Cryptosporidiosis frequently asked questions

What is cryptosporidiosis?
Cryptosporidiosis is a diarrhoeal disease caused by a microscopic parasite (Cryptosporidium). Once an animal or person is infected, the parasite lives in the intestine and passes in the stool. The parasite is protected by an outer shell that allows it to survive outside the body for long periods of time and makes it very resistant to chlorine-based disinfectants. It can survive temperatures greater than 70oC. It is found (particularly in water) through the world.

How is cryptosporidiosis spread?
Cryptosporidium lives in the intestine of infected humans or animals. Millions of parasites can be released in a bowel movement from an infected human or animal. It is therefore found in soil, food, water, or surfaces that have been contaminated with human or animal faeces. It is a common cause of waterborne outbreaks of gastroenteritis. 

What are the symptoms of cryptosporidiosis?
The most common symptom of cryptosporidiosis is watery diarrhoea. Other symptoms include:

  • Dehydration
  • Weight loss
  • Stomach cramps or pain
  • Fever
  • Nausea
  • Vomiting

Some people with cryptosporidiosis will have no symptoms at all.

How long after infection do symptoms appear?
Symptoms of cryptosporidiosis generally begin 2 to 10 days (average 7 days) after becoming infected with the parasite.

How long will symptoms last?
In persons with healthy immune systems, symptoms usually last about 1 to 2 weeks. The symptoms may go in cycles in which you may seem to get better for a few days, then feel worse again before the illness ends. It is a mild disease in healthy people. It is often more severe in small children and elderly people and can be very serious in those people who are immunocompromised (such as patients undergoing cancer treatment, those living with HIV). 

If you have cryptosporidiosis, how do you limit spread to other people?
Cryptosporidium can be quite contagious. These simple measures will reduce the likelihood of spread:

  • Wash your hands with soap and water after using the toilet, changing nappies, and before eating or preparing food.
  • Do not swim in recreational water (pools, hot tubs, lakes or rivers, etc.) if you have cryptosporidiosis and for at least 2 weeks after diarrhoea stops. Cryptosporidium can be spread in a chlorinated pool because it is resistant to chlorine.

Who is most at risk for cryptosporidiosis?
People who are most likely to become infected with cryptosporidium include:

  • Children who attend day care centres, including children in nappies.
  • Child care workers
  • Parents of infected children
  • International travellers
  • Backpackers, hikers, and campers who drink unfiltered, untreated water
  • Swimmers who swallow water while swimming in swimming pools, lakes, rivers, ponds, and streams
  • People who swallow water from contaminated sources.

During an outbreak of cryptosporidiosis, what measures will be taken to protect people's health?
If drinking water is contaminated (or suspected of being contaminated), a Boil Water Notice may be put in place. Householders will be instructed to boil any water that will be used for:

  • Drinking,
  • Making drinks with water,
  • Preparation of salads and similar foods, which are not cooked prior to eating,
  • Brushing teeth and
  • Making ice.

Water should be bought to the boil to make sure the parasite is killed and then left to cool. Do not use ice or cold drinks made with unboiled water.

Information on inadequate treatment of drinking water is available on the HSE website.

How should I make up my baby's infant feed?
Baby feeds should be prepared with tap water that has been brought to the boil once and cooled. Do not use water that has been reboiled several times. At all times, bottled mineral water should not be used to prepare baby feeds as most brands contain concentrations of minerals that are too high for babies.

Updated on: 5th July 2010