Cryptosporidiosis

Purpose of review: Cryptosporidiosis is a self-limited diarrheal disease that occurs in the community setting but can be chronic and potentially serious in immunocompromised patients. Community outbreaks are often associated with water-borne transmission. Cryptosporidium research has increased dramatically since the human disease was first recognized in 1976. The present review summarizes recent work in three of the several areas of active Cryptosporidium investigation. Recent findings: Molecular techniques have revealed that current taxonomic designations need re-evaluation and that humans are host to several Cryptosporidium spp. that were once believed to be limited to the veterinary realm. These findings have important public health implications for water quality standards in the USA and other developed countries. Second, techniques for detecting the parasite in infected individuals (or environmental samples) have progressed from acid-fast staining of fecal smears to the currently used antibody-based systems (enzyme immunoassays and immunofluorescent assays). New molecular methodologies, based on polymerase chain reaction amplification of gene loci, are being developed to improve the sensitivity and specificity for diagnostic and epidemiologic purposes. Third, curative therapy is attained only by an effective immune response or the reconstitution of a failing immune system in the compromised host. However, several drugs are in development, and compounds such as nitazoxanide appear to hold some promise. Summary: Cryptosporidiosis continues to be a serious problem in immunocompromised patients and on a worldwide scale in undernourished infants and children. The lack of an effective treatment, and the propensity of the parasite to survive in and be transmitted through source waters make this an important public health threat.