|Rapid test detect HIV before Western Blot?
Oct 24, 2008
Could a rapid HIV test (specifically Uni-Gold which claims to be able to detect HIV as soon as 3-4 weeks post exposure), detect HIV before a Western Blot is capable of detecting HIV? Asked another way, could a person have a reactive rapid test result 3-4 weeks post exposure and a negative Western Blot, but actually be infected? Thanks for your help!
| Response from Dr. Frascino
No. If someone had a reactive rapid test and negative Western Blot, they would be HIV negative. The Western Blot test is the more "specific" test, while the ELISA or rapid test is more "sensitive." See below.
testing (SENSITIVITY VERSUS SPECIFICITY) Feb 9, 2008
On previous posts you say that the western blot test is more sensetive and other informaton that I have read says it is the more specific test. What is the difference between the western blot and the elisa test? Thank You
Response from Dr. Frascino
You are correct. I was using the word sensitive in its generic sense. That is trying to reassure the questioner that the Western Blot was the test to rely on to confirm a positive ELISA or determine the ELISA was falsely reactive.
The technical terms sensitivity and specificity are defined below:
The specificity is the number of true negatives (disease-free) divided by the number of all negative cases in the population.
The sensitivity is the number of true positives (with disease) divided by the number of all positive cases in the population.
Consequently, using the technical definitions, what you read is correct. Western Blot (WB) tests would be more "specific." They would be able to determine "true negatives" better than an ELISA, which is more sensitive (i.e. able to determine more true positives than the WB).
Hope that helps. I know it's a bit confusing.
Get Email Notifications When This Forum Updates or Subscribe With RSS
- Can Hiv Subtype A/e Be Detected By Hiv Rapid Tests?
- How Do You Know If You Have Oral Thrush?
- Can You Get HIV From Touching A Bloody Scab?
- Itchy Testicles After Oral Sex Form Sex Worker Does It Mean I Have HIV
- Swollen Lymph Nodes After Oral Sex Form Sex Worker What Are The Chances Of HIV
- Testicular Pain After Open Mouth Kissing Worried I Have HIV
This forum is designed for educational purposes only, and experts are not rendering medical, mental health, legal or other professional advice or services. If you have or suspect you may have a medical, mental health, legal or other problem that requires advice, consult your own caregiver, attorney or other qualified professional.
Experts appearing on this page are independent and are solely responsible for editing and fact-checking their material. Neither TheBody.com nor any advertiser is the publisher or speaker of posted visitors' questions or the experts' material.