Food poisoning factsheets - Cryptosporidiosis infection

What is Cryptosporidiosis and how is it caught?

Cryptosporidiosis is the term for an infection with a microscopic single celled animal called Cryptosporidiosis parvum. The infection occurs all year round but there is often a rise in cases a couple of weeks after an episode of heavy rainfall following a long dry spell.

The main source of the organism is the human intestine and animal intestines. Affected animals and humans may be entirely well. Cryptosporidiosis is easily caught because only a small number of organisms are needed to cause infection.

It can be spread directly, for example the hands coming into contact with a contaminated animal and then touching the mouth, or indirectly whereby a person or animal contaminates a water source and another drinks from that water.

The time between getting the infection and becoming ill is usually between 3 and 10 days. The organisms are present in the stools for several weeks after an ill person becomes well again so infection can be transmitted to others throughout this period.

What are the symptoms and are there any long term complications?

In otherwise healthy people, symptoms are diarrhoea and abdominal pain, sometimes severe, and lasting 2 to 3 weeks before full recovery. Symptoms typically come and go over several weeks before the person recovers. A person can get Cryptosporidiosis and remain well. In people with impaired immune systems, Cryptosporidiosis is much more protracted and the symptoms may be far more severe.

Cryptosporidiosis can only be diagnosed by examining a stool sample in a laboratory. Normally there are no long‐term implications but there can be problems for those with impaired immunity.

How is Cryptosporidiosis treated and what can I do to prevent it?

There is no proven treatment for the condition. A drug called Spiramycin is sometimes used in patients with impaired immunity but it does not appear to be particularly effective.

There is no vaccine nor do you become immune to it long‐term. The most important means of avoiding infection is by strict hygiene, particularly after handling animals or dealing with babies and young children with diarrhoea.

Occasionally, contaminated water is the source of infection and the only way to make contaminated water fit to drink is to bring it to the boil. Just bringing it to the boil kills Cryptosporidium instantly, there is no need to hold it at the boil.

Cryptosporidium is resistant to disinfectants such as ammonia and chlorine.