelae of debilitating disease, therapy with steroids or other immunosuppressive agents may be a prime factor in the development and course of cryptococcosis. Avian habitats, especially those of the pigeon, furnish a prime source of human and animal infection. The pigeon has been shown to be moderately susceptible to experimental infection with C. neoformans and to carry the organism mechanically on its beak and feet, although spontaneous infection has not yet been demonstrated. The excreta of pigeons and other birds has been shown to be a rich source of C. neoformans. Pigeon handlers have been found to have a much higher incidence of cryptococcal antibodies than nonhandlers. Measures for the prevention of cryptococcosis include the control of pigeons and decontamination of pigeon sites.
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