Posted by Sumati Kanwar on November 03, 2006

Tuberculosis (abbreviated as TB for Tubercle Bacillus) is a common and deadly infectious disease caused by the bacterium Mycobacterium tuberculosis, which most commonly affects the lungs (pulmonary TB) but can also affect the central nervous system, lymphatic system, circulatory system, genitourinary system, bones and joints.

The cause of tuberculosis, Mycobacterium tuberculosis (MTB), is a slow-growing aerobic bacterium that divides every 16 to 20 hours; this is extremely slow compared to other bacteria that have division times measured in minutes.

TB is primarily an airborne disease which is spread through the air from one person to another. The aerosol droplets expelled in the air by people with the active disease of the lungs when they cough, sneezes, speak, or spit, then they propel TB germs, known as bacilli, into the air. People nearby may breathe in these bacteria and become infected. When a person breathes in TB bacteria, the bacteria can settle in the lungs and begin to grow. From there, they can move through the blood to other parts of the body, such as the kidney, spine and brain.

However, not everyone infected with TB bacteria becomes sick. People who are not sick have what is called latent TB infection. People who have latent TB infection do not feel sick, do not have any symptoms, and cannot spread TB to others. But, some people with latent TB infection go on to get TB disease.

In the patients where TB becomes an active disease, 75% of these cases affect the lungs, where the disease is called pulmonary TB commonly known as active TB. Symptoms include a productive, prolonged cough of more than three weeks duration, chest pain, and coughing up blood. Systemic symptoms include fever, chills, night sweats, appetite loss, weight loss, and easy fatigability.

People with prolonged, frequent, or intense contact are at highest risk of becoming infected, with an estimated 22% infection rate. A person with untreated, active tuberculosis can infect 10-15 other people per year. Others at risk include those from areas where TB is common, patients immunocompromised by conditions such as HIV/AIDS,

HIV/AIDS and TB

HIV and TB form a lethal combination, each speeding the other's progress. HIV weakens the immune system. Someone who is HIV-positive and infected with TB bacilli is many times more likely to become sick with TB than someone infected with TB bacilli who is HIV-negative. One of the first signs that a person is infected with HIV may be that he or she suddenly develops TB. This form of TB often occurs in areas outside the lungs, particularly when the person is in the later stages of AIDS.

Testing for TB

One should get tested for TB if they have spent time with a person known to have active TB disease or suspected to have active TB disease; or have HIV infection or from a country( or visited a place) where active TB disease is very common.

The TB skin test

The TB skin test may be used to find out if you have TB infection. A health care worker will inject a small amount of testing fluid (called tuberculin or PPD) just under the skin on the under side of the forearm. After 2 or 3 days, you must return to have your skin test read by the health care worker. You may have a swelling where the tuberculin was injected. The health care worker will measure this swelling and tell you if your reaction to the test is positive or negative. A positive reaction usually means that you have been infected by someone with active TB disease.

QuantiFERON®-TB Gold

QuantiFERON®-TB Gold (QFT) is a blood test used to find out if you are infected with TB bacteria. The QFT measures the response to TB proteins when they are mixed with a small amount of blood. Currently, few health departments offer the QFT. If your health department does offer the QFT, only one visit is required, at which time your blood is drawn for the test.

Treatment

With appropriate antibiotic treatment, TB can be cured in most people. These antibiotics kill the bacteria. Latent TB treatment usually uses a single antibiotic, while active TB disease is best treated with combinations of several antibiotics, to reduce the risk of the bacteria developing drug resistance. People with these latent infections are treated to prevent them from progressing to active TB disease later in life.

Drug resistant tuberculosis is transmitted in the same way as regular TB. Primary resistance occurs in persons who are infected with a resistant strain of TB. A patient with fully-susceptible TB develops secondary resistance (acquired resistance) during TB therapy because of inadequate treatment, not taking the prescribed regimen appropriately, or using low quality medication.

Successful treatment of TB depends on close cooperation between patient and health care provider. Treatment usually combines several different antibiotic drugs that are given for at least 6 months, sometimes for as long as 12 months.

Some people with TB do not get better with treatment because their disease is caused by a TB strain that is resistant to one or more of the standard TB drugs. If that happens, their health care providers will prescribe different drugs and increase the length of treatment.

Prevention

TB prevention and control takes two parallel approaches. In the first, people with TB and their contacts are identified and then treated. Identification of infections often involves testing high-risk groups for TB. In the second approach, children are vaccinated to protect them from TB. Unfortunately, no vaccine is available that provides reliable protection for adults. However, in tropical areas where the incidence of atypical mycobacteria is high, exposure to nontuberculous mycobacteria gives some protection against .

If a person is infectious, there are certain things one can do to protect themselves and others near you. These are the guidelines to follow:

• The most important thing is to take your medicine.

• Always cover your mouth with a tissue when you cough, sneeze, or laugh. Put the tissue in a closed bag and throw it away.

• Do not go to work or school. Separate yourself from others and avoid close contact with anyone. Sleep in a bedroom away from other family members.

• Air out your room often to the outside of the building (if it is not too cold outside). TB spreads in small closed spaces where air doesn't move. Put a fan in your window to blow out (exhaust) air that may be filled with TB bacteria. If you open other windows in the room, the fan also will pull in fresh air. This will reduce the chances that TB bacteria will stay in the room and infect someone who breathes the air.

People with active TB disease can be treated and cured if they seek medical help. Even better, people with latent TB infection can take medicine so that they will not develop active TB disease.


Live Punjab News Service

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