Using zoos as sentinels for re-emerging arboviruses: Vector surveillance during an outbreak of epizootic hemorrhagic disease at the Minnesota Zoo

Authors: McGregor, Bethany; Reister-Hendricks, Lindsey; NORDMEYER, CALE - Minnesota Zoological Garden; STAPLETON, SETH - Minnesota Zoological Garden; Davis, Travis; Drolet, Barbara

Submitted to: Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2023
Publication Date: 1/14/2023
Citation: McGregor, B.L., Reister-Hendricks, L.M., Nordmeyer, C., Stapleton, S., Davis, T.M., Drolet, B.S. 2023. Using zoos as sentinels for re-emerging arboviruses: Vector surveillance during an outbreak of epizootic hemorrhagic disease at the Minnesota Zoo. Pathogens. 12(1):140-149. https://doi.org/10.3390/pathogens12010140.
DOI: https://doi.org/10.3390/pathogens12010140

Interpretive Summary: Diseases spread by insects are becoming more common and, unfortunately, our ability to monitor for these diseases is unable to keep up. By using locations that already possess the infrastructure to monitor animal health, such as zoos, we can expand insect collections to improve our ability to detect and monitor these diseases more effectively. In Fall 2020, an outbreak of epizootic hemorrhagic disease (EHD), which is caused by a virus that is spread by biting midges mainly to deer and other hoofed animals, occurred at the Minnesota Zoo. Several animals at the zoo showed evidence of EHD and four caribou died. To better understand this outbreak, insects were collected around the property and tested for the presence of this virus. The virus was found in two species of biting midges, including one that wasn't previously considered an important vector for this disease. This information helps us to better understand which midge species are important for the movement of this virus. It also highlights the usefulness of locations like zoos as sentinels for the early detection of insect-borne pathogens, which could help us to identify and prevent outbreaks that may cause sickness or death in zoo animals, surrounding wildlife, and livestock.

Technical Abstract: Vector-borne disease prevalence is increasing at a time when surveillance capacity in the United States is decreasing. One way to address this surveillance deficiency is to utilize established infrastructure, such as zoological parks, to investigate animal disease outbreaks and improve our epidemiological understanding of vector-borne pathogens. During fall 2020, an outbreak of epizootic hemorrhagic disease (EHD) at the Minnesota Zoo resulted in morbidity and seroconversion of several collection animals. In response to this outbreak, insect surveillance was conducted and collected insects were tested for the presence of epizootic hemorrhagic disease virus (EHDV) by RT-qPCR to better understand the nature of the outbreak. Six pools of Culicoides biting midges were positive for EHDV, including three pools of Culicoides sonorensis, two pools of Culicoides variipennis, and a pool of degraded C. variipennis complex midges. All three endemic serotypes of EHDV (1, 2, and 6) were detected in both animals and midge pools from the premises. Despite this outbreak, no EHDV cases had been confirmed in wild animals near the zoo. This highlights the importance and utility of using animal holding facilities, such as zoos, as sentinels to better understand spatio-temporal dynamics of pathogen transmission.