West Nile Fever (WNF) is caused by a virus that is transmitted by mosquitos. It is a notifiable disease that can affect birds, horses, humans and, occasionally, some mammals.
Defra has put together a risk assessment and the risk in the UK is very low. No cases of West Nile Virus infection in either humans or horses have ever been reported in the UK.
The assessment states that there is a level of uncertainty around the situation in Germany and the lack of wild bird surveillance data across Europe. Virus could arrive through the movement of infected wild birds and subsequent transmission to local mosquito populations or assisted movement of infected mosquitos (in containers, vehicles, used car tyres etc). However, mosquito activity declines from October and from then virus transmission would not occur.