A Qualitative Risk Assessment for Bluetongue Disease and African Horse Sickness: The Risk of Entry and Exposure at a UK Zoo.

Elisabeth Nelson,Hannah Jenkins,Amanda Guthrie,Paul Pearce-Kelly,William Thurston,Marion England,Mary Cameron,Simon Carpenter

doi:10.3390/v14030502

Abstract

Bluetongue virus (BTV) and African horse sickness virus (AHSV) cause economically important diseases that are currently exotic to the United Kingdom (UK), but have significant potential for introduction and onward transmission. Given the susceptibility of animals kept in zoo collections to vector-borne diseases, a qualitative risk assessment for the introduction of BTV and AHSV to ZSL London Zoo was performed. Risk pathways for each virus were identified and assessed using published literature, animal import data and outputs from epidemiological models. Direct imports of infected animals, as well as wind-borne infected Culicoides, were considered as routes of incursion. The proximity of ongoing disease events in mainland Europe and proven capability of transmission to the UK places ZSL London Zoo at higher risk of BTV release and exposure (estimated as low to medium) than AHSV (estimated as very low to low). The recent long-range expansion of AHSV into Thailand from southern Africa highlights the need for vector competence studies of Palearctic Culicoides for AHSV to assess the risk of transmission in this region.

Highlights

Bluetongue virus (BTV: Reoviridae: Orbivirus) was detected in 2007 following an unprecedented outbreak in northern Europe that began in 2006 and was subsequently eradicated from the United Kingdom (UK) in the winter of 2007/2008, following a voluntary vaccination campaign [15–17]. Prior to this incursion, which involved a strain of BTV serotype 8 with a sub-Saharan origin, no Culicoides-borne arbovirus had ever been detected in the UK
This study examines the potential routes of incursion of BTV and African horse sickness virus (AHSV) to the UK
If an infected animal is imported into ZSL London Zoo, the suitable species composition and feeding preferences of the zoo Culicoides populations render the probability of BTV-infected Culicoides in the zoo, P2, as medium during the vector active season

Summary

Introduction

Vector-borne diseases are an increasing global threat to the health of humans and animals with the spread of exotic pathogens facilitated by climate change, urbanization and extensive global travel and trade [1–3]. The United Kingdom (UK) has been largely protected from such pathogen incursion through its geographic isolation, temperate climate and socioeconomic development, but recent incursions of both novel vectors and vector-borne pathogens have occurred [4–8] These events have triggered a series of exercises to identify future incursion risks and to highlight potential drivers of these events, including climate and land change [9–13]. Bluetongue virus (BTV: Reoviridae: Orbivirus) was detected in 2007 following an unprecedented outbreak in northern Europe that began in 2006 and was subsequently eradicated from the UK in the winter of 2007/2008, following a voluntary vaccination campaign [15–17] Prior to this incursion, which involved a strain of BTV serotype 8 with a sub-Saharan origin, no Culicoides-borne arbovirus had ever been detected in the UK

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