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Tuberculosis

Tuberculosis began to decline in the early 20th century, although it rebounded in the mid-1980s, and there are currently between 1.6 and 2 million deaths a year due to this illness. They are mainly in Africa, south-east Asia and areas to the east of the Mediterranean. What is tuberculosis? How are sufferers affected? Is it fatal? In which cases? How can it be prevented? We tell you everything there is to know about tuberculosis.

Chronology of Tuberculosis

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    Neolithic (7000-2000 BC)

    Bones found in Neolithic settlements indicate the existence, even then, of a strain of tuberculosis similar to those around in the 21st century.

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    4000 BC

    Evidence has been found of Mycobacterium tuberculosis in ancient Egyptian mummies.

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    4th- 5th Centuries BC

    The Greek physician Hippocrates, considered the “father of medicine”, already refers to “consumption” in his writings.

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    18th and 19th Centuries

    Tuberculosis (or “white plague”) reaches near epidemic proportions in the rapidly urbanized and industrialized societies of Europe and North America. It becomes the main cause of death (1 in 4 deaths) in the West until the early twentieth century, when sanitary conditions in cities are improved.

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    1849

    The Polish composer Frédéric Chopin dies in Paris due to tuberculosis. Other victims of the disease in the nineteenth century are the English writers the Brontë sisters

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    1864

    Louis Pasteur invents pasteurization, which destroys the bacilli in milk and aids the disappearance of bovine tuberculosis in humans in many countries.

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    1865

    The French physician Jean Antoine Villemin demonstrates that tuberculosis is contagious, vaccinating from healthy to sick animals.

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    1882

    The German physician Robert Koch identifies the bacteria causing tuberculosis, Mycobacterium tuberculosis, also called “Koch’s bacillus”.

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    1905

    Robert Koch receives the Nobel Prize for Medicine.

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    1920

    The Italian painter Amedeo Modigliani dies of tuberculosis. Other victims in the twentieth century are the Russian playwright Anton Chekhov and the German writer Franz Kafka.

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    1921

    The French bacteriologists Camille Guérin and Albert Calmette use a reduced amount of bovine tuberculosis bacillus as a vaccine against the disease in humans. Many children are immunized in Europe and South America. From the 30s onwards, vaccination is performed on a large scale.

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    1952

    The drug isoniazid, which is still the most important drug against tuberculosis today, is successfully tested. It is followed by the antibiotics pyrazinamide (1954), ethambutol (1962) and rifampicin (1963). Their use reduces to months the length of treatment, causing sanatoriums to disappear

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    80s in the 20th Century

    The cases of tuberculosis see a resurgence in developed countries, largely due to AIDS.

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    1995

    To prevent the spread of multi-drug resistant tuberculosis, the WHO encourages countries to implement Directly Observed Therapy (DOT) instead of letting the patient take their daily medication alone, they are watched by medical staff or family members while taking the doses which are reduced to two per week. This system gives good results in controlling the disease.

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    21st Century

    A multi-drug resistant tuberculosis is identified, immune to first and second-line drugs.

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    2013

    9 million people (including 550,000 children) are ill with tuberculosis in the world. 1.5 million die from the disease. 56% of new cases occur in Southeast Asia and Western Pacific regions, although the highest incidence is in Africa: more than 280 cases per 100,000 inhabitants.

What is tuberculosis?

Tuberculosis is an infection caused by the Mycobacterium tuberculosis bacterium also known as Koch’s bacillus.

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    The Koch bacillus is a long, extremely resistant bacterium. It is able to survive for months in dry conditions and can withstand mild disinfectants. It was discovered in 1882 by the German physician Robert Koch, who also concluded, years later, that the bacillus which causes bovine tuberculosis is not the same as that which causes tuberculosis in humans. Although on this point Koch ran into opposition from colleagues at the time, today we know he was right. He was awarded the Nobel Prize for Medicine in 1905 for his research and discoveries into tuberculosis.

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It mainly affects the lungs (pulmonary tuberculosis) but can also affect other parts of the body such as the kidneys, lymphatic system or bones (extrapulmonary tuberculosis)

In most cases the bacillus spreads slowly through the lungs, forming nodules (tubers) that make cavities and destroy the respiratory tissue. Blood vessels can also be eroded with the progression of the disease, causing the infected person to cough blood. It is curable and preventable, but without proper treatment can be fatal.

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    A tuber contains a core of dead cells and tissues, within which are the bacteria. Around this core are phagocytes (a type of white blood cell) and a wall of connective tissue. Tubers are microscopic in size, but joined together they become visible and give the tissue the appearance of holey cheese.

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Forms of TB

Latent TB infection

This occurs when a person inhales the bacteria but their immune system is able to fight them and prevent them from multiplying. The patient has no symptoms and they cannot spread the disease, but eventually, if their immune system is weakened for some reason (HIV, malnutrition, drugs, diabetes …), bacteria can begin to multiply and the disease develops. According to the WHO, one third of the world population has latent tuberculosis.

No symptoms

Cannot transmit the disease

Normally, blood or skin test indicates TB infection

The chest x-ray is normal and sputum smear is negative

In some cases, should be treated to prevent the disease from developing

Active TB Disease

This occurs when the bacteria multiply in the body of the infected person. In this case, the disease is contagious.

Develop symptoms

Can spread the disease

The skin or blood test indicates TB infection

The chest x-ray is abnormal and the sputum smear is positive

In all cases, treatment is needed

How it is spread

Tuberculosis is transmitted from person to person through the air.

  • When a sick person coughs, sneezes, spits or even speaks bacilli are expelled into the air.

  • If another person inhales them, they become infected.

Even so, it’s not easy to catch the disease, it is usually necessary to spend a long time with the patient.

Who is most at risk

Only 1 in 10 people infected with the bacteria develop the disease. However, this risk is greater if the infection is recent (less than two years), occurs in people whose immune system is damaged (as in HIV cases) or in smokers.

People infected with HIV are between 26 and 31 times more likely to get sick.

According to the WHO, more than 20% of cases are attributed to smoking.

More than 95% of cases and deaths occur in developing countries. Living in crowded or unsanitary conditions increases the risk.

Who is most at risk

Children, the elderly and immunocompromised individuals are more likely to develop extrapulmonary tuberculosis, which occurs when the bacillus enters the bloodstream and can travel almost anywhere in the body, such as the lymph nodes, bones, skin, kidneys, intestines, meninges or the spleen.

Prevention

People who test positive in the tuberculin test may take medication, if their doctor decides, to stop the disease from developing. In this way, and because only active tuberculosis is contagious, the patient cannot infect anyone.

Active tuberculosis

If a person has developed the disease, they can take some simple precautions to avoid transmitting it:

Home. Do not go to school, work or public places, or sleep in the same room as other people.

Ventilation. The TB bacteria are spread more easily in enclosed spaces, where the air is not moving.

Mouth. Use a tissue to cover your mouth when laughing, coughing or sneezing. Always dispose of tissues after use.

Mask. Use a surgical mask which covers the mouth when you are with other people.

Symptoms

At first, the symptoms may be mild for many months, which is why patients are often slow to seek medical attention and meanwhile can transmit the bacteria to others. Over the course of a year, a Tuberculosos patient can infect about 10 -15 people through close contact.

Incubación

When Tuberculosis passes from latent to the active form, it manifests the following symptoms, although they may be mild for months

Incubación

Over time, the initial symptoms worsen and others appear:

Diagnosis

Currently, the most commonly used methods to diagnose the disease are:

Sputum Smear

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    A sputum sample is examined under a microscope to see if it contains bacilli. With this technique many less infectious cases of the disease are detected. If bacilli are detected, a culture is performed to check whether they are tuberculosis.

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X-rays of the lungs

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    These show the characteristic tubers which cause the disease.

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Tuberculin skin test

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    This has a high rate of false positives, so should not be used as the sole diagnostic criteria. It is performed by intradermal injection (into the skin, not under it) of a purified tuberculin protein. It causes a skin rash, which usually disappears in a few hours. After 48-72 hours, the physician should examine the area to assess the reaction.

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Blood test

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    This is less used, is useful in people who are at high risk of having contracted the disease but have tested negative in the tuberculin test, or people who have recently been vaccinated against tuberculosis (in this case the result of the skin test can give a false positive).

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Treatment in 18th and 19th centuries

In the 18th and 19th centuries the sick were isolated in sanatoriums, as it was believed that hygiene and fresh air helped the body’s defenses to stop (or at least minimize) the progress of the disease. Treatments consisted of:

bloodletting

administration of expectorants and purgatives

healthy diet and exercise

opiates for those already in the final stage of the disease

Treatment today

Today, the standard treatment involves the administration of a combination of four antimicrobial drugs for a period of six months. In countries where Tuberculosis is common, the BCG vaccine (Bacillus Calmette-Guérin) is administered during childhood. Its effectiveness is limited, which is why it is not routinely given in all countries.

It is critical to always follow the guidelines when taking medication, and do not stop the treatment prematurely for any reason. If treatment is not followed properly or is stopped prematurely, bacteria can become resistant to drugs which can lead to a multi-drug resistant tuberculosis (+)*.

Multi-drug resistant tuberculosis shows resistance to at least the two most effective first line drugs, which is why it is treated with second-line drugs. It is not impossible to cure, but treatment has many side effects and lasts at least two years. In some cases, it can develop into an even more resistant form of tuberculosis, an ultra resistant tuberculosis, which responds to only a few drugs.

In some cases, the patient may be hospitalized until the disease is no longer contagious.

Current Situation

In developed countries, infection began to decrease from the early twentieth century.

However, in the mid 80s deaths from tuberculosis began to increase again due to immigration from countries where infection is prevalent, and the spread of HIV.

In the 90s, the disease also increased in Africa, but the rates returned to normal after 2000.

Despite the stabilization of the incidence of tuberculosis per capita, the total number of cases is increasing due to population increase, especially in Africa, Southeast Asia and the eastern Mediterranean regions.

Each year, between 1.6 and 2 million people die from the disease.

The World Tuberculosis Day is held every 24 March, commemorating the day (in 1882) when Robert Koch presented his discovery of Mycobacterium tuberculosis, the bacillus that causes the disease.

Some figures

Tuberculosis is the 2nd largest cause of death caused by an infectious agent. The first is AIDS.

45% drop in death rate from tuberculosis since 1990

480,000 people worldwide developed multi-drug resistant tuberculosis 2013.

Latin America

  • In Latin America, tuberculosis is the second leading cause of death due to an infectious agent, after AIDS. According to the Pan American Health Organization (PAHO) in 2011 168,400 cases of the disease were reported in the Americas, of which 67% were in South America, 17% in Central America, 11% in the Caribbean and 5.1% in North America.
  • The World Bank estimates that in the period 2010-2014, the Latin American countries with the highest incidence (number of new cases in a given period) of tuberculosis were Haiti (206 cases per 100,000 of population), Peru (124) and Bolivia (123). However, the South American country with the highest prevalence (total number of cases) is Brazil, which is among the 22 countries which account for 80% of patients in the world. Since 1990, the incidence has declined gradually in most countries, except for the Caribbean region, where this reduction is very recent, and Central America, where the number remains stable due to a slight increase in cases in Mexico.
  • The burden of tuberculosis varies by country and focuses on the most vulnerable groups, such as ethnic minorities, migrant populations and those with limited access to medical care. They tend to be people living in the slums of the cities, often in overcrowded housing and affected by economic inequality, unemployment and violence. Therefore, PAHO is conducting the Regional Plan for Tuberculosis Control 2006-2015, with the long term goal of eradicating the disease on the continent by 2050.