Tuberculosis is an infectious disease caused by a causative organism called mycobacteria tuberculosis. It affects the lungs primarily and is the second deadliest disease in the world.

In 2015, 1.8 million people died from the disease, with 10.4 million falling ill.

In the 18th and 19th centuries, a tuberculous epidermic rampaged throughout Europe and North America, before the German microbiologist Robert Koch discovered the microbial causes of tuberculosis in 1882.

Following Koch’s discovery, the development of vaccines and effective drug treatment led to the belief that the disease was almost defeated. Indeed, at one point, the United Nations, predicted that tuberculosis (TB) would be eliminated worldwide by 2025.

However, in the mid-80s, TB cases began to rise worldwide, so much so, that in 1993, the World Health Organization (WHO) declared that TB was a global emergency; the first time that a disease had been labeled as such.

TB affects all age groups and all parts of the world. However, the disease mostly affects young adults and people living in developing countries. In 2012, 80 percent of reported TB cases occurred in just 22 countries.

Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person’s immune system so it can’t fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993 but remains a concern.

Many strains of tuberculosis resist the drugs most used to treat the disease. People with active tuberculosis must take several types of medications for many months to eradicate the infection and prevent the development of antibiotic resistance.

Fortunately, with proper treatment, the vast majority of cases of tuberculosis are curable. Cases of TB have decreased in the United States since 1993, but the disease remains a concern. Without proper treatment, up to two-thirds of people ill with tuberculosis will die.

Epidemiology of Tuberculosis

  • The World Health Organization estimates that 9 million people a year get sick with TB, with 3 million of these “missed” by health systems
  • TB is among the top 3 causes of death for women aged 15 to 44
  • TB symptoms (a cough, fever, night sweats, weight loss, etc.) may be mild for many months, and people ill with TB can infect up to 10-15 other people through close contact over the course of a year
  • TB is an airborne pathogen, meaning that the bacteria that cause TB can spread through the air from person to person

Types of Tuberculosis

  • Latent tuberculosis: This is a type of tuberculosis, in which the bacteria are inactive in this individual. The person suffering from latent tuberculosis are asymptomatic and cannot spread the disease and is not contagious. However, latent tuberculosis can progress to infectious and dangerous active tuberculosis. According to research, one-third of the world’s population is suffering from latent tuberculosis.
  • Active tuberculosis: This is the type of disease, in which the individuals are symptomatic and can transmit the disease to other people.
  • Drug-resistant tuberculosis: Another reason tuberculosis remains a major killer is the increase in drug-resistant strains of the bacterium. Since the first antibiotics were used to fight tuberculosis more than 60 years ago, some TB germs have developed the ability to survive, and that knowledge gets passed on to their descendants.

Drug-resistant strains of tuberculosis emerge when an antibiotic fails to kill all of the bacteria it targets. The surviving bacteria become resistant to that particular drug and frequently other antibiotics as well. Some TB bacteria have developed resistance to the most commonly used treatments, such as isoniazid and rifampin.

Some strains of TB have also developed resistance to drugs less commonly used in TB treatment, such as the antibiotics known as fluoroquinolones, and injectable medications including amikacin, kanamycin, and capreomycin. These medicines are often used to treat infections that are resistant to the more commonly used drugs.

Types of Tuberculosis

Causes and Mode of Transmission Tuberculosis

Tuberculosis is caused by a bacteria called mycobacteria tuberculosis. It can be transmitted when tuberculosis-infected individual coughs, speaks, spits or speaks. It is spread through respiratory droplets. 

Risk Factors for Tuberculosis

  • Immunococmpressed individuals: People with immunocompromised or suppressed immune system such as individuals who have HIV are at a higher risk of contracting tuberculosis. Hiv patients have reduced immune system, which reduces their ability to fight infection s because the CD4+ cells are affected by the HIV. Hiv infected patients are predisposed to opportunity infections due to their suppressed immune system.
  • Smokers: Smokers or people exposed to high concentration of tobacco are at a high risk of having tuberculosis.
  • Overcrowding or overpopulation: Tuberculosis has been linked to overpopulation and congestion due to poor breathing options patterns
  • Malnutrition: Individuals suffering from malnutrition are predisposed to tuberculosis and other opportunistic infections due to the reduced immune system caused by inadequate diet and nutrition.
  • Genetics: Tuberculosis has been linked recently  to genetic etiologies
  • Unhealthy lifestyle: Individuals with unhealthy lifestyle choices such as consistent alcohol intake, intravenous drug users, and sedentary lifestyle are at high risk of having tuberculosis.
  • Medications: Some medications such as corticosteroids and infliximab, drugs for treating rheumatoid arthritis, psoriasis and Chron’s disease, increases the chances of a patient having tuberculosis.
  • Age: it is common in people of very young age or older adults.
  • Underlying disease: Some preexisting or underlying illness such as diabetes, and kidney diseases can increase the chance of an individual having tuberculosis.
  • Location and occupation: Health workers are more predisposed to tuberculosis due to their frequent contacts with patients suffering from tuberculosis. People who live or work in prisons, immigration centers or nursing homes are all at a higher risk of tuberculosis. That’s because the risk of the disease is higher anywhere there is overcrowding and poor ventilation.  Weakened by poor nutrition and ill health and living in crowded, unsanitary conditions, refugees are at exceptionally high risk of tuberculosis infection.

Risk Factors for Tuberculosis

Countries with High Incidence of Tuberculosis

  • Africa – mainly West African and sub-Saharan Africa
  • Afghanistan
  • Southeast Asia – including Pakistan, India, Bangladesh, and Indonesia
  • China
  • Russia
  • South America
  • Western Pacific region – including the Philippines, Cambodia, and Vietnam

Signs and Symptoms of Tuberculosis

  • Hemoptysis
  • Fever
  • Weight loss
  • Night sweat
  • Fever
  • Chills
  • Loss of appetite
  • Fatigue
  • Cachexia and muscle wasting
  • Pneumonitis
  • Dyspnea
  • Chest pain
  • lymphadenopathy

Tuberculosis that is left untreated can spread to other organs and cause distant symptoms in the organs they affect. Some of the symptoms present when tuberculosis spreads to other organs includes:

  • TB infecting the bones can lead to spinal pain and joint destruction
  • TB infecting the brain can cause meningitis
  • TB affecting the liver and kidneys can impair their waste filtration functions and lead to hematuria
  • TB affecting the heart can weaken the heart’s ability to pump blood, resulting in a  fatal condition called cardiac tamponade
  • Gastrointestinal tuberculosis is causing nausea, vomiting, dysphagia, malabsorption, and diarrhea.
  • Miliary tuberculosis which predisposes themselves in the form of millet.`
  • Pleural tuberculosis in the form of empyema and pleural effusion
  • Caseous tuberculosis which includes the formation of necrotic cells with a cheesy appearance.

Signs and Symptoms of Tuberculosis

When to See a Doctor

See your doctor if you have a fever, unexplained weight loss, drenching night sweats or a persistent cough. These are often signs of TB, but they can also result from other medical problems. Your doctor can perform tests to help determine the cause.

The Centers for Disease Control and Prevention recommends that people who have an increased risk of tuberculosis be screened for latent TB infection. This recommendation includes:

  • People with HIV/AIDS
  • IV drug users
  • Those in contact with infected individuals
  • Health care workers who treat people with a high risk of TB

When to See a Doctor

Diagnosis of Tuberculosis

  • Medical history: The doctor tries to rule other genetic causes or different etiology of the signs and symptoms
  • Signs and symptoms: The signs and symptoms present in the individual can be used as a diagnostic measure
  • Skin tuberculin test: This is done by injecting of an extract of the tuberculin bacteria(PPD tuberculin) into the forearm.

The injection site should be checked after 2-3 days, and, if a hard, red bump has swollen up to a specific size, then it is likely that TB is present.

Unfortunately, the skin test is not 100 percent accurate and has been known to give incorrect positive and negative readings.

  • Blood test: A blood test could be performed to detect the presence of the mycobacteria
  • Sputum test: The mycobacteria tuberculum can be detected in the sputum, this is used as a form of diagnosis especially when combined with the tuberculin skin test.
  • Chest x-ray: Tuberculosis majorly affect the lungs so that the lungs could be viewed with a chest- x-ray. The chest x-ray can also be used to check for distant spread of tuberculosis, and detect if other organs are affected by the disease.

Prevention of Tuberculosis

If you have active TB, keep your germs to yourself. It takes a few weeks of treatment with TB medications before you’re not contagious anymore. Follow these tips to help keep your friends and family from getting sick:

  • Stay home- Don’t go to work or school or sleep in a room with other people during the first few weeks of treatment for active tuberculosis.
  • Ventilate the room- Tuberculosis germs spread more easily in small closed spaces where air doesn’t move. If it’s not too cold outdoors, open the windows and use a fan to blow indoor air outside.
  • Cover your mouth- Use a tissue to cover your mouth anytime you laugh, sneeze or cough. Put the dirty fabric in a bag, seal it and throw it away.
  • Wear a mask- Wearing a surgical mask when you’re around other people during the first three weeks of treatment may help lessen the risk of transmission.

Prevention of Tuberculosis

Treatment of Tuberculosis

According to center for disease control(CDC), TB disease can be treated by taking several drugs for 6 to 9 months.  There are 10 drugs currently approved by the U.S. Food and Drug Administration (FDA) for treating TB. Of the approved drugs, the first-line anti-TB agents that form the core of treatment regimens are:

  • Isoniazid (INH)
  • Rifampin (RIF)
  • Ethambutol (EMB)
  • Pyrazinamide (PZA)

Treatment of Drug-resistant Tuberculosis

Drug-resistant TB is caused by TB bacteria that are resistant to at least one first-line anti-TB drug. Multidrug-resistant TB (MDR TB) is resistant to more than one anti-TB medication and at least isoniazid (INH) and rifampin (RIF).

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).

Treating and curing drug-resistant TB is complicated. Inappropriate management can have life-threatening results. Drug-resistant TB should be managed by or in close consultation with an expert in the disease.

Continuation Phase of Treatment for Tuberculosis

The continuation phase of treatment is given for either 4 or 7 months. The 4-month continuation phase should be used in most patients. The 7-month continuation phase is recommended only for the following groups:

  • Patients with cavitary pulmonary TB caused by drug-susceptible organisms and whose sputum culture obtained at the time of completion of 2 months of treatment is positive;
  • Patients whose intensive phase of therapy did not include PZA;
  • Patients with HIV who are not receiving antiretroviral therapy (ART) during TB treatment; and
  • Patients being treated with once weekly INH and rifapentine and whose sputum culture obtained at the time of completion of the intensive phase is positive.
    (Use of once-weekly therapy with INH 900 mg and rifapentine 600 mg in the continuation phase is not recommended. In uncommon situations where more than once-weekly DOT is challenging to achieve, once-weekly continuation phase therapy with INH 900 mg plus rifapentine 600 mg may be considered for use only in HIV uninfected persons without cavitation on chest radiography.)

Tuberculosis is a dangerous and fatal disease because it can be asymptomatic such as in the case of latent tuberculosis. However, early detection and completion of treatment is the key to eliminating tuberculosis. If you notice any unusual symptoms, don’t keep it to yourself, contact the nearest doctor near you.



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By Biotechnology on Incline