Table 2.

Risk pathways for the introduction of West Nile virus into the UK [adapted from Defra (32)].

Pathway	Risk
Introduction by migrating birds	Very low
Importation by legal trade in horses	Very low
Importation by legal trade in biological materials (equine semen, ova, embryos)	Negligible
Importation by legal trade in poultry	Negligible
Importation by legal trade in non-equine/non-avian species	Negligible
Illegal importation of infected animal	Impossible to quantify
Importation of infected vector	Very low
Air-borne movement of vector from continental Europe	Negligible