PULMONARY TUBERCULOSIS

Márcio Lança, M.D., Pneumology. Medical Residency in Internal Medicine and Pneumology, Catholic University São Lucas Hospital (PUC-RS).

What is it?

It’s an infection caused by a microorganism called Mycobacterium tuberculosis, also known as Koch’s bacillus.

The disease usually affects the lungs, but it can also occur in other organs of the body, even without causing pulmonary damage.

This disease occurs worldwide. With the emergence of the Acquired Immunodeficiency Syndrome (AIDS) in the early 80’s, the number of pulmonary tuberculosis cases has increased highly.

Tuberculosis is more common in the world’s regions where there are poverty, malnutrition, unsanitary conditions and precarious public health care.

It has a high incidence in confined areas, such as prisons, homes for the elderly, and military headquarters.

How is it acquired?

The disease is contracted through contaminated air. A healthy person inhales droplets sprayed into the air from a sick patient’s respiratory secretion. This, on coughing, sneezing or speaking, spreads contaminated droplets into the environment, which may survive, dispersed in the air, for hours, as long as they have no contact with sunlight. The healthy individual, breathing in a contaminated environment, eventually inhales these mycobacteria, which will settle down at a site in the lung. Within a few weeks, a minor inflammation will occur at the settlement zone. It isn’t the disease yet. It’s the first contact of the germ with the organism. Afterwards, the bacteria may spread and settle down at several sites of the body.

If the organism’s defense system has a good surveillance, in most cases the bacteria won’t cause the disease and will remain inactive (dormant period). If the defense system weakens at some point, the bacteria that were in latency may become active and come to cause the disease. However, there’s also the possibility of the individual acquiring the disease in the first contact with the germ.

What are the signs and symptoms?
 

persistent coughing that may be associated to phlegm production
there may be blood in the phlegm or cough with blood alone
fever
excessive night sweats
weight loss
appetite loss
fatigue

How does the doctor diagnose it?

The presumptive diagnosis is made relying on signs and symptoms reported by the patient, associated with chest radiography showing changes compatible with pulmonary tuberculosis. The physical examination can be of little help to the physician.

The certainty of diagnosis, by its turn, is achieved through the collection of pulmonary secretion. Phlegm can be collected (in the morning, preferentially) on coughing. In tuberculosis cases, Mycobacterium tuberculosis is found, and then the disease is confirmed.

Another test used is the Mantoux test, which can aid in the disease diagnosis. It is performed by injecting tuberculin (a substance extracted off bacteria) intracutaneously. If, after 48-72 h, a major skin reaction occurs, it means that an active infection may be present or there’s hypersensitivity due to previous BCG vaccination in childhood. Thus, this test doesn’t confirm the diagnosis, but it may help the doctor out.

How is it treated?

Tuberculosis treatment is conducted with medications denominated RHZ. Each letter stands for a drug that fights off the disease: R from rifampicin, H from hydrazide, and Z from pyrazinamide. This is the first-line regimen used by health-care centers for tuberculosis treatment. It’s quite effective. The cure using the RHZ plan for six months, which is advocated by the public health-care system, gets close to 100% when the medications are used on a regular basis, that is, every day.

Generally, the treatment lasts six months, but, in special cases, it can take longer. In the first two months, the three drugs are used together. In the last four months, though, only rifampicin and hydrazide are used. The reason why more than one drug is used against the same germ is that the microorganism’s resistance rate to this triple regimen is low. The medications act on different locations, in a synergic fashion.

How is it prevented?

For a good prevention, the most important is to detect and treat all bacillipherous patients, that is, all those carrying Koch’s bacillus in their lungs (the diseased individuals).

With this purpose, it’s important that a good public system for disease control be in place to early identify the diseased individuals, preventing new cases from occurring.

The diseased individual must protect their mouth with the hand when coughing up to the first two treatment weeks. They also should avoid to stay close to healthy people, especially in confined places. These are simple measures for preventing the disease from contaminating other individuals.

Another important measure is the control of those people in close contact with the infected (living at the same house, for instance). In case these present symptoms of the disease, they must subject to chest x-ray for investigation.

If indicated, people in close contact must begin chemoprophylaxis, a treatment conducted with hydrazide (tuberculosis medication) with the intent of preventing the disease in these people. This treatment is continued for six months.

Questions you can ask your doctor:

What should be done in case of tuberculosis during pregnancy?

What’s the situation like for a newborn baby living with a tuberculosis-infected adult?

Do anti-tuberculosis drugs diminish the effect of oral contraceptives?

What are the most frequent side effects that may appear with the use of anti-tuberculosis medications?

Can people with chronic liver disease undergo the usual treatment against tuberculosis?

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