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Journal of medical entomology2026; 63(5); tjag121; doi: 10.1093/jme/tjag121

Evaluation of mosquito transmission of equine hepacivirus in laboratory and field studies.

Abstract: Equine hepacivirus (EqHV) is a hepatotropic virus, closely related to human hepatitis C virus (HCV), that can cause acute or chronic infection in horses. As with HCV, transmission is thought to occur primarily through parenteral, particularly blood-borne, routes. Vertical transmission from mare to foal has been reported but appears to be uncommon. The high seroprevalence in horse populations and the occurrence of infection in isolated horses indicate efficient horizontal transmission routes exist. One such possibility is biological or mechanical transmission by arthropods, such as mosquitoes, stable flies, or ticks. Here, we conducted 2 complementary studies to evaluate the possible role of mosquitoes as EqHV biological vectors. In the laboratory, we orally exposed Aedes albopictus (Skuse) females to EqHV through artificial bloodfeeding with blood collected from 2 chronically infected horses. Mosquito samples (body, legs, and saliva) were collected at multiple time points post-exposure and tested for EqHV RNA by molecular assays. In the field, 2,138 mosquitoes were collected from New York and Florida, United States, and screened for EqHV RNA. No EqHV RNA was detected in any samples from the laboratory experiment or among field-collected mosquitoes. These findings indicate that the Ae. albopictus strain evaluated here is unlikely to serve as a biological vector of EqHV and corroborate previous negative findings in field-collected mosquitoes. Nevertheless, low infection rates may have gone undetected. Laboratory studies of additional horse-feeding mosquito species and expanded field collections in EqHV-endemic regions are needed to further clarify any potential role for mosquitoes in EqHV transmission.
© The Author(s) 2026. Published by Oxford University Press on behalf of Entomological Society of America.
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Publication Date: 2026-09-06 PubMed ID: 42700390PubMed Central: PMC13545984DOI: 10.1093/jme/tjag121Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

Overview

  • This study investigated whether mosquitoes, specifically the species Aedes albopictus, can transmit equine hepacivirus (EqHV) to horses.
  • Both laboratory experiments and field collections found no evidence of EqHV in mosquitoes, suggesting these insects are unlikely to be biological vectors of the virus.

Background

  • Equine Hepacivirus (EqHV): A liver-targeting virus related to human hepatitis C virus (HCV), infecting horses and causing acute or chronic liver infections.
  • Transmission routes: Mainly blood-borne (parenteral) transmission, with rare vertical transmission from mare to foal.
  • Horizontal transmission mystery: Despite known modes, high prevalence in horse populations and isolated infections imply other efficient transmission routes exist.
  • Possible role of arthropods: Mosquitoes, stable flies, and ticks could potentially transmit EqHV either biologically (virus replicates inside vector) or mechanically (virus transferred externally).

Research Purpose

  • To evaluate whether mosquitoes, specifically the Aedes albopictus species, can act as biological vectors for EqHV.
  • To investigate both under controlled laboratory conditions and natural field environments for presence and potential transmission of EqHV by mosquitoes.

Laboratory Study Design

  • Female Aedes albopictus mosquitoes were fed artificial blood meals spiked with blood from two chronically infected horses carrying EqHV.
  • Samples were collected from mosquitoes at multiple time points post-exposure, including bodies, legs, and saliva.
  • Molecular assays targeting EqHV RNA were used to detect viral presence inside the mosquito samples.

Field Study Design

  • Collected 2,138 mosquitoes from two different US locations: New York and Florida.
  • The collected mosquitoes were screened using molecular techniques for the presence of EqHV RNA.

Key Findings

  • No detection of EqHV RNA in any mosquito samples from the laboratory experiments.
  • No EqHV RNA found in field-collected mosquito samples from both New York and Florida populations.
  • Results indicate the tested Ae. albopictus strain is unlikely to be a biological vector of EqHV.
  • These findings align with previous negative results from field studies regarding mosquito involvement in EqHV transmission.

Limitations and Future Research

  • It is possible that very low infection rates or rare transmission events were not detected given sample size and testing sensitivity.
  • Only one mosquito species was tested in the lab, and more species that feed on horses may also need to be examined.
  • Field collections were limited to certain geographic areas; more extensive sampling in regions where EqHV is endemic could provide additional insights.
  • Further research could clarify if mosquitoes might act as mechanical vectors or if other arthropods contribute to horizontal transmission.

Conclusions

  • The Aedes albopictus mosquito strain tested does not appear to serve as a biological vector for EqHV transmission to horses.
  • Current evidence suggests mosquitoes are not a significant factor in the natural spread of EqHV but further studies are required.
  • Understanding transmission routes fully is crucial for controlling spread and managing EqHV infection in horse populations.

Cite This Article

APA
Magalhaes T, Carvalho Leandro D, Ozel E, Liang X, Lyons B, Scheel TKH, Salomon J, Luethy D, Kaufman PE, Tomlinson JE. (2026). Evaluation of mosquito transmission of equine hepacivirus in laboratory and field studies. J Med Entomol, 63(5), tjag121. https://doi.org/10.1093/jme/tjag121

Publication

Journal of medical entomology
ISSN: 1938-2928
NlmUniqueID: 0375400
Country: England
Language: English
Volume: 63
Issue: 5
PII: tjag121

Researcher Affiliations

Magalhaes, Tereza
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Carvalho Leandro, Danilo de
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
  • Colégio de Aplicação, Universidade Federal de Pernambuco, Recife, PE, Brazil.
Ozel, Emrah
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Liang, Xiao
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Lyons, Brandon
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Scheel, Troels K H
  • Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Hvidovre Hospital and Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.
Salomon, Jordan
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Luethy, Daniela
  • Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA.
  • Department of Clinical Studies - New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, USA.
Kaufman, Phillip E
  • Department of Entomology, Texas A&M University, College Station, TX, USA.
Tomlinson, Joy E
  • Department of Clinical Studies - New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, USA.
  • Baker Institute for Animal Health, Cornell University College of Veterinary Medicine, Ithaca, NY, USA.

MeSH Terms

  • Animals
  • Horses
  • Female
  • Aedes / virology
  • Hepacivirus / physiology
  • Hepacivirus / isolation & purification
  • Horse Diseases / transmission
  • Horse Diseases / virology
  • Mosquito Vectors / virology
  • Hepatitis C / transmission
  • Hepatitis C / veterinary
  • Hepatitis C / virology
  • Florida
  • New York

Grant Funding

  • # 2022-67015-36343 / United States Department of Agriculture
  • #6070 / National Institute of Food and Agriculture Hatch
  • Texas A&M AgriLife Research

Conflict of Interest Statement

The authors declare they have no conflict of interest.

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