Diagnosing Giardia lamblia infection

Giardiasis can cause watery or greasy diarrhoea, bloating, cramps, excess gas, nausea and tiredness. Symptoms may begin after unsafe water, contaminated food, swallowing water while swimming or close contact with an infected person. Tell the clinician about travel, household illness, childcare exposure and when symptoms began.

A stool sample is checked for Giardia or its markers. More than one sample may be requested because the parasite is not released constantly. Testing also helps separate giardiasis from bacterial infection, intolerance and other causes of diarrhoea. A clinician may assess hydration and ask about weight change or difficulty eating.

Arrange a GP consultation if diarrhoea continues, returns after travel or is accompanied by persistent bloating, cramps or weight loss. Drink suitable fluids and wash hands with soap after using the toilet and before preparing food. Avoid preparing food for others while unwell. Do not take antibiotic treatment without a clinician’s advice; the choice depends on the confirmed cause and your health history.

Seek urgent care for severe dehydration, fainting, confusion, very little urine, blood in stool, severe abdominal pain, repeated vomiting or an inability to keep fluids down. Babies, older adults, pregnant people and those with weakened immunity may need earlier assessment when diarrhoea develops.

Ask how to collect and store the stool sample, whether repeat samples are needed, and what other infections or conditions are being considered. Ask how to protect household members, when you can return to work or school, and what improvement should look like after prescribed treatment.