ARS | Publication request: EFFECT OF PASTEURIZATION ON INFECTIVITY OF CRYPTOSPORIDIUM PARVUM OOCYSTS IN WATER AND MILK

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 30, 1996
Publication Date: N/A

Interpretive Summary: Cryptosporidium parvum is a parasite that causes diarrhea in humans and other mammals. Several large outbreaks of human disease have been caused by C. parvum contamination of drinking water. Heat- treated bottled water could provide a safe alternative for people at high risk for C. parvum infection, such as children and AIDS patients. C. parvum is also commonly found on dairy farms, and could be transmitted to humans through contaminated milk. Thus, it is important to know if pasteurization kills C. parvum. In this study, C. parvum was suspended in either water or whole milk and pasteurized in a laboratory scale pasteurizer. Pasteurized C. parvum was then tested to see if it could cause disease in laboratory mice. No mice receiving pasteurized C. parvum became infected with the parasite. These results show that pasteurization kills C. parvum in water and milk.

Technical Abstract: Cryptosporidium parvum is a major cause of diarrheal disease in humans and has been identified in 78 other species of mammals. The oocyst stage, excreted in feces of infected humans and animals, has been responsible for recent waterborne outbreaks of human cryptosporidiosis. High temperature, long exposure time has been shown to render oocysts (suspended in water) noninfectious but, for practical purposes, it is important to know if high temperature-short time conditions (71.7 deg C for 15 sec) used in commercial pasteurization are sufficient to destroy infectivity of oocysts. In this study, oocysts were suspended in either water or whole milk and heated to 71.7 deg C for 15, 10, or 5 sec in a laboratory scale pasteurizer. Pasteurized and non-pasteurized (control) oocysts were then tested for ability to infect infant mice. No mice (0 of 177) given 10**5 oocysts pasteurized for 15, 10, or 5 sec in either water or milk were found infected with C. parvum, based on histologic examination of the terminal ileum. In contrast, all (80 of 80) control mice given non- pasteurized oocysts were heavily infected. These data indicate that high temperature-short time pasteurization is sufficient to destroy infectivity of C. parvum oocysts in water and milk.