Is drinking water a risk factor for endemic cryptosporidiosis? A case-control study in the immunocompetent general population of the San Francisco Bay Area

BACKGROUND: Cryptosporidiosis, caused by Cryptosporidium, is an enteric illness that has received much attention as an infection of immunocompromised persons as well as in community outbreaks (frequently waterborne). There are, however, no studies of the risk factors for sporadic community-acquired cryptosporidiosis in the immunocompetent US population. We undertook a case-control study in the San Francisco Bay Area as part of a national study sponsored by the Centers for Disease Control and Prevention to ascertain the major routes of transmission for endemic cryptosporidiosis, with an emphasis on evaluating risk from drinking water. METHODS: Cases were recruited from a population-based, active surveillance system and age-matched controls were recruited using sequential random-digit dialing. Cases (n = 26) and controls (n = 62) were interviewed by telephone using a standardized questionnaire that included information about the following exposures: drinking water, recreational water, food items, travel, animal contact, and person-to-person fecal contact, and (for adults) sexual practices. RESULTS: In multivariate conditional logistic regression analyses no significant association with drinking water was detected. The major risk factor for cryptosporidiosis in the San Francisco Bay Area was travel to another country (matched odds ratio [95% confidence interval]: 24.1 [2.6, 220]). CONCLUSION: The results of this study do not support the hypothesis that drinking water is an independent risk factor for cryptosporidiosis among the immunocompetent population. These findings should be used to design larger studies of endemic cryptosporidiosis to elucidate the precise mechanisms of transmission, whether waterborne or other

Natural history of AIDS related sclerosing cholangitis: a study of 20 cases.

A case control study of AIDS related sclerosing cholangitis indicates that it has no overall influence on prognosis, but is responsible for a striking reversal of the usual inverse correlation of age and survival in HIV infection. Pain, the principal symptom, was controlled in surviving patients with analgesics alone. Twenty consecutive patients with AIDS related sclerosing cholangitis, defined from at least two characteristic lesions at endoscopic retrograde cholangiopancreatography, were followed for a minimum of 10 months or until death. Median age was 33.5 years (range 27-50). All had abdominal pain; 11 had diarrhoea. Alkaline phosphatase was > 2X normal in 13, but the bilirubin was raised in only three. The median CD4 was 0.024 x 10(9)/l (0.005-0.341). Thirteen had cryptosporidiosis, six had active cytomegalovirus, five had no gastrointestinal pathogen. Three patients are alive without AIDS related sclerosing cholangitis symptoms at 10, 11, and 21 months. Seventeen have died at median 7 (1-23) months. Cytomegalovirus therapy had no apparent influence. The initial CD4 was < 0.11 in all those dying within six months, but correlation of CD4 with prognosis was otherwise poor. Controls, matched for age, CD4, and opportunistic infections had virtually identical overall outcome (median survival 7.5 months) and the expected worse prognosis with increasing age. Increasing age, however, appeared protective in AIDS related sclerosing cholangitis (r = +0.6; p < 0.05): this is not explained by disproportionate degrees of immunosuppression, nor by opportunistic infections