Rickettsia typhi is a type of bacteria that causes typhus, a disease often spread by fleas. It primarily infects rodents, which serve as the main reservoir for the bacteria. Humans can become infected through flea bites or contact with contaminated materials, such as feces from infected fleas. Symptoms of typhus include fever, headache, and rash, typically appearing one to two weeks after exposure. While the disease can be serious, it is treatable with antibiotics. Preventive measures include controlling flea populations and maintaining good hygiene to reduce the risk of infection.