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rickettsia Syllabification: rick·ett·si·a
Pronunciation: /rəˈketsēə/

Definition of rickettsia in English:

noun (plural rickettsiae-sēˌē-sēˌī or rickettsias)

Any of a group of very small bacteria that includes the causative agents of typhus and various other febrile diseases in humans. Like viruses, many of them can only grow inside living cells, and they are frequently transmitted by mites, ticks, or lice.
Example sentences
  • These diseases result from a variety of infectious agents including bacteria, rickettsia, viruses and protozoa, or they may be caused by substances produced by the tick.
  • It was interesting to note that neither the viruses nor the rickettsiae multiplied in this cell line.
  • Typhus is caused by rickettsia, bacteria-like microorganisms transmitted through blood-sucking insects such as fleas, lice, and ticks.


Example sentences
  • Other viral, bacterial, and rickettsial diseases (such as Rocky Mountain Spotted Fever) have also created a niche for themselves in response to behavioral and environmental changes.
  • Post-infectious glomerulonephritis has also been associated with other bacterial, viral, parasitic, rickettsial and fungal infections.
  • Serology showed no recent mycoplasma, legionella, or rickettsial infection, and a serum cryptococcal latex agglutination test was negative.


Modern Latin, named after Howard Taylor Ricketts (1871–1910), American pathologist.

Definition of rickettsia in:
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