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Tuberculosis Testing at Cornell

Facts

Many people think that Tuberculosis (TB) is a disease of the past, an illness that no longer threatens us today. However, with one third of the world’s population estimated to be infected with the bacteria that causes TB, and more than 8 million TB disease cases every year, TB is very much with us today.

TB is endemic in 125 countries and affects all the rest. In 2007, a total of 13,299 TB cases were reported in the United States. The World Health Organization 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.

Tuberculosis is an airborne infectious disease that is preventable and curable. It is spread from one person to another when someone with active TB disease releases TB bacteria into the air (particularly by coughing). People nearby may breathe in these bacteria and develop TB infection. Generally, this takes prolonged exposure. The infectious particles can spread in close quarters and rooms with limited ventilation.

People who are exposed to someone with active TB disease can become infected with TB bacteria, but in most cases their immune system prevents that infection from causing TB disease. This condition is called latent tuberculosis infection (LTBI).

However, in people with latent TB infection, the bacteria can become active and cause TB disease over time, sometimes even decades after initial infection. People with LTBI and a healthy immune system have a 10% chance of developing active TB disease before the age of 65. Any condition that weakens the immune system will increase the chance of activating TB. Simply getting older is a major cause of TB activation, as well as common cancers, low body weight, or HIV infection.

Testing

Cornell University has the responsibility to protect its population from many contagious diseases. Active TB disease does appear in this population on a regular basis. The Tompkins County Health Department assists Gannett Health Services with evaluating and treating TB infection and disease. One case of active disease can infect dozens of people in this close-knit community.

TB testing is done using the Mantoux Skin Test, in which a small amount of protein derived from TB bacillus is placed just under the skin surface. Two or three days later a trained person measures any resulting reaction. You cannot get TB from the test, and it is safe for those who are pregnant, breast-feeding, HIV-positive or undergoing chemotherapy. Those with a positive reaction need to have a chest x-ray to determine if they have active TB disease.

TB testing is recommended for all incoming students and mandatory for international students. International students (not including students from Canada) must be tested at Gannett Health Services after arrival at Cornell. Call 607 255-5155 to schedule an appointment.

Testing is also recommended for those who have been identified by the Tompkins County Health Department as having some risk of exposure to a person with active TB. Testing is not effective until 8 weeks after the possible exposure. It can be done on campus at Gannett for members of the Cornell community. Those who are no longer in Ithaca should seek testing from another health care provider.

Treatment

TB infection and TB disease are curable. If TB disease is detected early and fully treated, people with the disease quickly become non-infectious and eventually cured.

Efforts in the United States to control TB have been very successful. This is due to aggressive efforts to treat everyone who develops active disease and encourage as many people as possible to cure their underlying latent TB infection. For every 15 people who finish treatment, we prevent one case of TB disease. It is much easier and safer to treat the latent TB infection. For most people, the course of medicine is tolerated easily. The benefit is the elimination of the TB bacteria from your body, significantly reducing your own risk of disease for the rest of your life, and reducing the spread of TB in the community.

BCG Vaccine

Many people had the “BCG vaccine” when they were young and were told it would protect them from TB. Unfortunately, this is not always the case. If the vaccine were effective, TB would not be the problem it is today. The fact that TB is spreading rapidly throughout the world, especially in those countries that depend on the BCG vaccine, is proof that BCG does not protect against getting infected or developing TB disease. Most people who were vaccinated with BCG as children do not have any skin test reaction after the age of 10. A positive reaction to a skin test in someone who has had a BCG vaccination is considered serious medical evidence that a person is likely infected with TB.

For More Information

Please call Gannett (607) 255-5155 and ask to speak with a nurse.
You may also find it helpful to read more about TB:

Print Gannett's Fact Sheet (pdf) on this topic.


What does a positive TB test mean?

Positive results may be due to a latent or active TB infection, or occasionally due to a false positive. Positive results must be followed up by other tests such as chest X-rays to look for signs of active TB disease.