Understanding and controlling one of history’s greatest killers
Treatment of TB uses antibiotics to kill the bacteria. The antibiotics most commonly used are isoniazid, pyrazinamide, ethambutol, rifampicin, and treatments can be prolonged, taking several months
Tuberculosis is closely linked to both overcrowding and malnutrition, making it one of the principal diseases of poverty.
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.
TB is an infectious disease caused by the organism (bacteria) namedMycobacterium tuberculosis (MTB). Tuberculosis generally affects thelungs, but can also affect other parts of the body.
Tuberculosis has been present in humans since antiquity. The earliest unambiguous detection of Mycobacterium tuberculosis involves evidence of the disease in the remains of bison in Wyoming dated to around 17,000 years ago.
In Europe, rates of tuberculosis began to rise in the early 1600s to a peak level in the 1800s, when it caused nearly 25pc of all deaths. By the 1950s, mortality in Europe had decreased about 90pc.
Improvements in sanitation, vaccination, and other public health measures began significantly reducing rates of tuberculosis even before the arrival of streptomycin and other antibiotics, although the disease remained a significant threat.
In 1946, the development of the antibiotic streptomycin made effective treatment and cure of TB a reality. Prior to the introduction of this medication, the only treatment was surgical intervention, including the “pneumothorax technique”, which involved collapsing an infected lung to “rest” it and allow tuberculous lesions to heal.
One-third of the world’s population is thought to be infected with TB. New infections occur in about 1pc of the population each year. In 2014, there were 9.6 million cases of active TB which resulted in 1.5 million deaths. More than 95pc of deaths occurred in developing countries One-third of the world’s population is thought to be infected with TB. New infections occur in about 1pc of the population each year. In 2014, there were 9.6 million cases of active TB which resulted in 1.5 million deaths. More than 95pc of deaths occurred in developing countries
India had the highest total number of TB cases worldwide in 2010, in part due to poor disease management within the private and public health care sector. Programs such as the Revised National Tuberculosis Control Program are working to reduce TB levels amongst people receiving public health care.
In 2007, the country with the highest estimated incidence rate of TB wasSwaziland, with 1,200 cases per 100,000 people. India had the largest total incidence, with an estimated 2.0 million new cases
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 extrapulmonary 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 that’s a change in shape of nail that can be detected by doctor.
If a tuberculosis infection does become active, it most commonly involves the lungs (in about 90pc of cases). Symptoms may includechest pain and a prolonged cough producing sputum. About 25pc 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 aRasmussen’s aneurysm, resulting in massive bleeding.
In 15–20pc of active cases, the infection spreads outside the lungs, causing other kinds of TB. These are collectively denoted as “extrapulmonary tuberculosis”.
A number of factors make people more susceptible to TB infections. The most important risk factor globally is HIV; 13pc of all people with TB are infected by the virus. This is a particular problem in sub-Saharan Africa, where rates of HIV are high. Of people without HIV who are infected with tuberculosis, about 5–10pc develop active disease during their lifetimes; in contrast, 30pc of those co-infected with HIV develop the active disease.
Those at high risk thus include: people who inject illicit drugs, inhabitants and employees of locales where vulnerable people gather (e.g. prisons and homeless shelters), medically underprivileged and resource-poor communities, high-risk ethnic minorities, children in close contact with high-risk category patients, and health-care providers serving these patients.
People with prolonged, frequent, or close contact with people with TB are at particularly high risk of becoming infected, with an estimated 22pc infection rate. A person with active but untreated tuberculosis may infect 10–15 (or more) other people per year.
A definitive diagnosis of TB is made by identifying M. tuberculosis in a clinical sample (e.g., sputum, pus, or a tissue biopsy).
The Mantoux tuberculin skin test is often used to screen people at high risk for TB. Those who have been previously immunised may have a false-positive test result. The test may be falsely negative in those withsarcoidosis, Hodgkin’s lymphoma, malnutrition, and most notably, active tuberculosis. Interferon gamma release assays (IGRAs), on a blood sample, are recommended in those who are positive to the Mantoux test.
The World Health Organisation has achieved some success with improved treatment regimens, and a small decrease in case numbers.
The BCG vaccine has limitations, and research to develop new TB vaccines is ongoing. A number of potential candidates are currently inphase I and II clinical trials. Two main approaches are being used to attempt to improve the efficacy of available vaccines. The only availablevaccine is Bacillus Calmette-Guérin (BCG).
In children it decreases the risk of getting the infection by 20pc and the risk of infection turning into disease by nearly 60pc..It is the most widely used vaccine worldwide, with more than 90pc of all children beingvaccinated. The immunity it induces decreases after about ten years.
As tuberculosis is uncommon in most of Canada, the United Kingdom, and the United States, BCG is administered to only those people at high risk
Treatment of TB uses antibiotics to kill the bacteria. The antibiotics most commonly used are isoniazid, pyrazinamide, ethambutol, rifampicin, and treatments can be prolonged, taking several months.
The World Health Organisation, Bill and Melinda Gates Foundation, and US government are subsidising a fast-acting diagnostic tuberculosis test for use in low- and middle-income countries.
Tuberculosis has been neglected even in countries with a high burden and often forgotten by donors and those investing in health interventions.It is our collective responsibility to spread the tuberculosis prevention awareness message in our population.
