Pulmonary Tuberculosis

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What is Tuberculosis?

Tuberculosis is a chronic, recurrent, infection caused by Mycobacterium Tuberculosis, M. Bovis or M. Africanum. The common TB popular in the Philippines and other Asian countries is Pulmonary (lung) Tuberculosis due to M. tuberculosis. In the United States, where tuberculosis was practically under control, there has been a resurgence, attributed to immigrant carriers. In 1996, there were 21,337 cases reported. Many of these cases were also found to be resistant to the conventional drug therapy against PTB. The prevalence of PTB among Afro-Americans appears to be twice of that among whites.

Does exposure to TB confer immunity?

To some extent, yes, but the immunity is not absolute. Specific immunologic defense against TB occurs only after an infection. However, many healthcare workers exposed to patients with Pulmonary Tuberculosis (PTB) for years develop immunity to the point that their Tuberculin Skin Test may not even show conversion to "positive."

How is Pulmonary TB transmitted?

Tuberculosis of the lungs is transmitted by inhalation of the M. tuberculosis organism dispersed as droplet nuclei from a person with pulmonary TB whose sputum is positive. The bacteria may float in the air for several hours. Other modes of transmission is by direct hand or mouth (kissing) contact with infected saliva. The preventive measures are obvious. If one is near a person known to have active TB, one should cover his/her nose and avoid handling items previously touched by the patient, including eating utensils. Washing hands following an unavoidable contact is a good practice. If one suspects the possibility of having TB, it is most prudent to consult a physician without delay.

What are the signs and symptoms of PTB?

Some people with pulmonary TB may not have any symptom whatsoever. The first sign could be a bloody sputum, or a chest X-ray finding of TB, a conversion to "positive" of a previously "negative" Tuberculin Skin Test, or recurrent cough and/or loss of weight. The symptoms could even be so subtle to escape attention. It is therefore important to have a high index of suspicion when a cough or weight loss persists, especially after exposure to someone with PTB. When in doubt, consult a physician and have a baseline chest X-Ray.

Is Tuberculin Test helpful?

Among us Asians, who had been exposed to PTB before, this skin test will not be of much help, since most of us, if not all, will be tuberculin positive. For Americans who have never been exposed to PTB, for example, a conversion to positive Tuberculin Test is of diagnostic significance.

Is PTB more common among AIDS patients?

Yes, the incidence of PTB among persons infected with HIV is very high, especially among blacks and Hispanics (up to 30% in New York State in 1992-93). This is also true among drug addicts. Because of the impaired immune system among AIDS patients, they are more prone to develop pulmonary tuberculosis, and other infections for that matter.

How much PTB goes unrecognized?

As much as 90% to 95% of primary TB infection go unrecognized. Besides the primary or initial infection, the other stages of PTB are latent or dormant, and recrudescent or adult-type TB. Primary TB may become active in any age group, most frequently affecting the apex (top) of the lungs, but may also affect the kidney, long bones, vertebra, lymph nodes and other sites. The disease may become active after 1 to 2 years after initial infection, but may be delayed for years, even a decade, and activate after the onset of diabetes mellitus, during the period of stress, after steroid treatment, or when the immune system is impaired, like in AIDS.

When is preventive medication needed?

Chemoprophylaxis (drug treatment before the disease sets in) is indicated among children (less than 4 years old, whether Tuberculin positive or negative) who lives in a household where someone has active tubeculosis, where the sputum is positive for M. tuberculosis (also called acid fast bacilli). This preventive drug treatment is also used among AIDS patients, or those persons whose immune system is low.

How effective are today's drugs against PTB?

Modern day multiple drug regimens, either for the initial treatment, retreatment, or specialized treatment, are very effective to control the disease, when adhered to strictly, together with other recommended measures. Today, tuberculosis is no longer as "wild, virulent and deadly" as it was several decades ago, when the old treatment strategy was not as effective as it is now. Tuberculosis used to spread all over the body, to the brain, bones, kidneys, liver, spleen, etc. like a wild cancer, killing millions and millions of people around the world.

What are the drugs commonly used for the treatment of PTB?

The commonest are: Isoniazid, Rifampin, Streptomycin,Pyrazinamide, Ethambutol, and Capreomycin. These medications have potential side effects that can be serious, and, therefore, should be taken only under the advise and supervision of a physician.

As always, prevention is the key to maintaining good health. Your physician and the Department of Health are good sources of information on this disease, its prevention, detection and treatment. There are also public health service centers in various cities in the country that function to help the community fight this dreaded malady.

©2003Raoul R. Diez, M.A.O.D.