Cryptosporidiosis

What is cryptosporidiosis?

Cryptosporidiosis is an infection of the intestines caused by a very small parasite. The disease is usually contracted by drinking contaminated water. Drinking water systems supplied from surface water sources (rain, creeks, rivers, lakes, etc.) are vulnerable to contamination by the faeces of infected animals.

What are the symptoms?

Symptoms usually start anywhere from two to ten days after exposure to the parasite, although not everyone who is infected with it will feel sick. If symptoms do occur, they may include watery diarrhea, stomach cramps, nausea, vomiting, and mild fever.

Symptoms may come and go and usually last fewer than 30 days in people who are otherwise healthy; however, the infection may last longer and be more serious in people whose immune system is not working properly. Persons with AIDS, those who have had an organ or bone marrow transplant, and those who have had cancer treatment are examples of people who may get serious infections.

How is it spread?

The parasite that causes Cryptosporidiosis is often found in the bowel movements (faeces) of infected humans and animals, such as rodents, pets, livestock (particularly cattle and sheep), poultry and other birds, reptiles, fish, and wild animals. These animals may have a bowel movement in or near rivers, creeks or lakes that are used as a source of drinking water.

It can be spread by eating uncooked food contaminated with Cryptosporidium. Thoroughly wash all vegetables and fruits you plan to eat raw with clean, safe water. It can also be spread by accidentally swallowing Cryptosporidium picked up from surfaces, such as bathroom fixtures, changing tables, diaper pails, or toys, contaminated with feces from an infected person.

Current methods used to treat drinking water do not always remove this very hardy parasite. One has to ingest the parasite to potentially become ill. The infection can also be spread from hand to mouth by accidentally putting something into your mouth or swallowing something that has come into contact with feces of a person or animal infected with Cryptosporidium (ie. by touching an infected animal, faecal matter from animals or their bedding and your hands and not washing your hands prior to eating). A person can also become infected by hand to mouth transfer of the parasite from contaminated surfaces or items. This is possible because the parasite can live outside of the body for several months under moist conditions.

Outbreaks of Cryptosporidiosis have occurred in daycare centres and in locations where drinking water (or beverages made from drinking water) or swimming pools have been contaminated. This parasite can be spread in a chlorinated pool because it is resistant to chlorine and, therefore, can live for days in chlorine-treated swimming pools. It is also spread by swallowing recreational water contaminated with Cryptosporidium (swimming pools, hot tubs, Jacuzzis, fountains, lakes, rivers, springs, ponds, or streams that can be contaminated with sewage or feces from humans or animals).

In many cases the source of infection is difficult to determine. Some people are more likely than others to become infected. They include health care workers, child care providers, children in daycare, those exposed to faeces through sexual contact, and those caring for a person infected with the parasite.

How can I prevent it?

Wash your hands well after going to the toilet or changing diapers and after touching farm animals, pets or wild animals. This is especially important before eating or preparing food. You should also avoid drinking water directly from rivers, creeks or lakes, or when you are uncertain whether the water has been properly treated, such as during foreign travel.

You should also avoid uncooked food or drinks which have been prepared with untreated water. Unpasteurized milk or milk products should be avoided. If you have a weakened immune system you should discuss your risk of cryptosporidiosis with your doctor. This includes people with HIV/AIDS, cancer and transplant patients taking immuno-suppressive drugs. People who wish to take extra precautions can boil their drinking water, as outlined below.

Water treatment against cryptosporidiosis

When travelling, camping or hiking, or when a "boil water" advisory has been issued by the local Medical Officer of Health, bring the tap water to a rolling boil for one minute. This is not effective in purifying water that is chemically contaminated. This boiled water should be used for drinking, brushing teeth, rinsing dentures or contact lenses, making ice cubes, washing uncooked fruit and vegetables, and in recipes which require water. Dishes, glasses and cutlery should be washed with water which has been boiled.

Bottled water can also be bought for these purposes. Make sure you break the seal on the bottled water yourself to ensure that the empty bottle was not simply re-filled with local untreated water. It is best to drink it straight from the bottle with a straw, or to pour it into a disposable cup.

Bottled water must meet certain federal health and safety standards, although as with other consumer products the quality of bottled water may vary from one distributor to the next. Persons who use bottled water as an alternative to boiled tap water should choose their supplier carefully to ensure that their product meets the level of purity they want. The most common and effective methods of purifying bottled water are ozonation, reverse osmosis and distillation.

Iodine, chlorine and portable household water filters are not effective against this parasite and should not be used to prevent Cryptosporidiosis.

In spite of doing all the right things, you may still become ill. Get medical attention if the illness doesn't go away within 48 hours.

If you have any questions contact Public Health or your doctor.

BC Ministry of Health and Ministry Responsible for Seniors Number 48, September 1995
CDC, September 2004