Tuberculosis+Disease

May 20th, 2010
 * Tuberculosis ** Author: Chelsea Tabellion

**Abstract** Tuberculosis is a disease caused by //Mycobacterium tuberculosis// that mainly affects the lungs. It is a highly curable disease, as long as the proper medications are administered and taken correctly. In this research project I examine the difference between tuberculosis disease which is infectious and can be spread, and latent TB infection which is not infectious. I also review the various symptoms of tuberculosis, and the different types of testing and diagnoses given to provide the best course of treatment. The different forms of treatment and medications are covered, as well as the forms of TB that are resistant to them. Finally I address the means of TB prevention, and how this disease is affecting the United States and the rest of the world. I was interested in studying and researching tuberculosis because I recently had to get a TB skin test. The TB skin test was unique, as it looked as if they blew a bubble of air into my forearm. This experience sparked an interest in tuberculosis, and how and why it is caused. Although TB is generally considered to be a highly infectious and worrisome disease, I was surprised to discover the relative simplicity of treatment in developed nations nowadays. By taking the prescribed medications thoroughly, TB patients can expect to recover and kill off all of the TB germs. I was also particularly intrigued by the incidences of TB in the United States, as the majority of Americans who were diagnosed with TB in 2007 were minorities. (CDC, 2009) **Discussion** What is Tuberculosis?
 * Introduction**
 * Tuberculosis disease**, also known as TB, is an infectious disease caused by mycobacterium tuberculosis. This disease mostly affects the lungs, but can also effect almost any other organ in the body. Tuberculosis is spread by sputum (matter expelled from the respiratory tract) in the air. Sputum typically gets in the air by an infected person either coughing, sneezing, laughing, or spitting. Therefore, those nearby can possibly breathe in the bacteria into their lungs. **Latent TB infection** is when bacteria live in the body without making one sick. In these cases, the body is able to fight off the bacteria and prevent it from growing. Those with latent TB infection will have no symptoms and will not be infectious, but will have a positive TB skin test. If the bacteria do become active and multiply, the person will become sick with TB disease. (CDC, 2009)

History of Tuberculosis Robert Koch first identified tuberculosis as an infectious disease in 1882. In the 19th century, patients infected by TB were treated by injecting air into the chest cavity, or had a thoracoplasty (lung surgery) performed to reduce lung size. In 1946, streptomycin was introduced as the first antibiotic used against TB, and in 1952 isoniazid, another antibiotic, was introduced. (eMedicineHealth, 2010)The Lubeck disaster in Germany marked the first major event associated with tuberculosis. In 1926, four years after the first TB vaccine was introduced, 249 babies were accidentally inoculated with virulent strains of TB bacteria instead of the attenuated (weakened) strain. While most of the infants did not become seriously ill, there were 76 deaths related to this event. (Tortora, 2009) Symptoms Tuberculosis symptoms are often times not noticed until the disease is advanced. (eMedicineHealth, 2010) Testing & Diagnosis There are two types of testing used to determine if someone is infected with TB. **A Mantoux tuberculin skin test** (TST) is performed by injecting a small amount of tuberculin fluid into the lower arm. After 48-72 hours, the person being tested must return to have a health professional look at the area of injection for a sign of a reaction. The reaction is measured in millimeters of induration ( the raised, hardened, or swollen area.) An induration of 5 mm or more is considered to be a positive TB test. (CDC, 2010) **QuantiFERON®-TB Gold tests** are also used to determine if someone is infected with TB. In this test, blood samples are mixed with antigens (mixtures of synthetic peptides representing m. tuberculosis proteins) and controls. After incubation for 16 to 24 hours, the blood is measured for the amount of interferon-gamma (IFN-gamma) present. If the patient is positive for TB, their white blood cells will release IFN-gamma in response to TB antigens. This type of TB testing was approved by the FDA in 2005, and is therefore relatively new. Few health centers perform this type of TB testing. (CDC, 2010) **Chest x-rays** are also performed to help diagnose TB. A posterior-anterior chest radiograph may be performed to detect abnormalities in the lungs. Chest x-rays are particularly used to rule out pulmonary TB in people who have received positive TB skin and blood tests, but have not shown any symptoms of the disease. (CDC, 2010) The **Ziehl-Neelsen acid-fast stain** is a differential stain used to identify mycobacterium. (Port, 2008) (CDC, 2010) Treatment TB is treated differently based on the patients' symptoms, TST results, and chest x-ray results. For a patient with a **positive TST, a normals chest x-ray, and no symptoms**, a doctor may prescribe an antibiotic treatment. The antibiotics will prevent the inactive form of TB from turning into an active infection. Isoniazid (INH) is the antibiotic used, and it is taken by the patient for 6 to 12 months to prevent TB from becoming active in the future. For a patient with a **positive TST, abnormal chest x-ray, and symptoms**, the treatment is different. Active TB is treated with a combination of medications, including **Isoniazid (INH**). The other drugs taken include **Rifampin, ethambutol**, **streptomycin** and **pyrazinamide**. Typically, four drugs are taken for the first 6 months to insure the destruction of resistant strains of mycobacterium. (Tortora, 2009) After two months however, two drugs are taken for the remainder of the treatment. Treatment can last from several months to even years. The length usually depends on how responsible the patient is in taking the prescribed treatment. Although it is fairly unusual, surgery on the lungs may also be performed if the drug treatments don't succeed. It is important to note that without any course of treatment, tuberculosis can lead to a lethal infection, so it is necessary to seek medical help. (CDC, 2010)
 * Productive cough for 3 weeks or longer
 * Chest pain
 * Weight loss or loss of appetite
 * Weakness or fatigue
 * Chills
 * Fever
 * Night sweats
 * You should get tested for TB if you:**
 * Have symptoms of TB
 * Have spent time with a person infected with TB, or suspected of being infected with TB
 * Have HIV or other diseases that weaken the immune system
 * Are from a country or region where active TB is common
 * Inject illegal drugs

Drug-Resistant Tuberculosis (WHO, //Drug Resistant TB,// 2010) Prevention Introduced in 1922, the Bacillus Calmette-Guerin (BCG) vaccine is the only vaccine available today that protects against tuberculosis. The vaccine contains a live but weakened strain of mycobacterium bovis. The vaccine is most effective in protecting children against tuberculosis. (WHO, //The Current Vaccines,// 2010) (Tortora, 2009)
 * Multi-Drug Resistant TB:** caused by mycobacteria that are resistant to at least isoniazid and rifampin, the two most effect TB antibiotics.
 * Extensively Drug-Resistant TB:** caused by mycobacteria that are resistant to the first line of anti-TB drugs, as well as second-line anti-TB drugs. This form of TB does not respond to the initial 6 month treatment, and can take years to treat with other drugs that are less potent, and more toxic and expensive.
 * Nearly 50% of MDR-TB cases occur in India and China
 * Out of 440,000 people diagnose with MDR-TB in 2008, approximately one third of them died.

Worldwide Incidence/Prevalence of TB Tuberculosis is considered to be a global epidemic. One third of the world's population is infected with TB. Globally, there are nearly 9 million TB-active cases and 2 million deaths due to the disease per year. TB is the leading killer of people infected with HIV, as it poses serious harm to those who have a compromised immune system. High incidences of TB occur in Africa, and parts of Asia and South America. In the United States, the majority of the cases occur in foreign-born individuals. (CDC, 2010) Africa: United States: (CDC, 2010)
 * The number of new TB cases in most African countries has more that quadrupled since 1990
 * 2 million active cases of TB per year
 * 540,000 deaths due to the disease
 * Accounts for one quarter of all cases/deaths. (WHO, 2005)
 * The TB rate is nearly 10 times higher in foreign-born Americans than in U.S. citizens born in the U.S.
 * 45% of TB cases in the U.S. are African-American.

Literature Cited Ajibola, S. 2005. //WHO declares TB an emergency in Africa.// Published online on WHO website. .

Centers for Disease Control and Prevention. Division of Tuberculosis Elimination. //Tuberculosis (TB)//. 5 May 2010. Web. .

Huang, Audrey. 2009. //The Health of Nations.// Berkely Science Review. .

Port, T. 2008. //Acid-Fast Ziehl Neelsen Stain Reaction.// Published online in //Microbiology Suite.// .

Tortora, G. 2009. //Microbiology: An Introduction (10th Edition).// Benjamin Cummings, San Francisco.

Townsend, Krista. 2007. First Line Treatment of Tuberculosis. .

World Health Organization. Initiative for Vaccine Research. //The Current Vaccines for Tuberculosis.// 2010. .

World Health Organization. Programmes and Projects. //Drug Resistant Tuberculosis Now at Record Levels.// 2010. .

Yates, Tom. 2005. //Tuberculosis and the Future.// .