( CNN ) -- The Fairfax County , Virginia , health department is investigating a tuberculosis outbreak at an area school after three people tested positive for the potentially fatal bacteria , officials said Thursday . The health department has contacted 430 people who may have been exposed and need to be tested as a result of exposure to the three , the officials said . Health officials declined to say whether the three were students or teachers . They also said they did not know what strain of TB the three contracted . The first case of tuberculosis at Robert E. Lee High School was diagnosed in December 2012 , and the health department opened and completed an investigation , the agency said . But because two more people from the same school were diagnosed with it in June , the department re-opened the December case and is investigating whether they are related . TB bacteria usually attack the lungs , but they can also attack other parts of the body such as the kidneys , spine and brain , according to the Centers for Disease Control and Prevention . If not treated properly , TB can be fatal .
Three people tested positive for tuberculosis at the County school , officials said . School officials have declined to say whether the three are students or teachers . The health department has identified 430 people who they believe need to be tested .