Mite Vector Research Articles

Pathological Responses in Asian House Shrews (Suncus murinus) to the Naturally Acquired Orientia tsutsugamushi Infection.

Scrub typhus is a re-emerging disease caused by Orientia tsutsugamushi, transmitted by mites belonging to the family Trombiculidae. Humans and rodents acquire the infection by the bite of larval mites/chiggers. Suncus murinus, the Asian house shrew, has been reported to harbor the vector mites and has been naturally infected with O. tsutsugamushi. The present study aimed to localize and record O. tsutsugamushi in the tissues and the host response in shrews naturally infected with O. tsutsugamushi. Sheehan's modified May-Grunwald Giemsa staining was carried out in 365 tissues from 87 animals, and rickettsiae were documented in 87 tissues from 20 animals. Immunohistochemical (IHC) staining, using polyclonal antibodies raised against selected epitopes of the 56-kDa antigen, was carried out, and 81/87 tissue sections were tested positive for O. tsutsugamushi. By IHC, in addition to the endothelium, the pathogen was also demonstrated by IHC in cardiomyocytes, the bronchiolar epithelium, stroma of the lungs, hepatocytes, the bile duct epithelium, the epithelium and goblet cells of intestine, the tubular epithelium of the kidney, and splenic macrophages. Furthermore, the pathogen was confirmed by real-time PCR using blood (n = 20) and tissues (n = 81) of the IHC-positive animals. None of the blood samples and only 22 out of 81 IHC-positive tissues were tested positive by PCR. By nucleotide sequencing of the 56-kDa gene, Gilliam and Karp strains were found circulating among these animals. Although these bacterial strains are highly virulent and cause a wide range of pathological alterations, hence exploring their adaptive mechanisms of survival in shrews will be of significance. Given that the pathogen localizes in various organs following a transient bacteremia, we recommend the inclusion of tissues from the heart, lung, intestine, and kidney of reservoir animals, in addition to blood samples, for future molecular surveillance of scrub typhus.

Brevipalpus yothersiBaker (Tenuipalpidae) development in sweet orange plants is influenced by previous mite infestation and the presence of shelters.

Citrus leprosis is the most important viral disease affecting citrus. The disease is caused predominantly by CiLV-C and is transmitted by Brevipalpus yothersi Baker mites. This study brings some insight into the colonization of B. yothersi in citrus [(Citrus × sinensis (L.) Osbeck (Rutaceae)] previously infested by viruliferous or non-viruliferous B. yothersi. It also assesses the putative role of shelters on the behavior of B. yothersi. Expression of PR1 and PR4 genes, markers of plant defense mechanisms, were evaluated by RT-qPCR to correlate the role of the plant hormonal changes during the tri-trophic virus-mite-plant interplay. A previous infestation with either non-viruliferous and viruliferous mites positively influenced oviposition and the number of adult individuals in the resulting populations. Mite populations were higher on branches that had received a previous mite infestation than branches that did not. There was an increase in the expression of PR4, a marker gene in the jasmonic acid (JA) pathway, in the treatment with non-viruliferous mites, indicating a response from the plant to their feeding. Conversely, an induced expression of PR1, a marker gene in the salicylic acid (SA) pathway, was observed mainly in the treatment with viruliferous mites, which suggests the activation of a plant response against the pathogen. The earlier mite infestation, as well as the presence of leprosis lesions and a gypsum mixture as artificial shelters, all fostered the growth of the B. yothersi populations after the second infestation, regardless of the presence or absence of CiLV-C. Furthermore, it is suggested that B. yothersi feeding actually induces the JA pathway in plants. At the same time, the CiLV-C represses the JA pathway and induces the SA pathway, which benefits the mite vector.

Genetic diversity of Orientia tsutsugamushi circulating among trombiculid mite vectors identified in Mizoram, Northeast India

Genetic diversity of Orientia tsutsugamushi circulating among trombiculid mite vectors identified in Mizoram, Northeast India

A Breakthrough in Kitavirids: Genetic Variability, Reverse Genetics, Koch's Postulates, and Transmission of Hibiscus Green Spot Virus 2.

Hibiscus green spot virus 2 (HGSV-2), a member of the genus Higrevirus (family Kitaviridae), is a positive-stranded RNA virus associated with leprosis-like symptoms in citrus and green spots on leaves in hibiscus. HGSV-2 has only been reported in Hawaii, and while it is speculated that mites in the genus Brevipalpus might be responsible for its transmission, proper transmission assays have yet to be conducted. This study characterizes additional citrus and hibiscus isolates of HGSV-2 collected from two Hawaiian Islands. We constructed an infectious cDNA clone from a hibiscus isolate of HGSV-2 collected on Oahu and demonstrated its ability to infect several experimental hosts, including Phaseolus vulgaris, Nicotiana tabacum, and N. benthamiana, as well as natural hosts, Citrus reticulata and Hibiscus arnottianus. Bacilliform virions with varied sizes of 33 to 120 nm (length) and 14 to 70 nm (diameter) were observed in partially purified preparations obtained from agroinoculated leaves. Virus progeny from the infectious cDNA clone was found to be infectious after mechanical transmission to N. benthamiana and to cause local lesions. Finally, an isoline colony of the mite Brevipalpus azores had vector competence to transmit a citrus isolate of HGSV-2 collected from Maui to citrus and hibiscus plants, demonstrating the mite-borne nature of HGSV-2. The infectious cDNA clone developed in this study is the first reverse-genetics system for a kitavirid and will be fundamental to better characterize basic biology of HGSV-2 and its interactions with host plants and mite vectors.

Shift in virus composition in honeybees (Apis mellifera) following worldwide invasion by the parasitic mite and virus vector Varroa destructor.

Invasive vectors can induce dramatic changes in disease epidemiology. While viral emergence following geographical range expansion of a vector is well known, the influence a vector can have at the level of the host's pathobiome is less well understood. Taking advantage of the formerly heterogeneous spatial distribution of the ectoparasitic mite Varroa destructor that acts as potent virus vector among honeybees Apis mellifera, we investigated the impact of its recent global spread on the viral community of honeybees in a retrospective study of historical samples. We hypothesized that the vector has had an effect on the epidemiology of several bee viruses, potentially altering their transmissibility and/or virulence, and consequently their prevalence, abundance, or both. To test this, we quantified the prevalence and loads of 14 viruses from honeybee samples collected in mite-free and mite-infested populations in four independent geographical regions. The presence of the mite dramatically increased the prevalence and load of deformed wing virus, a cause of unsustainably high colony losses. In addition, several other viruses became more prevalent or were found at higher load in mite-infested areas, including viruses not known to be actively varroa-transmitted, but which may increase opportunistically in varroa-parasitized bees.

Awareness and knowledge of scabies and ringworm among parents of school-age children in Calabar, Cross River State, Nigeria: Implications for prevention of superficial skin infestations.

Risk factors for the persistence of superficial skin infestations are prevalent in humid tropical environments, which are favorable for breeding of the causative vector mite Sarcoptes scabiei (ectoparasite) and dermatophyte fungi. This study aimed at assessing the awareness and knowledge of childhood scabies and ringworm infestations among parents in Calabar, a highly humid rainforest tropical environment. Cross-sectional study design and systematic random sampling were used to recruit school-age children in selected primary schools in Calabar. Researcher-driven administration of a structured questionnaire was conducted to obtain quantitative data from parents of recruited children. : Chi-square was used to assess factors associated with ever hearing or seeing scabies and ringworm infestations. Statistical significance was set at P < 0.05. One hundred and eighty-two (56.7%) and 218 (67.9%) of the respondents had heard of or seen scabies and ringworm infestation. Among respondents that were aware of scabies, 53.3% knew of the cause, 50.5% were aware of the risk factors while 68.1% and 78.0% knew their treatment and prevention, respectively; 98.6%, 60.6%, 76.6%, and 80.7% of respondents knew the cause, risk factors, treatment, and prevention of ringworm infestation, respectively. Fathers with at least secondary school literacy level and sharing beds were significantly associated with awareness of scabies. There is a suboptimal level of awareness and knowledge of two of the most common superficial skin infestations among parents of primary school children in the study setting. There is a need to redouble our effort at sensitization of parents toward improved awareness of these common infestations.

Scrub typhus in Northeast India: epidemiology, clinical presentations, and diagnostic approaches.

Scrub typhus is one of the most neglected tropical diseases, a leading cause of acute undifferentiated febrile illness in areas of the 'tsutsugamushi triangle', diagnosed frequently in South Asian countries. The bacteria Orientia tsutsugamushi is the causative agent of the disease, which enters the human body through the bite of trombiculid mites (also known as chiggers) of the genus Leptotrombidium deliense. Diagnosis of the disease is challenging, as its early symptoms mimic other febrile illnesses like dengue, influenza and corona viruses. Lack of rapid, reliable and cost-effective diagnostic methods further complicates the identification process. Northeast India, a mountainous region with a predominantly rural tribal population, has witnessed a resurgence of scrub typhus cases in recent years. Various ecological factors, including rodent populations, habitat characteristics and climatic conditions, influence its prevalence. Entomological investigations have confirmed the abundance of vector mites, highlighting the importance of understanding their distribution and the probability of transmission of scrub typhus in the region. Proper diagnosis, awareness campaigns and behavioural interventions are essential for controlling scrub typhus outbreaks and reducing its impact on public health in Northeast India. Further research and community-based studies are necessary to accurately assess the disease burden and implement effective prevention strategies.

Evolutionarily diverse origins of deformed wing viruses in western honey bees

Novel transmission routes can allow infectious diseases to spread, often with devastating consequences. Ectoparasitic varroa mites vector a diversity of RNA viruses, having switched hosts from the eastern to western honey bees (Apis cerana to Apis mellifera). They provide an opportunity to explore how novel transmission routes shape disease epidemiology. As the principal driver of the spread of deformed wing viruses (mainly DWV-A and DWV-B), varroa infestation has also driven global honey bee health declines. The more virulent DWV-B strain has been replacing the original DWV-A strain in many regions over the past two decades. Yet, how these viruses originated and spread remains poorly understood. Here, we use a phylogeographic analysis based on whole-genome data to reconstruct the origins and demography of DWV spread. We found that, rather than reemerging in western honey bees after varroa switched hosts, as suggested by previous work, DWV-A most likely originated in East Asia and spread in the mid-20th century. It also showed a massive population size expansion following the varroa host switch. By contrast, DWV-B was most likely acquired more recently from a source outside East Asia and appears absent from the original varroa host. These results highlight the dynamic nature of viral adaptation, whereby a vector's host switch can give rise to competing and increasingly virulent disease pandemics. The evolutionary novelty and rapid global spread of these host-virus interactions, together with observed spillover into other species, illustrate how increasing globalization poses urgent threats to biodiversity and food security.

Molecular detection of spotted fever group of Rickettsiae in acute encephalitis syndrome cases from eastern Uttar Pradesh region of India.

The Eastern Uttar Pradesh region of India is known for its endemicity of acute encephalitis syndrome (AES). Decades of research have established that Orientia tsutsugamushi, a causative of scrub typhus, is a substantial contributor (>60%) for the AES cases besides other aetiology, but additional factors in the remaining proportion are still unidentified. Rickettsial infections are challenging to diagnose in clinical settings due to overlapping clinical symptoms, the absence of definitive indicators, a low index of suspicion, and the lack of low-cost, rapid diagnostic tools. Hence, the present study was designed to determine the load of rickettsial infections among AES cases. Furthermore, we aim to find out the prevalent rickettsial species in AES cases as well as in the vector population at this location. The study included the whole blood/cerebrospinal fluid of AES patients and arthropod specimens from rodents. The molecular identification was performed using the 23S-5S intergenic spacer region and ompB gene with genomic DNA obtained from studied specimens. We detected 5.34% (62/1160) of rickettsial infection in AES cases. Among these, phylogenetic analysis confirmed the presence of 54.8% Rickettsia conorii (n = 34) and 16.1% of Rickettsia felis (n = 10), while the rest proportion of the isolates was unidentified at the species level. Furthermore, R. felis was identified in one CSF sample from AES patients and three flea samples from Xenopsylla cheopis. Rickettsia spp. was also confirmed in one Ornithonyssus bacoti mite sample. The results of this investigation concluded the presence of spotted fever group Rickettsia spp. among AES identified cases as well as in the mite and flea vectors that infest rodents.

An artificial positive control for routine detection of rose rosette virus and Phyllocoptes fructiphilus that fit most primers for PCR, LAMP and RPA based assays

AbstractRose (Rosa spp.) is a very important ornamental shrub cultivated worldwide and of value for the pharmaceutical industry. The plant is broadly susceptible to pathogens, including viruses. Rose rosette virus (RRV; virus species Emaravirus rosae) causes multiple symptoms typically rosettes, ultimately leading to death. The virus transmission is by grafting and a wind‐dispersed eriophyoid mite, Phyllocoptes fructiphilus, which survives in winter‐dormant plants. Due to extensive globalization RRV is a threat for the European rose, landscape, nursery and tourism industries. The most common and reliable method used for RRV detection is RT‐PCR. Positive control is indispensable for PCR reliability and can be difficult to obtain for emerging or highly contagious pathogens and are subject to BSL‐2 quarantine. A synthetic artificial positive control (APC) using custom DNA inserts of sense and anti‐sense primers was designed de novo and inserted in a circular plasmid vector to create a positive control for use with most RRV reported primers and eriophyoid mites. This study describes a functional demonstration and development of a rapid, consistent, adaptable and cost‐effective alternative to infected true‐tissue positive control for detection of RRV. The inserted RRV primers are for end point and quantitative RT‐PCR, reverse transcription loop‐mediated isothermal amplification (RT‐LAMP), recombinase‐polymerase amplification (RPA), broad detection of emaravirus and the eriophyoid mite vector Phyllocoptes fructiphilus. The APC‐RRV and RRV infected rose (leaf tissue) were tested side to side. Results demonstrated APC‐RRV is a safe, cloneable and reliable approach subjected to quality control with application in quarantine surveillance and routine diagnostics of RRV.

Current status of mites and mite-borne diseases in India.

Mites act as the vectors of zoonotic vector-borne disease scrub typhus caused by the rickettsial pathogen Orientia tsutsugamushi. In India, scrub typhus is transmitted by the mite Leptotrombidium deliense. Rodents are the reservoirs and support the spread of this disease. Sarcoptes scabiei or the itch mite is causing scabies which is a common skin infection in India. Dermatitis, trombiculosis, and mite dust allergy are common mite-borne diseases transmitted by Pyemotidae family. D. brevis folliculorum and Demodex brevis are two major mite species found on humans also causing a disease; "Demodicosis", common in India. Dermanyssus gallinae, fowl mite causes pruritis in poultry birds, transmits infections to poultry workers when they come into contact with birds. There is a re-emergence of mite-borne diseases, especially scrub typhus, in many parts of India requiring urgent attention for its control. This review is aimed to update the available information on mites and mite transmitted diseases prevalent in India to highlight the importance of rodent and chigger mite vector control to prevent forthcoming mite-borne diseases in India.

The Complex World of Emaraviruses—Challenges, Insights, and Prospects

Emaravirus (Order Bunyavirales; Family Fimoviridae) is a genus comprising over 20 emerging plant viruses with a worldwide distribution and economic impact. Emaraviruses infect a variety of host plants and have especially become prevalent in important long-living woody plants. These viruses are enveloped, with a segmented, single-stranded, negative-sense RNA genome and are transmitted by eriophyid mites or mechanical transmission. Emaraviruses have four core genome segments encoding an RNA-dependent RNA polymerase, a glycoprotein precursor, a nucleocapsid protein, and a movement protein. They also have additional genome segments, whose number varies widely. We report here that the proteins encoded by these segments form three main homology groups: a homolog of the sadwavirus Glu2 Pro glutamic protease; a protein involved in pathogenicity, which we named “ABC”; and a protein of unknown function, which we named “P55”. The distribution of these proteins parallels the emaravirus phylogeny and suggests, with other analyses, that emaraviruses should be split into at least two genera. Reliable diagnosis systems are urgently needed to detect emaraviruses, assess their economic and ecological importance, and take appropriate measures to prevent their spread (such as routine testing, hygiene measures, and control of mite vectors). Additional research needs include understanding the function of emaravirus proteins, breeding resistant plants, and clarifying transmission modes.

A TaqMan RT-qPCR assay for absolute quantification of citrus leprosis virus C lineage SJP: disclosing the subgenomic/genomic ratio in plant and mite vector, plant organ-specific viral loads, and the kinetics of viral accumulation in plants

A TaqMan RT-qPCR assay for absolute quantification of citrus leprosis virus C lineage SJP: disclosing the subgenomic/genomic ratio in plant and mite vector, plant organ-specific viral loads, and the kinetics of viral accumulation in plants

Orientia tsutsugamushi in Chiggers and Small Mammals in Laos.

Background: Scrub typhus is a leading cause of febrile illness in Laos and accounts for a high burden of disease. There have been no previous studies on the causative agent, Orientia tsutsugamushi, in vector mites ("chiggers") or their small mammal hosts in Laos. Materials and Methods: Small mammals and free-living chiggers were trapped in districts of Vientiane Province and Capital. Tissues were tested for O. tsutsugamushi by PCR and serum for IgG to O. tsutsugamushi by immunofluorescence assays (IFAs). Chiggers removed from small mammals and collected in their free-living stage using black plates were identified and tested for O. tsutsugamushi by PCR. Results: Over an 18-month period, 131 small mammals of 14 species were collected in 5 districts. Seventy-eight of 131 small mammals were infested with chiggers, but all tissues were O. tsutsugamushi PCR negative. Eighteen species of chigger were identified and 1,609 were tested by PCR. A single pool of chiggers tested O. tsutsugamushi positive. Sera from 52 small mammals were tested by IFA, with 16 testing positive. Conclusions: These are the first molecular and serological data on O. tsutsugamushi in chiggers and small mammals in Laos. Further studies are needed to better understand the key vector species and ecology of scrub typhus in areas with high disease incidence in Laos.

Increasing Incidence of Spotted Fever Group Rickettsioses in the United States, 2010-2018.

Spotted fever group Rickettsia species are intracellular bacteria transmitted by tick or mite vectors and that cause human diseases referred to as spotted fever group rickettsioses, or spotted fevers. In the United States, the most recognized and commonly reported spotted fevers are Rocky Mountain spotted fever (RMSF) (Rickettsia rickettsii), Rickettsia parkeri rickettsiosis, Pacific Coast tick fever (Rickettsia species 364D), and rickettsialpox (Rickettsia akari). In this study, we summarize and evaluate surveillance data on spotted fever cases reported to the Centers for Disease Control and Prevention (CDC) through the National Notifiable Diseases Surveillance System from 2010 to 2018. During this period, there were 36,632 reported cases of spotted fevers with 95.83% (N = 35,104) reported as meeting the case definition as probable and 4.17% (N = 1528) reported as meeting the case definition as confirmed. The average national incidence of total cases, both probable and confirmed, was 12.77 cases per million persons per year. The highest statewide incidence was in Arkansas, with 256.84 per million per year, whereas the lowest incidence occurred in California, with 0.32 per million per year (note that spotted fevers were not notifiable in Hawaii and Alaska). Cases of spotted fevers were reported more frequently among males by gender, White by race, and non-Hispanic by ethnicity. The incidence of spotted fevers increased significantly from 2010 to 2018, but it is uncertain how many of the reported cases were RMSF and how many developed from more moderate spotted fevers. Improvement of the ability to differentiate between spotted fever group Rickettsia species is needed.

Effect of acaricide and insecticide mixtures against citrus leprosis vector, Brevipalpus yothersi, under laboratory and field conditions

The intense spraying of insecticides has negatively affected the management of the leprosis vector mite, Brevipalpus yothersi, requiring additional acaricide applications. Therefore, the main objective of this study was to assess the toxicity of the acaricide spirodiclofen and several insecticides, alone or combined, on different developmental stages of B. yothersi in the laboratory and field. Additionally, the concentration of the active ingredient spirodiclofen was quantified in the spray solutions. The efficacy of spirodiclofen on the eggs and adults of B. yothersi was drastically reduced when spirodiclofen was sprayed in a mixture with cypermethrin, phosmet, or imidacloprid, with 65.4%, 57.2%, and 53.4% of reduction in eggs mortality, and 24.4%, 57.7%, and 17.6% of reduction in adult mortality, respectively. In the field, the addition of insecticides to the spirodiclofen solution decreased the period for reinfestation of the mites by the acaricide from 127 days with spirodiclofen alone to 42 (cypermethrin), 43 (phosmet), and 52 (imidacloprid) days. There was no significant reduction in the spirodiclofen concentration when mixed with insecticides. Our results indicate that the insecticides cypermethrin, phosmet, and imidacloprid antagonize the efficacy of spirodiclofen on eggs and adults of B. yothersi.

Quantitative and Qualitative Changes in the Deformed Wing Virus Population in Honey Bees Associated with the Introduction or Removal of Varroa destructor.

Varroa destructor is an ectoparasitic mite associated with significant losses of honeybee colonies globally. The mite vectors a range of pathogenic viruses, the most important of which is the Deformed wing virus (DWV). In the absence of Varroa, DWV exists as a low-level, highly diverse virus population. However, when transmitted by Varroa, certain variants become highly elevated, and may become near-clonal and cause symptomatic infections. Mite transmission between colonies can occur when parasitised workers drift from or rob adjacent hives. These activities can result in elevated mite levels, but the resulting change in the DWV population, the primary determinant of winter colony losses, has not been determined. In reciprocal studies, we investigated the influence of the removal of mites, or their acquisition, on the DWV population. When mites were removed from heavily infested colonies, there was a striking and rapid reduction in virus load. Conversely, siting Varroa-naïve colonies in a mite-infested apiary resulted in the acquisition of mites and concomitant changes in the virus population. We observed both near-clonal and highly divergent virus populations regardless of titre, suggesting changes were stochastic and colony-specific. Our findings have implications for the outcome of strategies in areas with total or patchy implementation of Varroa control plans.

Cross sectional studies on the ectoparasites among rodents in scrub typhus cases in Karnal and Kaithal Districts of Haryana, India

Orientia tsutsugamushi is a mite-borne bacterium belonging to the family Rickettsiaceae and is responsible for a disease called scrub typhus in humans, which is transmitted by the vector mite Leptotrombidium deliense (common ectoparasite on rodents) in most of Asian countries including India. The study conducted in selected villages of Karnal and Kaithal districts of Haryana state, India revealed four species of rodents - Rattus rattus, norveigicus, Bandicota indica and Suncus murinus. Dust mite Dermatophagoides farina; chigger mite L. deliense and fleas Xenopsylla astia and X. cheopis were prevalent on the rodents.

Occurrence and Characterization of Wheat Streak Mosaic Virus Found in Mono- and Mixed Infection with High Plains Wheat Mosaic Virus in Winter Wheat in Ukraine.

Although wheat streak mosaic virus (WSMV) is a well-known pathogen inducing significant crop losses and endangering wheat production worldwide, the recent discovery of High Plains wheat mosaic virus (HPWMoV) in Ukraine raises questions on the co-existence of these two viruses having a similar host range and the same mite vector. Here we report on the screening of winter wheat industrial plantings in several important regions of Ukraine for WSMV and HPWMoV. WSMV was identified in an extremely high number of symptomatic plants (>85%) as compared to HPWMoV detected in 40% of wheat samples. Importantly, the preferred mode of HPWMoV circulation in Ukraine was mixed infection with WSMV (>30%) as opposed to WSMV, which was typically found in monoinfection (60%). Screening wheat varieties for possible virus resistance indicated that all but one were susceptible to WSMV, whereas over 50% of the same varieties were not naturally infected with HPWMoV. Overall, phylogenetic analysis of the collected WSMV and HPWMoV isolates indicated their high identity and similarity to other known isolates of the respective viruses. Here we first characterize WSMV isolates found in winter wheat plants in mono- or mixed infection with HPWMoV, which was recently reported as a typical wheat pathogen in Ukraine.

Mapping the distributions of blood-sucking mites and mite-borne agents in China: a modeling study

BackgroundEmerging mite-borne pathogens and associated disease burdens in recent decades are raising serious public health concerns, yet their distributions and ecology remain under-investigated. We aim to describe the geographical distributions of blood-sucking mites and mite-borne agents and to assess their ecological niches in China.MethodsWe mapped 549 species of blood-sucking mites belonging to 100 genera at the county level and eight mite-associated agents detected from 36 species of blood-sucking mites in China during 1978–2020. Impacts of climatic and environmental factors on the ecology of 21 predominant vector mites and a leading pathogen, Orientia tsutsugamushi, were assessed using boosted regression tree (BRT) models, and model-predicted risks were mapped. We also estimated the model-predicted number, area and population size of affected counties for each of the 21 mite species in China.ResultsLaelaps echidninus is the leading mite species that potentially affects 744 million people, followed by La. jettmari (517 million) and Eulaelaps stabularis (452 million). Leptotrombidium scutellare is the mite species harboring the highest variety of mite-borne agents including four Rickettsia species and two viruses, followed by Eu. stabularis (2 agents), L. palpale (2) and La. echidninus (2). The top two agents that parasitize the largest number of mite species are O. tsutsugamushi (28 species) and hantavirus (8). Mammalian richness, annual mean temperature and precipitation of the driest quarter jointly determine the ecology of the mites, forming four clusters of major mite species with distinct geographic distributions. High-risk areas of O. tsutsugamushi are mainly distributed in southern and eastern coastal provinces where 71.5 million people live.ConclusionsEcological niches of major mite species and mite-borne pathogens are much more extensive than what have been observed, necessitating expansion of current filed surveillance.Graphic