Definition of Rickettsia

Rickettsia: A member of a group of microorganisms that (like viruses) require other living cells for growth but (like bacteria) use oxygen, have metabolic enzymes and cell walls, and are susceptible to antibiotics. Rickettsiae cause a series of diseases named for the American pathologist Howard Ricketts who discovered that ticks spread Rocky Mountain spotted fever and then isolated the microorganism responsible for Rocky Mountain spotted fever, typhus, trench fever and other similar conditions from the infecting insects. While in Mexico in 1910 studying a typhus epidemic, Ricketts contracted the disease and died at age 39.

See also Rickettsial diseases.