Rickettsiales is an order of bacteria that are primarily known for being obligate intracellular parasites. This means they can only survive and reproduce inside the cells of a host organism. Members of this order are often transmitted to humans through the bites of infected arthropods, such as ticks, fleas, and lice. The order includes several important genera, such as Rickettsia, Ehrlichia, and Anaplasma. These bacteria can cause various diseases, including Rocky Mountain spotted fever and Ehrlichiosis. Understanding Rickettsiales is crucial for public health, as they can lead to serious infections if not diagnosed and treated promptly.