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If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, University of California, San Francisco
If I Had - Recurring Cough and Positive TB Test - Dr. Masae Kawamura, MD, University of California, San Francisco

(September 11, 2008 - Insidermedicine) Welcome to Insidermedicine's If I Had, where we get a chance to ask an expert what they would do if they had a medical condition.
At the recent American Thoracic Society conference in Toronto, we caught up with Dr. Masae Kawamura, M.D., who is the Director of Tuberculosis Control in San Francisco, and an Assistant Clinical Professor at the University of California, San Francisco.

If I had a recurring cough and a positive TB skin test…
If I had  cough for more than three weeks and a positive skin test I should be seen immediately because of the possibility of contagious tuberculosis. And you should see your doctor and if you are concerned about TB you should always mention it because if the doctor does not think about TB you may never get worked up for it. It would be immediate. Even without the skin test if you’ve had a cough for more than three weeks and you have risk factors for tuberculosis, such as myself as a healthcare worker working in a tuberculosis clinic, TB should be foremost on their minds in terms of my diagnosis. There are risk factors of exposure, I’ve already given you one, its healthcare workers, foreign born who come from endemic countries with TB, TB is a global problem. Ninety million cases world-wide. Many of our immigrants in North America come from areas of the world that have very high rates of TB, Asia, Africa etc. Foreign born status, if you are a traveler and you have prolonged travel to these endemic areas as well you should be screened for tuberculosis. Folks who are in residential facilities, nursing homes, institutional settings like jails, shelters, so our homeless as well, they are at risk for tuberculosis. TB is a disease of poverty and crowding in general. For those who work with those individuals, certainly they have to be screened as well.

What is involved in the TB screening process?
TB screening involves more than just a skin test. A symptom review should always be done. The symptoms that you are looking for are chronic cough, fever, weight loss, night sweats, and coughing up blood in very severe cases. In general the most common symptoms are chronic cough and weight loss.

What is the first thing that should be done if I have a positive skin test?
Anyone with a positive skin test should be screened first with a chest x-ray. Especially if they are symptomatic. Even without a skin test, someone with risk factors and symptoms should be screened with a chest x-ray. You are looking for Pulmonary Tuberculosis, which is the contagious form of TB. TB is spread through the air through very small droplet nuclei that are one to five microns across. They have properties such that they can stay in the air for long periods of time.

If the chest x-ray is abnormal…
I should be immediately be isolated and not go into the public because of the risk of contagion. I have a cough which is the most efficient way to spread TB. They say one cough is as effective as five minutes of yelling. I shouldn’t go to work. I shouldn’t be going to restaurants or to the movies until I know my status. If the x-ray is suspicious enough for tuberculosis I should be started on treatment that very day while I am waiting for my tests. Once the sputum comes back, if the smears are negative, that indicates a lower burden of disease, then after four days, five days, a week of treatment and of course not suspecting drug resistant disease I can actually return to my job, school, or whatever I need to do. If however if my smears are positive, that means that a high burden of disease, a high level of contagion, then that would require at least two weeks of treatment and three negative smears before returning to work. A positive smear requires at least ten thousand organism per mL, so it is a very high burden of disease. Every time you cough you are really putting a lot of organisms out there in the air.

What follow-up tests are required if the chest x-ray is abnormal?
If I had an abnormal chest x-ray, sputum tests should be ordered immediately to look for Acid-Fast Bacilli, which is the organism, on smear and that would tell the doctor that I’m very contagious or not. If the smears are negative then I have a lower burden of disease. The second test that is done on the sputum is the culture. And that’s really the definitive test. That takes a long time for the results to come back because TB grows very slowly. That’s one of the problems with tuberculosis. There are more rapid tests, they are not available widely throughout the United States, but if you have access to rapid tests and you have a positive AFB sputum smear, perhaps the diagnosis could be made within a few days. Otherwise you are actually waiting for anywhere between ten days to about six weeks.

How is tuberculosis managed?

Tuberculosis first of all is a curable disease if you have pan-susceptible disease. Meaning that you have no drug resistance to the first line agents. It is very difficult  treatment, as I said TB grows very slowly, and the only time it can be killed is when it’s growing. One organism takes one to two days to divide, as opposed to a normal bacteria that only takes twenty minutes. It’s  also hard to kill. It has a thick waxy coat. It is often intracellular and it survives very well. What you are doing is using a lot of drugs, four drugs at a time. Trying to kill it in its different environments, in the cell, outside the cell, in acidic environments, etc. That’s very important to lowering that burden rapidly and at the same time preventing drug resistance. That is the first two months is the most difficult. Often patients are on nine pills and capsules a day, including a vitamin to prevent numbness and tingling from one of the drugs. After the susceptibility has come back, that’s usually around two months, certain drugs can be dropped and then you are continued on usually two drugs for another four months. So the total duration of treatment is quite long, its at least six months. And that’s if you don’t have any problems with the medication, and you are doing well, you are clinically responding.

In Summary…
If I was diagnosed with active tuberculosis I would seek out someone who has experience in treating the disease. I would get started on treatment right away. But I would have a lot of hope because TB is a curable and preventable disease. And even though I might feel bad about the people I’ve exposed, unknowingly, if any of them did get infected they can be treated, and TB can be prevented as well.