Disease Prevention

Tuberculosis

Key Points

• Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis.

• The bacteria usually attacks the lungs, but TB bacteria can attack any part of the body such as the kidney, spine, and brain.

• If not treated properly, TB disease can be fatal.

History of TB

A. Historically known by a variety of names:

1. Consumption

2. Wasting disease

3. White plague

B. Scientific Discoveries in the 1800s

1. Until mid-1800s, many believed TB was hereditary

2. 1865 Jean Antoine-Villemin proved TB was contagious

3. 1882 Robert Koch discovered M. tuberculosis, the bacterium that causes TB

History of TBC. Sanatoriums

1. Before TB antibiotics, many patients were sent to sanatoriums

2. Patients followed a regimen of bed rest, open air, and sunshine

3. TB patients who could not afford sanatoriums died at home

History of TB

D. Breakthrough in the Fight Against TB

1. Drugs that could kill TB bacteria were discovered in 1940s and 1950s

a. Streptomycin (SM) discovered in 1943

b. Isoniazid (INH) and p-aminosalicylic acid (PAS) discovered between 1943 and 1952

2. TB death rates in U.S. began to drop dramatically

3. Most TB sanatoriums in U.S. had closed by mid 1970s

History of TB

E. Increase in TB in mid 1980s

1. Inadequate funding for TB control programs

2. HIV epidemic

3. Increased immigration from countries where TB is common

4. Spread in homeless shelters and

correctional facilities

5. Increase and spread of multidrug-resistant TB

Symptoms of TB

1. Bad cough that lasts 3 weeks or longer

2. Pain in the chest

3. Coughing up blood or sputum

4. Weakness or fatigue

5. Weight loss

6. No appetite

7. Chills

8. Fever

9. Sweating at night

Facts about TB

A. Slow-growing, rod-shaped bacterium that can live only in people

B. Unusual waxy coating on cell surface

C. Over 60% of the mycobacterial cell wall is lipid. The lipid portion of the Mycobacterium tuberculosis cell wall consists of mycolic acids, cord factor, and wax-D

D. Because of the thick and complex cell wall, Mycobacterium tuberculosis is resistant to many disinfectants and antibiotics

E. Ziehl-Neelsen staining acid for fast detection used instead of gram staining for detection

F. Divides every 15–20 hours, which is extremely slow compared to other bacteria

G. Aerobic bacterium (needs oxygen to survive). For this reason, during active TB disease, Mycobacterium tuberculosis is found in the upper air sacs of the lungs

How is TB spread?

A. TB germs are put into the air when a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings.

B. These germs can stay in the air for several hours, depending on the environment.

C. Persons who breathe in the air containing these TB germs can become infected; this is called latent TB infection.

Latent TB Infection

• TB bacteria can live in the body without making you sick.• This is called latent TB infection. • In most people who breathe in TB bacteria and become

infected, the body is able to fight the bacteria to stop them from growing.

• People with latent TB infection do not feel sick and do not have any symptoms.

• People with latent TB infection are not infectious and cannot spread TB bacteria to others.

• However, if TB bacteria become active in the body and multiply, the person will go from having latent TB infection to being sick with TB disease.

Treatment for Latent TB Infection

• If you have latent TB infection but not TB disease, your health care provider may want you be treated to keep you from developing TB disease.

• Treatment of latent TB infection reduces the risk that TB infection will progress to TB disease.

• Treatment of latent TB infection is essential to controlling and eliminating TB in the United States.

• The decision about taking treatment for latent TB infection will be based on your chances of developing TB disease.

TB Disease

• TB bacteria become active if the immune system can't stop them from growing.

• When TB bacteria are active (multiplying in your body), this is called TB disease.

• People with TB disease are sick. • They may also be able to spread the bacteria to people they spend

time with every day.• Many people who have latent TB infection never develop TB disease. • Some people develop TB disease soon after becoming infected (within

weeks) before their immune system can fight the TB bacteria. • Other people may get sick years later when their immune system

becomes weak for another reason.• For people whose immune systems are weak, especially those with

HIV infection, the risk of developing TB disease is much higher than for people with normal immune systems.

Treatment for TB Disease

• TB disease can be treated by taking several drugs, usually for 6 to 9 months.

• It is very important to finish the medicine, and take the drugs exactly as prescribed.

• If you stop taking the drugs too soon, you can become sick again.

• If you do not take the drugs correctly, the germs that are still alive may become resistant to those drugs.

• TB that is resistant to drugs is harder and more expensive to treat.

Testing for TB

• There are three tests that are used to detect TB bacteria in the body. These tests can be given by a health care provider or local health department.

1. TB skin test (TST)

2. TB blood tests

3. Chest radiographs

Drug Resistant TB

• caused by M. tuberculosis organisms that are resistant to at least one first-line TB treatment drug.

• Drug-resistant TB can be difficult to treat.o Primary resistance is caused by person-to-person

transmission of drug-resistant organisms.o Secondary resistance develops during TB treatment.

Either the patient was not treated with the right TB drugs or the patient did not properly follow the prescribed treatment regimen.