Ehrlichia is a genus of bacteria that are primarily transmitted to humans through the bite of infected ticks. These bacteria can cause a group of diseases known as ehrlichiosis, which affects white blood cells and can lead to various symptoms, including fever, fatigue, and muscle aches. There are several species of Ehrlichia, with Ehrlichia chaffeensis being the most common in the United States. Diagnosis typically involves blood tests, and treatment usually consists of antibiotics, which are effective if administered early. Preventive measures include avoiding tick bites through protective clothing and using insect repellent.