1. Lyme Disease
Most people have heard of the bulls-eye rash that appears when a Lyme-infected deer tick infects its victim, but not every patient gets the telltale rash. In those cases, Lyme disease is usually marked by body aches, fever, and fatigue that doctors often write off as the flu, says Albert Ahn, MD, clinical instructor of internal medicine at NYU Langone Health. And it’s easy to see why: The body won’t have time to develop the antibodies that signal the disease until a few weeks after the bite, meaning blood tests won’t reveal it. The symptoms can disappear temporarily, so see if your doctor will give you a one-time antibiotic if you suspect Lyme, suggests Dr. Ahn. “If you miss it and continue to miss it, the long-term effects of Lyme could be debilitating,” he says.