Antigen Tests For Giardiasis

Submitted on March 27, 2012

Living beings are prone to infections. This includes all plants, animals, and human beings. Infections can be caused by various causative agents including bacteria, viruses, protozoa, fungi, and various other microbes. The carriers of all these various infections include air, water, soil, insects, animals, or humans themselves. From the very beginning, these infections have affected the lives of all human beings. A few infections include common cold, conjunctivitis, and flu to serious problems like giardiasis, leshmaniasis, kala-azar, and amoebiasis.

What Is Giardiasis?

Giardia lamblia causes giardiasis in humans, which is an infection in the small intestine. It is a cause of concern in the majority of the developing countries as the proportion of affected population is much higher than in the developed nations. It is wide spread in developing nations due to poor sanitation and contamination of food and water. An official study reports that giardiasis takes a toll of around 2.5 million human lives each year.

This protozoon can be observed or detected in stools. The most common reason for its spread is poor personal hygiene. It can be transferred through open fecal matter of humans or any mammalian species via a contaminated water source.


The most common symptoms of giardiasis are intestinal cramps, diarrhea, vomiting, fever, indigestion, anorexia, and fatigue. The treatment of giardiasis includes medication and chemotherapy. Various multi-drugs combinations are available to treat drug resistant strains.

Diagnostic Tests For Giardiasis

The initial diagnostic test for giardiasis is to detect the presence of ova and parasites in the stool. Other tests available are antibody assay or enzyme-linked immunosorbent assay (ELISA) for cyst antigens. However, other techniques like stool culture are not applicable here.

The examination of at least three different stools samples is done in order to confirm the presence of the infection. These are cheap tests and can be performed in all diagnostic centers. The antibody generating agents, or antigens, are tested after treatment with antigen- antibody tests so as to confirm the complete elimination of infection.

The specific presence of giardia pathogen antigens is confirmed by a change in color on addition of different chemicals to the antigen solution. In ELISA tests, antigens are linked to specific antibodies and when the enzyme solution is put into it, enzymes initiate the reaction and lead to the production of different colored products. These diagnostic tests are very specific and accurate in results.

Antigen tests can also be applied to detect giardiasis-like infectious states that are difficult, slow, or hazardous. Hence, giardiasis can be detected with antigen detection methods which are particularly useful for rapid diagnosis, whether in the clinic, emergency department, doctor’s office, or the central laboratory. In general, antibody tests for all of the antigen tests are available as commercial kits. In the case of giardiasis, Direct Fluorescent-antibody Assay (DFA); Enzyme Immuno Assay (EIA); Indirect Fluorescent-antibody Assay (IFA) and Rapid Immunochromatographic Diagnostic test (Rapid) are widely used.