Cryptococcosis in humans was rare before the AIDS era. AIDS
is the underlying factor in 80+% of cases
in human beings, with most of the remaining cases occurring subsequent
to other immunosuppressive disorders. The majority of these cases
are due to reactivation of a persistent asymptomatic infection.
Clinical disease in humans:
Cryptococcus in humans, as in cats and dogs, most commonly
localizes to the CNS.
- This may be due to a lack of natural anti-cryptococcal substances
in the CSF that are present in serum, and because of a limited
inflammatory response to the organism in the CNS.
- The production of melanin by Cryptococcus may act
as a virulence factor by protecting the organisms from oxygen
radical-induced destruction.
- The clinical symptoms vary, depending on the specific CNS
sites affected, and the course of disease may be acute or chronic.
- CNS disease may be complicated by the development of hydrocephalus.
- The disease can rarely be cured in patients with AIDS, but
mortality is reported to be reduced to approximately 30% with
amphotericin B and 5-FC lifelong combination therapy.
