Epidemiology and host- and variety-dependent characteristics of infection due to Cryptococcus neoformans in Australia and New Zealand

A prospective population-based study was conducted in Australia and New Zea land during 1994-1997 to elucidate the epidemiology of cryptococcosis due t o Cryptococcus neoformans var. neoformans (CNVN) and C, neoformans var. gat tii (CNVG) and to relate clinical manifestations to host immune status and cryptococcal variety. The mean annual incidence per 10(6) population was 6. 6 in Australia and 2.2 in New Zealand, Of 312 episodes, CNVN caused 265 (85 %; 98% of the episodes in immunocompromised hosts) and CNVG caused 47 (15%; 44% of the episodes in immunocompetent hosts). The incidence of AIDS-assoc iated cases in Australia declined annually (P <.001), Aborigines in rural o r semirural locations (P <.001) and immunocompetent males (P <.001) were at increased risk of CNVG infection. Cryptococcomas in lung or brain were mor e common in immunocompetent hosts (P less than or equal to.03) in whom ther e was an association only between lung cryptococcomas and CNVG, An AIDS-ass ociated genetic profile of CNVN serotype A was confirmed by random amplific ation of polymorphic DNA analysis. Resistance to antifungal drugs was uncom mon. The epidemiology of CNVN infection has changed substantially. Clinical manifestations of disease are influenced more strongly by host immune stat us than by cryptococcal variety.