[Cryptococcus species--etiological agents of zoonoses or sapronosis?]

Cryptococcus strains are doubtless the cause of a sapronosis which occurs worldwide as cryptococcosis in humans and warm-blooded animals. The etiological agent is Cryptococcus neoformans with the varieties neoformans and gattii. The infection proceeds from environmental sources and not from animals suffering from cryptococcosis. Therefore the designation as zooanthroponosis is not right. There is a correlation between the geographical distribution of the varieties of Cryptococcus neoformans in the environments and the clinical manifestation of cryptococcosis. The reservoir of var. neoformans, serotypes A and D, are worldwide pigeons and pet birds which are frequent healthy carriers. They excrete these yeasts with their excrements. Bird droppings favour the propagation of cryptococci in natural substrates. The cryptococcal infection arises from inhalation of contaminated dust. Variety gattii, serotype B, occurs mainly in tropical and subtropical climates and its environmental niche has been identified in Eucalyptus trees. Var. gattii was detected in the air and in decaying wood debris under the canopies of these trees. Serotype C was isolated once from almond trees in Colombia. Cryptococcoses in men caused by var. gattii are endemic in Australia, California, Brazil and other tropical and subtropical regions. Modern molecular typing procedures are available for studying ecological problems of cryptococci and epidemiological questions of cryptococcosis. Immunosuppressed individuals, especially HIV infected persons and AIDS patients, should avoid contact with pigeons and pet birds.