Giardiasis

Giardiasis is an intestinal infection in which a microscopic Giardia parasite colonises the small intestine and causes diarrhoea and bloating. It spreads through contaminated water or food, contact with infected people or animals, and unprotected anal or oral sex; travellers, campers and people in daycare or care homes are at particular risk. Typical features are smelly non-bloody diarrhoea, abdominal cramps, gas, nausea, loss of appetite and weight loss, although some infected people have no symptoms, and dehydration or malabsorption can complicate it. Stool tests, including antigen testing, polymerase chain reaction and examination for ova and parasites, confirm the diagnosis. Antibiotics such as tinidazole treat the infection, with a different antibiotic tried if symptoms persist; mild or symptom-free infections may need no treatment, and in most pregnant women treatment is delayed because some medicines can harm the unborn baby.

Seek urgent care for a high fever with a stiff neck, rash, confusion, difficulty breathing, or fever after travel to a malaria area. See a doctor when a fever lasts more than three days, when symptoms return after treatment, or when you may have been exposed to an infection that needs testing. Call the local emergency number for any symptom that is sudden and severe. This page is a reference for healthcare professionals and does not replace an assessment.