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Parasites and Testing
There are a variety of lab tests for parasites in humans. The Centers for Disease Control and Prevention (CDC) defines a parasite as “an organism that lives on or in a host and gets its food from or at the expense of the host". The CDC further explains that while the majority of parasitic infections occur in tropical and subtropical communities, they do also occur in people of developed countries.
The CDC’s A-Z listing of parasitic diseases contains more than 100 entries, including trichomoniasis, tapeworm infection, swimmer’s itch, malaria, head lice infestation, giardiasis, crabs and foodborne diseases.
The following are some of the lab tests used to identify parasitic conditions in humans.
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Ova and Parasite Exam
The ova and parasite (O&P) exam checks for gastrointestinal tract parasites using a microscopic evaluation of the patient’s stool sample. The type of parasite can be identified by the size, shape and internal structure of the parasites and ova present in the sample.
Gastrointestinal parasitic infections generally occur when a person consumes contaminated food or water. It should be noted that the food and water may not have any indication in smell, taste or appearance that it has been contaminated.
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T. Vaginalis Test
T. vaginalis is a protozoan, microscopic parasite that is picked up through sexual contact with an infected person. This parasite can cause prostatitis and urethritis in men; vaginal infections in women.
To test for the presence of this parasite in men, a urethral swab is used. In women, the tested sample can come from a Pap smear or a cervical or vaginal secretion swab may be used.
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African Trypanosomiasis (African Sleeping Sickness) Testing
There are two types of infection that can occur in African trypanosomiasis. The parasite can be identified through microscopic testing of tissues or body fluids.
To test for T.b. rhodesiense infection, lymph node fluids can be used. To test for T. b. gambiense infection, lymph node aspirate should be used.
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Known as a soil-transmitted helminths, hookworms are parasites that live in the small intestine. Infection can occur in a person who defecates outdoors near bushes, tall grasses, trees or other foliage or if an infected person’s feces is used as fertilizing manure on foliage and produce.
According to the CDC, approximately 576 to 740 million people worldwide are infected with hookworms.
A microscopic examination of a stool sample can identify the presence of hookworm in an infected patient.
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Lab tests for parasites are generally simple blood, tissue or stool sample evaluations. Some parasitic infections present symptoms in patients, while others do not, so any person who is at risk for a parasitic infection should be screened.
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Ova and Parasite Exam. Lab Tests Online. http://www.labtestsonline.org/understanding/analytes/op/sample.html
Parasites. Centers for Disease Control and Prevention (CDC). http://www.cdc.gov/parasites/