Tuberculosis Transmission Risks and Testing Procedures

Q: Tuberculosis Transmission Risks and Testing Procedures

Dear Chen： I apologize for the late reply. <br>The definition of a close contact for tuberculosis (TB) is someone who has been in contact for at least 8 hours in one day or a cumulative total of at least 40 hours in a month. <br>Only then would they be considered for screening as

The transmission rate of pulmonary tuberculosis?

Hello, Doctor.

1.
Last week, while I was sitting and eating at a convenience store near the hospital, an elderly person in a hospital gown was brought in to rest.
They coughed several times without wearing a mask.
I would like to know if the risk of transmission is high if the person is a tuberculosis (TB) patient.
I have a weakened immune system and often catch colds, so I am a bit concerned.
2.
If a chest X-ray shows no issues and the IGRA test is negative, can we conclude that there are no tuberculosis bacteria in my body?
Thank you for your response, Doctor.

Chen, 20~29 year old female. Ask Date: 2018/07/18

Dr. Huang Yiwen reply Pulmonology

Dear Chen: I apologize for the late reply.
The definition of a close contact for tuberculosis (TB) is someone who has been in contact for at least 8 hours in one day or a cumulative total of at least 40 hours in a month.
Only then would they be considered for screening as a contact.
Tuberculosis is transmitted via respiratory droplets, so it is necessary for the person to have the Mycobacterium tuberculosis and to cough out droplets that are then inhaled by another person.
The probability of this occurring is very low.
Both the chest X-ray and IGRA (Interferon Gamma Release Assay) tests are negative, which can exclude TB with 99% certainty (keeping in mind the 8-12 week window period).
If you are still concerned, you can repeat the IGRA test after three months; if it is negative, TB can be completely ruled out.

Reply Date: 2018/07/18

More Info

Understanding the risks associated with tuberculosis (TB) transmission and the testing procedures is crucial, especially for individuals with compromised immune systems. Let's address your concerns one by one.

1. Transmission Risk from Exposure: You mentioned being in close proximity to an elderly person in a hospital gown who was coughing without a mask. The risk of transmission of TB in such a scenario depends on several factors, including the infectiousness of the person, the duration of exposure, and your own immune status. TB is primarily spread through airborne droplets when an infected person coughs, sneezes, or talks. If the individual was indeed infectious (i.e., had active TB), and you were in close proximity for a prolonged period, there is a potential risk of transmission. However, casual contact, such as briefly sitting near someone, typically poses a lower risk. Given your concerns about your immune system, it would be wise to monitor for any symptoms of TB, such as a persistent cough, fever, night sweats, or unexplained weight loss.

2. Testing Procedures: If you have undergone a chest X-ray that shows no abnormalities and an Interferon Gamma Release Assay (IGRA) test that is negative, these results are generally reassuring. A normal chest X-ray suggests that there is no active TB disease, and a negative IGRA indicates that there is no evidence of latent TB infection. However, it is important to note that no test is 100% definitive. In some cases, particularly in individuals with weakened immune systems, tests may yield false-negative results. Therefore, if you have ongoing concerns or symptoms, it may be advisable to consult with a healthcare provider for further evaluation.

3. Follow-Up and Monitoring: If you have been exposed to someone with TB, even if your tests are negative, it is essential to remain vigilant. Regular follow-ups with your healthcare provider can help ensure that any potential TB infection is caught early. If you develop symptoms or if there are changes in your health status, further testing may be warranted.

4. Preventive Measures: To reduce your risk of TB infection, especially given your compromised immune system, consider the following preventive measures:
- Avoid close contact with individuals known to have active TB.

- Ensure good ventilation in living spaces.

- Practice good hygiene, such as frequent handwashing.

- If you are in a high-risk environment, consider wearing a mask.

5. Consultation with Healthcare Providers: Given your concerns about your immune system and potential exposure to TB, it is advisable to maintain open communication with your healthcare provider. They can provide personalized advice based on your health history and current condition.

In summary, while the risk of TB transmission from a brief encounter may be low, it is essential to remain vigilant, especially if you have a weakened immune system. Negative test results from a chest X-ray and IGRA are reassuring, but ongoing monitoring and consultation with healthcare professionals are crucial for your peace of mind and health. If you have any further questions or concerns, do not hesitate to reach out to your healthcare provider for guidance.

Similar Q&A

Understanding Tuberculosis Transmission and Risks in Family Members

Hello, Doctor! My father was diagnosed with open pulmonary tuberculosis in 2020 and was hospitalized for nearly a year for treatment. After that, both my mother and my daughter tested positive and received preventive medication. I, myself, had negative results for tuberculosis ba...

Dr. Huang Yiwen reply Pulmonology
Dear Megan: In 2020, your father had tuberculosis, so it is most likely that he was the source of transmission. Tuberculosis is primarily transmitted within households. Currently, the incidence rate in Taiwan has decreased to 31 per 100,000. The chance of contracting it from outs...

Understanding Tuberculosis Testing: X-rays, Interferon, and More

Currently, the tests for tuberculosis (TB) include chest X-rays, tuberculin skin tests (TST), and other more accurate out-of-pocket tests. One such test is the Interferon Gamma Release Assay (IGRA), which is a blood test that detects the immune response to TB bacteria. Your chi...

Dr. Jian Shuntian reply Pulmonology
Hello, no test is 100% accurate, so it is necessary to consider all examinations to make a judgment on whether preventive medication is needed. The physician will explain the benefits and risks, but the final decision rests with the parents. Preventive treatment will only be admi...

Understanding Tuberculosis Testing: Risks and Precautions for Family Members

Hello, Doctor. I would like to ask a question. Previously, a family member was diagnosed with tuberculosis, so both my mother and I received a notice from the health department to undergo chest X-ray examinations. We first went to Hospital A for the check-up. Fortunately, I did n...

Dr. Zhou Ziguang reply Pulmonology
Hello: 1. For tuberculosis contact screening, a chest X-ray is typically performed first. According to the information provided, this was conducted at Hospital A. Initially, there were concerns regarding your mother's X-ray results, but upon re-examination, no lesions were f...

Understanding Tuberculosis Risk and Screening After Exposure

Hello, my family member is a patient with open pulmonary tuberculosis and has just returned home after a week of treatment in the hospital. They are still continuing medication for control, and I sleep in the same room as the patient. What is the likelihood that I will contract t...

Dr. Jiang Zhenyuan reply Pulmonology
If your family member tests positive for acid-fast bacilli in sputum smear, their infectiousness is higher, and there is a possibility of transmission if sleeping in the same room as a tuberculosis patient. As long as your family member adheres to their medication regimen, their ...