The hidden pandemic

Tuberculosis is caused by bacteria. It usually affect the lungs but tuberculosis is not just a respiratory disease. It can affect other parts of the body as well. People who are infected with the bacteria will not necessarily become sick immediately. The infection can flare up months to even years later.

This global crisis is fueled by several factors. Lack of access to diagnostic tests that are practical for use in low-resource settings is one issue. There is also an alarming rise in drug resistance. 3% of new cases no longer respond to cheap first-line antibiotics. 10% of people who have tuberculosis develop a drug resistance due to not being able to continue the lengthy treatment required. This is frequently caused by lack of access to antibiotics or people who stop treatment because of side-effects of the antibiotics. Multi drug resistant tuberculosis requires expensive cocktails of newly developed antibiotics. People in low- and mid- salary countries are even less likely to be able to afford these expensive medicines.



New infections per year








Dead per year

What causes Tuberculosis

The main cause of tuberculosis is Mycobacterium tuberculosi. Other bacteria can also cause tuberculosis. The M. tuberculosis complex  includes four other TB-causing mycobacteria: M. bovis, M. africanum, M. canetti, and M. microti. M. africanum is not widespread, but it is a significant cause of tuberculosis in parts of Africa. M. bovis was once a common cause of tuberculosis, but the introduction of pasteurized milk has almost completely eliminated this as a public health problem in developed countries. M. canetti is rare and mostly limited to the Horn of Africa. M. microti is also rare and is seen almost only in immunodeficient people.

Other known pathogenic mycobacteria include M. leprae, M. avium, and M. kansasii.They can cause lung disease that resembles tuberculosis.

Photo: Mycobacterium tuberculosis culture

When people with active pulmonary tuberculosis cough, sneeze, speak, sing, or spit, they expel infectious droplets. People with prolonged, frequent, or close contact with people with TB are at particularly high risk of becoming infected. A person with an active but untreated lung infection may infect 10 or more other people per year. People with latent tuberculosis are thought not to be contagious.

About 90% of those infected with M. tuberculosis have asymptomatic, latent infections, with only a 10% lifetime chance that the latent infection will progress to overt, active tuberculous disease.

While tuberculosis is mostly known as a lung disease, they can damage tissue in other places. People with this disseminated tuberculosis have a high fatality rate even with treatment.

Tuberculosis is closely linked to both overcrowding and malnutrition, making it one of the principal diseases of poverty

Where is Tuberculosis found

Tuberculosis is a global problem. Roughly one quarter of the world’s population has been infected with M. tuberculosis. The distribution of tuberculosis is not uniform across the globe.

About 80% of the population in many African, Caribbean, south Asian, and eastern European countries test positive for tuberculosis.

In developed countries, tuberculosis is less common and is found mainly in urban areas.

Image: Geographical distribution of all forms of Tuberculosis per 100 thousand

What are the symptoms of Tuberculosis

General signs and symptoms include fever, chills, night sweats, loss of appetite, weight loss, and fatigue.

Pulmonary tuberculosis causes symptoms that may include chest pain and prolonged cough. Some people may cough up blood in small amounts.

Extra-pulmonary tuberculosis occurs more frequent in people with weakened immune systems. The disease can manifest in bones and joints, the central nervous system, the lymphatic system and other places where it causes a range of non-specific symptoms.

While 90% of people have pulmonary tuberculosis, both forms may occur at the same time, when the disease enters the bloodstream.

How can Tuberculosis be prevented

Tuberculosis prevention rely primarily on the vaccination of infants and the detection and treatment of active cases. The immunity the current child vaccine induces decreases after about ten years.

There is currently no vaccine available that works for adults.

How is Tuberculosis diagnosed

Diagnosing active tuberculosis based only on signs and symptoms is difficult. A chest X-ray and multiple sputum cultures for acid-fast bacilli are typically part of the initial evaluation, though cultures can take up to 6 weeks.

A faster test is a polymerase chain reaction (PCR) test that identifies the bacterium. These tests can also rapidly determine antibiotic resistance and are available from the WoIDMo. These tests are not routinely done for active pulmonary tuberculosis, as they rarely alter how a person is treated but can be required in specific cases.

Serological tests to detect antibodies are not specific or sensitive and are not recommended. Skin tests have high incidences of both false-positives and false-negatives.

How is Tuberculosis treated

Treatment of tuberculosis uses antibiotics to kill the bacteria. Effective treatment is difficult, due to the unusual structure and chemical composition of the mycobacterial cell wall. It hinders the entry of drugs and makes many antibiotics ineffective.

Treatment frequently consists of 6 months to up to a year of antibiotics. The lengthy treatment, with people abandoning their drug regimen due to costs or side-effects, has increased the number of antibiotic resistant strains. Multi Drug Resistant Tuberculosis is becoming more prevalent. Here the 2 most effective drugs isoniazid and rifampicin no longer work. This increases the costs of treating the disease significantly and leads to people in low-resource countries not being able to afford the treatment they require.

Image: Multi Drug Resistant TBC

Latent tuberculosis is treated with isoniazid or rifampin alone, or a combination of isoniazid with either rifampicin or rifapentine. The treatment takes three to nine months depending on the medications used. People with latent infections are treated to prevent them from progressing to active tuberculosis disease later in life.

New onset tuberculosis is treated with six months of a combination of antibiotics containing rifampicin, isoniazid, pyrazinamide, and ethambutol for the first two months, and only rifampicin and isoniazid for the last four months.

Recurring tuberculosis requires tests to determine which antibiotics are suitable for treatment.

Some strains of tuberculosis mycobacteria are resistant to all therapies, making the disease untreatable.

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