Tuberculosis

  Tuberculosis (TB) & its correlation with HIV

Author: Alexandra Merrifield Date: May 20, 2010  **ABSTRACT **

 Tuberculosis is a growing epidemic that is infecting individuals worldwide. This communicable disease affects nearly one third of our population in either its latent or active from. Possible exposure or symptoms are reason to begin testing for the presence of the //Mycobacterium tuberculosis //. Tuberculosis is treatable with a combination of prescription drugs, but if left untreated can be fatal. TB is the leading cause of death in individuals affected by HIV/AIDS, for which reason they are frequently studied together. HIV (human immunodeficiency virus) is the cause of AIDS (acquired immunodeficiency syndrome) and affects the body’s immune system and consequently the ability to fight off disease. TB and HIV/AIDS are a deadly duo you do not want to meet.


 * INTRODUCTION **

 Tuberculosis became an area of interest to me from hearing about a new study in Hanoi, Vietnam. My mother has done work with Tuberculosis for many years and works in the TB clinic at UCSF. She does both research and clinical work related to TB. Most recently the university was awarded a 10-year grant to do tuberculosis research in Vietnam and my mother is traveling between clinics for the study. Currently they are trying to shorten the course of treatment for Tuberculosis and since TB is seen in larger numbers globally than in the United States, an internationally study is ideal for conducting their research. Tuberculosis infects nearly one third of the population and can be fetal if it is not treated. Tuberculosis in its active form is also communicable, so treatment is vital to decrease the number of infected individuals (Nature Medicine 2006). TB is easily developed into its active form if the immune system is weakened, as the immune system cannot suppress the growth of the mycobacterium, and their division causes active TB. For this reason the infection of HIV, which weakens the immune system puts people with a latent TB infection at high risk for the development of active TB. Tuberculosis is still treatable in individuals co-infected with HIV and TB. There are many treatment options for those infected with TB as well as those co-infected with HIV and TB (CDC handout 2008).

DISCUSSION

 Tuberculosis is contracted by the inhalation of //Mycobacterium tuberculosis // or //M. tuberculosis //<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> (Tortora 2009). TB is most commonly pulmonary (influences the lungs), although it can affect the kidneys brain and skeleton. In 1882 the world-renowned scientist, Robert Koch, discovered the tubercle bacillus. At the time of his discovery, approximately 7 million people died annually from TB (NobelPrize.org 2003). Tuberculosis has been infecting and killing people since the BC era; Tubercular decay has been found as far back as in the remains of Egyptian mummies. TB was recorded in ancient history as “white plague” and “phthisis” or “consumption,” prior to its scientific name, Tuberculosis (NobelPrize.org 2003). Despite the availability of successful treatment, Tuberculosis today remains a leading deadly infectious disease, annually taking the lives of nearly 1.87 million people and affecting one third of the world’s population, which is further increasing by approximately 8 million people each year (Nature Medicine 2006). <span style="font-family: 'Times New Roman',Times,serif;">

<span style="font-family: 'Times New Roman',Times,serif;"> <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">The chart above shows the connection between LTBI and TB as well as the tests and treatments of TB.

Tuberculosis is contracted through the inhalation of microscopic airborne droplets called sputum, which are ejected from the respiratory tract of an infected individual primarily via coughing, sneezing or spitting (NobelPrize.org 2003). The bacterium is inhaled into the lungs infecting the individual with //<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Mycobacterium tuberculosis //<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">. The exposure to the bacteria can remain latent or persist to TB in its active form. Latent TB infection (LTBI) is when the bacteria are dominated by your natural immune system suppressing them from actively dividing (CDC handout 2008). The significance of LTBI is that it can turn into active TB, which is the potentially fatal disease. There are prescription drugs that when administered and taken properly can eradicate the disease from the body very effectively (NobelPrize.org 2003).

<span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;"> Symptoms are only seen in individuals with active Tuberculosis, and the symptoms vary with the location of the growth of the mycobacterium (NobelPrize.org 2003). Pulmonary symptoms are typically as follows: <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Additional symptoms of active TB include: <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">(CDC) <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">An infection of tuberculosis is commonly tested for by a tuberculin skin test (TST), where a small amount of tuberculin fluid is injected into the lower arm. Results are determined by the reaction after 2-3 days, visible at the injection site. A positive result for a TST is a firm inflamed area wider than 5mm, which shows that you have most likely been infected with TB, but does not determine if it is active or dormant. The other method for determining a TB infection is the QuantiFERON-TB Gold (QFT-G) test, which is a blood test that measures how the immune system of the individual reacts to the germs that cause tuberculosis (CDC handout 2008).
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Cough for >3 weeks
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Chest Pain
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Coughing up blood or sputum
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Fatigue or weakness
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Loss of appetite
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Fever
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Chills
 * <span style="font-family: 'Times New Roman',Times,serif; font-size: 110%;">Night sweats

Active tuberculosis is diagnosed by a chest x-ray, acid-fast stain of sputum, and/or culture on special media (Tortora 2009). A chest x-ray (in this case is specifically a posterior-anterior chest radiograph) is typically the next step after a positive TST, as it is used to detect abnormalities in the lungs caused by the presence of TB. The acid-fast stain of sputum or acid-fast bacilli smear (AFB) is used to identify the presence of mycobacterium, but cannot isolate //Mycobacterium tuberculosis//. AFB is administered monthly during treatment to track the levels of bacteria present in the infected individual. Cultures take 6-8 weeks, which is a long wait period in which time the infected individual could be spreading the disease, so often treatment will begin prior to receiving the results (CDC 2008) (Tortora 2009).

Active TB is treated with a combination of four drugs, typically: Ethambutol, Isoniazid (INH), Rifampin or Rifabutin, and Pyrazinamide (PZA) (CDC handout 2008). A vitamin B6 supplement is commonly added for individuals with diabetes or alcoholics to reduce the side effects of numbness and tingling in the extremities caused by INH. Treatment typically ranges from 6-12 months, which is overseen by health professionals through directly observed therapy (DOT). Because the treatments success depends on the consistency in taking the drugs patients are required to come in daily to receive their medicines health professionals see to it that the medications are taken correctly. Prior to the drug regimen being started, each patient undergoes drug susceptibility testing which tests for the effectiveness of the available drugs against the TB that the patient is infected with. Unfortunately, sometimes the TB is multiple-drug resistant and other, less effective drugs must take a place in the regimen. Treatment becomes increasingly difficult if it is extensively drug resistant (XDR-TB). XDR-TB will be treated over a longer period, as less effective drugs will be used in the regimen (CDC handout 2008).

The following diagrams show the process in which TB and the replication of HIV in the body.



HIV, Human Immunodeficiency Virus is the cause of AIDS, Acquired Immunodeficiency syndrome. HIV can be contracted though contact with bodily fluid and through the skin and mucous membranes can affect a non-infected individual. HIV attacks the immune system, preventing the body from being able to ward off infections, often giving way to AIDS (the body 2009). Tuberculosis is the leading cause of death for people infected with HIV/AIDS. Further, individuals living with HIV/AIDS are 50x more likely to contract TB. There are over 40 million people infected with HIV/AIDS and one third have TB. It is important to get treatment right away if you are co-infected by HIV and TB, even in its latent form, as you are more susceptible to the reactivation of LTBI to active disease (NobelPrize.org 2003).

Tuberculosis is an infectious disease that is not noticeable until it is in its deadly, active form, for which reason you should be tested for TB if you think you have been exposed to it or shows symptoms of TB. Tuberculosis is treatable, so if you have TB, get treated and do not wait or it could be life threatening. Awareness of TB symptoms and treatment is key to ridding the world of TB. If you have HIV and are infected with TB you can still get rid of TB with treatment.


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