Cryptosporidiosis is the commonest protozoal cause of diarrhoea in the UK. Two species, Cryptosporidium hominis and Cryptosporidium parvum account for the majority cases.

• Cryptosporidiosis is more common in immunocompromised patients (e.g. HIV) and young children.
• 1 week incubation, symptoms for several weeks

PC

• watery diarrhoea
• abdominal cramps
• fever
• in immunocompromised patients, the entire gastrointestinal tract may be affected resulting in complications such as sclerosing cholangitis and pancreatitis

Investigations

• stool: modified Ziehl-Neelsen stain (acid-fast stain) of the stool may reveal the characteristic red cysts of Cryptosporidium

Management

• is largely supportive for immunocompetent patients
• if the patient has HIV and is not on antiretroviral therapy then this should be started and often will be enough to resolve the infection
• nitazoxanide may be used for immunocompromised patients
• rifaximin is also sometimes used for immunocompromised patients/patients with severe disease