Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and often deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. Tuberculosis usually attacks the lungs (as pulmonary TB) but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, the gastrointestinal system, bones, joints, and even the skin. Other mycobacteria such as Mycobacterium bovis, Mycobacterium africanum, Mycobacterium canetti, and Mycobacterium microti also cause tuberculosis, but these species are less common. The classic symptoms of tuberculosis are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss. Infection of other organs causes a wide range of symptoms. The diagnosis relies on radiology (commonly chest X-rays), a tuberculin skin test, blood tests, as well as microscopic examination and microbiological culture of bodily fluids. Tuberculosis treatment is difficult and requires long courses of multiple antibiotics. Contacts are also screened and treated if necessary. Antibiotic resistance is a growing problem in (extensively) multi-drug-resistant tuberculosis. Prevention relies on screening programs and vaccination, usually with Bacillus Calmette-Guérin (BCG vaccine). Tuberculosis is spread through the air, when people who have the disease cough, sneeze, or spit. One third of the world's current population has been infected with M. tuberculosis, and new infections occur at a rate of one per second. However, most of these cases will not develop the full-blown disease; asymptomatic, latent infection is most common. About one in ten of these latent infections will eventually progress to active disease, which, if left untreated, kills more than half of its victims. In 2004, mortality and morbidity statistics included 14.6 million chronic active cases, 8.9 million new cases, and 1.6 million deaths, mostly in developing countries. In addition, a rising number of people in the developed world are contracting tuberculosis because their immune systems are compromised by immunosuppressive drugs, substance abuse, or AIDS. The distribution of tuberculosis is not uniform across the globe with about 80% of the population in many Asian and African countries testing positive in tuberculin tests, while only 5-10% of the US population test positive. It is estimated that the US has 25,000 new cases of tuberculosis each year, 40% of which occur in immigrants from countries where tuberculosis is endemic.
When the disease becomes active, 75% of the cases are pulmonary TB. Symptoms include chest pain, coughing up blood, and a productive, prolonged cough for more than three weeks. Systemic symptoms include fever, chills, night sweats, appetite loss, weight loss, pallor, and often a tendency to fatigue very easily. Main sites of extrapulmonary tuberculosis In the other 25% of active cases, the infection moves from the lungs, causing other kinds of TB, collectively denoted extrapulmonary tuberculosis. This occurs more commonly in immunosuppressed persons and young children. Extrapulmonary infection sites include the pleura in tuberculosis pleurisy, the central nervous system in meningitis, the lymphatic system in scrofula of the neck, the genitourinary system in urogenital tuberculosis, and bones and joints in Pott's disease of the spine. An especially serious form is disseminated TB, more commonly known as miliary tuberculosis. Although extrapulmonary TB is not contagious, it may co-exist with pulmonary TB, which is contagious.
Tuberculosis (TB) is caused by a strain of bacteria called mycobacterium tuberculosis.
TB is spread when a person with an active infection of TB in their lungs coughs or sneezes, and somebody else inhales a droplet of contaminated saliva. However, despite being spread in the same way as a cold or the flu, TB is not as contagious.
Once infectious particles reach the alveoli (small saclike structures in the air spaces in the lungs), another cell, called the macrophage, engulfs the TB bacteria.
Then the bacteria are transmitted to the lymphatic system and bloodstream and spread to other organs occurs.
The bacteria further multiply in organs that have high oxygen pressures, such as the upper lobes of the lungs, the kidneys, bone marrow, and meninges -- the membrane-like coverings of the brain and spinal cord.
When the bacteria cause clinically detectable disease, you have TB.
You would usually need to spend a prolonged period of time in close contact with an infected person before you contracted the TB infection yourself.
For example, infections usually spread between family members who are living in the same house. It would be highly unlikely that you would contract a TB infection by sitting next to an infected person on a bus or train.
People who have inhaled the TB bacteria, but in whom the disease is controlled, are referred to as infected. Their immune system has walled off the organism in an inflammatory focus known as a granuloma. They have no symptoms, frequently have a positive skin test for TB, yet cannot transmit the disease to others. This is referred to as latent tuberculosis infection or LTBI.
In the following lines, we have listed the causes of tuberculosis.
- Excessive alcohol intake
- Too much smoking
- Mental stress and strain
- Unhealthy living style
- Low body resistance
- Dietetic errors
- Living in stuffy rooms
- Loss of sleep
- Exposure to cold
- Coming in contact with cough, sneeze, or spit of an infected person
- Breathing infected air
TB prevention and control takes two parallel approaches. In the first, people with TB and their contacts are identified and then treated. Identification of infections often involves testing high-risk groups for TB. In the second approach, children are vaccinated to protect them from TB. Unfortunately, no vaccine is available that provides reliable protection for adults. However, in tropical areas where the levels of other species of mycobacteria are high, exposure to nontuberculous mycobacteria gives some protection against TB. The World Health Organization (W.H.O.) declared TB a global health emergency in 1993, and the Stop TB Partnership developed a Global Plan to Stop Tuberculosis that aims to save 14 million lives between 2006 and 2015. Since humans are the only host of Mycobacterium tuberculosis, eradication would be possible: a goal that would be helped greatly by an effective vaccine.
Tuberculosis is diagnosed definitively by identifying the causative organism (Mycobacterium tuberculosis) in a clinical sample (for example, sputum or pus). When this is not possible, a probable diagnosis may be made using imaging (X-rays or scans) and/or a tuberculin skin test. The main problem with tuberculosis diagnosis is the difficulty in culturing this slow-growing organism in the laboratory (it may take 4 to 12 weeks for blood or sputum culture). A complete medical evaluation for TB must include a medical history, a physical examination, a chest X-ray, microbiological smears and cultures. It may also include a tuberculin skin test, a serological test. The interpretation of the tuberculin skin test depends upon the person's risk factors for infection and progression to TB disease, such as exposure to other cases of TB or immunosuppression. Currently, latent infection is diagnosed in a non-immunized person by a tuberculin skin test, which yields a delayed hypersensitivity type response to an extract made from M. tuberculosis. Those immunized for TB or with past-cleared infection will respond with delayed hypersensitivity parallel to those currently in a state of infection, so the test must be used with caution, particularly with regard to persons from countries where TB immunization is common. Tuberculin tests have the disadvantage in that they may produce false negatives, especially when the patient is co-morbid with sarcoidosis, Hodgkins lymphoma, malnutrition, or most notably active tuberculosis disease. New TB tests are being developed that offer the hope of cheap, fast and more accurate TB testing. These include polymerase chain reaction detection of bacterial DNA, and assays to detect the release of interferon gamma in response to mycobacterial proteins such as ESAT-6. These are not affected by immunization or environmental mycobacteria, so generate fewer false positive results. The development of a rapid and inexpensive diagnostic test would be particularly valuable in the developing world.
Progression from TB infection to TB disease occurs when the TB bacilli overcome the immune system defenses and begin to multiply. In primary TB disease—1–5% of cases—this occurs soon after infection. However, in the majority of cases, a latent infection occurs that has no obvious symptoms. These dormant bacilli can produce tuberculosis in 2–23% of these latent cases, often many years after infection. The risk of reactivation increases with immunosuppression, such as that caused by infection with HIV. In patients co-infected with M. tuberculosis and HIV, the risk of reactivation increases to 10% per year. Patients with diabetes mellitus are at increased risk of contracting tuberculosis, and they have a poorer response to treatment, possibly due to poorer drug absorption Other conditions that increase risk include IV drug abuse; recent TB infection or a history of inadequately treated TB; chest X-ray suggestive of previous TB, showing fibrotic lesions and nodules; silicosis; prolonged corticosteroid therapy and other immunosuppressive therapy; head and neck cancers; hematologic and reticuloendothelial diseases, such as leukemia and Hodgkin's disease; end-stage kidney disease; intestinal bypass or gastrectomy; chronic malabsorption syndromes; vitamin D deficiency; and low body weight. Twin studies in the 1940s showed that susceptibility to TB was heritable. If one of a pair of twins got TB, then and the other was more likely to get TB if he was identical than if he was not. Since then, specific gene polymorphisms in IL12B have been linked to tuberculosis susceptibility. Some drugs, including rheumatoid arthritis drugs that work by blocking tumor necrosis factor-alpha (an inflammation-causing cytokine), raise the risk of activating a latent infection due to the importance of this cytokine in the immune defense against TB.
Treatment for TB uses antibiotics to kill the bacteria. The two antibiotics most commonly used are rifampicin and isoniazid. However, instead of the short course of antibiotics typically used to cure other bacterial infections, TB requires much longer periods of treatment (around 6 to 12 months) to entirely eliminate mycobacteria from the body. Latent TB treatment usually uses a single antibiotic, while active TB disease is best treated with combinations of several antibiotics, to reduce the risk of the bacteria developing antibiotic resistance. People with latent infections are treated to prevent them from progressing to active TB disease later in life. However, treatment using Rifampicin and Pyrazinamide is not risk-free. The Centers for Disease Control and Prevention (CDC) notified healthcare professionals of revised recommendations against the use of rifampin plus pyrazinamide for treatment of latent tuberculosis infection, due to high rates of hospitalization and death from liver injury associated with the combined use of these drugs. Drug resistant tuberculosis is transmitted in the same way as regular TB. Primary resistance occurs in persons who are infected with a resistant strain of TB. A patient with fully-susceptible TB develops secondary resistance (acquired resistance) during TB therapy because of inadequate treatment, not taking the prescribed regimen appropriately, or using low quality medication. Drug-resistant TB is a public health issue in many developing countries, as treatment is longer and requires more expensive drugs. Multi-drug resistant TB (MDR-TB) is defined as resistance to the two most effective first-line TB drugs: rifampicin and isoniazid. Extensively drug-resistant TB (XDR-TB) is also resistant to three or more of the six classes of second-line drugs. The DOTS (Directly Observed Treatment Short-course) strategy of tuberculosis treatment based on clinical trials done in the 1970s by Tuberculosis Research Centre, Chennai, India, focusing on a neglected area of infectious disease control is now showing promising results in effectively treating all TB cases in the community.
Dietary Tips for Tuberculosis Patients
Malnutrition is well known among adults with tuberculosis. Protein deficiency may have a particular detrimental effect on the ability of the body to fight tuberculosis. Multiple micronutrient deficiencies are also common during tuberculosis. Before antibiotics were used to treat tuberculosis, cod liver oil was a mainstay. Studies suggest that the Vitamin A found in cod liver oil may have helped treat the disease by boosting the immune systems response to the bacteria.
It is important to consume a balanced diet to provide your body with the nutrients that you need to fight tuberculosis. It particularly is important to avoid consuming any alcohol during the entire course of your treatment as this could result in treatment complications and side effects.
Weight gain generally improves during appropriate tuberculosis treatment and appropriate nutritional supplementation. However, persons who complete treatment are at risk of losing weight that was gained.
Recommendations For a Balanced Diet
Consume an adequate amount of fruit and vegetables but stay within the correct calorie level for a healthy weight. On a 2000-calorie diet, eat 2 cups of fruit and 2 and a half cups of vegetables per day. Eat more or less according to your calorie needs.
Eat a variety of fruit and vegetables each day. Choose from all five vegetable sub-groups (dark green, orange, legumes, starchy vegetables, and other vegetables) several times a week.
Consume 3 or more ounce-equivalents of whole-grain foods each day, with the rest of the recommended grains coming from enriched or whole-grain products. At least half your grains should come from whole grains. Eating at least 3 ounce-equivalents of whole grains per day can reduce the risk of heart disease, may help with weight maintenance, and will lower your health risk for other chronic diseases.
Consume 3 cups per day of fat-free or low-fat milk or equivalent milk products. Adults and children can consume milk and milk products without worrying that these foods lead to weight gain. There are many fat-free and low-fat choices without added sugars that are available and consistent with an overall healthy dietary plan. If a person has difficulty drinking milk, choose alternatives within the milk food group, such as yogurt or lactose-free milk, or consume the enzyme lactase prior to the consumption of milk products. For people who must avoid all milk products (e.g. individuals with lactose intolerance, vegans), non-dairy calcium-containing alternatives may be chosen to help meet calcium needs.
Eat less than ten percent of calories from saturated fats and less than 300 mg/day of cholesterol, and eat as few trans-fats (hydrogenated fat) as possible.
Maintain your total intake of fats/oils at between 20-35 percent of calories, with most fat coming from polyunsaturated and monounsaturated fat, such as oily fish, nuts, and vegetable oils.
Regarding meat, poultry, dry beans, and milk or milk products, choose lean, low-fat, or fat-free options.
Eat fiber-rich fruits, vegetables, and whole grains as often as possible.
Consume foods and drinks with little added sugars or caloric sweeteners.
Choose foods that contain lean protein, stating:
Eat lean meats and poultry.
Bake, broil, or grill food.
Eat a variety of protein rich foods, with more fish, beans, peas, nuts and seeds.
Choose low-sodium foods, and do not add salt when cooking. Also, eat potassium-rich foods, such as fruits and vegetables.