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Tian JW, Kong YC, Han PY, Xu FH, Yang WH, Zhang YZ. Molecular epidemiological study of Scrub Typhus in residence, farm and forest habitats from Yunnan Province, China. PLoS One 2024; 19:e0301841. [PMID: 38626103 PMCID: PMC11020965 DOI: 10.1371/journal.pone.0301841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 03/23/2024] [Indexed: 04/18/2024] Open
Abstract
The number of people suffering from scrub typhus, which is not of concern, is increasing year by year, especially in Yunnan Province, China. From June 1, 2021 to August 15, 2022, a total of 505 mammalian samples were collected from farm, forest, and residential habitats with high incidence of scrub typhus in Yunnan, China, for nPCR (nested PCR) and qPCR (quantitative real-time PCR) detection of Orientia tsutsugamushi. A total of 4 orders of murine-like animals, Rodentia (87.52%, n = 442), Insectivora (10.29%, n = 52), Lagomorpha (1.79%, n = 9) and Scandentia (0.40%, n = 2) were trapped. Comparing the qPCR infection rates in the three habitats, it was no significant difference that the infection rate of residential habitat (44.44%) and that of the farm habitat (45.05%, P>0.05), which is much larger than that of the forest habitat (3.08%) (P<0.001). Three genotypes (Karp-like, Kato-like and TA763-like) of O. tsutsugamushi were found from Yunnan, China in this study.
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Affiliation(s)
- Jia-Wei Tian
- Yunnan Key Laboratory of Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan, Yunnan Key Laboratory of Zoonotic Disease Cross-border Prevention and Quarantine, Institute of Preventive Medicine, School of Public Health, Dali University, Dali, Yunnan, China
| | - Yi-Chen Kong
- Yunnan Key Laboratory of Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan, Yunnan Key Laboratory of Zoonotic Disease Cross-border Prevention and Quarantine, Institute of Preventive Medicine, School of Public Health, Dali University, Dali, Yunnan, China
| | - Pei-Yu Han
- Yunnan Key Laboratory of Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan, Yunnan Key Laboratory of Zoonotic Disease Cross-border Prevention and Quarantine, Institute of Preventive Medicine, School of Public Health, Dali University, Dali, Yunnan, China
| | - Fen-Hui Xu
- Yunnan Key Laboratory of Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan, Yunnan Key Laboratory of Zoonotic Disease Cross-border Prevention and Quarantine, Institute of Preventive Medicine, School of Public Health, Dali University, Dali, Yunnan, China
| | - Wei-Hong Yang
- Yunnan Institute of Endemic Diseases Control and Prevention, Dali, Yunnan, China
| | - Yun-Zhi Zhang
- Yunnan Key Laboratory of Screening and Research on Anti-pathogenic Plant Resources from Western Yunnan, Yunnan Key Laboratory of Zoonotic Disease Cross-border Prevention and Quarantine, Institute of Preventive Medicine, School of Public Health, Dali University, Dali, Yunnan, China
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Ogawa T, Tsuzuki S, Ohbe H, Matsui H, Fushimi K, Yasunaga H, Kutsuna S. Analysis of Differences in Characteristics of High-Risk Endemic Areas for Contracting Japanese Spotted Fever, Tsutsugamushi Disease, and Severe Fever With Thrombocytopenia Syndrome. Open Forum Infect Dis 2024; 11:ofae025. [PMID: 38312217 PMCID: PMC10836194 DOI: 10.1093/ofid/ofae025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 01/13/2024] [Indexed: 02/06/2024] Open
Abstract
Background Tick-borne infections, including tsutsugamushi disease, Japanese spotted fever, and severe fever with thrombocytopenia syndrome (SFTS), are prevalent in East Asia with varying geographic distribution and seasonality. This study aimed to investigate the differences in the characteristics among endemic areas for contracting each infection. Methods We conducted an ecologic study in Japan, using data from a nationwide inpatient database and publicly available geospatial data. We identified 4493 patients who were hospitalized for tick-borne infections between July 2010 and March 2021. Mixed-effects modified Poisson regression analysis was used to identify factors associated with a higher risk of contracting each tick-borne disease (Tsutsugamushi, Japanese spotted fever, and SFTS). Results Mixed-effects modified Poisson regression analysis revealed that environmental factors, such as temperature, sunlight duration, elevation, precipitation, and vegetation, were associated with the risk of contracting these diseases. Tsutsugamushi disease was positively associated with higher temperatures, farms, and forests, whereas Japanese spotted fever and SFTS were positively associated with higher solar radiation and forests. Conclusions Our findings from this ecologic study indicate that different environmental factors play a significant role in the risk of transmission of tick-borne infections. Understanding the differences can aid in identifying high-risk areas and developing public health strategies for infection prevention. Further research is needed to address causal relationships.
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Affiliation(s)
- Takahisa Ogawa
- Department of Orthopedic, Saku General Hospital Saku Medical Center, Nagano, Japan
- Department of Health Policy and Informatics, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shinya Tsuzuki
- Disease Control and Prevention Center, National Center for Global Health and Medicine, Tokyo, Japan
- Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Hiroyuki Ohbe
- Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan
| | - Hiroki Matsui
- Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan
| | - Kiyohide Fushimi
- Department of Health Policy and Informatics, Tokyo Medical and Dental University, Tokyo, Japan
| | - Hideo Yasunaga
- Department of Clinical Epidemiology and Health Economics, School of Public Health, The University of Tokyo, Tokyo, Japan
| | - Satoshi Kutsuna
- Department of Infection Control and Prevention, Graduate School of Medicine, Faculty of Medicine, Osaka University, Osaka, Japan
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Pangjai D, Saengsawang P, Kidsin K, Choongkittaworn N, Morita Y, Boonmar S. Seroprevalence of Orientia tsutsugamushi and Rickettsia typhi in water buffaloes ( Bubalus bubalis) from Southern Thailand. Vet World 2023; 16:1600-1604. [PMID: 37766717 PMCID: PMC10521187 DOI: 10.14202/vetworld.2023.1600-1604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 07/06/2023] [Indexed: 09/29/2023] Open
Abstract
Background and Aim Scrub typhus and murine typhus are globally distributed zoonoses caused by the intracellular Gram-negative bacteria Orientia tsutsugamushi and Rickettsia typhi, respectively. Numerous studies have been undertaken on rickettsial illnesses in humans and animals, including arthropod vectors, in Thailand. However, the reports on the seroprevalence of antibodies to O. tsutsugamushi and R. typhi in buffaloes is extremely rare. Thus, this study aimed to estimate the seroprevalence of both rickettsial infections in water buffaloes (Bubalus bubalis) in Phatthalung Province, southern Thailand. Materials and Methods From February to March 2023, a total of 156 serum samples were collected from 156 water buffaloes on 29 farms in Phatthalung province. The sera were screened for antibodies against O. tsutsugamushi and R. typhi using an indirect immunofluorescence assay. Results The seroprevalence of antibodies against O. tsutsugamushi and R. typhi in individual water buffaloes was 4.49% (95% confidence interval [CI]: 2.19%-8.97%) and 3.85% (95% CI: 1.77%-8.14%), respectively, whereas 31% (9/29) of the herds had buffaloes with antibodies. The number of buffaloes with scrub typhus infection and ectoparasite infestation was statistically significant (p < 0.05; odds ratio = 6.25 [95% CI: 1.19-33.33]). Intriguingly, the prevalence of scrub typhus antibodies in buffaloes that were not infested with ectoparasites was much higher than those that were. Conclusion This is the first report of O. tsutsugamushi and R. typhi antibodies in water buffalo sera in Southern Thailand. Two serum samples showed a high antibody titer against O. tsutsugamushi. Seroprevalence mainly occurred in non-ectoparasite-infested buffaloes, especially for O. tsutsugamushi antibodies. At the herd level, one-third of the studied farms showed seroprevalence. Additional research on the occurrence of these pathogens in vectors and in other animal reservoirs is necessary.
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Affiliation(s)
- Decha Pangjai
- Department of Medical Sciences, National Institute of Health, Ministry of Public Health, Nonthaburi 11000, Thailand
| | - Phirabhat Saengsawang
- Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat, 80160, Thailand
- One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand
| | - Kamchai Kidsin
- Animal Health Section, The Eight Regional Livestock Development, Surat Thani 84000, Thailand
| | - Ngamchit Choongkittaworn
- Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat, 80160, Thailand
- One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand
| | - Yukio Morita
- Department of Veterinary Medicine, School of Veterinary Medicine, Azabu University, 1-17-71 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5201, Japan
| | - Sumalee Boonmar
- Akkhraratchakumari Veterinary College, Walailak University, Nakhon Si Thammarat, 80160, Thailand
- One Health Research Center, Walailak University, Nakhon Si Thammarat, 80160, Thailand
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Chaisiri K, Linsuwanon P, Makepeace BL. The chigger microbiome: big questions in a tiny world. Trends Parasitol 2023; 39:696-707. [PMID: 37270375 DOI: 10.1016/j.pt.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Revised: 05/06/2023] [Accepted: 05/09/2023] [Indexed: 06/05/2023]
Abstract
'Chiggers' (trombiculid mite larvae) are best known as vectors of rickettsial pathogens, Orientia spp., which cause a zoonosis, scrub typhus. However, several other pathogens (e.g., Hantaan orthohantavirus, Dabie bandavirus, Anaplasma spp., Bartonella spp., Borrelia spp., and Rickettsia spp.) and bacterial symbionts (e.g., Cardinium, Rickettsiella, and Wolbachia) are being reported from chiggers with increasing frequency. Here, we explore the surprisingly diverse chigger microbiota and potential interactions within this microcosm. Key conclusions include a possible role for chiggers as vectors of viral diseases; the dominance in some chigger populations of unidentified symbionts in several bacterial families; and increasing evidence for vertical transmission of potential pathogens and symbiotic bacteria in chiggers, suggesting intimate interactions and not simply incidental acquisition of bacteria from the environment or host.
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Affiliation(s)
- Kittipong Chaisiri
- Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Ratchathewi, Bangkok 10400, Thailand
| | - Piyada Linsuwanon
- Department of Entomology, US Army Medical Component, Armed Forces Research Institute of Medical Sciences, Ratchathewi, Bangkok 10400, Thailand
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK.
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Alam AM, Easton A, Nicholson TR, Irani SR, Davies NWS, Solomon T, Michael BD. Encephalitis: diagnosis, management and recent advances in the field of encephalitides. Postgrad Med J 2023; 99:815-825. [PMID: 37490360 DOI: 10.1136/postgradmedj-2022-141812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 04/25/2022] [Indexed: 11/03/2022]
Abstract
Encephalitis describes inflammation of the brain parenchyma, typically caused by either an infectious agent or through an autoimmune process which may be postinfectious, paraneoplastic or idiopathic. Patients can present with a combination of fever, alterations in behaviour, personality, cognition and consciousness. They may also exhibit focal neurological deficits, seizures, movement disorders and/or autonomic instability. However, it can sometimes present non-specifically, and this combined with its many causes make it a difficult to manage neurological syndrome. Despite improved treatments in some forms of encephalitides, encephalitis remains a global concern due to its high mortality and morbidity. Prompt diagnosis and administration of specific and supportive management options can lead to better outcomes. Over the last decade, research in encephalitis has led to marked developments in the understanding, diagnosis and management of encephalitis. In parallel, the number of autoimmune encephalitis syndromes has rapidly expanded and clinically characteristic syndromes in association with pathogenic autoantibodies have been defined. By focusing on findings presented at the Encephalitis Society's conference in December 2021, this article reviews the causes, clinical manifestations and management of encephalitis and integrate recent advances and challenges of research into encephalitis.
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Affiliation(s)
- Ali M Alam
- Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
- NIHR Health Protection Unit for Emerging and Zoonotic Infection, Liverpool, UK
- Department of Clinical Infection, Microbiology, & Immunology, University of Liverpool, Liverpool, UK
| | - Ava Easton
- Department of Clinical Infection, Microbiology, & Immunology, University of Liverpool, Liverpool, UK
- Encephalitis Society, Malton, UK
| | | | - Sarosh R Irani
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
- Department of Neurology, John Radcliffe Hospital, Oxford, UK
| | | | - Tom Solomon
- NIHR Health Protection Unit for Emerging and Zoonotic Infection, Liverpool, UK
- The Pandemic Institute, Liverpool, UK
| | - Benedict D Michael
- NIHR Health Protection Unit for Emerging and Zoonotic Infection, Liverpool, UK
- Department of Clinical Infection, Microbiology, & Immunology, University of Liverpool, Liverpool, UK
- Department of Neurology, The Walton Centre NHS Foundation Trust, Liverpool, UK
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Mohd-Azami SNI, Loong SK, Khoo JJ, Husin NA, Lim FS, Mahfodz NH, Ishak SN, Mohd-Taib FS, Makepeace BL, AbuBakar S. Molecular Surveillance for Vector-Borne Bacteria in Rodents and Tree Shrews of Peninsular Malaysia Oil Palm Plantations. Trop Med Infect Dis 2023; 8:tropicalmed8020074. [PMID: 36828490 PMCID: PMC9965954 DOI: 10.3390/tropicalmed8020074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/16/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Many human clinical cases attributed to vector-borne pathogens are underreported in Malaysia, especially in rural localities where healthcare infrastructures are lacking. Here, 217 small mammals, consisting of rodents and tree shrews, were trapped in oil palm plantations in the Peninsular Malaysia states of Johor and Perak. Species identification was performed using morphological and DNA barcoding analyses, and 203 small mammals were included in the detection of selected vector-borne bacteria. The DNA extracted from the spleens was examined for Orientia tsutsugamushi, Borrelia spp., Bartonella spp. and Rickettsia spp. using established PCR assays. The small mammals collected in this study included Rattus tanezumi R3 mitotype (n = 113), Rattus argentiventer (n = 24), Rattus tiomanicus (n = 22), Rattus exulans (n = 17), Rattus tanezumi sensu stricto (n = 1) and Tupaia glis (n = 40). Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis were detected in the small mammals with the respective detection rates of 12.3%, 5.9% and 4.9%. Rickettsia spp., however, was not detected. This study encountered the presence of both Lyme disease and relapsing fever-related borreliae in small mammals collected from the oil palm plantation study sites. All three microorganisms (Orientia tsutsugamushi, Borrelia spp. and Bartonella phoceensis) were detected in the R. tanezumi R3 mitotype, suggesting that the species is a competent host for multiple microorganisms. Further investigations are warranted to elucidate the relationships between the ectoparasites, the small mammals and the respective pathogens.
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Affiliation(s)
- Siti Nurul Izzah Mohd-Azami
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Institute for Advanced Studies (IAS), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Shih Keng Loong
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Correspondence:
| | - Jing Jing Khoo
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK
| | - Nurul Aini Husin
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
- Institute for Advanced Studies (IAS), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Fang Shiang Lim
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Nur Hidayana Mahfodz
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Siti Nabilah Ishak
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia
- Kuantan Fisheries Biosecurity Centre, Department of Fisheries Malaysia, Kuantan 25100, Malaysia
| | - Farah Shafawati Mohd-Taib
- Department of Biological Sciences and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi 43600, Malaysia
| | - Benjamin L. Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, Liverpool L3 5RF, UK
| | - Sazaly AbuBakar
- Tropical Infectious Diseases Research & Education Centre (TIDREC), Higher Institution Centre of Excellence, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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Elliott I, Kumlert R, Thangnimitchok N, Blacksell SD, Tanganuchitcharnchai A, Paris DH, Newton PN, Morand S. Orientia tsutsugamushi in Chiggers and Small Mammals in Laos. Vector Borne Zoonotic Dis 2022; 22:505-511. [PMID: 36255415 PMCID: PMC7613890 DOI: 10.1089/vbz.2022.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023] Open
Abstract
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.
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Affiliation(s)
- Ivo Elliott
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Rawadee Kumlert
- Division of Vector-Borne Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi, Thailand
| | - Neeranuch Thangnimitchok
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
| | - Stuart D. Blacksell
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ampai Tanganuchitcharnchai
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Daniel H. Paris
- Department of Medicine, Swiss Tropical and Public Health Institute, Basel, Switzerland
- Department of Clinical Research, University of Basel, Basel, Switzerland
| | - Paul N. Newton
- Lao-Oxford-Mahosot Hospital-Wellcome Trust Research Unit, Microbiology Laboratory, Mahosot Hospital, Vientiane, Lao PDR
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Serge Morand
- MIVEGEC, CNRS, IRD, Montpellier University, Montpellier, France
- Faculty of Veterinary Technology, Kasetsart University, Bangkok, Thailand
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Moniuszko H, Wojnarowski K, Cholewińska P. Not Only Leptotrombidium spp. an Annotated Checklist of Chigger Mites (Actinotrichida: Trombiculidae) Associated with Bacterial Pathogens. Pathogens 2022; 11:pathogens11101084. [PMID: 36297141 PMCID: PMC9611227 DOI: 10.3390/pathogens11101084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/19/2022] [Accepted: 09/20/2022] [Indexed: 12/02/2022] Open
Abstract
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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Affiliation(s)
- Hanna Moniuszko
- Section of Basic Research in Horticulture, Department of Plant Protection, Institute of Horticultural Sciences, Warsaw University of Life Sciences—SGGW, 02-776 Warsaw, Poland
- Correspondence:
| | - Konrad Wojnarowski
- Chair for Fish Diseases and Fisheries Biology, Ludwig-Maximilians-University of Munich, 80539 Munich, Germany
| | - Paulina Cholewińska
- Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, 51-630 Wroclaw, Poland
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Abstract
Scrub typhus is a common bacterial infection in Asia caused by Orientia tsutsugamushi. This serological cohort study estimated the incidence of infection in a rural population in South India. Participants were enrolled through systematic sampling in 46 villages at baseline, and revisited the following year. Blood samples were tested for IgG antibodies using ELISA, followed by indirect immunofluorescence assays (IFA) in those positive for ELISA at both rounds. A case was defined as sero-conversion (ELISA), or at least a 4-fold titre increase (IFA), between the two time points. In addition to crude incidence rate estimates, we used piecewise linear rates across calendar months, with rates proportional to the monthly incidence of local hospital cases to address seasonality and unequal follow-up times. Of 402 participants, 61.7% were female. The mean age was 46.7 years, (range 13–88). 21 participants showed evidence for serological infection. The estimated incidence was 4.4 per 100 person-years (95% CI 2.8–6.7). The piecewise linear rates approach resulted in a similar estimate of 4.6 per 100 person years (95% CI 2.9–6.9). Considering previous estimates of symptomatic scrub typhus incidence in the same study population, only about 2–5% of infections may result in clinically relevant disease.
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