The accuracy of these tests varies depending on the disease stage at which a person is tested. In the few weeks immediately following infection, the tests are expected to be negative. At this stage a person may have developed a rash and fever but no other symptoms. The best time to test for Lyme disease is several weeks after infection occurs. This is when the tests are most accurate.
An infected person may also test negative if they take antibiotics immediately after being bitten by a tick. In this case the person may not develop antibodies against Lyme disease, or may develop antibodies at levels too low to be detected by the tests.
Not everyone who has Lyme disease is diagnosed right away, if at all. For this reason, it’s important to inspect your skin after being outdoors in wooded areas where ticks are common. Wear light-colored clothing that provides an easy contrast for the dark insects. Call your doctor if you develop a rash or feel sick after being in an area that’s known for ticks.
The CDC reports that 96 percent of Lyme disease cases occur in the Northeast and upper Midwest regions of the United States. If you live in one of these regions, you may be at increased risk for infection.