Epidemiologic differences between the two varieties of Cryptococcus neoformans.

This report of the worldwide distribution of two varieties of Cryptococcus neoformans was drawn from data on 628 clinical isolates and from data on 97 additional isolates from other laboratories. Tests showed that 100% of the cultures from Austria, Belgium, Denmark, France, Germany, Holland, Italy, Switzerland, and Japan belonged to C. neoformans var. neoformans. More than 85% of the isolates from Argentina, Canada, the United Kingdom, and the United States (except southern California) were of C. neoformans var. neoformans, the remainder being of C. neoformans var. gattii . There was an unusually high prevalence (35-100%) of C. neoformans var. gattii in Australia, Brazil, Cambodia, Hawaii, southern California, Mexico, Paraguay, Thailand, Vietnam, Nepal, and countries in central Africa. These findings indicated that C. neoformans var. gattii is prevalent only in tropical and subtropical regions. Seventy per cent of the total isolates studied were of serotype A of C. neoformans var. neoformans. Serotype D (9% of the total) was common in Europe, but was found infrequently in other regions. Among the two serotypes of C. neoformans var. gattii , serotype B was 4.5 times more prevalent than serotype C. The majority (88%) of type C isolates in our collection were from southern California.

Epidemiologic differences among serotypes of Cryptococcus neoformans.

In the USA, the most prevalent serotype of the fungus, Cryptococcus neoformans, was serotype A. The serotype constituted 203 of 272 isolates from infections and 85 of 89 isolates from the environment. Serotype B or C isolates were infrequent causes of infection, except in Southern California, and were infrequent causes of infecand were not isolated at all from environmental sources. In Southern California, the absence of serotypes B and C in 67 soil and pigeon dropping isolates was striking, considering that 25 of 49 isolates from infections were serotypes B or C. The site in nature where serotypes B and C exist is currently unknown but differs from that of serotypes A and D. Serotype D may be unusually prevalent in both environmental and patient isolates from Denmark and Italy. Of 24 isolates from those countries, 21 were serotype D.