(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 need to be tested as a result of exposure to the three, the officials said.
Health officials declined to identify whether the three were students or teachers but said those who needed to be tested have been notified.
They also said they did not know what strain of TB the three contracted.
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.