The chigger microbiome: big questions in a tiny world

Chaisiri, Kittipong; Linsuwanon, Piyada; Makepeace, Benjamin L.

doi:10.1016/j.pt.2023.05.002

Cited by 10 publications

(10 citation statements)

References 74 publications

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“…in Southeast Asia [ 31 , 103 ], sometimes even in chiggers of the same species collected from a single host. However, as chigger populations can harbour several vertically transmitted bacteria with the potential to induce reproductive manipulations [ 3 ] and cytonuclear discordance [ 104 ], it is important to investigate potential cryptic species using nuclear as well as mitochondrial loci as we have explored here.…”

Section: Discussionmentioning

confidence: 99%

“…Trombiculid mite larvae or “chiggers” (Actinotrichida: Trombiculidae) are globally distributed etiological agents of trombiculiasis, a form of dermatitis resulting from their bites [ 1 , 2 , 3 ]. Trombiculiasis can affect a wide range of wild and domestic terrestrial vertebrate hosts, including humans, in which the condition is sometimes referred to as “scrub itch”.…”

Section: Introductionmentioning

confidence: 99%

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Multi-Locus Sequence Analysis Indicates Potential Cryptic Speciation in the Chigger Mite Neoschoengastia gallinarum (Hatori, 1920) Parasitising Birds in Asia

Rajasegaran,

Koosakulnirand,

Tan

et al. 2024

Animals

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Neoschoengastia gallinarum is widely distributed in Asia, preferentially parasitising birds, and heavy infestations have clinical impacts on domestic fowl. In common with other trombiculid mites, the genetic diversity and potential variation in host preferences or pathology induced by N. gallinarum are poorly understood. This study aimed to unravel the geographical variation and population structure of N. gallinarum collected from galliform birds in Peninsular Malaysia and Thailand by inference from concatenated mitochondrial-encoded cytochrome c oxidase subunit I (COI), and nuclear-encoded internal transcribed spacer 2 (ITS2) and 18S ribosomal DNA gene sequences, including a comparison with previously published data from southeastern China. Our multi-locus sequence analysis revealed three monophyletic clades comprising (A) specimens from Peninsular Malaysia, (B) the samples from Thailand together with a minority of Chinese sequences, and (C) the majority of sequences from China. Similarly, most species delimitation approaches divided the specimens into three operational taxonomic units. Analysis of molecular variance revealed 96.41% genetic divergence between Malaysian and Thai populations, further supported by the absence of gene flow (Nm = 0.01). In conclusion, despite the two countries sharing a land border, populations of N. gallinarum from Peninsular Malaysia and Thailand appear to be genetically segregated and may represent distinct cryptic species.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-Locus Sequence Analysis Indicates Potential Cryptic Speciation in the Chigger Mite Neoschoengastia gallinarum (Hatori, 1920) Parasitising Birds in Asia

Rajasegaran,

Koosakulnirand,

Tan

et al. 2024

Animals

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“…Several Rickettsia species, such as Rickettsia honei and R. felis , cause SFG and are transmitted to humans through infectious tick bites. Additionally, trombiculid mites are suspected to be potential vectors [ 26 , 27 , 28 ]. TG, however, is caused by typhus group R. typhi and is transmitted to humans through contact with the infected feces of rodent fleas.…”

Section: Introductionmentioning

confidence: 99%

Identification of Bacteria and Viruses Associated with Patients with Acute Febrile Illness in Khon Kaen Province, Thailand

Jitvaropas,

Sawaswong,

Poovorawan

et al. 2024

Viruses

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The majority of cases of undifferentiated acute febrile illness (AFI) in the tropics have an undefined etiology. In Thailand, AFI accounts for two-thirds of illnesses reported to the Ministry of Public Health. To characterize the bacterial and viral causes of these AFIs, we conducted molecular pathogen screening and serological analyses in patients who sought treatment in Chum Phae Hospital, Khon Kaen province, during the period from 2015 to 2016. Through integrated approaches, we successfully identified the etiology in 25.5% of cases, with dengue virus infection being the most common cause, noted in 17% of the study population, followed by scrub typhus in 3.8% and rickettsioses in 6.8%. Further investigations targeting viruses in patients revealed the presence of Guadeloupe mosquito virus (GMV) in four patients without other pathogen co-infections. The characterization of four complete genome sequences of GMV amplified from AFI patients showed a 93–97% nucleotide sequence identity with GMV previously reported in mosquitoes. Nucleotide substitutions resulted in amino acid differences between GMV amplified from AFI patients and mosquitoes, observed in 37 positions. However, these changes had undergone purifying selection pressure and potentially had a minimal impact on protein function. Our study suggests that the GMV strains identified in the AFI patients are relatively similar to those previously reported in mosquitoes, highlighting their potential role associated with febrile illness.

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“…In addition to Orientia spp., a number of other potentially pathogenic bacteria and viruses have been reported from chiggers in targeted surveys or 16S rRNA amplicon sequencing, including Bartonella spp., Rickettsia spp., Borrelia spp., Anaplasma spp., hantaviruses, and Dabie bandavirus (reviewed in [ 9 ]). Among the bacteria, the genera Rickettsia (family Rickettsiaceae) and Anaplasma (family Anaplasmataceae) are obligate intracellular organisms related to Orientia .…”

Section: Introductionmentioning

confidence: 99%

“…Lastly, vertically-transmitted endobacteria that do not infect vertebrates (predominantly Wolbachia , Rickettsiella and Cardinium ) have been detected in several chigger microbiome studies (reviewed in [ 9 ]), all of which were performed on Asian species of trombiculids. However, any potential phenotypic effects of these symbionts (such as cytoplasmic incompatibility) [ 29 ], or inhibition or enhancement of pathogen transmission [ 30 ] by chiggers, remain unexplored.…”

Section: Introductionmentioning

confidence: 99%

Microbiome and mitogenomics of the chigger mite Pentidionis agamae: potential role as an Orientia vector and associations with divergent clades of Wolbachia and Borrelia

Alkathiry,

Alghamdi,

Sinha

et al. 2024

BMC Genomics

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Background Trombiculid mites are globally distributed, highly diverse arachnids that largely lack molecular resources such as whole mitogenomes for the elucidation of taxonomic relationships. Trombiculid larvae (chiggers) parasitise vertebrates and can transmit bacteria (Orientia spp.) responsible for scrub typhus, a zoonotic febrile illness. Orientia tsutsugamushi causes most cases of scrub typhus and is endemic to the Asia-Pacific Region, where it is transmitted by Leptotrombidium spp. chiggers. However, in Dubai, Candidatus Orientia chuto was isolated from a case of scrub typhus and is also known to circulate among rodents in Saudi Arabia and Kenya, although its vectors remain poorly defined. In addition to Orientia, chiggers are often infected with other potential pathogens or arthropod-specific endosymbionts, but their significance for trombiculid biology and public health is unclear. Results Ten chigger species were collected from rodents in southwestern Saudi Arabia. Chiggers were pooled according to species and screened for Orientia DNA by PCR. Two species (Microtrombicula muhaylensis and Pentidionis agamae) produced positive results for the htrA gene, although Ca. Orientia chuto DNA was confirmed by Sanger sequencing only in P. agamae. Metagenomic sequencing of three pools of P. agamae provided evidence for two other bacterial associates: a spirochaete and a Wolbachia symbiont. Phylogenetic analysis of 16S rRNA and multi-locus sequence typing genes placed the spirochaete in a clade of micromammal-associated Borrelia spp. that are widely-distributed globally with no known vector. For the Wolbachia symbiont, a genome assembly was obtained that allowed phylogenetic localisation in a novel, divergent clade. Cytochrome c oxidase I (COI) barcodes for Saudi Arabian chiggers enabled comparisons with global chigger diversity, revealing several cases of discordance with classical taxonomy. Complete mitogenome assemblies were obtained for the three P. agamae pools and almost 50 SNPs were identified, despite a common geographic origin. Conclusions P. agamae was identified as a potential vector of Ca. Orientia chuto on the Arabian Peninsula. The detection of an unusual Borrelia sp. and a divergent Wolbachia symbiont in P. agamae indicated links with chigger microbiomes in other parts of the world, while COI barcoding and mitogenomic analyses greatly extended our understanding of inter- and intraspecific relationships in trombiculid mites.

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The chigger microbiome: big questions in a tiny world

Cited by 10 publications

References 74 publications

Multi-Locus Sequence Analysis Indicates Potential Cryptic Speciation in the Chigger Mite Neoschoengastia gallinarum (Hatori, 1920) Parasitising Birds in Asia

Multi-Locus Sequence Analysis Indicates Potential Cryptic Speciation in the Chigger Mite Neoschoengastia gallinarum (Hatori, 1920) Parasitising Birds in Asia

Identification of Bacteria and Viruses Associated with Patients with Acute Febrile Illness in Khon Kaen Province, Thailand

Microbiome and mitogenomics of the chigger mite Pentidionis agamae: potential role as an Orientia vector and associations with divergent clades of Wolbachia and Borrelia

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