Cryptosporidium as a cause of human illness has only been recognized since 1976. The disease gained national attention in 1993 when an outbreak of cryptosporidiosis affected over 400,000 people in Milwaukee. The source of this outbreak was the city’s water treatment system.

People become infected when they inject the infective cysts of this protozoan parasite. Disease symptoms usually include diarrhea, abdominal cramps, nausea, and less frequently fever, headache, and vomiting. Persons with healthy immune systems improve without medication. Those with compromised immune systems, including AIDS patients, cancer patients undergoing chemotherapy, transplant patients, the very young, and the elderly, may develop a severe, long-lasting infection, with diarrhea, that persists for several weeks to months, or even years.

Exposure to this infection can be minimized by:

• Washing hands after any possible contact with human or animal feces, and before and prior to handling food.
• Avoiding drinking or accidentally swallowing water from rivers, lakes, streams, swimming pools or jacuzzis.
• The most certain treatment to destroy Cryptosporidium is to bring water to a rolling boil for one minute (Add an additional minute for each 1,000 feet above sea level). Boiling will also destroy other organisms causing waterborne disease.
• A far less reliable treatment is the use of portable water filters combined with disinfection. Some claim to remove Cryptosporidium oocysts, but test protocols are not uniform in the industry and many have not been tested in unbiased laboratories. Purchase only from reputable dealers, and check product literature to ensure that the filter is labeled according to filter manufacturing standards as at least an "Absolute" 1 micron filter, or one labeled as meeting American National Standards Institute (ANSI/NSF) (formerly the National Sanitation Foundation) International Standard #53 for "Cyst Removal" followed by disinfection. Add 8 drops of bleach or 20 drops of tincture of iodine per gallon of water and let stand for 30 minutes. No other filters are reliable for removing Cryptosporidium.

For short trips, take a supply of water from home or from other treated domestic sources. Due to the lack of labeling and manufacturing standards, there is no assurance that bottled water is safer than public drinking water and may require boiling also.

Reference:
Health Information, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Department of Health and Human Services.