Definition
Rickettsiales are an order of bacteria, all of which are obligate intracellular parasites, meaning they must live inside other cells to survive. They're Gram-negative and transmitted to humans and animals through arthropod vectors like ticks, fleas, and mites. These bacteria cause diseases such as Rocky Mountain spotted fever and typhus. Think of them as tiny stowaways hijacking cells for their own benefit, similar to a virus but technically bacteria. Unlike many other bacteria, they cannot survive independently.