Rickettsias are a group of small, obligate intracellular bacteria that belong to the family Rickettsiaceae. They are primarily transmitted to humans through arthropod vectors, such as ticks, fleas, and lice, and can cause various diseases, including typhus and Rocky Mountain spotted fever. Rickettsias are known for their ability to invade and multiply within host cells, leading to inflammatory responses and various clinical symptoms. Due to their unique characteristics, they are often studied in the context of Infectious Diseases and public health.