Distribution of Leptotrombidium (Leptotrombidium) Arenicola (Acarina: Trombiculidae) on the Ground in West Malaysia1

Mites of the family Trombiculidae are known for playing a role in maintaining and spreading the scrub typhus etiologic agent, an intracellular Gram-negative bacterium, Orientia tsutsugamushi. Species of the genus Leptotrombidium are investigated most thoroughly, particularly in SE Asia, and a few are proven vectors for the pathogen. The mentioned association, however, is not the only one among trombiculids. Here, we present a list of chiggers indicated in the literature as positive for bacterial pathogens, tested throughout almost 100 years of research. Taxonomic identities of trombiculids follow recent revisions and checklists. Results point at 100 species, from 28 genera, evidenced for association with 31 bacterial taxa. Pathogen-positive mites constitute around 3.3% of the total number of species comprising the family. Discussed arachnids inhabit six biogeographic realms and represent free-living instars as well as external and internal parasites of rodents, soricomorphs, scadents, lagomorphs, peramelemorphs, bats, passerine birds, reptiles and humans. A variety of so far detected bacteria, including novel species, along with the mites’ vast geographical distribution and parasitism on differentiated hosts, indicate that revealing of more cases of Trombiculidae-pathogens association is highly probable, especially utilizing the newest techniques enabling a large-scale bacterial communities survey.

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“…Orientia tsutsugamushi -infected larvae were collected from Rattus spp. and from the ground in Indonesia and Malaysia [ 81 , 82 ].…”

Section: Resultsmentioning

confidence: 99%

Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens

2022

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“…Interestingly, we recorded a Malaysian endemic, L. arenicola , for the first time since the 1970s, and this species alone exhibited a positive association with O. tsutsugamushi infection in small mammals in the current study. Sandy beaches were reported to be the strict ecological niche of L. arenicola [ 48 ], which is clearly not the case, albeit it was found only at the Johor site (which is situated less than 20 km from the coast). This species has been a major focus of epidemiological and experimental studies at the Institute for Medical Research, Kuala Lumpur, where it was shown to harbour O. tsutsugamushi naturally and in the laboratory could transmit the pathogen horizontally to mice, as well as transovarially from adult female mites to larval progeny [ 49 ].…”

Section: Discussionmentioning

confidence: 99%

Habitat and Season Drive Chigger Mite Diversity and Abundance on Small Mammals in Peninsular Malaysia

et al. 2022

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Chigger mites are vectors of the bacterial disease scrub typhus, caused by Orientia spp. The bacterium is vertically transmitted in the vector and horizontally transmitted to terrestrial vertebrates (primarily wild small mammals), with humans as incidental hosts. Previous studies have shown that the size of the chigger populations is correlated with the density of small mammals in scrub typhus-endemic regions. Here, we explore interactions between the small mammals and chiggers in two oil palm plantations located in the Perak and Johor states of Peninsular Malaysia. The location in Perak also contained an aboriginal (Orang Asli) settlement. A ~5% sub-sample from 40,736 chigger specimens was identified from five species of small mammals (n = 217), revealing 14 chigger species, including two new records for Malaysia. The abundance and species richness of chiggers were significantly affected by habitat type (highest in forest border), state (highest in Perak), and season (highest in dry). The overall prevalence of Orientia tsutsugamushi DNA in small-mammal tissues was 11.7% and was not significantly affected by host or habitat characteristics, but in Johor, was positively associated with infestation by Leptotrombidium arenicola. These findings highlight the risk of contracting scrub typhus in oil palm plantations and associated human settlements.

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“…Black plates ( Figure 3 B) are attractive to unfed chiggers when heated by the sun, and the black color makes it easy to see the reddish color of chiggers on the plate, especially when they are crawling. Thus, black plates were commonly used to collect unengorged, free-living chiggers in rodent runways and near nests [ 25 , 26 , 27 , 28 ]. A set of black plates (10 cm by 10 cm) are laid at a possible breeding site at intervals.…”

Section: Chigger Biologymentioning

confidence: 99%

Biology, Systematics, Microbiome, Pathogen Transmission and Control of Chiggers (Acari: Trombiculidae, Leeuwenhoekiidae) with Emphasis on the United States

Chen

Roe

Ponnusamy

2022

IJERPH

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Chiggers are the larval stage of Trombiculidae and Leeuwenhoekiidae mites of medical and veterinary importance. Some species in the genus Leptotrombidium and Herpetacarus vector Orientia species, the bacteria that causes scrub typhus disease in humans. Scrub typhus is a life-threatening, febrile disease. Chigger bites can also cause dermatitis. There were 248 chigger species reported from the US from almost every state. However, there are large gaps in our knowledge of the life history of other stages of development. North American wide morphological keys are needed for better species identification, and molecular sequence data for identification are minimal and not clearly matched with morphological data. The role of chiggers in disease transmission in the US is especially understudied, and the role of endosymbionts in Orientia infection are suggested in the scientific literature but not confirmed. The most common chiggers in the eastern United States were identified as Eutrombicula alfreddugesi but were likely misidentified and should be replaced with Eutrombicula cinnabaris. Scrub typhus was originally believed to be limited to the Tsutsugamushi Triangle and the chigger genus, Leptotrombidium, but there is increasing evidence this is not the case. The potential of Orientia species establishing in the US is high. In addition, several other recognized pathogens to infect humans, namely Hantavirus, Bartonella, Borrelia, and Rickettsia, were also detected in chiggers. The role that chiggers play in these disease transmissions in the US needs further investigation. It is possible some of the tick-borne diseases and red meat allergies are caused by chiggers.

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Distribution of Leptotrombidium (Leptotrombidium) Arenicola (Acarina: Trombiculidae) on the Ground in West Malaysia1

Cited by 9 publications

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Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens

Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens

Habitat and Season Drive Chigger Mite Diversity and Abundance on Small Mammals in Peninsular Malaysia

Biology, Systematics, Microbiome, Pathogen Transmission and Control of Chiggers (Acari: Trombiculidae, Leeuwenhoekiidae) with Emphasis on the United States

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