Giardiasis

Giardiasis is an intestinal infection caused by a parasite that is usually acquired by swallowing contaminated material.

The parasite can be present in water, food, surfaces or hands that have been contaminated with stool. Infection may be mild, but it can also cause digestive symptoms that disrupt work, travel and normal eating.

Diarrhoea is a very common presentation of giardiasis. Abdominal pain and bloating are also common, and stools may be loose, greasy or particularly unpleasant smelling. Nausea, reduced appetite, tiredness and weight loss can occur when symptoms persist.

Seek urgent care for signs of serious dehydration such as confusion, marked drowsiness, very little urine, or inability to keep fluids down. Babies, older adults and people with a weakened immune system may need earlier assessment.

Giardia parasites spread when material containing stool reaches the mouth. This can happen after drinking untreated water, eating contaminated food, swallowing water during recreation, close contact with an infected person, or inadequate handwashing after using the toilet or changing nappies.

The infection can spread in homes, childcare settings and during travel when hand hygiene or safe water access is difficult.

Symptoms may begin after an exposure and can continue for some time if the infection is not recognised. Some people recover with supportive care, while ongoing diarrhoea, weight loss or recurrent symptoms need assessment. Gut sensitivity can persist briefly after the parasite has cleared.

Risk may be higher when using untreated drinking water, travelling where sanitation is unreliable, caring for a person with diarrhoea, attending childcare, or having close contact that allows contamination to pass from hands to mouth.

A clinician will ask about the diarrhoea pattern, travel, water exposure, food, contacts and medicines. A stool sample can be tested for Giardia. More than one sample may be requested because the parasite is not always present in every sample.

Other causes of diarrhoea may need consideration, especially when there is fever, blood in the stool, severe pain or persistent illness.

Care focuses on replacing fluids and salts, maintaining food intake as tolerated, and treating the parasite with prescribed antimicrobial medicine when indicated. A clinician can select a medicine based on your symptoms, pregnancy status, allergies and other medicines.

Take the treatment exactly as prescribed and discuss continuing symptoms rather than taking leftover antibiotics. Avoid preparing food for others while diarrhoea is active.

Drink little and often if large drinks worsen nausea. Simple foods can be reintroduced as appetite returns. Wash hands before eating or preparing food, and use separate towels where practical until the diarrhoea has settled.

Arrange a GP appointment for persistent diarrhoea, abdominal symptoms after travel or untreated water exposure, or symptoms affecting hydration and nutrition. Prompt assessment is especially helpful for young children, pregnancy, older age or reduced immunity.