noun. any of a group of very small rod-shaped bacteria that live in biting arthropods (as ticks and mites) and cause disease in vertebrate hosts; they cause typhus and other febrile diseases in human beings.
- true bacteria
- family Rickettsiaceae
Example sentences of the word rickettsia
1. Noun, singular or mass
If your dog hosts the wrong tick, he can become infected with rickettsia rickettsii, the organism causing Rocky Mountain spotted fever.