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- Mon Jul 05, 2010 11:29 am
A week ago, I with indoors for more than six hours with a friend whom i'd hardly seen before then. She told me that she had a persisting cough and other symptoms which sounded very much to me like tuberculosis. I advised her to go to the hospital and the next day I offered to go to the hospital with her. I was with her there for about 4-5 hours while she waited to see the doctor. Well, the symptoms and her x-ray made the Dr strongly suspect tb and she was kept in the hospital. Tests have since been done to confirm tb but they didnt start her on meds till after 3 days in the hospital. She is HIV negative
I have been to see her (in an isolation room) on three different occassions since her admission, usually for not more than 1-2 hours. I always wore an N95 respirator mask though she didnt wear any.
Two days ago (four days after our first prolonged hang-out), I developed a slight cough which hasn't gone away. I have been to the doctor who says to come back in a couple of weeks for the ppd test.
I am really worried now. Is it possible I could have caught it and the symptoms would be appearing so soon? Or am i just being paranoid? I hardly ever fall ill (I don't have HIV and my lifestyle does not put me at risk). Is it possible to have such a bad immune system that you could catch tb and express symptoms in less than a week?
I'm quite scared. Please tell me what could be happening (or not) and what to expect.
I have read a lot about tb - incubation period, symptoms etc so please I would really appreciate an answer that is specific to my concerns.
| Dr.M.Aroon kamath
- Tue Jul 13, 2010 7:35 am
Firstly, let me thank you for this thought-provoking post.
When persons with "open" pulmonary tuberculosis cough, sneeze, or speak, they emit tiny droplets of less than 25 μm in diameter, which evaporate instantly, leaving particulate organisms( each droplet containing roughly 10 bacilli). Once inhaled by another person,the droplet nuclei are then deposited within the alveoli lung. Macrophages then arrive and upon encountering the bacilli, they ingest and transport the bacteria to the regional lymph nodes.
The bacilli then have several potential fates:
1) They may be destroyed by the immune system,
2) they may overwhelm the defences, multiply and go onto cause primary TB,
3) they may remain dormant and remain completely asymptomatic(even for years), or
4) they may begin to proliferate after a latency period (reactivation).
There is one very interesting study that is very pertinent to the question posed by you.
This is a study wherein the incidence of clinical tuberculosis and clinical leprosy among household members of tuberculosis and leprosy patients in Sri Lanka was studied.The study period was approximately 20 years (January 1981 to December 2001) and the total number of patients and contacts were 325 and 968 for tuberculosis and 726 and 3066 for leprosy, respectively.
This study concludes thus: "These data show that in populations of comparable socio-economic, environmental and geographic locations, tuberculosis and leprosy show very different transmission patterns. In general, in tuberculosis household contacts, in spite of exposure, infection did not proceed to clinical disease. In contrast, a significant number of leprosy household contacts developed clinical leprosy. These findings have implications in the design and implementation of control programmes for these two diseases".
(http://www.tropicalmedandhygienejrnl.ne ... 35-9203(03)00039-7/abstract).
Thus, based on these available facts, i will try to answer you as follows:
Assuming that your friend has "open" cavitory pulmonary tuberculosis,
assuming that the droplets from her very first cough (in your presence) contained droplets harbouring viable tubercle bacilli,
assuming that you indeed inhaled these droplets,
assuming that the bacilli indeed reached your alveoli...........
the further fate of these bacilli will still remain an open question.
Going by the evidence, the chances of contracting clinical tuberculosis in a situation such as yours appears very small, although theoretically NOT IMPOSSIBLE.