The bacteria that cause tuberculosis are spread from one person to another through tiny droplets released into the air via coughs and sneezes. 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. As a result, two TB-related conditions exist: latent TB infection (LTBI) and TB disease. If not treated properly, TB disease can be fatal. What Are the Symptoms of TB? A person with latent, or inactive, TB will have no symptoms. You may still have a TB infection, but the bacteria in your body is not yet causing harm
Symptoms of active TB include:
A cough that lasts more than three weeks
Loss of appetite and unintentional weight loss
Fever
Chills
Night sweats
You may experience other symptoms related to the function of a specific organ or system that is affected. Coughing up blood or mucus (sputum) is a sign of in TB of the lungs. Bone pain may mean that the bacteria have invaded your bones. These symptoms can also occur with other diseases, so it is important to see a healthcare provider and to let them find out if you have TB. If you think you have been exposed to TB, get a TB test. How Is TB Diagnosed? Your doctor will start by collecting a patient history to determine if you may have been exposed. During a physical exam, they will use a stethoscope to listen to your lungs and check the lymph nodes in your neck for swelling. If your doctor suspects TB, they may order a skin or blood test. The skin test is done by injecting a small amount of fluid called tuberculin into the skin in the arm. You will be told to return to the office within 48 to 72 hours to have a healthcare worker check the arm to see if a bump or an induration (thickening) of the skin has developed. It may be difficult to feel so an experienced healthcare worker should examine the reaction. The healthcare worker will measure the bump or induration and tell you if your reaction to the test is positive or negative. If it's positive, it usually means you have been infected with the TB germ. It does not tell whether you have developed clinically active TB disease. The skin test isn’t 100% accurate, meaning you may have a false-positive or a false-negative, so your doctor may order further testing regardless of the result. The TB blood test measures how your immune system reacts to the germs that cause TB. This information will be used to more precisely confirm or rule out latent or active TB. It requires only one office visit. If the skin or blood tests indicate the need for further analysis, your doctor may order a chest X-ray or CT scan to look for visible signs of TB in your lungs. They may also check your sputum (coughed-up mucus) for bacteria, to see whether you have clinically active TB disease and if so, which strain of TB you have. These tests can take one to two months before results are available. When to See Your Doctor
Tuberculosis (TB) is a potentially serious infectious disease that mainly affects the lungs. The bacteria that cause tuberculosis are spread from person to person through tiny droplets released into the air via coughs and sneezes. Once rare in developed countries, tuberculosis infections began increasing in 1985, partly because of the emergence of HIV, the virus that causes AIDS. HIV weakens a person's immune system, so it can't fight the TB germs. In the United States, because of stronger control programs, tuberculosis began to decrease again in 1993. But it remains a concern. Many tuberculosis strains resist the drugs most used to treat the disease. People with active tuberculosis must take many types of medications for months to get rid of the infection and prevent antibiotic resistance. Symptoms
Although your body can harbor the bacteria that cause tuberculosis, your immune system usually can prevent you from becoming sick. For this reason, doctors make a distinction between:
Latent TB. You have a TB infection, but the bacteria in your body are inactive and cause no symptoms. Latent TB, also called inactive TB or TB infection, isn't contagious. Latent TB can turn into active TB, so treatment is important. Also called TB disease, this condition makes you sick and, in most cases, can spread to others. It can occur weeks or years after infection with the TB bacteria. Signs and symptoms of active TB include:
Coughing for three or more weeks
Coughing up blood or mucus
Chest pain, or pain with breathing or coughing
Unintentional weight loss
Fatigue
Fever
Night sweats
Chills
Loss of appetite
Tuberculosis can also affect other parts of your body, including the kidneys, spine or brain. When TB occurs outside your lungs, signs and symptoms vary according to the organs involved. For example, tuberculosis of the spine might cause back pain, and tuberculosis in your kidneys might cause blood in your urine. Tuberculosis Risk-Assessment Questionnaire for Parents
Does your child have regular contact with adults who are at high risk for tuberculosis (e.g., homeless or incarcerated persons, persons infected with HIV, persons who use illicit drugs)? Has your child had contact with someone infected with tuberculosis? Is your child infected with HIV? Was any household member, including your child, born in an area where tuberculosis is common (e.g., Africa, Asia, Latin America, Caribbean)? Has anyone in your family traveled to one of these areas? note: Children whose parents answer “Yes” to any of these questions should be screened for tuberculosis. HIV = human immunodeficiency virus. Information from reference 6. Primary prevention efforts have focused on the bacille Calmette-Guérin (BCG) vaccine, a live vaccine derived from an attenuated strain of Mycobacterium bovis. Although BCG vaccine is used commonly in many parts of the world, few data support its effectiveness in reducing tuberculosis-related morbidity and mortality in the general population. However, vaccination does reduce the occurrence of severe (e.g., meningeal) and disseminated forms of tuberculosis in young children. In the United States, vaccination may be considered for children with continuous and unavoidable exposure to adults with inadequately treated or multi-drug-resistant active disease.7 The decision to vaccinate should be made in consultation with local tuberculosis control programs. Diagnosis
The diagnosis of active tuberculosis begins with a high index of suspicion for disease. A positive acid-fast bacillus (AFB) smear or positive culture for M. tuberculosis confirms active disease. However, if the suspicion for active disease is high enough, treatment should begin without waiting for a final diagnosis. HISTORY AND CLINICAL EXAMINATION
Most patients with active tuberculosis have non-specific findings on clinical examination, such as fever, wasting, and ill appearance.8 Patients also may present with headaches, back pain, or abdominal pain. Patients with active pulmonary tuberculosis may have nonspecific findings on clinical examination, ranging from normal lung sounds to rales. Patients with extrapulmonary tuberculosis may present with altered sensorium, cranial nerve palsy, seizures, monoarticular joint swelling, and painless lymphadenopathy. DIAGNOSTIC TESTS
A sample of tissue or fluid should be obtained from the suspected site of infection, and AFB smears, nucleic amplification (if necessary), and culture should be performed. Chest radiographs should be obtained in patients with cough or other evidence of pulmonary disease. Pleuropulmonary tuberculosis may present in a variety of ways on chest radiographs, including unilateral pleural effusion, cavitary lesions, hilar lymphadenopathy, and infiltrates in the lower lobes. If pulmonary tuberculosis is suspected, three induced sputum samples, obtained on three separate days, should be obtained for AFB smears and cultures. In children who are unable to produce sputum specimens, gastric aspirate may be used for AFB smears and cultures.9
If extrapulmonary TB is suspected, fluid or tissue from the suspected site of infection (e.g., gastric aspirates, urine, cerebrospinal fluid, pleural fluid, exudates from abscesses, bone marrow) should be evaluated. To detect AFB, a smear must contain between 5,000 and 10,000 bacilli per mL.9 Many specimens do not have a large concentration of bacilli, and further testing must be performed. An “enhanced” nucleic acid amplification test may be used to help confirm the diagnosis; however, the role for nucleic amplification is still unclear.10 After evaluating for AFB, all specimens should be cultured. Mycobacterial cultures are more sensitive than AFB smears and can detect as few as 10 bacilli per mL. The culture may be used to test drug susceptibility and genotype organisms for epidemiologic links.9
Treatment
Ten drugs have been approved for treatment of patients with tuberculosis. In addition, several others that have not been approved are used commonly, including certain fluoroquinolones, rifabutin (Mycobutin), amikacin (Amikin), and kanamycin (Kantrex). Isoniazid (INH), rifampin (Rifadin), ethambutol (Myambutol), and pyrazinamide are first-line therapies.11 A summary of treatment guidelines for handheld computers is available from the Centers for Disease Control and Prevention Web site ath
INITIATION OF TREATMENT
The decision to initiate treatment is based on clinical suspicion of disease; physicians should not necessarily await the results of cultures or smears before beginning treatment .11 Patients in whom there is high clinical suspicion for active tuberculosis should begin treatment with a four-drug regimen. Treatment of patients with negative sputum smears depends on the degree of clinical suspicion and is summarized in Patients with low clinical suspicion, negative cultures, and stable radiographic findings are candidates for treatment of latent tuberculosis. Tuberculosis Transmission
When someone who has TB coughs, sneezes, talks, laughs, or sings, they release tiny droplets that contain the germs. If you breathe in these germs, you can get it. Tuberculosis (TB) is a contagious infection that usually attacks your lungs. It can also spread to other parts of your body, like your brain and spine. A type of bacteria called Mycobacterium tuberculosis causes it. Can tuberculosis be cured? In the 20th century, TB was a leading cause of death in the United States. Today, most cases are cured with antibiotics. But it takes a long time. You have to take medications for at least 6 to 9 months. Tuberculosis Types
A TB infection doesn’t always mean you’ll get sick. There are two forms of the disease:
Latent TB. You have the germs in your body, but your immune system keeps them from spreading. You don’t have any symptoms, and you’re not contagious. But the infection is still alive and can one day become active. If you’re at high risk for re-activation -- for instance, if you have HIV, you had an infection in the past 2 years, your chest X-ray is unusual, or your immune system is weakened -- your doctor will give you medications to prevent active TB. The germs multiply and make you sick. You can spread the disease to others. Ninety percent of active cases in adults come from a latent TB infection. A latent or active TB infection can also be drug-resistant, meaning certain medications don’t work against the bacteria. Tuberculosis Signs and Symptoms
Latent TB doesn’t have symptoms. A skin or blood test can tell if you have it. Signs of active TB disease include:
A cough that lasts more than 3 weeks
Chest pain
Coughing up blood
Feeling tired all the time
Night sweats
Chills
Fever
Loss of appetite
Weight loss
If you have any of these symptoms, see your doctor to get tested. Get medical help right away if you have chest pain. Tuberculosis Causes
Tuberculosis is caused by bacteria that spread through the air, just like a cold or the flu. You can get TB only if you come into contact with people who have it. Bovine TB is a chronic debilitating disease usually characterized by formation of nodular granulomas known as tubercles. In many animals the course of the infection is chronic and signs may be absent, even in advanced cases when many organs may be involved. Subclinical signs include weakness, dyspnea, anorexia, emaciation, enlargement of lymph nodes, and cough, particularly with advanced tuberculosis. Lesions are commonly observed in the lymph nodes mainly of the head and thorax, lungs, intestines, liver, spleen, pleura, and peritoneum. Head and neck lymph nodes may become visibly affected, sometimes rupture, drain, and in advanced cases may be greatly enlarged and may obstruct air passages, alimentary tract, or blood vessels. Clinical signs vary with the involvement of the lung manifested through cough, dyspnea, and other signs of low-grade pneumonia which can be induced by changes in temperature or manual pressure on the trachea. Digestive tract involvement is manifested by intermittent diarrhea or constipation, extreme emaciation, and acute respiratory distress may occur during the terminal stages of tuberculosis
3.2. In humans
M. bovis infection in humans has similar clinical forms as those caused by M. tuberculosis . Most of the studies have suggested that the common clinical manifestation of M. bovis infection in man is associated with the extra-pulmonary form of the disease; however, about half of the post-primary cases involve the lung which is responsible for human-to-human transmission of tuberculosis due to M. bovis The primary infection of the organism in the intestine may heal or it may progress in the intestines or disseminate to other organs . Cervical lymphadenopathy, intestinal lesions, chronic skin tuberculosis, and other non-pulmonary forms are particularly common . Infection due to M bovis in humans usually has a prolonged course and symptoms generally takes months or years to appear. Sometimes, the bacteria remain dormant in the host without causing diseases The common clinical signs of zoonotic TB include loss of appetite, diarrhea, weight loss, intermittent fever, intermittent hacking cough, large prominent lymph nodes, weakness, and so on. Young children infected with M. bovis typically have abdominal infections and older patients suffer from swollen and sometimes ulcerated lymph glands in the neck . Pulmonary disease is more common in people with reactivated infections and this would occur only when some of the animals had active tuberculosis . The symptoms may include fever, cough, chest pain, cavitation, and hemoptysis . The pulmonary form of tuberculosis occurs less frequently and is usually occupationally related
TB Disease in Pregnancy
While dealing with a TB diagnosis in pregnancy is not easy, there is a greater risk to the pregnant woman and her baby if TB disease is not treated. Babies born to women with untreated TB disease may have lower birth weight than those babies born to women without TB. Rarely, a baby may be born with TB. Testing for TB Infection for Pregnant Women
Pregnant women at high risk for developing TB disease should be tested for TB infection. Generally, pregnant women at high risk for developing TB disease include:
Persons who have been recently infected with TB bacteria
Persons with medical conditions that weaken the immune system
The tuberculin skin test is both safe and reliable to use throughout pregnancy. The TB blood test is safe to use during pregnancy, but has not been fully evaluated for diagnosing TB infection in pregnant women. Therefore, TB blood test results should be interpreted with the help of a TB expert. If a tuberculin skin test or TB blood test is positive, other tests are needed to diagnose TB disease. Healthcare providers should obtain a chest radiograph using proper shielding.
