Giardia (lamblia) in stool – laboratory test

Description

Why test for Giardia

Giardia lamblia is the most common small-intestinal parasite in Poland, particularly among children in nurseries and preschools and people who have travelled or swum in lakes. Infection occurs through swallowing cysts from water, food or dirty hands; symptoms appear after 1–3 weeks and can become chronic: watery or fatty diarrhoea, bloating, abdominal pain, weight loss and, in children, poor weight gain. The immunochromatographic test detects parasite antigens in stool; it is simpler and more sensitive than looking for cysts under a microscope because it does not depend on whether cysts are being shed at the time.

When to consider this test

• diarrhoea lasting more than 7–10 days, foul-smelling, fatty stools, bloating, nausea, weight loss,
• in children: recurrent abdominal pain, loss of appetite, poor weight gain, anaemia, attendance at nursery or preschool,
• after returning from countries with poor sanitation, or after drinking water from streams or lakes,
• for household members of someone diagnosed with giardiasis,
• a negative stool parasite test with persistent symptoms,
• checking treatment effectiveness after 2–4 weeks.

How to collect the sample

• Use a sterile container with a scoop (from a pharmacy or sample collection point). Pass stool into a clean, dry receptacle or a toilet collection tray, avoiding contamination with urine or water.
• Use the scoop to take material from three different areas, especially those containing mucus; fill approximately 1/4 of the container.
• Label the container (first name, surname, date, time). Deliver it as soon as possible, from Monday to Friday; keep it refrigerated until then.
• Do not collect during menstruation or when haemorrhoids are bleeding. Wait 7–10 days after barium and bismuth, and 2–3 weeks after antibiotics and antiparasitic medicines.
• If the result is negative and symptoms persist, repeat the test with another sample after 2–3 days; CDC recommends three samples collected over several days.

Understanding your result

The result is qualitative (present / absent), with no numerical value. Some infections cause no symptoms; carriers can infect others, so a positive result in a child without symptoms also usually leads to treatment.

Other tests to consider alongside this test

stool parasite test (other parasites), calprotectin (intestinal inflammation), stool culture, for weight loss and anaemia, full blood count and ferritin, and for chronic diarrhoea, coeliac disease antibodies. Read more: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Giardia in stool, Giardia lamblia antigen (immunochromatographic method, sampling from 3 areas, symptoms, routes of infection, turnaround time 4 days); CDC, Clinical Testing and Diagnosis for Giardia Infection (methods: microscopy with DFA, immunochromatography, EIA, PCR; recommendation to collect three stool samples over several days). This information does not replace a medical consultation.