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TB Questions and Answers - Section 2

-Transmission of the disease-


Q: How is tuberculosis spread?

A: Tuberculosis is usually spread when someone inhales the airborne TB bacteria which is normally carried on droplet nuclei. The bacteria, because of its small size, is able to avoid most of the body's defense mechanisms and reaches the lower respiratory tract lodging in the aveoli of the lung.

Q: Who may be at risk of becoming infected with TB?

A: Anyone who comes into contact with someone with active TB. This may include friends, family, doctors, nurses, radiologists, home health aides, prison guards, etc. In addition, those who are immunosuppressed have a greater risk of developing the clinically active disease.

Q: Where are outbreaks of TB presently occurring?

A: The spread of TB is now considered to be at an epidemic stage throughout many areas of the US with certain regions experiencing a 30+% increase in active cases per year. The Centers for Disease Control (CDC) reports that outbreaks of TB are occurring in health care facilities, shelters for the homeless, drug treatment facilities, and especially prisons.

Q: How long can the TB bacteria remain airborne?

A: Because of its small size, the bacteria is virtually weightless and can remain suspended in air almost indefinitely. Due to this characteristic, it is able to be carried by normal air currents throughout a room or facility.

Q: Is there concern for transmission of TB once the bacteria comes in contact with a surface?

A: Usually only if the particle can once again become airborne. The CDC states that non-critical items (those that either do not ordinarily touch the patient or those that touch intact skin) do not transmit tuberculosis infection.

Q: What happens to the droplet nuclei when it comes in contact with a surface?

A: Particles this small normally come in contact with walls and ceilings. Once deposited, they are imbedded or attached to the surface by a process called molecular adhesion. Scrubbing usually becomes the only way to remove them. After a period of time, the droplet nuclei evaporate and the TB bacteria eventually ceases to be virulent.

Q: What are the chances of a susceptible person becoming infected with TB?

A: That probability depends upon the concentration of infectious droplet nuclei in the air and the amount of time spent in the contaminated environment.

Q: How much risk is a person in a health care facility?

A: Many factors vary that risk, some considerations are the population served, job category, and where within the facility the worker functions as well as the amount of time spent with TB patients.

Q: Is there a greater risk in some areas than others?

A: There may be a higher risk where patients with TB are provided care before any positive diagnosis for TB takes place. This would include areas such as clinic waiting areas and emergency rooms. Other areas of risk would be any place where an active TB patient spends time or receives treatment.

Q: How concerned should health care workers be if they function in settings where those diagnosed with HIV receive care?

A: They should be particularly alert to prevention of TB transmission, especially if, for example, medical procedures which induce coughing are used.



-End of Section 2-

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