What is tuberculosis?

Tuberculosis (TB) is an infectious disease caused by the tuberculosis bacteria. The TB germ can cause an infection in the lungs but may travel in the blood stream and affect other parts of the body.

How is tuberculosis spread?

Tuberculosis is only infectious if the disease is in the lungs (pulmonary TB) and the person is coughing the germ into the air. It usually requires close, prolonged contact with the case to get the TB germ.

What is the difference between "TB infection" and "Active TB disease"?

• The first infection often goes unnoticed. The body's defences (antibodies) usually destroy the TB germs or wall off the germs so no damage is done. A skin test is able to detect TB anti-bodies. It shows whether someone has been exposed to the TB germ. People who have had sufficient contact with the TB germ will have a positive skin test 2-12 weeks after initial exposure. This is known as TB infection.
• At the time of first infection only about 5% go on to develop active tuberculosis disease (where the germ is doing damage). These are usually the very young or those whose health is poor. Others may develop active disease later in life when the TB germs that were walled off start to grow again and cause damage in the body. This happens in approximately 10% of those with a positive skin test. The elderly, the immunocompromised (such as HV infection) or those with poor general health are at highest risk, as their ability to fight infection is weaker.

What are the symptoms of active TB disease?

• Pulmonary tuberculosis may not produce any early symptoms until the infection in the lung has reached a size that is visible on x-ray. Symptoms include cough, loss of appetite, fatigue, weight loss, fever and night sweats. Cough and sputum production are often present and may be misdiagnosed as bronchitis or pneumonia. Any cough greater than three weeks duration should be thoroughly investigated.
• If the disease is outside the lung such as in the kidney, lymph nodes, bone, etc. symptoms such as pain or discomfort, would be in relation to those sites.

Is there treatment for tuberculosis?

Tuberculosis is curable. Antibiotic treatment for tuberculosis has been available since the late 1940's. People are treated at home under the supervision of their doctor. Usually after two weeks they are no longer contagious and can return to work or school. Medication must be taken daily for at least 6 - 9 months or as the doctor orders. The full treatment must be completed to prevent drug resistance from developing. Drug resistance means that the drug is no longer effective in destroying the TB germ.

What is preventive treatment?

• Anyone with a positive skin test should have a chest x-ray and medical assessment done to determine if there is active tuberculosis disease. Preventive medicine, usually Isoniazid (INH) pills, are routinely prescribed for persons with a positive skin test. Taken daily Isoniazid has been shown to prevent "TB infection" from becoming "active TB disease".
• Persons who have a positive skin test and do not complete preventive therapy, run a risk of breakdown to active tuberculosis disease. Their doctor should have this information so that TB might be considered if a prolonged infection or chronic cough occurs.

Conclusion

Tuberculosis is a reportable disease. The Health Department must be notified so appropriate case and contact follow-up is done.

For more information call a member of Communicable Disease Services at 519-426-6170, Monday to Friday from 8:30 a.m. to 4:30 p.m.

Adapted from the Region of Peel Public Health Department.