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Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species.
PLoS Negl Trop Dis. 2020 01; 14(1):e0007619.PN

Abstract

BACKGROUND

Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloé Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of orientiae responsible for scrub typhus on Chiloé Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA.

METHODOLOGY/PRINCIPAL FINDINGS

During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloé Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus.

CONCLUSIONS/SIGNIFICANCE

This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America.

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Authors+Show Affiliations

Acosta-Jamett G
Instituto de Medicina Preventiva Veterinaria, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile. Programa de Investigación Aplicada en Fauna Silvestre, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile.
Martínez-Valdebenito C
Departamento de Enfermedades Infecciosas e Inmunología Pediátricas, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. Laboratorio de Infectología y Virología Molecular, Red Salud UC-Christus, Santiago, Chile.
Beltrami E
Instituto de Medicina Preventiva Veterinaria, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile. Escuela de Graduados, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile.
Silva-de La Fuente MC
Departamento de Ciencias Animal, Facultad de Ciencias Veterinarias, Universidad de Concepción, Concepción, Chile. Programa de Doctorado en Ciencias Veterinarias, Facultad de Ciencias Veterinarias, Universidad de Concepción, Chillán, Chile. Facultad de Medicina Veterinaria, Universidad San Sebastián, Concepción, Chile.
Jiang J
Viral and Rickettsial Diseases Department, Naval Medical Research Center, Silver Spring, MD, United States of America.
Richards AL
Department of Preventive Medicine and Biostatistics, Uniformed Services University of the Health Sciences, Bethesda, MD, United States of America.
Weitzel T
Laboratorio Clínico, Clínica Alemana de Santiago, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile. Hantavirus and Zoonoses Program, Instituto de Ciencias e Innovación en Medicina (ICIM), Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago, Chile.
Abarca K
Departamento de Enfermedades Infecciosas e Inmunología Pediátricas, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. Millennium Institute on Immunology and Immunotherapy, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.

MeSH

AnimalsChileDNA, ProtozoanEctoparasitic InfestationsOrientia tsutsugamushiReal-Time Polymerase Chain ReactionRodentiaScrub TyphusTrombiculidaeZoonoses

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

31971956

Citation

Acosta-Jamett, Gerardo, et al. "Identification of Trombiculid Mites (Acari: Trombiculidae) On Rodents From Chiloé Island and Molecular Evidence of Infection With Orientia Species." PLoS Neglected Tropical Diseases, vol. 14, no. 1, 2020, pp. e0007619.
Acosta-Jamett G, Martínez-Valdebenito C, Beltrami E, et al. Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species. PLoS Negl Trop Dis. 2020;14(1):e0007619.
Acosta-Jamett, G., Martínez-Valdebenito, C., Beltrami, E., Silva-de La Fuente, M. C., Jiang, J., Richards, A. L., Weitzel, T., & Abarca, K. (2020). Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species. PLoS Neglected Tropical Diseases, 14(1), e0007619. https://doi.org/10.1371/journal.pntd.0007619
Acosta-Jamett G, et al. Identification of Trombiculid Mites (Acari: Trombiculidae) On Rodents From Chiloé Island and Molecular Evidence of Infection With Orientia Species. PLoS Negl Trop Dis. 2020;14(1):e0007619. PubMed PMID: 31971956.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Identification of trombiculid mites (Acari: Trombiculidae) on rodents from Chiloé Island and molecular evidence of infection with Orientia species. AU - Acosta-Jamett,Gerardo, AU - Martínez-Valdebenito,Constanza, AU - Beltrami,Esperanza, AU - Silva-de La Fuente,María Carolina, AU - Jiang,Ju, AU - Richards,Allen L, AU - Weitzel,Thomas, AU - Abarca,Katia, Y1 - 2020/01/23/ PY - 2019/06/27/received PY - 2019/12/03/accepted PY - 2020/02/04/revised PY - 2020/1/24/pubmed PY - 2020/4/14/medline PY - 2020/1/24/entrez SP - e0007619 EP - e0007619 JF - PLoS neglected tropical diseases JO - PLoS Negl Trop Dis VL - 14 IS - 1 N2 - BACKGROUND: Scrub typhus is an emerging vector-borne zoonosis, caused by Orientia spp. and transmitted by larvae of trombiculid mites, called chiggers. It mainly occurs within a region of the Asia-Pacific called the tsutsugamushi triangle, where rodents are known as the most relevant hosts for the trombiculid vector. However, the reservoir(s) and vector(s) of the scrub typhus outside Asia-Pacific are unknown. The disease has recently been discovered on and is considered endemic for Chiloé Island in southern Chile. The aim of the present work was to detect and determine the prevalence of chiggers on different rodent species captured in probable sites for the transmission of orientiae responsible for scrub typhus on Chiloé Island in southern Chile and to molecularly examine collected chiggers for the presence of Orientia DNA. METHODOLOGY/PRINCIPAL FINDINGS: During the austral summer 2018, rodents were live-trapped in six sites and examined for chigger infestation. All study sites were rural areas on Chiloé Island, previously identified as probable localities where human cases acquired the scrub typhus. During a total of 4,713 trap-nights, 244 rodents of seven species were captured: the most abundant was Abrothrix olivacea. Chiggers were detected on all seven rodent species with a 55% prevalence rate. Chiggers showed low host specificity and varied according to site specific host abundance. Three genera of trombiculids were identified. Herpetacarus was the most abundant genus (93%), prevalent in five of the six sites. Infestation rates showed site specific differences, which were statistically significant using a GLM model with binomial errors. Molecular analyses proved that 21 of 133 (15.8%) mite pools were positive for Orientia species, all of them belonged to the genus Herpetacarus. CONCLUSIONS/SIGNIFICANCE: This study firstly reports the presence of different rodent-associated chigger mites positive for Orientia sp., in a region endemic for scrub typhus in southern Chile. Herpetacarus and two other genera of mites were found with high infestation rates of rodents in sites previously identified as probable exposure of scrub typhus cases. A substantial percentage of mite pools were positive for Orientia DNA, suggesting that chigger mites serve as vectors and reservoirs of this emerging zoonosis in South America. SN - 1935-2735 UR - https://www.unboundmedicine.com/medline/citation/31971956/Identification_of_trombiculid_mites__Acari:_Trombiculidae__on_rodents_from_Chiloé_Island_and_molecular_evidence_of_infection_with_Orientia_species_ DB - PRIME DP - Unbound Medicine ER -