Tuberculosis (TB)

1. Tuberculosis (TB)

2. History • Tuberculosis is nothing new, from the earliest history of man, it has been there. The oldest findings of TB are found in fossil bones dating back to a spinal form of TB from 8000BC. It was also found in Egyptian mummies dating back to 2400 BC, a mummified Inca child from 700 BC, and mentioned frequently in the time of Hippocrates and Aristotle 460-322 BC. It

3. History • Despite the commonality of the disease of TB and it’s presence throughout history, study of the disease did not really begin until the 19th century. Finally in 1844, JakobHenle proposed that TB was contagious, but not until 1882 did Robert Koch ( a student of Henle’s ) produce irrefutable evidence that a microbe was the fundamental cause of Tuberculosis.

4. History • Not until the middle of the second world war did an effective treatment for Tuberculosis arrive via antibiotics and synthetic anti-TB drugs. Great efforts were made to eliminate TB from the U.S. livestock population in the early to mid 1900’s by mass slaughter of cattle found to be tuberculin positive, thus nearly eliminating gastrointestinal entry of TB into the human population.

5. TB Deaths by Year

6. Case Study of TB • Patient A is a registered nurse, 40 years of age, working in southern California at a large medical center. The hospital is located in an area with a large population of immigrants from southeast Asia, so she has cared for many of those patients during her 12 years of work on the surgical floor. • In December, she got a cold that developed into bronchitis and seemed to hang on forever. She was often awake at night, either coughing or having drenching night sweats. Finally, in April, she went to her family practice physician to have it checked. • Her chest x-ray showed questionable cavitary lesions in her right upper lobe. Although Patient A's first panicky thoughts were cancer, her physician investigated further, ordering a TB skin test and sputum for acid-fast bacilli. Both tests were positive.

7. Case Study of TB • She was started on INH, 300 mg/day, and rifampin, 600 mg/day. She was shocked by her diagnosis and embarrassed to tell her friends that she, a nurse who should know good universal precautions technique, would develop a contagious disease. • Patient A, however, is the perfect candidate for infection. Working in a community with a large immigrant population from underdeveloped countries means she had a greater risk for exposure than other nurses. Although she worked on a surgical unit, many of the patients were possibly infected. • Her healthy immune system most likely quickly suppressed the initial infection, but when the stressors in her life mounted so high, a breakdown occurred. She had the death of a parent, change in family financial status, concern for a child, and a new job to manage. Any of these alone might have been insufficient to cause the immune system to fail, but grouped together, it was only a matter of time until the latent infection re-emerged.

8. What is TB? • Tuberculosis (TB) is caused by a bacterium called Mycobacterium tuberculosis. The bacteria usually attack the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain. When outside the lungs it is called extrapulmonary TB. Most TB infections are asymptomatic and only about one in ten cases progress to active diseases if not treated properly, TB kills more that 50% of those with an active infection.

9. TB Details • Worldwide, two billion people are currently infected. Humans are naturally resistant to the bacteria, but it is still relatively easy to get infected. Only about 5% of those infected actually develop TB disease. The minimum infectious dose is around only 10 bacterial cells, while the immune system macrophages do phagocytose the bacterial cells they are not killed and continue to reproduce in the macrophages. The body responds to the enlargement of the macrophages by producing a granuloma composed of fibroblasts, lymphocytes and macrophages to surround and isolate the enlarged bacteria filled macrophages. This protective wall is what forms the tubercles from which the name Tuberculosis comes.

10. TB Details • Mycobacterium tuberculosis is an acid fast rod and is a strict aerobe. There is still debate over whether or not it is Gram negative or Gram positive. This very slow growing bacteria requires 15 to 20 hours to reproduce and a period of 6 weeks to produce colonies in a culture media. Some of the virulence factors of M. tuberculosis are cell walls of this bacteria are high in lipids giving them their acid fast properties, making it resistant to drying out and disinfectants. Additionally as noted by Koch in the 1880’s, the TB bacterium that form long serpentine cords are more virulent than ones that do not. This cord factor seems to be associated with the lipid component of the cell wall.

11. Two ways to have TB • Latent TB Infection • TB bacteria can live in the body without making you sick. This is called latent TB infection. In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria to stop them from growing. People with latent TB infection do not feel sick and do not have any symptoms, they are not infectious and cannot spread TB bacteria to others. However, if TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with TB disease.

12. Two ways to have TB • TB Disease • TB bacteria become active if the immune system can't stop them from growing. When TB bacteria are active (multiplying in your body), this is called TB disease. People with TB disease are sick, they may be able to spread the bacteria to people they spend time with every day. • Many people who have latent TB infection never develop TB disease. Some people develop TB disease soon after becoming infected (within weeks) before their immune system can fight the TB bacteria. Other people may get sick years later when their immune system becomes weak for another reason. • For people whose immune systems are weak, especially those with HIV infection, the risk of developing TB disease is much higher than for people with normal immune systems.

13. How does TB spread? • TB is spread through the air from one person to another. The TB bacteria are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby may breathe in these bacteria and become infected. Since the pasteurization of milk was begun, transmission of the TB bacterium is almost exclusively by fine droplets of respitory mucus suspended in the air. Living conditions are the most significant factor of the epidemiology of TB. Close living quarters , confined work spaces, compromised immune system and inadequate nutrition are all significantly affect the spread of TB.

14. TB Symptoms • Symptoms of TB disease include: • a bad cough that lasts 3 weeks or longer • pain in the chest • coughing up blood or sputum • weakness or fatigue • weight loss • no appetite • chills • fever • sweating at night

15. TB testing. • There are two kinds of tests that are used to detect TB bacteria in the body: the TB skin test and TB blood test. These tests can be given by a health care provider or local health department. These tests detect latent TB while a diagnosis of active TB is confirmed by a chest X-ray usually done after other symptoms are reported (cough, night sweats, fever and weight loss are most common). It is vital to have close personal contacts evaluated for TB if a patient is diagnoses with an active case of TB diease.

16. Treatment for TB • Treatment for Latent TB Infection • If you have latent TB infection but not TB disease, treatment will stop the disease from becoming active. Treatment of latent TB infection is essential to controlling and eliminating TB in the United States. • Treatment for TB Disease • TB disease can be treated by taking several drugs, usually for 6 to 9 months If you do not take the drugs correctly, the germs that are still alive may become resistant to those drugs. Drug resistant TB strains are becoming more common every year.

17. Treatment for TB • Some commonly used antituberculosisdrugs are cycloserine (Seromycin), ethambutol (Myambutol), ethionamide (TrecatorSC), isoniazid (Nydrazid, Laniazid), pyrazinamide, rifabutin (Mycobutin), and rifampin (Rifadin, Rimactane). • Because people may neglect to take their medication for tuberculosis, it is common to have tuberculosis centers develop a program of Directly Observed Therapy (DOT.) In these programs, patients come to the hospital or clinic, and take their medication in front of an observer. These programs may be annoying to the patients, but are justified by the risks to public health if tuberculosis germs which have become resistant to drugs were to be spread.

18. References • http://www.thebody.com/content/art6109.html?ic=sabottom A website focusing on health issues in the gay community. • http://www.modernmedicalguide.com/antituberculosis-drugs/ An online medical guide. • http://www.ssb.no/english/magazine/fig-2009-08-04-01-en.gif A Norwegian website that compiles health statistics. • Cowan, M. K., & Bunn, J. (2013). Microbiology Fundamentals, A Clinical Approach. McGraw Hill. Our textbook. • Cornwall, J. (1997). Tuberculosis: A Clinical Problem of International Importance. The Lancet, 601-674. A journal article in “The Lancet”, a well respected journal. • http://www.cdc.gov/tb/events/WorldTBDay/resources_global.htm The Center for Disease Control website.