Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis (MTB). Tuberculosis generally affects the lungs, but can also affect other parts of the body. Most infections do not have symptoms; in which case it is known as latent tuberculosis. About 10% of latent infections progress to active disease which, if left untreated, kills about half of those infected. The classic symptoms of active TB are a chronic cough with blood-containing sputum, fever, night sweats, and weight loss. The historical term “consumption” came about due to the weight loss. Infection of other organs can cause a wide range of symptoms.

 

Mode of Transmission

TB is airborne, which means you can get TB after breathing air exhaled by someone with tuberculosis. This can be air from:

  • Coughing
  • Sneezing
  • Laughing
  • Singing

 

The germs can stay in the air for several hours. It’s possible to inhale them even when the infected person isn’t in the room. But usually you have to be close to someone with TB for a long period of time to catch it.

 

You cannot get TB by:

  • shaking hands
  • sharing food or drink

 

Diagnosis

There are 2 types of tests that are used to detect TB bacteria in the body: the TB skin test (TST) and TB blood tests.  A positive TB skin test or TB blood test only tells that a person has been infected with TB bacteria. It does not tell whether the person has latent TB infection (LTBI) or has progressed to TB disease. Other tests, such as a chest x-ray and a sample of sputum {AFB}, are needed to see whether the person has TB disease. Listed below are samples of the tests considered very essential to determine the TB status of an individual;

 

Imaging test                       a CT scan to check lungs for signs of an infection

Bronchoscopy                   your doctor inserts a scope through your mouth or nose to see your lungs and airways

Sputum examination      a lab examines a sample of your mucus for AFB

Thoracentesis                    a procedure that removes fluid from the space between the outside of your lungs and the wall of your chest

Lung biopsy                        a procedure to remove a sample of lung tissue

 

 

Signs and symptoms

Tuberculosis may infect any part of the body, but most commonly occurs in the lungs (known as pulmonary tuberculosis). Extra-pulmonary TB occurs when tuberculosis develops outside of the lungs, although extra-pulmonary TB may coexist with pulmonary TB.

General signs and symptoms include fever, chills, night sweats, loss of appetite, weight loss, and fatigue. Significant nail clubbing may also occur. The signs and symptoms of TB could be classified based on its type.

Pulmonary

If a tuberculosis infection does become active, it most commonly involves the lungs (in about 90% of cases). Symptoms may include chest pain and a prolonged cough producing sputum. About 25% of people may not have any symptoms (i.e. they remain “asymptomatic”). Occasionally, people may cough up blood in small amounts, and in very rare cases, the infection may erode into the pulmonary artery or a Rasmussen’s aneurysm, resulting in massive bleeding. Tuberculosis may become a chronic illness and cause extensive scarring in the upper lobes of the lungs. The upper lung lobes are more frequently affected by tuberculosis than the lower ones. The reason for this difference is not clear. It may be due to either better air flow, or poor lymph drainage within the upper lungs.

Extra-pulmonary

In 15–20% of active cases, the infection spreads outside the lungs, causing other kinds of TB. These are collectively denoted as “extra-pulmonary tuberculosis”. Extra-pulmonary TB occurs more commonly in immunosuppressed persons and young children. In those with HIV, this occurs in more than 50% of cases. Notable extra-pulmonary infection sites include the pleura (in tuberculous pleurisy, i.e the sheath covering the lungs), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones and joints (in Pott disease of the spine), among others.

Spread to lymph nodes is the most common. An ulcer originating from nearby infected lymph nodes may occur and is painless, slowly enlarging and has an appearance of “wash leather”.

When it spreads to the bones, it is known as “osseous tuberculosis”, a form of osteomyelitis. A potentially more serious, widespread form of TB is called “disseminated tuberculosis”, also known as miliary tuberculosis. Miliary TB currently makes up about 10% of extra-pulmonary cases.

 

Prevention of TB

Prevention is better than cure. Management of TB is expensive and time consuming; it is therefore wise to prevent the disease. The disease may be prevented by the following steps;

  • Provide education on preventing TB like cleaning equipment and cough etiquette.
  • Avoid extended close contact with someone who has TB.
  • Air out rooms regularly.
  • Cover your face with a mask that is approved for protection against TB.

 

Treatment

For those with latent TB, it is still advisable to take treatment. Only one drug will be required to be taken by those with latent TB.

If it is pulmonary TB disease, the doctor may prescribe several medicines. These drugs will be taken for six months or longer for the best results. The first-line anti-TB agents that form the core of treatment regimens are:

  • Isoniazid
  • Pyrazinamide
  • ethambutol,
  • rifampin,

 

It is very important that people who have pulmonary TB disease are treated, finish the medicine, and take the drugs exactly as prescribed. If they stop taking the drugs too soon, they can become sick again; if they do not take the drugs correctly, the TB bacteria that are still alive may become resistant to those drugs. TB that is resistant to drugs is harder and more expensive to treat.

 

TB disease can be treated by taking several drugs for 6 to 9 months.

The doctor might recommend an approach called directly observed therapy (DOT) to ensure completion of treatment. Stopping treatment or skipping doses can make pulmonary TB resistant to medicines, leading to multidrug-resistant (MDR-TB).

When on DOT, a healthcare professional meets with the client every day or several times a week to administer his/her medication.

For those who aren’t on DOT, make a schedule for taking medication. Here are some tips to help remember to take the medication:

  • Take medicines at the same time every day.
  • Make a note on your calendar each day to show that you’ve taken your medicine.
  • Ask someone to remind you to take your medicine every day.
  • Keep your medicines in a pill organizer.

 

Management of Multi-Drug Resistant TB {MDR-TB} and Extensively Drug Resistant TB {XDR-TB}

 

Drug-resistant TB is caused by TB bacteria that are resistant to at least one first-line anti-TB drug. Drug-resistant TB can occur when the drugs used to treat TB are misused or mismanaged. Examples of misuse or mismanagement include;

  • People do not complete a full course of TB treatment
  • Health care providers prescribe the wrong treatment (the wrong dose or length of time)
  • Drugs for proper treatment are not available
  • Drugs are of poor quality

 

Drug-resistant TB is more common in people who;

  • Do not take their TB drugs regularly
  • Do not take all of their TB drugs
  • Develop TB disease again, after being treated for TB disease in the past
  • Come from areas of the world where drug-resistant TB is common
  • Have spent time with someone known to have drug-resistant TB disease

 

Multidrug-resistant TB {MDR TB} is caused by TB bacteria that are resistant to at least isoniazid and rifampin, the two most potent TB drugs. These drugs are used to treat all persons with TB disease. Extensively drug-resistant TB (XDR TB) is a rare type of MDR TB that is resistant to isoniazid and rifampin, plus any fluoroquinolone and at least one of three injectable second-line drugs (i.e., amikacin, kanamycin, or capreomycin). Because XDR TB is resistant to the most potent TB drugs, patients are left with treatment options that are much less effective. XDR TB is of special concern for people with HIV infection or other conditions that can weaken the immune system. These people are more likely to develop TB disease once they are infected, and also have a higher risk of death once they develop TB.

Prevention of MDR-TB and XDR-TB

Preventing drug resistance is an important aspect of TB management because it is expensive, time consuming and may not be effective. The most important way to prevent the spread of drug-resistant TB is to take all TB drugs exactly as prescribed by the health care provider. No doses should be missed and treatment should not be stopped early. People receiving treatment for TB disease should tell their health care provider if they are having trouble taking the drugs.

 

Health care providers can help prevent drug-resistant TB by quickly diagnosing cases, following recommended treatment guidelines, monitoring patients’ response to treatment, and making sure therapy is completed.

 

Another way to prevent getting drug-resistant TB is to avoid exposure to known drug-resistant TB patients in closed or crowded places such as hospitals, prisons, or homeless shelters. People who work in hospitals or health-care settings where TB patients are likely to be seen should consult infection control or occupational health experts.

 

Epidemiological Statistics on TB

In 2015, 10.4 million people fell ill TB and 1.8 million died from the disease {including 0.4 million among people living with HIV}. Over 95% of TB deaths occur in low- and middle-income countries. Six countries account for 60% of the total population with TB, with India leading, followed by Indonesia, China, Nigeria then Pakistan and South Africa. In 2015, an estimated 1 million children became ill with TB and 170,000 children died of TB {excluding children with HIV}. In 2015, 35% of HIV deaths were due to TB. Globally in 2015, an estimated 480,000 people developed multi-drug resistant TB {MDR-TB}. TB incidence has fallen by average of 1.5% per year since 2000 and an estimated 49 million lives were saved through TB diagnosis and treatment between 2000 and 2015. As at 2010, Oyo State has the third highest TB prevalence in Nigeria increasing by 46.5% from 2008 to 2010.

 

 

References

 

See more at: http://www.tbfacts.org/tb-statistics/#sthash.n9DLS3g4.dpuf