Tuberculosis is one of the world’s deadliest diseases, affecting one third of the world’s population. It is a contagious infection caused by bacterium Mycobacterium tuberculosis that mainly affects the lungs but can also affect any other organ including bone, brain and spine.
Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS.
Many tuberculosis strains resist the drugs most used to treat the disease. People with active tuberculosis must take many types of medications for months to get rid of the infection and prevent antibiotic resistance.
Tuberculosis mostly affects adults in their most productive years. However, all age groups are at risk. Over 95% of cases and deaths are in developing countries.
People who are infected with HIV are 18 times more likely to develop active TB. The risk of active TB is also greater in persons suffering from other conditions that impair the immune system. People with undernutrition are 3 times more at risk. Globally in 2020, there were 1.9 million new TB cases that were attributable to undernutrition.
Alcohol use disorder and tobacco smoking increase the risk of TB disease by a factor of 3.3 and 1.6, respectively. In 2020, 0.74 million new TB cases worldwide were attributable to alcohol use disorder and 0.73 million were attributable to smoking.
Causes of Tuberculosis
The main cause of TB is Mycobacterium tuberculosis (MTB), a small, aerobic, nonmotile bacillus. The high lipid content of this pathogen accounts for many of its unique clinical characteristics. It divides every 16 to 20 hours, which is an extremely slow rate compared with other bacteria, which usually divide in less than an hour. Mycobacteria have an outer membrane lipid bilayer.
If a Gram stain is performed, MTB either stains very weakly “Gram-positive” or does not retain dye as a result of the high lipid and mycolic acid content of its cell wall. MTB can withstand weak disinfectants and survive in a dry state for weeks. In nature, the bacterium can grow only within the cells of a host organism, but M. tuberculosis can be cultured in the laboratory.
How is it transmitted?
When people with active pulmonary TB cough, sneeze, speak, sing, or spit, they expel infectious aerosol droplets 0.5 to 5.0 µm in diameter. A single sneeze can release up to 40,000 droplets. Each one of these droplets may transmit the disease, since the infectious dose of tuberculosis is very small (the inhalation of fewer than 10 bacteria may cause an infection).
Symptoms of Tuberculosis
Common symptoms of active lung TB are cough with sputum and blood at times, chest pains, weakness, weight loss, Fatigue, Chills, Loss of appetite fever and night sweats. But, tuberculosis is particularly difficult to diagnose in children.
Tuberculosis can also affect other parts of your body, including the kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine might cause back pain, and tuberculosis in your kidneys might cause blood in your urine.
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TB is a treatable and curable disease. Active, drug-susceptible TB disease is treated with a standard 6-month course of 4 antimicrobial drugs that are provided with information and support to the patient by a health worker or trained volunteer. Without such support, treatment adherence is more difficult.
Prevention of TB involves screening those at high risk, early detection and treatment of cases, and vaccination with the bacillus Calmette-Guérin (BCG) vaccine
Some Key Facts according to W.H.O
- A total of 1.5 million people died from TB in 2020 (including 214 000 people with HIV). Worldwide, TB is the 13th leading cause of death and the second leading infectious killer after COVID-19 (above HIV/AIDS).
- In 2020, an estimated 10 million people fell ill with tuberculosis (TB) worldwide. 5.6 million men, 3.3 million women and 1.1 million children. TB is present in all countries and age groups. But TB is curable and preventable.
- Globally, TB incidence is falling at about 2% per year and between 2015 and 2020 the cumulative reduction was 11%. This was over halfway to the End TB Strategy milestone of 20% reduction between 2015 and 2020.
- An estimated 66 million lives were saved through TB diagnosis and treatment between 2000 and 2020.
- Globally, close to one in two TB-affected households face costs higher than 20% of their household income, according to latest national TB patient cost survey data. The world did not reach the milestone of 0% TB patients and their households facing catastrophic costs as a result of TB disease by 2020.
- By 2022, US$ 13 billion is needed annually for TB prevention, diagnosis, treatment and care to achieve the global target agreed at the UN high level-meeting on TB in 2018.