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What Does QuantiFERON-TB Gold Test Mean?
Question: I am an Australian man. Back in 1999 at the age of 36, I was exposed to an active case of TB from a friend who was staying in my house in Papua New Guinea. The friend was confirmed TB positive on XRay and Sputum. He was treated and recovered.
I have a history of BCG vaccination in 1986 and so do normally react to a Mantoux test. This was the case in 1999 however because of being exposed to my friend it was decided to treat me also with a 4 month course of Rifampicin. I completed the full course of treatment without interruption.
That was all sixteen years ago and since then I have never had any serious disease, no fevers and no other symptoms of TB whatsoever. I've had also had five chest XRays over that period, including two in the past three weeks for pre-employment medicals. All XRays were clear and normal. Spirometry tests were done and were also normal. I am 50 years old, have never smoked and am generally in good health.
I recently underwent an AntiFERON Gold TB screening test for a pre-employment medical. The test came back positive and so I was referred to the Government Health Department TB Control Centre Australia. My case was reviewed by the Medical Director of the TB Control unit of the government Health Department and he gave me an "all clear". He confirmed that my recent XRays showed no indications of TB, that I have no clinical evidence of TB and also said that my "latent TB" was adequately treated back then and so I represent no risk to anyone else adding that my chance of developing TB is very low.
I then provided the result of the Quantiferon test AND the followup report written by the TB Medical Director, Australian Health Department to the medical assessors doing my pre-employment medical evaluation.
MY QUESTIONS:
1. On the basis of the above medical history and data provided, , is there any cause for me to worry that I might be rejected on medical grounds? The employment type is non-medical or food industry related. I'm an engineer who works in the mining industry.
2. What does the AntiFEFON Gold test mean? Does it mean I have an anti-body response to TB Bacteria or does it mean I still have TB Bacteria inside me?
I really need this employment and am very worried that I may be rejected for medical reasons.
I have a history of BCG vaccination in 1986 and so do normally react to a Mantoux test. This was the case in 1999 however because of being exposed to my friend it was decided to treat me also with a 4 month course of Rifampicin. I completed the full course of treatment without interruption.
That was all sixteen years ago and since then I have never had any serious disease, no fevers and no other symptoms of TB whatsoever. I've had also had five chest XRays over that period, including two in the past three weeks for pre-employment medicals. All XRays were clear and normal. Spirometry tests were done and were also normal. I am 50 years old, have never smoked and am generally in good health.
I recently underwent an AntiFERON Gold TB screening test for a pre-employment medical. The test came back positive and so I was referred to the Government Health Department TB Control Centre Australia. My case was reviewed by the Medical Director of the TB Control unit of the government Health Department and he gave me an "all clear". He confirmed that my recent XRays showed no indications of TB, that I have no clinical evidence of TB and also said that my "latent TB" was adequately treated back then and so I represent no risk to anyone else adding that my chance of developing TB is very low.
I then provided the result of the Quantiferon test AND the followup report written by the TB Medical Director, Australian Health Department to the medical assessors doing my pre-employment medical evaluation.
MY QUESTIONS:
1. On the basis of the above medical history and data provided, , is there any cause for me to worry that I might be rejected on medical grounds? The employment type is non-medical or food industry related. I'm an engineer who works in the mining industry.
2. What does the AntiFEFON Gold test mean? Does it mean I have an anti-body response to TB Bacteria or does it mean I still have TB Bacteria inside me?
I really need this employment and am very worried that I may be rejected for medical reasons.
Brief Answer:
Most likely you have TB antibodies circulating in the immune system
Detailed Answer:
Hi XXXX,
Thanks for writing in to us.
I have read through your query in detail.
Please find my observations below.
1. TB is a common infective condition in the developing countries and due to its easy transmission, many countries over the world and including Australia have laid down pre employment guidelines to avoid contamination at the work place.
2. The TB bacteria might enter any human being but only a few people, especially those with a weak immunity, have disease manifestation. Your friend might have been infected in 1999 due to decreased immunity. At the same time, your immunity was good and therefore you did not show any active disease.
3. You have also taken prophylaxis with rifampicin and as a result you probably never really had TB ever in your lifetime. Being exposed to a friend who suffered from the disease 15 years back does not have any effects in the present.
4. The Quantiferon TB gold test is a test to check for TB infection by using cell mediated immunity. However this test is unable to differentiate between active and latent infection in an individual. It is not affected by BCG vaccine status.
5. The test result means that your immune system has produced antibodies against TB bacteria in the past. You do not have any clinical feature of TB right now and your X ray and spirometry test is normal. Therefore, an active pulmonary TB infection is ruled out. It is most likely that you do not have any TB bacteria and only your immune system still shows antibodies.
6. Since TB can affect any organ system and not only the lungs, it is important to get a documentary evidence from the authorized panel of doctors and get a TB clearance for your employment.
7. I do hope that your case will be given due attention and there will be no rejection after carefully analyzing your situation.
Please feel free to correct any oversight in my interpretation of your problems and discuss them in detail as per your requirements.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
Most likely you have TB antibodies circulating in the immune system
Detailed Answer:
Hi XXXX,
Thanks for writing in to us.
I have read through your query in detail.
Please find my observations below.
1. TB is a common infective condition in the developing countries and due to its easy transmission, many countries over the world and including Australia have laid down pre employment guidelines to avoid contamination at the work place.
2. The TB bacteria might enter any human being but only a few people, especially those with a weak immunity, have disease manifestation. Your friend might have been infected in 1999 due to decreased immunity. At the same time, your immunity was good and therefore you did not show any active disease.
3. You have also taken prophylaxis with rifampicin and as a result you probably never really had TB ever in your lifetime. Being exposed to a friend who suffered from the disease 15 years back does not have any effects in the present.
4. The Quantiferon TB gold test is a test to check for TB infection by using cell mediated immunity. However this test is unable to differentiate between active and latent infection in an individual. It is not affected by BCG vaccine status.
5. The test result means that your immune system has produced antibodies against TB bacteria in the past. You do not have any clinical feature of TB right now and your X ray and spirometry test is normal. Therefore, an active pulmonary TB infection is ruled out. It is most likely that you do not have any TB bacteria and only your immune system still shows antibodies.
6. Since TB can affect any organ system and not only the lungs, it is important to get a documentary evidence from the authorized panel of doctors and get a TB clearance for your employment.
7. I do hope that your case will be given due attention and there will be no rejection after carefully analyzing your situation.
Please feel free to correct any oversight in my interpretation of your problems and discuss them in detail as per your requirements.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
Dear Doctor XXXXXXX
Thank you for answering my questions. I understand your response clearly.
Regarding your comments in point number 6 regarding TB infection of other parts of the body and importance of getting a TB clearance:
The following remarks were made within the final paragraph of the report given to me by the the Medical Director of the Australian Department of Health, TB Control Centre, which I forwarded to the medical assessor doing my preemployment medical:
"The QantiFERON test like the previous Mantoux test is indicative of latent TB infection. This has in fact been adequately treated many years ago. There is no clinical or radiological evidence of TB currently and he should therefore be free to undertake his employment as he does not represent a risk to others. His future risk of developing active TB is very low and therefore followup screening or further preventative therapy is not indicated."
Is this the type of clearance that you mean and with this type of finalizing remarks, would an evaluating clinician therefore be satisfied that I have been fully cleared and am fit for work?
Thank you and regards, XXXXXXX
Thank you for answering my questions. I understand your response clearly.
Regarding your comments in point number 6 regarding TB infection of other parts of the body and importance of getting a TB clearance:
The following remarks were made within the final paragraph of the report given to me by the the Medical Director of the Australian Department of Health, TB Control Centre, which I forwarded to the medical assessor doing my preemployment medical:
"The QantiFERON test like the previous Mantoux test is indicative of latent TB infection. This has in fact been adequately treated many years ago. There is no clinical or radiological evidence of TB currently and he should therefore be free to undertake his employment as he does not represent a risk to others. His future risk of developing active TB is very low and therefore followup screening or further preventative therapy is not indicated."
Is this the type of clearance that you mean and with this type of finalizing remarks, would an evaluating clinician therefore be satisfied that I have been fully cleared and am fit for work?
Thank you and regards, XXXXXXX
Brief Answer:
The clearance from TB Control Center shows that you are fit for employment
Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.
1. Yes, I meant the clearance as given by the Medical Director of the Australian Department of Health, TB Control Center which is clearly giving an indication that you are fit to take up the employment.
The above clearance should satisfy the employment authorities and I do not find any hindrance to taking up your new job. You are fit for the new job.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
The clearance from TB Control Center shows that you are fit for employment
Detailed Answer:
Hi XXXX,
Thanks for writing back with an update.
1. Yes, I meant the clearance as given by the Medical Director of the Australian Department of Health, TB Control Center which is clearly giving an indication that you are fit to take up the employment.
The above clearance should satisfy the employment authorities and I do not find any hindrance to taking up your new job. You are fit for the new job.
Hope your query is answered.
Do write back if you have any doubts.
Regards,
Dr.Vivek
Above answer was peer-reviewed by :
Dr. Chakravarthy Mazumdar
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