- History of Tsutsugamushi Disease in Korea. [Review]
- ICInfect Chemother 2019; 51(2):196-209
- Tsutsugamushi disease or scrub typhus in Korea was first officially reported in foreign soldiers in 1951 and in indigenous persons in 1986. However, the history is further prolonged. The book Dong Ui…
Tsutsugamushi disease or scrub typhus in Korea was first officially reported in foreign soldiers in 1951 and in indigenous persons in 1986. However, the history is further prolonged. The book Dong Ui Bo Gam, published in 1613, described "Soo Dok" (water poisoning), which is similar to tsutsugamushi disease. Further, the term was mentioned in the book Hyang Yak Gu Geup Bang, first published in 1232-1251. During the Japanese colonial rule (1910-1945), Trombicula akamushi was identified in Suwon, Korea, in 1917. Although cases of tsutsugamushi disease in Korea with a murine typhus-like illness and OXK-positivity were reported in 1935, such atypical presentation was not recognized as tsutsugamushi disease. During the Korean War, in 1951, tsutsugamushi disease developed in two British soldiers stationed in the Imjin River, who presented typical features and positive OXK reactions. Indigenous cases have re-emerged since 1986. Thereafter, there were many studies on various aspects of tsutsugamushi disease: epidemiology, vector, small mammals, clinical features and complications, diagnosis, and treatment. Persistence of Orientia tsutsugamushi and its possible recrudescence with pneumonia were reported in 2012 and 2014, respectively.
- Severe Trombiculiasis in Hunting Dogs Infested With Neotrombicula inopinata (Acari: Trombiculidae). [Journal Article]
- JMJ Med Entomol 2019 May 23
- This study records the clinical findings in nine hunting dogs showing systemic illness associated with trombiculids and identifies the mite species involved. In fall, coinciding with the seasonality …
This study records the clinical findings in nine hunting dogs showing systemic illness associated with trombiculids and identifies the mite species involved. In fall, coinciding with the seasonality of mites, all dogs were infested with mites and had been in the risk area (Sierra Cebollera Natural Park, La Rioja, Spain) a few hours before the onset of symptoms. The symptoms included vomiting, anorexia, weakness and lethargy, diarrhea, and even stupor. The clinical picture was fast-acting and potentially fatal. The infestations varied from low to severe. Molecular analysis of mites that fed on the dogs confirmed that they were larvae of Neotrombicula inopinata (Oudemans, Acari, Trombiculidae). This is the first time that N. inopinata has been identified as feeding on dogs and implicated in canine systemic illness associated with trombiculids. In contrast to other chiggers, N. inopinata does not seem to cause dermatitis. Likewise, the clinical and epidemiological similarity between the clinical symptoms we describe herein and the occurrence of seasonal canine illness (SCI) led us to suspect that this illness may be caused by infestation with these mites. The condition could be the consequence of severe infestation from large numbers of feeding mites, especially N. inopinata. Whether or not the cases were due to a severe allergic host response to salivary proteins or the result of the transmission of a new or emerging trombiculid-borne pathogen is not known.
- First report of Neotrombicula inopinata infestation in domestic cats from Portugal. [Case Reports]
- VPVet Parasitol 2019; 267:1-3
- Trombiculids parasitize a wide variety of terrestrial vertebrates, including domestic animals, throughout the world. They are parasites only during their larval stages, causing several dermatological…
Trombiculids parasitize a wide variety of terrestrial vertebrates, including domestic animals, throughout the world. They are parasites only during their larval stages, causing several dermatological lesions on their hosts, such as acute dermatitis, erythema, excoriation, erosion, papules, crusts and alopecia on the ear margins, face, interdigital spaces and abdomen. Neotrombicula is one of the several genera in Trombiculidae family, which cause trombiculosis. The most common species implicated in clinical cases is Neotrombicula autumnalis. However, several reports have shown that Neotrombicula inopinata (Oudemans, 1909) can also play a role in trombiculosis. Here, we describe the first case of N. inopinata infestation in domestic cats from mainland Portugal. Since nucleic acids of Anaplasma phagocytophilum and Borrelia burgdorferi have been found in Neotrombicula autumnalis and Rickettsia spp. in Neotrombicula inopinata, a correct taxonomical identification is essential to understand the role of these mite species as possible vectors of pathogens.
- StatPearls: Chigger Bites [BOOK]
- BOOKStatPearls Publishing: Treasure Island (FL)
- “Chigger” is the common name for species of the Trombiculid family of mites. Bites from the larva of these mites can cause local pruritus and irritation, formally known as trombiculiasis or trombicul…
“Chigger” is the common name for species of the Trombiculid family of mites. Bites from the larva of these mites can cause local pruritus and irritation, formally known as trombiculiasis or trombiculosis. The reaction is usually mild and self-limited, but the bites may rarely transmit disease or result in a bacterial superinfection. While there are many species of parasitic mites in a variety of habitats all over the world, the species most commonly referred to as chiggers include Eutrombicula alfreddugesi in the south of the United States, Trombicula autumnalis in Europe, and species of the Leptotrombidium genus in Asia and Oceania. The larvae of these species feed on the skin of a variety of animals, including humans. Adult mites burrow into the soil and feed on detritus while the larvae of these species accumulate on the edges of leaves and grass before hitching on to a passing host. They then migrate to a preferred feeding site, attach themselves to the host’s skin, and secrete proteolytic enzymes to digest host epidermal cells. This provokes an inflammatory reaction with surrounding erythema, a variable degree of swelling, and intense pruritus. They are easily dislodged by scratching. They rarely remain attached to humans for more than 48 hours, but the intense pruritus, inflammation, and localized allergic response may last for weeks afterward. Rarely, the light-red to orange colored larva, measuring 0.15 to 0.3 mm in length, may be identified on the skin. More typically, the diagnosis of trombiculiasis will depend on exposure to trombiculid habitat, the pattern of the lesions, and exclusion of other possible diagnoses. 
- Dermoscopy confirmed Trombiculidae larva infestation in Turkey. [Letter]
- IJInt J Dermatol 2019; 58(6):e120-e121
- Chigger mites (Acariformes: Trombiculidae) of Iran. [Journal Article]
- ZZootaxa 2019 Jan 22; 4549(1):1-66
- Chigger mites of Iran have been revised based on examination of type materials in the collection of Zoological Museum of Moscow University and reference data. Hitherto, 85 species of trombiculids wer…
Chigger mites of Iran have been revised based on examination of type materials in the collection of Zoological Museum of Moscow University and reference data. Hitherto, 85 species of trombiculids were recorded in Iran; synonymy, diagnoses, data on depositories of type specimens, lists of hosts and collection localities are given for each species. Original measurements of holotypes or paratypes are provided for 46 species. Four new combinations are proposed: Ornithogastia merops (Vercammen-Grandjean, Rohde and Mesghali, 1970) comb. nov., transferred from Guntherana; O. oenanthe (Vercammen-Grandjean, Rohde and Mesghali, 1970) comb. nov., transferred from Guntherana; Microtrombicula galerida (Vercammen-Grandjean, Rohde and Mesghali, 1970), comb. nov., transferred from Eltonella; and M. meriones (Vercammen-Grandjean, Rohde and Mesghali, 1970), comb. nov., transferred from Eltonella. Comparison of our measurements of holotypes with those given in the original species descriptions published by Kudryashova was carried out using statistical methods to establish probable systematic bias between metric data obtained by different researchers. A key to species of Iranian trombiculid larvae is compiled. With the use of public geoinformation online resources, actual names and coordinates were established for all 48 sites of Iran where chigger mites were collected.
- Bacterial microbiome of the chigger mite Leptotrombidium imphalum varies by life stage and infection with the scrub typhus pathogen Orientia tsutsugamushi. [Journal Article]
- PlosPLoS One 2018; 13(12):e0208327
- Scrub typhus is a mites-borne rickettsiosis caused by the obligate intracellular Gram-negative bacterium Orientia tsutsugamushi. The disease is potentially life threatening and is prevalent in tropic…
Scrub typhus is a mites-borne rickettsiosis caused by the obligate intracellular Gram-negative bacterium Orientia tsutsugamushi. The disease is potentially life threatening and is prevalent in tropical Asia, islands of the western Pacific Ocean and northern Australia where an estimated one million cases occur annually. Orientia tsutsugamushi is transmitted by the bite of larval mites in the genus Leptotrombidium. In the present study, the composition of the microbiome in larvae, deutonymphs and adult males and females from laboratory colonies of L. imphalum that were infected as well as uninfected with O. tsutsugamushi were investigated by high-throughput sequencing of the bacterial 16S rRNA gene. Notably, the bacterial microbiomes of infected adult females were dominated by sequences of O. tsutsugamushi and an unidentified species of Amoebophilaceae, which together comprised 98.2% of bacterial sequences. To improve the taxonomic resolution of the Amoebophilaceae OTU a nearly full length sequence of the 16S rRNA gene was amplified, cloned, and Sanger sequenced. Infected female mites had 89 to 92% nucleotide identity with the Amoebophilaceae family, indicating that the bacterium was likely to be a species of a novel genus. The species composition of bacterial communities varied between mite life stages regardless of their infection status. Uninfected adults exhibited greater species diversity than adults infected with O. tsutsugamushi. In the infected colony, the rate of filial infection with Orientia was less than 100%. Larval and male mites that were PCR-negative for Orientia contained low numbers of sequences of Amoebophilaceae (0.01 and 0.06%, respectively) in their taxonomic profiles, suggesting that a mutualistic relationship exists between the novel species of Amoebophilaceae and O. tsutsugamushi. Our study findings provide the basis for further research to determine the influence of the novel Amoebophilaceae species on the bacterial microbiome and on vector susceptibility to and transovarial transmission of O. tsutsugamushi.
- Geometric morphometrics of the scutum for differentiation of trombiculid mites within the genus Walchia (Acariformes: Prostigmata: Trombiculidae), a probable vector of scrub typhus. [Journal Article]
- TTTicks Tick Borne Dis 2019; 10(2):495-503
- The vectors of scrub typhus are the larval stage of trombiculid mites, termed "chiggers". These vectors are very small - the larvae are approximately 0.2 mm in size - and therefore their morphologica…
The vectors of scrub typhus are the larval stage of trombiculid mites, termed "chiggers". These vectors are very small - the larvae are approximately 0.2 mm in size - and therefore their morphological identification is difficult. Trombiculid mites are widely distributed across Asia and they can be identified at the genus level by the shape, size and setae/sensilla distribution of their dorsal chitin plate (scutum = shield), while morphological identification at the species level requires more mite characteristics. We recently developed a methodology to ascertain paired matched genotype and morphotype of individual chiggers, based on autofluorescence and brightfield microscopy with subsequent molecular identification using the COI gene (approximately 640bp length). However, based on 20 chigger specimens characterised by paired genotypic and morphological data consisting of the four species [Walchia ewingi with 2 subspecies]: Walchia ewingi lupella (n = 9), W. ewingi ewingi (n = 2), W. alpestris (n = 2), W. kritochaeta (n = 5) and W. minuscuta (n = 2) we found evidence of genetic polymorphism and morphological plasticity within the genus Walchia. The phylogenetic inference of the intra-genus relationships within the Walchia spp., based on COI gene (Blankaartia spp. served as outgroup), delineated the five included species by an average interspecific divergence of mean distance 0.218 (0.126 - 0.323). We therefore applied landmark-based and outline-based geometric morphometric (GM) approaches to differentiate Walchia species using scutum measurements. A total of 261 scutum images of Walchia spp. were examined by landmark-based GM (140 chigger specimens) and outline-based GM (121 specimens) techniques. All Walchia spp. showed significant differences in scutum size and shape. W. minuscuta showed the smallest mean scutum size in both techniques. The largest scutum was found in W. ewingi lupella and W. ewingi ewingi by landmark-based and outline-based GM analysis, respectively. The scutum shapes of W. alpestris and W. minuscuta were clearly distinguished from the other species. Cross-validated classification scores were different depending on species and digitizing techniques and landmark-based GM showed better scores than outline-based GM. We conclude that the morphologically closely-related trombiculid mite species can be further differentiated by their scutum features alone, using GM approaches. This technique is a promising tool for the much-needed characterization studies of chiggers and needs evaluation using matched morphometric and genotyping data for other genera of trombiculids.
- The chiggers (Acari: Trombiculidae) on wild birds in Honduras. [Journal Article]
- FPFolia Parasitol (Praha) 2018 Nov 12; 65
- The chiggers (Acari: Trombiculidae) Blankaartia sinnamaryi (Floch et Fauran, 1956), Parasecia soucouyanti (Brennan et Yunker, 1966), Eutrombicula lipovskyana (Wolfenbarger, 1952) and Neoschoengastia …
The chiggers (Acari: Trombiculidae) Blankaartia sinnamaryi (Floch et Fauran, 1956), Parasecia soucouyanti (Brennan et Yunker, 1966), Eutrombicula lipovskyana (Wolfenbarger, 1952) and Neoschoengastia dalmati Brennan, 1951 were found in Honduras on a total of twelve bird species. Parasecia soucouyanti was recorded parasitising birds for the first time. All these mites are here reported from Honduras for the first time.
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- Genomes of trombidid mites reveal novel predicted allergens and laterally transferred genes associated with secondary metabolism. [Journal Article]
- GGigascience 2018 12 01; 7(12)
- CONCLUSIONS: Trombidid mite genomes appear to be more dynamic than those of other acariform mites. A priority for future research is to determine the biological function of terpene synthesis in this taxon and its potential for exploitation in disease control.