title: Seasonality and factors associated with cryptosporidiosis among individuals with HIV infection.
abstract: The seasonality and factors associated with Cryptosporidium infection were assessed in a cohort of HIV-infected patients in Los Angeles County to better define the epidemiology of cryptosporidiosis among individuals with HIV. Data were analysed from a cohort of 4247 patients > or = 13 years of age with HIV infection enrolled from four outpatient facilities in Los Angeles, 1990-6. Cryptosporidiosis was 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 trend with the highest rates occurring in March-May and September-October. There was no difference in the rate of cryptosporidiosis for the periods of heaviest rainfall (December-March) and low rainfall (April-November). Infection rates were higher among males (1.59 per 100 person-years) than females (0.92) and lower in blacks (0.98) than other racial/ethnic groups (1.80). A significant trend of decreasing cryptosporidiosis was observed with increasing age, with the highest rate (2.34) in the 13-34 year age group. A strong association between cryptosporidiosis and CD4+ count was noted. These data suggest that cryptosporidiosis among HIV-infected individuals in Los Angeles County exhibits a modest spring and fall seasonality. This pattern of occurrence of cryptosporidiosis appears temporally unrelated to local rainfall patterns. Our findings suggest that HIV-infected men, individuals in younger age groups and those with CD4+ lymphocyte counts < 100 x 10(6)/l are at increased risk of cryptosporidiosis. Blacks with HIV infection appear less likely than other racial/ethnic groups to be diagnosed with Cryptosporidium infection. These results may provide insight into possible routes of transmission and sources of cryptosporidiosis infection in individuals with HIV.
authors.affiliation: HIV Epidemiology Program, Los Angeles County Department of Health Serivces, Los Angeles, CA 90005, USA.
authors.forename: F
authors.initials: F
authors.lastname: Sorvillo
authors.forename: G
authors.initials: G
authors.lastname: Beall
authors.forename: P A
authors.initials: PA
authors.lastname: Turner
authors.forename: V L
authors.initials: VL
authors.lastname: Beer
authors.forename: A A
authors.initials: AA
authors.lastname: Kovacs
authors.forename: P
authors.initials: P
authors.lastname: Kraus
authors.forename: D
authors.initials: D
authors.lastname: Masters
authors.forename: P R
authors.initials: PR
authors.lastname: Kerndt
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003457:Cryptosporidiosis / Q000150:complications* / Q000453:epidemiology*; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000453:epidemiology*; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D012621:Seasons; D016019:Survival Analysis