infections
Overview of Parasitic Infections
Diagnosis of Parasitic Infections
Laboratory analysis of samples of blood, stool, urine, skin, or sputum (phlegm) Doctors suspect a parasitic infection in people who have typical symptoms and who live in or have traveled to an area where sanitation is poor or where such an infection is known to occur. Laboratory analysis of specimens, including special tests to identify proteins released by the parasite (antigen testing) or genetic material (DNA) from the parasite, may be needed. Samples of blood, stool, urine, skin, or sputum may be used, depending on which parasite doctors are looking for. Doctors may test blood samples for antibodies to the parasite. Antibodies are proteins produced by the immune system to help defend the body against a particular attack, including that by parasites. Doctors may also take a sample of tissue that may contain the parasite. For example, a biopsy may be done to obtain a sample of intestinal or other infected tissue. A sample of skin may be snipped. Several samples and repeated examinations may be necessary to find the parasite. If parasites live in the intestinal tract, the parasite or its eggs or cysts (a dormant and hardy form of the parasite) may be found in the person’s stool when a sample is examined under a microscope. Or parasites may be identified by testing the stool for proteins released by the parasite or genetic materials from the parasite. Antibiotics, laxatives, and antacids should not be used until after the stool sample has been collected. These medications can reduce the number of parasites enough to make seeing the parasites in a stool sample difficult or impossible. 