Cryptosporidiosis

Cryptosporidiosis is a diarrhoeal illness caused by the microscopic parasite Cryptosporidium, spread through contaminated water or food. It usually causes a short, self-limiting illness in healthy people but can be prolonged and severe in those with weakened immunity, particularly advanced HIV infection.

• Watery diarrhoea, which can be profuse
• Abdominal cramps
• Nausea and mild fever
• Weight loss with prolonged illness
• In people with advanced HIV or other significant immune suppression, diarrhoea can be severe, prolonged, and associated with significant weight loss and dehydration

• Caused by the parasite Cryptosporidium, which is resistant to standard chlorine water treatment, making it a notable cause of waterborne outbreaks.
• Spread through the faecal-oral route via contaminated drinking or recreational water, contaminated food, or contact with infected animals or people.
• Risk of severe, prolonged disease is greatly increased in people with advanced HIV infection or other significant immune suppression.

• Diagnosed through stool microscopy or specific testing for Cryptosporidium, which may require a specific request to the laboratory as it is not always detected on routine stool examination.
• Persistent diarrhoea in someone with known or suspected advanced HIV should prompt specific testing for this and other opportunistic causes.

In healthy people, cryptosporidiosis usually resolves on its own within one to two weeks with supportive care — adequate fluids and rehydration, and rest.

Oral rehydration solution is important to prevent or treat dehydration, particularly given the profuse, watery nature of the diarrhoea.

In people with weakened immunity, particularly advanced HIV, the most important treatment is optimising immune function — starting or improving control of antiretroviral therapy — as this is often more effective than antiparasitic medicine alone in this group.

A specific antiparasitic medicine (nitazoxanide) may be used, though it is less effective in people with severe immune suppression until their immune function improves.

• Drink water from safe sources, or boil or filter water, particularly in areas with uncertain water treatment.
• Wash hands thoroughly after using the toilet, changing nappies, or contact with animals.
• Avoid swallowing water while swimming in pools, lakes, or rivers.
• For people with advanced HIV, adherence to antiretroviral therapy is an important protective measure against severe cryptosporidiosis.