What is tuberculosis? What causes tuberculosis?

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1 What is tuberculosis? What causes tuberculosis? Last updated: Thursday 4 September 2014 Tuberculosis Infectious Diseases / Bacteria / Viruses Respiratory / Asthma Some may see Tuberculosis as a historical disease. Evidence of its presence can be found in the preserved spines of Egyptian mummies. 1 An epidemic rampaged throughout Europe and North America during the 18th and 19th centuries, 2 before the German microbiologist Robert Koch discovered the microbial causes of tuberculosis in The development of vaccines and effective drug treatment led to the belief that the disease was almost defeated, and the United Nations, at one point predicted that tuberculosis (TB) would be eliminated worldwide by However, in the mid-80s, TB cases began to rise once more in the US and 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 labelled as such. 4 Fortunately, with proper treatment almost all cases of TB are curable. Cases of TB have decreased in the US since 1993, but the disease remains a concern. Without proper treatment up to two-thirds of people ill with TB will die. 5 Contents of this article: 1. What is tuberculosis? 2. What causes tuberculosis? 3. Signs and symptoms of tuberculosis 4. Tests and diagnosis of tuberculosis 5. Treatment and prevention of tuberculosis You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also, look out for links to information about related conditions.

2 Fast facts on tuberculosis: Here are some key points about tuberculosis. More detail and supporting information is in the main article. In 2012, 1.3 million people were believed to have died because of TB. TB predominantly affects the lungs, though it can also affect other organs such as the kidneys and heart. TB can either be active or latent (where no symptoms occur, and the condition cannot be passed on). Bacteria through the air spread TB from person to person. People with compromised immune systems are most at risk of developing active TB. Tobacco use has been found to increase the risk of developing active TB. TB bacteria can develop a resistance to antibiotics that fail to kill them completely. The most common diagnostic test for TB is a skin test. The majority of TB cases can be cured with antibiotic treatment. It is vital that any courses of treatment given are fully completed.

3 What is tuberculosis? TB is an infectious disease that usually affects the lungs. It is the second greatest killer due to a single infectious agent worldwide, and in 2012, 1.3 million people died from the disease, with 8.6 million falling ill. 5 TB usually affects the lungs, although it can spread to other organs around the body. Doctors make a distinction between two kinds of TB infection: latent and active. In latent TB, the TB bacteria remain in the body in an inactive state. They cause no symptoms and are not contagious, but they can become active. In active TB, the bacteria do cause symptoms and can be transmitted to others. 6 About one-third of the world's population is believed to have latent TB. There is a 10% chance of latent TB becoming active TB, but this risk is much higher in people who have compromised immune systems i.e. people living with HIV or malnutrition, or people who smoke. 5 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% of reported TB cases occurred in just 22 countries. 5

4 What causes tuberculosis? 578 The Mycobacterium tuberculosis bacterium causes TB. It is spread through the air from person to person, when people with TB affecting the lungs cough, sneeze, spit, laugh or talk. TB is contagious, but it is not easy to catch. The chances of catching TB from someone you live or work with are much higher than from a stranger. Most people with active TB who have received appropriate treatment for at least two weeks are no longer contagious. Since antibiotics began to be used to fight TB, some strains have become resistant to drugs. Multidrug-resistant TB (MDR-TB) arises when an antibiotic fails to kill all of the bacteria that it targets, with the surviving bacteria developing resistance to that antibiotic and often others at the same time. MDR-TB is treatable and curable only with the use of very specific anti-tb drugs, which are often limited or not readily available. In 2012, around 450,000 people developed MDR-TB. Who is at risk? People with compromised immune systems are most at risk of developing active TB. HIV suppresses the immune system, making it harder for the body to control TB bacteria. People who are infected with both HIV and TB are around 20-30% more likely to develop active TB than those who do not have HIV. Tobacco use has also been found to increase the risk of developing active TB. Over 20% of TB cases worldwide are related to smoking. 5 Recent developments on tuberculosis causes from MNT news Alarming spread of drug-resistant TB threatens global health The medical aid organization Medecins Sans Frontieres/Doctors Without Borders (MSF) has published a briefing paper about the alarming spread of

5 drug-resistant tuberculosis, which they refer to as the "biggest threat to global health you've never heard of." Patients with untreatable tuberculosis 'are spreading infection' A new study published in The Lancet has found that patients in South Africa with untreatable tuberculosis are being discharged into the community, which, according to researchers, is contributing to the spread of the disease. Signs and symptoms of tuberculosis 679 While latent TB is symptomless, the symptoms of active TB include the following: Coughing, sometimes with mucus or blood Chills Fatigue Fever Loss of weight Loss of appetite Night sweats. TB usually affects the lungs, but can also affect other parts of the body. When TB occurs outside of the lungs, the symptoms can vary accordingly. Without treatment, TB can spread to other parts of the body through the bloodstream: TB infecting the bones can lead to spinal pain and joint destruction TB infecting the brain can cause meningitis TB infecting the liver and kidneys can impair their waste filtration functions and lead to blood in the urine TB infecting the heart can impair the heart's ability to pump blood, resulting in a condition called cardiac tamponade that can be fatal.

6 Tests and diagnosis of tuberculosis 10 It is likely that a health care provider will use a stethoscope to listen to the lungs during breathing and check the lymph nodes for swelling. They will also ask about symptoms and medical history. TB is most commonly diagnosed via a skin test involving an injection into the forearm. The most common diagnostic test for TB is a skin test where a small injection of PPD tuberculin, an extract of the TB bacterium, is made just below the inside forearm. The injection site should be checked after 2-3 days, and if a hard, red bump has swollen up then it is likely that TB is present. Unfortunately, the skin test is not 100% accurate and has been known to give incorrect positive and negative readings. However, there are other tests that are available to diagnose TB. Blood tests, chest X-rays and sputum tests can all be used to test for the presence of TB bacteria, and may been used alongside a skin test. MDR-TB is more difficult to diagnose than regular TB. It is also difficult to diagnose regular TB in children. 5