Emerging public health concerns regarding cryptosporidiosis

C ryptosporidium parvum, a ubiquitous, highly infec- tious protozoan parasite, has recently emerged as a major worldwide public health concern.The single most dramatic event that highlighted emerging concerns of the scientific community, public health officials, and drinking water providers was a waterborne outbreak in Milwaukee in 1993 in which 403,000 people became ill, and 54 died. 1 In response to rising concern, cryptosporidiosis was targeted for active surveillance in 1997 under the Foodborne Disease Active Surveillance Network (FoodNet) program as an emerging pathogen.This is a joint initiative in which the Centers for Disease Control and Prevention, the Food and Drug Administration, and the USDA Food Safety and Inspection Service (USDA-FSIS) carry out active surveillance in collaboration with state and local health departments.In 1997, 468 confirmed identifications of Cryptosporidia spp were made at 4 FoodNet survey sites in California, Connecticut, Minnesota, and Oregon.2,3 In 1998, the number of survey sites was extended to 7 to include sites in Georgia, Maryland, and New York, and 565 confirmed identifications of Cryptosporidia spp were made.4 Since the original identification of C parvum in 1912 in the small intestines of mice, this species has been identified in more than 80 species of mammals worldwide.5 However, it was not until the 1970s that C parvum was recognized as a causative agent for diarrhea in young calves and other livestock.6 In 1976, C parvum was recognized as an enteric human pathogen associated with diarrhea in immunocompetent 7 and immunocompromised 8 hosts.In immunocompetent individuals, the acute diarrheal episode is usually selflimiting and lasts 7 to 14 days, along with abdominal pain, vomiting, anorexia, fever, flu-like symptoms, and weight loss.However, in patients with Acquired Immunodeficiency Syndrome (AIDS), the intensity and duration of diarrhea and accompanying malabsorption and dehydration have potentially fatal conse-quences.Other vulnerable individuals include young children, pregnant women, and individuals being treated with immunosuppressive drugs.5 Cryptosporidium is 1 of 5 coccidian genera that infect humans.Molecular techniques allow detection of different gene sequences among isolates of oocysts thought to be C parvum and similarities among oocysts of different species.Cryptosporidium parvum, C muris, C wrairi, and C felis have been identified in mammals, C meleagridis and C baileyi in birds, C serpentis in reptiles, and C nasorum in fish.9 Cryptosporidium parvum remains the primary focus of public health concern.Evidence is emerging that suggests the existence of several genotypes of C parvum, one with a life cycle confined to humans, independent of the cycle in other mammals.This development is important with regard to epidemiologic investigations that may have a bearing on instituting proper control measures against C parvum.The purpose of this report was to examine the potential role of food as a vehicle in the spread of cryptosporidiosis.