Leptotrombidium

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Genus of mites

title: "Leptotrombidium" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["parasitic-arthropods-of-humans", "trombiculidae", "arachnids-of-asia", "acari-genera"] description: "Genus of mites" topic_path: "general/parasitic-arthropods-of-humans" source: "https://en.wikipedia.org/wiki/Leptotrombidium" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Genus of mites ::

| taxon = Leptotrombidium | authority = Nagayo et al., 1916

Leptotrombidium () is a genus of mites in the family Trombiculidae, that are able to infect humans with scrub typhus (Orientia tsutsugamushi infection) through their bite. 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. 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). Instead, the bacterium persists in the mites through transovarial transmission,{{cite journal |title=Vertical transmission of Orientia tsutsugamushi in two lines of naturally infected Leptotrombidium deliense (Acari: Trombiculidae) |vauthors=Frances SP, Watcharapichat P, Phulsuksombati D |journal=J Med Entomol |year=2001 |volume=38 |issue=1 |pages=17–21 |pmid=11268685 |doi=10.1603/0022-2585-38.1.17}} where infected mites transmit the infection to their unborn offspring. Leptotrombidium mites are therefore both vector and reservoir for O. tsutsugamushi. The infection predominantly affects female mites,{{cite journal |title=Sex ratios in Rickettsia tsutsugamushi-infected and noninfected colonies of Leptotrombidium (Acari: Trombiculidae) |vauthors=Roberts LW, Rapmund G, Gadigan FG |journal=J Med Entomol |volume=14|issue=1|year=1977|pages=89–92|doi=10.1093/jmedent/14.1.89 |pmid=409845 }} and does not appear to otherwise harm the mites.

Life history

The larval stage lasts for 1 to 2 weeks. After feeding, the larvae drop to the ground and become nymphs. Nymphs are brick-red in colour and have four pairs of legs. The nymphal stage lasts for 1 to 3 weeks. Nymphs mature into adults which have four pairs of legs, the first pair being the largest. They are harmless to humans. In the postlarval stage, they are not parasitic and feed on plant materials. | title = Lifecycle of Leptotrombidium pallidum (Acari: Trombiculidae), one of the vector mites of scrub typhus in Japan |vauthors=Takahashi M, Misumi H, Urakami H, etal | journal = Ohara Sogo Byoin Nenpo | volume = 45 | issue = | pages = 19–30 | year = 2003

Taxonomy

L. akamushi is endemic to Japan and is the reservoir for the Kato serotype of O. tsutsugamushi;
L. deliense is the main vector in the south of China{{cite journal |vauthors=Wang S, Jiang P, Huang J, etal |title=Demonstration of the natural foci of tsutsugamushi disease in Nan Peng Lie Islands in China |volume=32 |issue=3 |year=2001 |pages=541–46 |url= https://www.tm.mahidol.ac.th/seameo/2001_32_3/18-2636.pdf |pmid=11944714 |journal=The Southeast Asian Journal of Tropical Medicine and Public Health}} and in Thailand; it is also endemic to Litchfield Park, in the Northern Territory, Australia, where is carries the Litchfield serotype.{{cite journal |doi=10.3201/eid0404.980416 |vauthors=Odorico DM, Graves SR, Currie B, etal |title=New Orientia tsutsugamushi strain from scrub typhus in Australia |journal=Emerg Infect Dis |year=1998 |volume=4 |issue=4 |pmid=9866742 |pages=641–4 |pmc=2640248}}
L. pallidum is endemic to Japan and is the reservoir for Karp and Gilliam serotypes;
L. scutellare is endemic to Japan and is the reservoir for Kawasaki and Kuroki serotypes.

References

Philip CB. (1948). "Tsutsugamushi disease (scrub typhus) in World War II". J Parasitol.
Fox JP. (1948). "The long persistence of ''Rickettsia orientalis'' in the blood and tissues of infected animals". J Immunol.
(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.
(1975). "Attempts to infect and demonstrate transovarial transmission of ''R. tsutsugamushi'' in three species of Leptotrombidium mites". Ann NY Acad Sci.
(1988). "Transovarial transmission of ''Rickettsia tsutsugamushi'' in ''Leptotrombidium pallidum'' successively reared in the laboratory". Jpn J Exp Med.
(2001). "Scrub typhus (tsutsugamushi disease) in Japan, 1996–2000". Byogen Biseibutsu Kenshutsu Joho Geppo.
(1999). "Seasonal occurrence of ''Leptotrombidium deliense'' (Acari: Trombiculidae) attached to sentinel rodents in an orchard near Bangkok, Thailand". J Med Entomol.
(1992). "Epidemiology of Tsutsugamushi disease in relation to the serotypes of Rickettsia tsutsugamushi isolated from patients, field mice, and unfed chiggers on the eastern slope of Mount Fuji, Shizuoka Prefecture, Japan". J Clin Microbiol.

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