Host Response & Symptoms

Host Response

Despite the importance of tuberculosis as the leading cause of death due to infectious disease in the world, it has only been recently that an understanding of the human host response in this infection has begun to emerge. The key components of this response are cytokines and components of cellular immunity, predominantly T-lymphocytes and macrophages. Though the relationships among the components of the immune response are complex, it seems likely that in response to mycobacterial infection associated with active disease, cytokines such as TNF-alpha and IL-1 beta are produced; these cytokines serve to recruit more lymphocytes, generally of the T(H) (T helper) phenotype, which then produces substances such as the macrophage activating factor interferon-gamma. Macrophages activated by IFN-gamma ar thus stimulating to enhance intracellular killing of mycobacteria. The role of other cytokines, such as IL-6 and IL-8, both of which are induced by M. tuberculosis or its cell was components, is less clear. Further elucidation of the human host response to tuberculosis should help in the development of new vaccines and treatment strategies.

A link to an article about the host response of tuberculosis : 

Mycobacterium tuberculosis and Host Response

Symptoms of Tuberculosis

Generally, symptoms of TB disease depend on where in the body the TB bacteria are growing. TB bacteria usually grow in the lungs (pulmonary TB). TB disease in the lungs may cause symptoms such as

• a bad cough that lasts 3 weeks or longer
• pain in the chest
• coughing up blood or sputum (phlegm from deep inside the lungs)

Other symptoms of TB disease are:

• weakness or fatigue
• weight loss
• no appetite
• chills
• fever
• sweating at night

Now, for some of you who wants a more detailed explanation,

In older infants and children, latent tuberculosis infection (LTBI), which is the first infection with the tuberculosis bacteria, usually produces no signs or symptoms. In addition, a chest X-ray shows no signs of infection.

In most cases, only a tuberculin skin test (used to figure out if someone has been infected by the tuberculosis bacteria) is positive, indicating that the child has been infected. Children with a positive tuberculin test, even if they show no disease, will usually need to receive medication.

This primary infection usually resolves on its own as a child develops immunity over a 6- to 10-week period. But in some cases, it can progress and spread all over the lungs (called progressive tuberculosis) or to other organs. This causes signs and symptoms such as fever, weight loss, fatigue, loss of appetite, and cough.

Another type of infection is called reactivation tuberculosis. Here, the primary infection has resolved, but the bacteria are dormant, or hibernating. When conditions become favorable (for instance, due to lowered immunity), the bacteria become active.

Tuberculosis in older kids and adults may be of this type. The most prominent symptom is a persistent fever, with sweating during the night. Fatigue and weight loss may follow. If the disease progresses and cavities form in the lungs, the person might have coughing and the production of saliva, mucus, or phlegm that may contain blood.

When a microorganism infects a person's body, he or she usually becomes sick within one to two weeks, but not with tuberculosis. Except for very young children, people can have live bacteria "sleeping" inside their bodies for many years. The body's defense mechanisms prevented the bacteria from developing into full-scale tuberculosis, but have not killed the bacteria. These sleeping bacteria cannot be spread to other people.

In the vast majority of people, the bacteria never cause problems. In five to 10 percent, however, the bacteria start to multiply and develop tuberculosis, usually within the first two years after infection. Although what causes the bacteria to become active is not known, it can happen because of an immune system weakened by advanced age, the use of corticosteroids or AIDS.

In this phase, an infected person feels sick and can spread the disease to other people. The bacteria that cause tuberculosis can live only in people. It cannot be carried by animals, insects, soil or nonliving objects. The bacteria spread only through the air when a person coughs, sneezes or speaks. The bacteria can stay in the air for several hours, making it possible for many other people to become infected with tuberculosis.

The signs of tuberculosis may not appear to be serious at first. They include:

• Coughing, which produces a small amount of green or yellow sputum in the morning. As the disease gets worse, the sputum may be streaked with small amounts of blood.
• Cold night sweats, which are heavy enough to wake a sleeper up and require a change of nightclothes or bed sheets
• Not feeling well in general
• A loss of energy and appetite
• Weight loss over time
• Sudden shortness of breath along with chest pain may be a sign that air or fluid has entered the space between the lungs and the chest wall (pneumothorax). For many people this is the first sign that leads them to seek a diagnosis.

When a tuberculosis infection first occurs, the bacteria may travel from the lungs to the lymph nodes that drain the lungs. If the body is able to bring the infection under control at this stage, the bacteria become dormant.

A dangerous complication for young children, whose immune systems are weaker and bodies are smaller, is that the lymph nodes can swell large enough to press on the bronchial tubes, causing a cough and possibly a collapsed lung. Sometimes, the bacteria spread up the lymph system to the lymph nodes in the neck, in which case, the infection may break through the skin and let loose pus.

In people with a fully functioning immune system, active tuberculosis is usually limited to the lungs (pulmonary tuberculosis). Tuberculosis that affects other parts of the body (extrapulmonary tuberculosis) comes from pulmonary tuberculosis that has spread through the blood. As in the lungs, the infection may not cause disease, but the bacteria may remain dormant in a very small scar. Latent organisms in these scars can reactivate later in life, leading to symptoms in the organs involved. In pregnant women, the tuberculosis bacteria may spread to the fetus and cause disease; however, such congenital tuberculosis is uncommon. If the tuberculosis infection occurs outside the lungs, it usually affects the kidneys and the lymph nodes. Symptoms of a tuberculosis infection elsewhere than the lungs tend to be vague and include:

• Fatigue
• Poor appetite
• Fevers that come and go
• Sweats
• Weight loss in some cases
• Pain

Other types of tuberculosis include:

• Tuberculosis meningitis, which affects the tissues that cover the brain. This is life threatening. Symptoms include fever, a headache that does not go away, stiffness in the neck, nausea and sleepiness that can develop into a coma.
• Tuberculoma, which affects the brain itself and forms a mass that causes headaches, seizures or muscle weakness
• Tuberculous pericarditis, which affects the membrane that covers the heart (pericardium). This type of tuberculosis causes the pericardium to thicken. Sometimeswhich affects the membrane that covers the heart (pericardium). This type of tuberculosis causes the pericardium to thicken. Sometimes fluid will leak from the layers of the pericardium into the space between the pericardium and the heart, making it harder for the heart to pump. It can cause swollen veins in the neck and difficulty breathing.
• Intestinal tuberculosis, which may not cause any symptoms but does create an abnormal mass of tissue that can be mistaken for cancer
• Miliary tuberculosis, which is a life-threatening type of tuberculosis that occurs when a large number of bacteria are spread throughout the body in the bloodstream. It gets its name from the millions of tiny lesions formed, which are the size of millet, a tiny round seed. If it gets into the bone marrow, it can cause severe anemia and blood conditions that seem like leukemia.

And here, i uploaded a video about the signs & symptoms of tuberculosis for u guys to watch.

 

How to Recognize the Signs and Symptoms of Tuberculosis

1. 1
   Be vigilant about checking for the symptoms and/or having a TB test if you:
   
   
   
   
   
   
   • have spent time with a person known to have active TB disease or suspected to have active TB disease; sharing glass, dishes or cutlery during a meal or food prep, kissing, exchange of saliva-sexual intercourse with a condom is not included as a means of transfer. Or
   • have HIV infection or another condition (weakened immune system from other auto-immune diseases including RA, FM, Lupus etc.) that puts you at high risk for developing active TB disease; or
   • think you might have active TB disease; or
   • are from a country where TB disease is common (most countries in Latin America and the Caribbean, Africa (including Middle East), Asia, Eastern Europe, and Russia); or
   • live in a place where TB disease is more common such as a homeless shelter, migrant farm camp, prison or jail, and some nursing homes. There are communities in U.S. where damp badly lit basements with little ventilation are rented, these are breeding grounds); or
   • inject illegal drugs
2. 2
   Recognize that the symptoms are dependent on where the TB bacteria are growing. Usually this will be in the lungs. However, TB can also grow in other parts of the body, such as the brain; TB even latent, can affect the joints, it is important to be tested even when you are older to distinguish between 'arthritis' from aging or TB so the following sets of symptoms should be checked off.
   
   
   
   
3. 3
   Check for these symptoms indicating the TB is in the lungs:
   
   
   
   
   • A bad or persistent cough that lasts 3 weeks or longer without having a cold
   • Pain in the chest, less sharp and more achy, could be felt inhaling or exhaling.
   • Coughing up blood or sputum (phlegm from deep inside the lungs)
4. 4
   There may be tiny blood droplets on pillow in morning, these can appear within drool or from breath during sleep.
   
   
   
   
5. 5
   Check for these symptoms that may indicate TB bacteria are growing somewhere in your body:
   
   
   
   
   • Weakness or extreme fatigue
   • Weight loss is common
   • Little or total lack of appetite
   • Chills (usually severe and repetitive)
   • Fever (can be low grade)
   • Sweating at night (may come and go)
6. 6
   Have a TB skin test taken. A TB skin test will tell you if you have ever had TB germs in your body. Additional tests including a simple chest x-ray will help show if you have a latent TB infection or active TB.
   
   
   
   

Reference:
1. http://www.wikihow.com/Recognize-the-Signs-and-Symptoms-of-Tuberculosis
2. http://www.ncbi.nlm.nih.gov/pubmed/8525336