Hi Michael, It is recommended to repeat a positive IGRA in a low-risk individual. Usually, it will be negative on retest. If it's persistently positive, interpret it considering how many tubes are positive, the absolute IFN-G value and a detailed history. If both tubes are positive, they’re from a country with medium or high TB rates, have a concerning travel history, spent time in other high-risk environments, or have a condition increasing their risk for TB progression, I would assume it's a true positive and recommend LTBI treatment.

I have seen a couple of healthy US-born individuals who have never traveled out of the country and are positive in QTF tube TB-2. They had nothing happening in tube 1, a great positive mitogen control, and no exposure risk or risks for TB progression. I suspected a false positive and they did turn negative on retesting with another QTF after 3 months. You could also do a 2 step TST if you needed quicker resolution.

But of course there are no concerns for them working in the meantime with a negative CXR and no symptoms.
Hope this helps,
Melanie

From: MCOH-EH <mcoh-eh-bounces+swift.melanie=mayo.edu@mylist.net> on behalf of Band, Michael DO <MBand@watsonclinic.com>
Sent: Friday, November 10, 2023 6:57:12 AM
To: mcoh-eh@mylist.net <mcoh-eh@mylist.net>
Subject: [EXTERNAL] [MCOH-EH] Possible false positive quantiferon TB
 
How are your institutions handling positive quantiferon test in asymptomatic nonexposed, prior negative skin test employees?

False positive rates can be high in low incidence cohort.

Chest xray negative

Michael Band DO,MS
Watson Clinic



Sent from my iPhone

NOTICE OF CONFIDENTIALITY
--------------------------------------------

The information in this email, including attachments, may be confidential and/or privileged
and may contain confidential health information. 
This email is intended to be reviewed only by the individual or organization named as addressee. 
If you have received this email in error please notify Watson Clinic immediately
by return message to the sender.
Destroy all copies of this message and any attachments. 
Please note that any views or opinions presented in this email are solely those of the author
and do not necessarily represent those of Watson Clinic. 
Confidential health information is protected by state and federal law, including, but not limited to:
The Health Insurance Portability and Accountability Act of 1996 and related regulations.


---------------------------------------
The MCOH-EH List has always been moderated by members of the ACOEM Medical Center Occupational Health Section. It is currently moderated by Joe Fanucchi MD FACOEM.
List membership is free, but only subscribers may post to the list.
To post send messages to: mcoh-eh@mylist.net
To become a subscriber, or to change your subscription options (turn off email while you're on vacation, etc):   https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.mcoh-eh.net%2F&data=05%7C01%7CSwift.Melanie%40mayo.edu%7Cbf333e39318144dcb71f08dbe2796b6e%7Ca25fff9c3f634fb29a8ad9bdd0321f9a%7C0%7C0%7C638352783364848372%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=006aGQtIgrZotb7zYO8viwLPcu5xdHQP%2Bqj3LhjaP34%3D&reserved=0
MediTrax / Occupational Health Systems, Inc. provides financial support to ensure the list remains a free resource for the occupational health community.
---------------------------------------
List archives (public): https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fmylist.net%2Farchives%2Fmcoh-eh%2F&data=05%7C01%7CSwift.Melanie%40mayo.edu%7Cbf333e39318144dcb71f08dbe2796b6e%7Ca25fff9c3f634fb29a8ad9bdd0321f9a%7C0%7C0%7C638352783364848372%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C2000%7C%7C%7C&sdata=XI80IbxMX%2Bjz5m6IPgA2uEEAztxg0eg0rNunan%2FVn7s%3D&reserved=0
---------------------------------------
Send administrative requests to: drjoe@meditrax.com
---------------------------------------
When replying to a message, PLEASE delete all footers, and all messages to which you're NOT replying.