Clinical Testing and Diagnosis for Giardia Infection (2024)

FAQs

Clinical Testing and Diagnosis for Giardia Infection? ›

To help diagnose giardia infection (giardiasis), your doctor is likely to test a sample of your stool. For accuracy, you may be asked to submit several stool samples collected over a period of days. The samples are then examined in a lab for the presence of parasites.

To see if Giardia is making you sick, a healthcare provider will ask you for one or more stool (poop) samples. They will send your samples to a laboratory to check if you have Giardia germs in your poop. If the laboratory finds Giardia in your poop, it means you have a Giardia infection.

Direct fluorescent antibody (DFA) assay

This technique offers the highest combination of sensitivity and specificity and is considered the gold standard by many laborato ries.

The capsule dissolves and the string continues via peristalsis into the duodenum. After about 4 hours the string is retrieved, and the mucous at the end of it is examined for parasites. Either a direct wet mount or a permanent stained smear can be made. This technique is ideal for finding Giardia sp.

Testing water for Giardia requires filtering 10 to 50 liters of water and having a trained analyst inspect the concentrated sample with a microscope. This testing typically costs several hundred dollars through an accredited water testing laboratory.

Diagnosis is usually by demonstration of cysts or antigens in fecal samples. Treatment regimens are variable and depend on specific indications. Hygiene measures are an essential component of control. Giardiasis is an intestinal infection with the protozoan parasite Giardia spp.

Detection of antigens on the surface of organisms in stool specimens is the current test of choice for diagnosis of giardiasis and provides increased sensitivity over more common microscopy techniques.

Giardia infection in dogs may lead to weight loss, chronic intermittent diarrhea, and fatty stool. The stool may range from soft to watery, often has a greenish tinge, and occasionally contains blood. Infected dogs tend to have excess mucus in their feces.

Enzyme immunoassay (EIA) technologies have been used to develop commercial products for the detection of Cryptosporidium oocysts and Giardia cysts. These assays can be performed in a few hours using a microplate format, and the results read using a spectrophotometric plate reader.

What type of fecal testing is used to detect amoeba Giardia? ›

Sometimes, doctors also order an ova and parasite (O&P) test, which checks a stool sample for parasites. The Giardia test can better find Giardia lamblia than the O&P test, but can't identify other parasites that might be causing the GI problems.

Overview. For a giardia antigen test, a stool sample or fluid from the upper part of the intestines (duodenal fluid) is tested in the lab for the presence of antigens from Giardia lamblia. This test is often done at the same time as a stool analysis.

The sensitivity and specificity of the antigen test in this patient group can therefore be calculated to be 60.7% and 96.7%, respectively, if using microscopy as the reference standard.

Giardiasis is diagnosed by the identification of cysts or trophozoites in the feces, using direct mounts as well as concentration procedures. Cysts are typically seen in wet mount preparations, while trophozoites are seen in permanent mounts (i.e. trichrome).

Symptoms usually begin 1 to 2 weeks after becoming infected with Giardia and last for 2 to 6 weeks.

What happens if Giardia is left untreated? Untreated Giardia infection often goes away by itself. But if it doesn't, it can cause long-term complications for your digestive system, and even your immune system. It's important to see a healthcare provider if you have symptoms lasting longer than six weeks.

CDC recommends collecting three stool samples from patients over several days for accurate test results. Commercial testing products for diagnosing giardiasis are available in the United States. CDC recommends retesting for Giardia only if a patient's symptoms continue after their treatment is complete.

Routine laboratory tests (eg, complete blood cell count, electrolyte levels) are often unremarkable. Eosinophilia is a rare feature of giardiasis. Because immunoglobulin G (IgG) levels remain elevated for long periods, they are not beneficial in making the diagnosis of acute giardiasis.

You can take steps to avoid getting or spreading Giardia. Key steps include washing your hands, avoiding unsafe water or food, and not touching animal poop. If a person or pet in your home has a Giardia infection, clean and disinfect areas where they recently had diarrhea.