How to Diagnose Chagas Disease: Tests and Procedures
Categories: HEALTH
Chagas disease is diagnosed by looking for antibodies against the parasite in the chronic phase and by looking for the parasite itself during the acute phase.
Tests during the acute phase (first few weeks to months of infection):
Microscopic analysis of blood: The Trypanosoma cruzi parasite can be directly seen in the bloodstream using a blood smear, which is a quick and reasonably priced test. When parasite levels are high in the initial weeks following infection, this test works well.
Tests during the chronic phase (years to decades after infection):
a. Serologic tests (ELISA): The primary method for identifying chronic Chagas disease is blood testing. They identify antibodies that the T. cruzi parasite has caused your body to manufacture. There are several serologic tests available, the most popular of which is the enzyme-linked immunosorbent assay (ELISA). Further testing may be necessary, though, as a positive test does not always imply an ongoing infection—it merely signals exposure to the parasite. Two varieties of serologic tests exist:
•IFA (indirect fluorescent antibody): This test is highly specific but less sensitive than ELISA.
•IFI (indirect fluorescent antibody): This test is more sensitive than IFA but less specific.
b. Parasitologic tests: Though less frequently employed, these tests can be useful in verifying a diagnosis, particularly in those who’s serologic testing come up negative. Among them are:
c. Xenodiagnosis: In this procedure, an infected person's blood is used to feed kissing bugs that were produced in a lab. After a month, the intestines of the bugs are checked for parasites. This is a laborious test that is not easily accessible.
d. Hemoculture: This test attempts to grow the T. cruzi parasite from a patient's blood in a laboratory setting. It is also not widely available and has low sensitivity.
Other diagnostic tests:
Once chronic Chagas disease is confirmed, your doctor may recommend additional tests to assess potential damage to your heart, esophagus, or intestines. These tests may include:
a. Electrocardiogram (ECG): This test measures the electrical activity of your heart and can detect abnormal heart rhythms or damage to the heart muscle.
b. Echocardiogram: This test uses ultrasound waves to create images of your heart, allowing your doctor to assess the structure and function of your heart valves and chambers.
c. X-ray or CT scan of the chest or esophagus: These imaging tests can help identify enlargement of the esophagus (megaesophagus) or colon (megacolon).