Leptotrombidium

Leptotrombidium
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Arachnida
Subclass:
Acari
Order:
Trombidiformes
Family:
Trombiculidae
Subfamily:
Trombiculinae
Tribe:
Trombiculini
Genus:
Leptotrombidium

Nagayo et al., 1916

Leptotrombidium (/ˌlɛptoʊtrɒmˈbɪdiəm/[1]) is a genus of mites in the family Trombiculidae, that are able to infect humans with scrub typhus (Orientia tsutsugamushi infection) through their bite.[2] The larval form (called chiggers) feeds on rodents, but also occasionally humans and other large mammals. They are related to the harvest mites of the North America and Europe.

Originally, rodents were thought to be the main reservoir for O. tsutsugamushi and the mites were merely vectors of infection: that is, the mites only transferred the contagion from the rodents to humans.[3][4] However, the mites are now known to only feed once in their lifetimes, which means that transmission from rodent to human via the mites is impossible (for it to have been possible, the mite would have to feed at least twice, once on the infected rodent and again on the human who would then be infected).[5] Instead, the bacterium persists in the mites through transovarial transmission,[6][7][8] where infected mites transmit the infection to their unborn offspring. Leptotrombidium mites are therefore both vector and reservoir for O. tsutsugamushi.[5] The infection predominantly affects female mites,[9] and does not appear to otherwise harm the mites.

  1. ^ "Leptotrombidium". Dictionary.com Unabridged (Online). n.d. Retrieved 2016-01-23.
  2. ^ Cite error: The named reference IASR was invoked but never defined (see the help page).
  3. ^ Philip CB (1948). "Tsutsugamushi disease (scrub typhus) in World War II". J Parasitol. 34 (3): 169–191. doi:10.2307/3273264. JSTOR 3273264.
  4. ^ Fox JP (1948). "The long persistence of Rickettsia orientalis in the blood and tissues of infected animals". J Immunol. 59 (2): 109–114. doi:10.4049/jimmunol.59.2.109. PMID 18864084.
  5. ^ a b Pham XD, Suzuki H, Takaoka H (2001). "Distribution of unengorged larvae of Leptotrombidium pallidum and other species in and around the rodent nest holes". Southeast Asian J Trop Med Public Health. 32 (3): 553–57. PMID 11944716.
  6. ^ Walker JS, Chan CT, Manikumaran C, Elisberg BL (1975). "Attempts to infect and demonstrate transovarial transmission of R. tsutsugamushi in three species of Leptotrombidium mites". Ann NY Acad Sci. 266: 80–90. doi:10.1111/j.1749-6632.1975.tb35090.x. PMID 829478.
  7. ^ Takahashi M, Murata M, Nogami S, Hori E, Kawamura A, Tanaka H (1988). "Transovarial transmission of Rickettsia tsutsugamushi in Leptotrombidium pallidum successively reared in the laboratory". Jpn J Exp Med. 58 (5): 213–218. PMID 3149693.
  8. ^ Frances SP, Watcharapichat P, Phulsuksombati D (2001). "Vertical transmission of Orientia tsutsugamushi in two lines of naturally infected Leptotrombidium deliense (Acari: Trombiculidae)". J Med Entomol. 38 (1): 17–21. doi:10.1603/0022-2585-38.1.17. PMID 11268685.
  9. ^ Roberts LW, Rapmund G, Gadigan FG (1977). "Sex ratios in Rickettsia tsutsugamushi-infected and noninfected colonies of Leptotrombidium (Acari: Trombiculidae)". J Med Entomol. 14 (1): 89–92. doi:10.1093/jmedent/14.1.89. PMID 409845.