Pharmacists can help patients understand the difference between latent and active tuberculosis infection and provide guidance for diagnosis and treatment.
Tuberculosis, often referred to as TB, is a bacterial infection caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs and can also affect the brain, kidneys, bones, and the spine. It can eventually cause death if left untreated. According to the Centers for Disease Control and Prevention (CDC), in 2009 there were 11,545 new cases of TB in the United States. TB remains one of the leading causes of infectious disease–related deaths worldwide. Emerging drug-resistant strains of TB are creating new challenges in treating and preventing the disease. But the good news is that TB can be treated and cured.
TB can be classified as either latent or active. Latent TB infection is also referred to as inactive TB or TB infection. In latent cases, TB bacteria are present, but do not make you sick or contagious, so you cannot spread TB to others. Some patients with this form of TB may develop active TB later on. Active TB disease means that you have the bacteria that cause TB in your body and that you are experiencing symptoms, you are contagious, and the infection can be spread to other people.
How is TB Transmitted?
TB is spread from one person to another through the air. This happens when someone with active TB of the lungs or throat coughs, laughs, sneezes, sings, or talks, and others breathe in microscopic droplets of bacteria. It is important to note that a person who is exposed to TB is not able to spread TB bacteria to others right away, and only those with active TB can transmit the disease to others.
Risk Factors for TB
Anyone can contract TB, but certain risk factors can increase a person’s risk of doing so. In general, individuals at high risk of developing TB include those who have recently been infected with TB bacteria and those with medical conditions that cause them to have weakened immune systems. Also, individuals who travel to or were born in areas of the world where untreated TB is common are at higher risk.
A complete list of people at greater risk for developing TB can be found on the CDC Web site at www.cdc.gov/tb/topic/ basics/risk.htm. Individuals at high risk for getting TB should be tested at least once or twice a year.
What Are the Symptoms of TB?
People with latent TB do not have symp- 76 n 02.11 | Pharmacy Times www.PharmacyTimes.com Demystifying Tuberculosis: Understanding Causes and Treatment Options Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia. Yvette C. Terrie, BSPharm, RPh Patient education a Patient Handout from Your Pharmacist toms unless the disease becomes active. Initially, some with active TB may have few or no symptoms. The signs and symptoms of active TB include a cough lasting at least 2 to 3 weeks, unexplained weight loss, difficulty breathing, chest pain, fever, chills, fatigue, night sweats, and loss of appetite. Some people may even cough up mucous or blood.
Diagnosing TB Infection
If you suspect you might have TB, you should contact your doctor immediately to be tested. Your doctor will probably conduct a physical exam to check for swelling of your lymph nodes and listen to your lungs. TB can be detected through a skin test or blood test. A skin test called a purified protein derivative (PPD) test, also referred to as a Mantoux test, will also be performed to determine if you are infected with TB. The PPD skin test is performed by injecting a small amount of fluid, known as tuberculin, under the top layer of the skin in your inner forearm. The injection site will be checked in 48 to 72 hours by your doctor.
A positive test may indicate that a person has been exposed to TB, but may not have active TB. If you have a positive skin test, chest x-rays (to show evidence of active TB infection), a physical exam, and samples of sputum and blood will likely be ordered by your doctor to determine if you have active TB.
Treatment of TB Infection
Treatment of TB depends on whether a person has active TB disease or latent TB infection. If you have latent TB, your doctor may prescribe preventive antibiotics to decrease your risks of getting active TB. According to the CDC, the most common preventive therapy is a daily dose of isoniazid for 9 months. Children and people with HIV may require a longer treatment.
If you have active TB disease, your doctor will prescribe a combination of several drugs to be taken for 6 to 12 months. Doctors may admit their patients to a hospital for at least 2 weeks to avoid spreading the disease to others until the patient is no longer contagious. If you are not hospitalized, you should stay home and cover your mouth and nose with a tissue when you cough or sneeze. Your doctor may suggest that you wear a surgical mask when you are around others to decrease the risk of transmission. It is important to follow these instructions for your health and the health of others. According to recommendations from the CDC, an individual with active TB needs to take TB medication for at least 2 to 3 weeks in order not to spread TB to others. Even if you start to feel better, you will need to complete the treatment regimen to be cured.
Ten drugs are approved for treating TB, but the drugs most commonly prescribed for the treatment of active TB include isoniazid, rifampin, pyrazinamide, and ethambutol. You will probably begin to feel better a few weeks after starting the TB medications, but you must complete the entire course of therapy even if you feel better. After a few weeks, your doctor may even allow you to resume your normal routine, and you will not have to worry about transmitting TB to others.
During treatment, your doctor will probably monitor your liver function and blood counts at least once a month. Your pharmacist and doctor will counsel you on the proper administration and possible side effects associated with TB medications.
If you are being treated for TB, it is important for you to remember to take your medications daily exactly as directed and complete the entire course of therapy. If you do not take the medicine correctly, you can become sick with TB again and the infection may be more difficult to treat if it has become drug resistant. This form of TB is known as multidrugresistant TB.
Avoid drinking alcohol or taking acetaminophen while taking medications for TB because this could damage your liver. Call your doctor immediately if you experience nausea, vomiting, fever, yellow color of the eyes or skin, rash, or itching. Be sure to tell your doctor about any allergies or other medical conditions you have or other medications you are taking, including nonprescription and prescription drugs. If you are pregnant or think you are pregnant, or if you are breastfeeding, inform your doctor before you start taking any TB medications. If you experience any reactions to your medications or your symptoms show signs of worsening, it is important to contact your doctor immediately. PT
Ms. Terrie is a clinical pharmacy writer based in Haymarket, Virginia.
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