Louse- and flea-borne rickettsioses: Biological and genomic analyses

Joseph J. Gillespie, Nicole C. Ammerman, Magda Beier-Sexton, Bruno S. Sobral, Abdu F. Azad

Research output: Contribution to journalReview articlepeer-review

40 Scopus citations


In contrast to 15 or more validated and/or proposed tick-borne spotted fever group species, only three named medically important rickettsial species are associated with insects. These insect-borne rickettsiae are comprised of two highly pathogenic species, Rickettsia prowazekii (the agent of epidemic typhus) and R. typhi (the agent of murine typhus), as well as R. felis, a species with unconfirmed pathogenicity. Rickettsial association with obligate hematophagous insects such as the human body louse (R. prowazekii transmitted by Pediculus h. humanus) and several flea species (R. typhi and R. felis, as well as R. prowazekii in sylvatic form) provides rickettsiae the potential for further multiplications, longer transmission cycles and rapid spread among susceptible human populations. Both human body lice and fleas are intermittent feeders capable of multiple blood meals per generation, facilitating the efficient transmission of rickettsiae to several disparate hosts within urban/rural ecosystems. While taking into consideration the existing knowledge of rickettsial biology and genomic attributes, we have analyzed and summarized the interacting features that are unique to both the rickettsiae and their vector fleas and lice. Furthermore, factors that underlie rickettsial changing ecology, where native mammalian populations are involved in the maintenance of rickettsial cycle and transmission, are discussed.

Original languageEnglish (US)
Article number12
JournalVeterinary Research
Issue number2
StatePublished - Mar 2009
Externally publishedYes


  • Ecology
  • Epidemic and murine typhus
  • Recrudescent typhus
  • Rickettsial biology

ASJC Scopus subject areas

  • General Veterinary


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