Newman and colleagues [1] describe new evidence for person-to-person transmission of Cryptosporidium parvum in urban households of northeast Brazil. They acknowledge the potentially catastrophic effects of high rates of human immunodeficiency virus (HIV) infection in endemic areas of C. parvum infection. Although the endemic rate of C. parvum infection is lower in the United States, microcosms of HIV infection exist in which introduction of a single case of cryptosporidiosis could also be catastrophic. For example, an outbreak of cryptosporidiosis among HIV-infected patients in an infectious diseases ward in Denmark was traced to an ice machine contaminated by a psychotic, incontinent patient with the acquired immunodeficiency syndrome (AIDS) who had cryptosporidiosis [2]. Group residential homes provide another location in which Cryptosporidium can be transmitted from one HIV-infected person to another, either by person-to-person transmission or by environmental contamination.

In the summer of 1992, we noted a cluster of cases of cryptosporidiosis among residents of two group residential homes for HIV-infected persons in the Raleigh-Durham area of North Carolina. Four cases of intestinal cryptosporidiosis occurred among the residents of the two group residential homes. The index case had previously been diagnosed with cryptosporidiosis before moving into the house. Subsequently, two of the four remaining residents of the home developed cryptosporidiosis. Possible sources of environmental transmission included a common ice bucket and a common hand towel in the bathroom used by residents. During the same period, a resident of another home developed cryptosporidiosis. None of the other five residents of that home developed cryptosporidiosis. Infection control practices were more strict because of heightened awareness related to recent diagnosis of the three cases in the other home.

Group residential homes for HIV-infected patients provide a valuable service to patients who do not have family or friends willing or able to care for them. However, there is a high risk for transmission of cryptosporidiosis from one resident to another because of the high prevalence of Cryptosporidium as a cause of diarrhea among HIV-infected persons [3], the prolongation and increased severity of symptoms in persons with greater immunosuppression [4], lack of effective treatment [3], and difficulty in eradicating the organism from the environment [5]. To reduce the potential for transmission of C. parvum in group residential homes, we recommend the use of strict infection control practices, including strict hand-washing after the use of the bathroom and before and after food preparation and eating, use of paper towels instead of a common cloth towel in communal areas, and use of a separate ice dispenser with a designated scoop. Environmental surfaces must be cleaned with full-strength bleach or 5% ammonia for more than 15 minutes to eradicate C. parvum.