Cryptosporidium infection - including symptoms, treatment and prevention

Cryptosporidium infection (cryptosporidiosis or 'crypto') is an infection of the bowel caused by the parasite Cryptosporidium which can result in gastroenteritis (also known as 'gastro').

Cryptosporidium infection is a notifiable condition1

How Cryptosporidium is spread

The Cryptosporidium parasite may be transmitted person-to-person. Infection is also spread:

  • directly - by drinking or swimming in contaminated water and eating uncooked food (such as fruits and vegetables) contaminated with Cryptosporidium
  • indirectly - when hands, objects and surfaces are contaminated with faeces of infected people or animals (cows and other domestic animals).

The parasite must be taken in by the mouth to cause infection.

Signs and symptoms of Cryptosporidium infection

The main symptom is watery diarrhoea which occurs with stomach cramps. Fever, vomiting and loss of appetite occur less commonly. Symptoms in people with normal immune systems usually last for about 1 to 2 weeks. People with severe immune suppression, particularly those with advanced HIV infection, may have severe, prolonged diarrhoea.

Diagnosis of Cryptosporidium infection

The infection is diagnosed by examining a specimen of faeces under a microscope or by detecting Cryptosporidium in a faecal sample using a PCR (polymerase chain reaction) test in a pathology laboratory.

Incubation period

(time between becoming infected and developing symptoms)

1 to 12 days with an average of 7 days.

Infectious period

(time during which an infected person can infect others)

As soon as the infected person develops symptoms and for up to several weeks after the disappearance of symptoms.

Treatment for Cryptosporidium infection

For those with normal immune systems, specific treatment is not required.

There is no available effective treatment for reducing diarrhoea in people with immune suppression.

The following are general recommendations for the treatment of gastroenteritis:

  • Give plenty of fluids. Oral rehydration solution is highly recommended for children with mild to moderate dehydration. It is available at pharmacies and should be administered following the instructions on the packaging.
  • Mildly unwell children should be given their usual fluids more often Carbonated (fizzy) drinks or undiluted juice should be avoided.
  • Medicines to prevent vomiting or diarrhoea should not be given (especially in children), except where specifically advised by a doctor.
  • Breastfed babies should continue to be breastfed throughout their illness.
  • Children on formula or solid diets should restart their normal diet (including full strength lactose containing milk) following rehydration with oral rehydration solution.
  • Children who are hungry or ask for food should be given small portions of their usual foods, but avoid foods high in sugar or fat.

When to seek medical advice

Seek medical advice if there are any of the following symptoms:


  • Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, feeling faint on standing
  • fever
  • severe abdominal pain
  • bloody diarrhoea.


  • Signs of dehydration, such as thirst and decreased urination, lethargy, dry mouth, sunken eyes, feeling faint on standing
  • fever
  • abdominal pain
  • bloody diarrhoea
  • any symptoms in a child less than 12 months of age.

Prevention of Cryptosporidium infection

  • Exclude people with Cryptosporidium infection from childcare, preschool, school and work until there has been no diarrhoea for at least 24 hours. If working as a food handler in a food business, the exclusion period should be until there has been no diarrhoea or vomiting for 48 hours.
  • Wash hands thoroughly with soap and water, paying attention to the backs of your hands, wrists, between fingers and under fingernails. Always wash your hands (even if you are wearing gloves):
    • before and after tending to someone who has Cryptosporidium infection
    • before preparing, handling or eating food
    • after using the toilet
    • after gardening
    • after changing nappies or assisting children with using the toilet
    • after coming into contact with animals, their faeces, or their environments.
  • Do not consume untreated ice or drinking water when travelling in countries where the water supply might be unsafe.
  • Avoid eating uncooked foods when travelling in countries with minimal water treatment and sanitation systems.
  • People who have diarrhoea should not use swimming pools or spa pools for 14 days after the symptoms have stopped. If you suspect someone with Cryptosporidium infection has recently used your pool or spa, see the swimming pool or spa pages on disinfection methods.
  • Babies and small children without diarrhoea who are not toilet trained should wear tight fitting waterproof pants or swimming nappies in swimming pools and changed regularly in the change room. When faecal accidents occur, swimming pools should be properly disinfected. See the swimming pool or spa pages on disinfection methods.
  • If a child in your household has Cryptosporidium infection, they should not share a bath with another child. After the infected child has been bathed, the bath should be emptied and cleaned with household bleach before refilling. Alternatively, a shower may be used rather than a bath as the risk of infection spreading through a shower is minimal.
  • Avoid touching farm animals, especially young calves and lambs.
  • Wash (with safe water) and/or peel all raw fruits and vegetables before eating.

Useful links

1 - In South Australia the law requires doctors and laboratories to report some infections or diseases to SA Health. These infections or diseases are commonly referred to as 'notifiable conditions'.