SEASONALITY AND FACTORS ASSOCIATED WITH CRYPTOSPORIDIOSIS AMONG INDIVIDUALS WITH HIV-INFECTION

The seasonality and factors associated with Cryptosporidium infection were assessed in a cohort of HIV-infected patients in Los Angeles Coun ty to better define the epidemiology of cryptosporidiosis among indivi duals with HIV. Data were analysed from a cohort of 4247 patients grea ter than or equal to 13 years of age with HIV infection enrolled from four outpatient facilities in Los Angeles, 1990-6. Cryptosporidiosis w as diagnosed in 120 (2.8 %) patients. Among the 1296 individuals with complete follow-up until death, cryptosporidiosis occurred in 69 (5.3 %). The seasonal rate of cryptosporidiosis showed a modest bimodal tre nd with the highest rates occurring in March-May and September-October , There was no difference in the rate of cryptosporidiosis for the per iods of heaviest rainfall (December-March) and low rainfall (April-Nov ember). Infection rates were higher among males (1.59 per 100 person-y ears) than females (0.92) and lower in blacks (0.98) than other racial /ethnic groups (1.80). A significant trend of decreasing cryptosporidi osis was observed with increasing age, with the highest rate (2.34) in the 13-34 year age group. A strong association between cryptosporidio sis and CD4+ count was noted. These data suggest that cryptosporidiosi s among HIV-infected individuals in Los Angeles County exhibits a mode st spring and fall seasonality. This pattern of occurrence of cryptosp oridiosis appears temporally unrelated to local rainfall patterns. Our findings suggest that HIV-infected men, individuals in younger age gr oups and those with CD4+ lymphocyte counts < 100 x 10(6)/l are at incr eased risk of cryptosporidiosis. Blacks with HIV infection appear less likely than other racial/ethnic groups to be diagnosed with Cryptospo ridium infection. These results may provide insight into possible rout es of transmission and sources of cryptosporidiosis infection in indiv iduals with HIV.