Accuracy of the Most Common Parasite Tests
There are 6 commonly used parasite tests. By comparing all 6, there is 1 parasite test that is most accurate for diagnosing parasitic infections.
Here are the 4 things you want to look for when evaluating your parasite test:
- How many species of parasites can it diagnose?
- How accurate is the test?
- Can the test tell the difference between an old parasite infection, and a current infection?
- How convenient is taking the test?
Ranking of the 6 Best Parasite Tests
Now we'll go through each of the 6 tests - ranking them from worst to best:
- Fecal Exam aka Ova & Parasite testing
- PCR (Parasite DNA) Testing
- Saliva Test
- Serology Blood Test
- Blood Smear
6. Endoscopy/Colonoscopy Parasite Test
What is an Endoscopy/Colonoscopy?
An endoscopy/colonoscopy involves sticking a small camera down your throat or up through your colon. Your gastroenterologist can look at a live video of your colon, or your stomach and small intestine.
How Can a Endoscopy/Colonoscopy Diagnose a Parasite Infection?
If your doctor spots a parasitic worm (helminth) in your intestines, then your doctor can diagnose a parasite infection.
How does this parasite lab test rate on the 4 criteria?
Range of parasites: Your doctor can only see large parasites with this method of diagnosis. Most parasites are microscopic - and can't be seen without magnification or other methods.
Accuracy: If your doctor can visually see a parasite wriggling around in your intestines, then you definitely have a parasite infection.
Differentiating Old and New Infections: Your doctor will only be able to see current infections.
Convenience: A colonscopy/endoscopy can only be performed with special equipment in a doctors office. Additionally, patients have to undergo uncomfortable bowel prep by taking a strong laxative.
I would personally not rely on a colonoscopy or endoscopy for complete diagnosis of parasite infections. Many parasites are invisible without staining and magnification, so it won't diagnose any parasites except the largest ones.
Click here to read our more in-depth analysis of the endoscopy/colonoscopy parasite test.
5. Blood Smear
The blood smear tests are very important for diagnosing blood-borne parasites. However, only certain parts of the world are endemic with these types of parasites. For example, the parasites that cause malaria and sleeping sickness (African trypanosomiasis) would be diagnosed by a blood smear test. But unless you've been travelling to parts of the world where these types of parasites are endemic, these blood smears would not be helpful in finding parasites.
So the accuracy of this test is very high, but the range of parasites is too limited for it to be useful for most people reading this website. Therefore I would not rate this as useful for most people. Be sure to refer to the CDC website to see if you're travelling to a place that is endemic with blood borne parasites.
4. Saliva Test + 3. Blood Test - Serology
In this test, blood is drawn (or saliva collected) and then tested for antigens and antibodies that are specific to certain parasites. While this is a relatively painless procedure, it has some serious drawbacks.
Here are the drawbacks:
- If you ever get infected by a parasite, you'll have antibodies and antigens in your body for life. So a positive test could mean you had an infection a decade ago and your body fought it off. Or, it could mean you are currently infected with parasites. Unfortunately these tests are also useless for knowing if you've beat the infection after treatment.
- The blood tests only look for specific species. For example, 3 parasites species of the genus schistosomiasis cause urinary issues. If your doctor's test kit only tests for 2 of the 3, then you could have a parasite infection, but have a negative test.
Blood Parasite Test vs. Saliva TestSaliva has fewer antibodies than blood. So that means the saliva test will show fewer antibodies. So that could mean that had were are are infected by a parasite, but your saliva may not show that.
The saliva test is convenient, but it has the same limitations as the blood test. Worse still, it may show you aren't infected with a parasite, even if you currently are infected.
2. PCR - Parasite DNA Testing
This test is quite amazing and can give testing results very quickly (as fast as 24 hours). Essentially the technician takes a stool sample, puts it into a machine, and it tells you which parasite DNA it has found.
According to my teacher Emma Lane of Integrative Health in the UK, PCR has a strong future in parasite testing. But, she also says that it isn't the ideal way to test for parasites today.
There are serious drawbacks to using PCR technology in its current state:
- The number of detectable parasites is small - for example, this company's machine can only detect 5 common parasite with PCR. While these are some of the most common parasites, there is a much wider range of parasites that infect people with low immunity, and people who travel extensively.
- In the sales document the company says: It is important to remember that...only those organisms that are designated and tested for can be detected. This is especially important when patients have been overseas. An even greater range of infectious organisms may be present in those who are immigrants, refugees or those who are immunocompromised...
Click to read in depth article about PCR parasite testing.
1. Fecal Exam AKA Ova & Parasite testing
This test, also known as microscopy, takes some feces, processes it, concentrates it, stains it, and then places it onto a microscope slide.
A technician then looks at the feces through a microscope and visually inspects and records what parasites, and parasite eggs (called ova) they observe.
In our high tech world, this "manual" method of parasite detection seems out of place. But when it comes to real world parasite infections, this is typically the most effective and reliable test for the following reasons:
- Samples are collected over 3-8 days - making it unlikely that the parasites will be missed while the parasite spends part of its life cycle outside of the intestines in other organs.
- Experienced technicians can identify a huge range of parasites that PCR and antibody/antigen tests can't identify.
- The severity of the infection can be judged by an experienced technician.
- This test doesn't confuse prior infections, with current infections (unlike PCR and antibody/antigen tests). If the test is negative for parasites, and symptoms are gone, then it's very likely that the parasite has been removed.
While this test is by far my favorite, it can also be very misleading if the technicians are inexperienced or trained poorly. Since my teacher Emma Lane works with many people with parasite infections, she needed to find the best laboratory that would give her:
- Consistent results
- Find as many parasites as possible (even rare and exotic ones)
Conclusion About The Best Parasite Test
In summary, here's how I would rate each of the tests:
Unless you've been travelling to a place that has malaria or other blood borne parasitic diseases, the stool test (Parasite and Ova) stool test is the best.
If the lab tech is skilled and experienced, the parasite and ova test:
- Can diagnose a huge number of human infecting parasites
- Can be taken in the comfort of your own home
- Won't confuse past and current infections
- Is extremely accurate
Click here to learn about the best home parasite stool test kit
Evan Jerkunica, Parasites.org's founder is happy to help. To get your questions answered, you can: