Diseases spread by midges and mosquitoes

A variety of diseases can be passed onto horses by biting insects. One group of these are equine arboviruses which are not currently an immediate threat to UK horses. However, increased global transport and climate change may increase the chance of a disease outbreak in the future in the UK. Horse owners and veterinary surgeons would be key in detecting an outbreak of a new disease so being aware of disease outbreaks Europe and knowing what signs to look for are key.

A recent survey carried out by the University of Liverpool asked horse owners about equine diseases spread by mosquitoes and midges and we are very grateful to the horse owners who took part. This study demonstrated that many horse owners are not aware of the types of diseases that midges and mosquitoes spread, the signs of disease or what would happen if a disease outbreak occurred in the UK. If you would like to read a copy of this paper, please click on this link.

What is an arbovirus?

An arbovirus is a viral disease that is spread by arthropods (insects) to people and / or animals. Virus is spread when an infected insect bites a person or animal and there are many different types of arboviruses. Different arboviruses affect people and / or specific groups of animals and various different clinical signs may be seen.

In some parts of the world such as Australia, USA and South Africa certain equine arboviruses are endemic and occur relatively frequently. Fortunately in the UK we are free from these at present.

Can UK midges and mosquitos spread these diseases?

We have performed research on midges and mosquitoes in the UK and this has shown that we have midges and mosquitoes on horse premises in the UK that are capable of spreading some important arboviruses that can affect horses. Please see this link for more information.

What diseases can they spread and what clinical signs do they cause?

Below is a list of some of the arboviruses spread by mosquitoes that can affect horses and the clinical signs (table is taken from Chapman et al. 2018):

WNV = West Nile Virus

JEV = Japanese Encephalitis Virus

MVEV = Murray Valley Encephalitis Virus

EEV = Eastern Equine Encephalitis Virus

WEEV = Western Equine Encephalitis Virus

VEEV = Venezuelan Equine Encephalitis Virus

RRV = Ross River Virus

Getah = Getah virus

Can these diseases be prevented?

Many of these diseases fortunately have vaccines available which would enable a disease outbreak to be kept under control. The most important factor would be for horse owners and vets to pick up an unusual disease quickly so that disease prevention measures could be enforced quickly to limit the number of horses affected.