In case you want to get an answer why especially the var. gatii appears more aggressive than other Cryptococcus species, the answer may be very multifactorial and may dependent on differences in T-cell interactions, hiding from immune recognition...

However, Cryptococci, although causing severe diseases in humans and especially in HIV infected patients, is generally a saprophytic basidiomycete. Vegetative yeast cells can desicate and survive for a long period. Unfortunately, these cells are also distributed by air and in endemic regions it is rather likely that people are confornted with these cells.

You may find additional information on Cryptococcus infections on the following web page:

http://www.mycology.adelaide.edu.au/Mycoses/Opportunistic/Cryptococcosis/

stating the following: "..., the distribution of cryptococcosis due to Cryptococcus gattii is geographically restricted, non-immunocompromised hosts are usually affected, large mass lesions in lung and/or brain (cryptococcomas) are characteristic and morbidity from neurological disease is high. Human disease is endemic in Australia, Papua New Guinea, parts of Africa, the Mediterranean region, India, south-east Asia, Mexico, Brazil, Paraguay and Southern California."

Dear Matthias ,thanks for valuable information

Dear Ali , I agree with Mr.Brock .this may attributed to immunological factors