Tiêu đề 16. COMMONLY OCCURRING COMMUNICABLE DISEASES - TUBERCULOSIS.pdf ✅

PHARMD GURU Page 1 TUBERCULOSIS INTRODUCTION: There are many subgroups in the genus mycobacterium such as: M aviumintracellulare, M kansasii, M bovis, but M tuberculosis alone is pathogenic in human. Mycobacterium tuberculosis, most commonly affects the lungs. It is transmitted from person to person via droplets from the throat and lungs of people with the active respiratory disease. Most commonly, tuberculosis is caused by air- borne infection. In healthy people, infection with Mycobacterium tuberculosis often causes no symptoms, since the person's immune system acts to “wall off” the bacteria. Most people who are exposed to TB never develop symptoms because the bacteria can live in an inactive form in the body. But if the immune system weakens, such as immunocompromised (HIV) or elderly adults, TB bacteria can become active and their active state causes death of tissue in the organs they infect. Active TB disease can be fatal if left untreated. Tuberculosis is communicable infection of lung tissue (Pulmonary TB), and potentially other tissues (extrapulmonary or miliary TB). EPIDEMIOLOGY:  Tuberculosis is most prevalent infectious disease in the world.  Tuberculosis is one of India's major public health problems. According to WHO estimates, India has the world's largest tuberculosis epidemic and approximately two to three million people are infected with tuberculosis out of a global incidence of 8.7 million cases. This is a public health problem. India bears a disproportionately large burden of the world's tuberculosis rates, as it resides to be the biggest health problem in India. ETIOLOGY: Tuberculosis is caused by Mycobacterium tuberculosis, which spread from person to person through microscopic droplets released into the air. This can happen COMMONLY OCCURRING COMMUNICABLE DISEASES
PHARMD GURU Page 2 when someone with the untreated, active form of tuberculosis, coughs, speaks, sneezes, spits, laughs or sings. RISK FACTORS: The person more prone to the infection includes:  Immigration and infection with HIV  Frequent and prolonged contact  Host debilitation due to malnutrition enhance risk of transmission (condition exist in refugee and living in poverty).  Opportunistic infection (immune-compromised)  Other risk factors include old age, alcoholism, diabetes and environmental lungs disease. PATHOPHYSIOLOGY: Infection with TB requires inhalation of droplet nuclei. Following deposition in the alveoli, Mycobacterium tuberculosis is engulfed by alveolar macrophages, but survives and multiplies within the macrophages. Proliferating bacilli kill macrophages and are released; this event produces a response from the immune system. Exposure may lead to clearance of Mycobacterium tuberculosis, persistent latent infection, or progression to primary disease. Successful containment of TB is dependent on the cellular immune system, mediated primarily through T-helper cells (TH1 response). T cells and macrophages form a granuloma with a centre that contains necrotic material (caseous centre). Mycobacterium tuberculosis, and peripheral granulation tissue consisting primarily of macrophages and lymphocytes; the granuloma serves to prevent further growth and spread of M.tuberculosis. These individuals are non-infectious and have latent TB infection; the majority of these patients will have a normal chest X-ray (CXR) and be tuberculin skin test (TST) positive. Active TB typically occurs through a process of re-activation. Approximately 10% of individuals with latent infection will progress to active disease over their lifetime. The risk is greatest within the two years following initial acquisition of M. tuberculosis. A number of conditions can alter this risk, particularly HIV infection, in which the annual risk of developing active TB is 8% to 10%. Immunocompromised conditions and treatment with immunosuppressing medicines,
PHARMD GURU Page 3 including systemic corticosteroids and TNF-α antagonists, also contribute to re- activation. CLINICAL MANIFESTATIONS: During initial infection and granulomas, there are no symptoms of mild bronchial pneumonia but sputum test is positive. In active TB, sign of chronic inflammation include:  Anorexia,  Overall sensation of feeling unwell,  Weight loss,  Fatigue,  Low grade fever,  Night sweating,  Coughing that lasts longer than 2 weeks with green, yellow, or bloody sputum,  Shortness of breath,  Chest pain,  Hemoptysis. The occurrence of additional symptoms depends on where the disease has spread beyond the chest and lungs. For example, if TB spreads to the lymph nodes, it can cause swollen glands at the sides of the neck or under the arms.
PHARMD GURU Page 4 When TB spreads to the bones and joints, it can cause pain and swelling of the knee or hip. Genitourinary TB can cause pain in the flank with frequent urination, pain or discomfort during urination, and blood in the urine. DIAGNOSIS: Medical history and physical exam include checking the symptoms such as an ongoing cough, fatigue, fever, loss of weight, anorexia and night sweats. LAB TESTS INCLUDE:  Sputum culture: Testing mucus from the lungs is used to diagnose active TB. But a sputum culture can take 1 to 8 weeks to provide results.  Sputum cytology: Examination of sample of sputum (mucus) under a microscope to determine whether abnormal cells are present. It may be done to help detect certain non-cancerous lung conditions, such as pneumonia or inflammatory diseases, or the buildup of asbestos fibers in the lungs.  Test for TB Infection: The Mantoux tuberculin skin test (TST) or the TB blood test can be used to test for M. tuberculosis infection. o Additional tests are required to confirm TB disease. The Mantoux tuberculin skin test is performed by injecting a small amount of fluid called tuberculin into the skin in the lower part of the arm. The test is read within 48 to 72 hours by a trained health care worker, who looks for a reaction on the arm. o The TB blood test measures the patient’s immune system reaction to M. tuberculosis. An uncertain reaction to the tuberculin skin test because of a