Rarity of Cryptococcal Infection in Children

To The Editors: The article by Gonzales et al.1 describes the clinical aspects of cryptococcosis in HIV-infected children and confirms the low incidence of this infection as compared with HIV-infected adults (0.85% compared with 5 to 15%). The infrequency of cryptococcosis in children has been noted previously2 and confirmed by our population-based survey (1980 to 1990)3 in which only 1 of 133 cryptococcosis cases occurred in a child younger than 16 years (age 15 years, non-HIV-related). This equates to a population-based pediatric incidence for Victoria of 0.1 cases per million per year. The rate for HIV-infected individuals in Victoria (1984 to 1990; all adults) was 55 432 cases per million per year compared to 8457 for the HIV-infected pediatric population reported by Gonzalez et al.1 Pediatric HIV infection in Victoria is also rare; AIDS data to September, 1996, show a total of eight AIDS cases younger than 16 years4 one of whom developed cryptococcosis (age 15 years; K. Grimwood, Royal Childrens Hospital, Melbourne, Australia, personal communication). The authors also suggest that the low incidence of cryptococcosis in children may reflect their lower exposure to sources of Cryptococcus neoformans. We report here evidence in support of this hypothesis. Utilizing a cryptococcal polysaccharide-based enzymelinked immunosorbent assay to investigate the seroepidemiology of cryptococcosis, we found that children ages 5 to 15 years (98 hospitalized noncryptococcal controls) had a seroprevalence of 5%, compared with 100% for the study population of immunocompetent adults with cryptococcosis.5 We have since tested further children including infants and neonates; overall the seroprevalence in 172 children ages 5 years and older was 4.1%, and 23 infants and neonates were all seronegative. In contrast the seroprevalence in adult blood donors was 69%. Hence, these data support the contention that the rarity of cryptococcosis in children and adolescents is most likely a consequence of lack of exposure to sources of C. neoformans. Bryan R. Speed, F.R.A.C.P. Jakov Kaldor, M.App.Sci.