Table 2. Key characteristics of West Nile virus (WNV) infection surveillance in the European Union, Austria, France, Greece, Italy and the United Kingdom.

Country/region	Intersectoral collaboration	Human surveillance	Animal surveillance	Vector surveillance
European Union	▪ ECDC provides WNF seasonal maps that include human cases and provides information on animal/vector WNV infection.   ▪ ECDC tool for WNF risk assessment proposes a classification of risk areas based on human, animal and vector surveillance data.   ▪ EFSA and ECDC publish the EU summary reports on trends and sources of zoonoses, zoonotic agents and food-borne outbreaks every year.	▪ WNF is an EU notifiable disease; cases are reported by EU countries to TESSy according to the EU case definition.   ▪ EU countries must implement a deferral of blood donations for 28 days after leaving an area with ongoing WNV transmission in humans.	▪ WNF, as a cause of equine encephalomyelitis in horses, is notifiable to the European Animal Disease Notification System.   ▪ WNF in animals is a disease listed in the OIE Terrestrial Animal Health Code and must be reported to the OIE.   ▪ EU countries should monitor WNV activity in animals, if warranted by the epidemiological situation, and report animal cases to the European Commission.	▪ There is no legal framework regarding mosquito surveillance at EU level.   ▪ ECDC developed guidelines for surveillance of native mosquitoes to support countries to plan and implement surveillance activities.
Austria	▪ A national WNV Task Force was established in 2013, with members nominated by the Ministry of Health.   ▪ No joint reporting system across the different authorities. However, reports are published on the AGES website.	▪ Human cases and fatalities are statutorily reportable as of September 2015.   ▪ Routine examination of donated blood was introduced in eastern Austria in the summer of 2014.	▪ Neurological disease in equidae is notifiable in Austria.   ▪ Surveillance covers birds and horses.	▪ Since 2011, active country-wide mosquito surveillance is conducted by AGES.
France	▪ The national guidelines for WNV surveillance, prevention and control activities are under the responsibility of the Ministries of Health, Agriculture and Environment.	▪ Suspected neuroinvasive human cases should be notified to regional health authorities in the Mediterranean region during the period of vector activity, from June to November.   ▪ Measures for the safety of blood products are taken in line with the EU directive for blood safety.	▪ Notification of suspected horse cases to regional veterinary services is compulsory, whatever the time period or their location.   ▪ Sentinel bird surveillance was discontinued in 2007.	▪ Mosquito surveillance is systematically implemented from March to November in the Mediterranean area.
Greece	▪ The Ministry of Rural Development and Food and the HCDCP share the results of human, animal and vector surveillance with each other and with regional and local public health authorities, local veterinary services, municipalities and local health units   ▪ There are a multisectoral committee for the prevention and management of tropical diseases (including WNF) and two multisectoral working groups: for vector-borne diseases and for the designation of areas affected by such diseases.	▪ Since 2010, all laboratory probable and confirmed WNF cases should be notified.   ▪ Enhanced surveillance is implemented at national level that includes awareness campaigns towards physicians, support of laboratory confirmation, active laboratory-based surveillance, cases investigation and daily dissemination of information to national and local stakeholders.   ▪ Measures for the safety of blood products are taken in line with the EU directive for blood safety.	▪ WNF in animals is a notifiable disease and disease suspicions must be reported to the competent veterinary authorities.   ▪ There is active serological surveillance of sentinel horses; active clinical surveillance of equidae around confirmed human and animal cases; passive surveillance of WNF in equidae all-year-round and some small scale surveillance in wild birds.	▪ Since 2010, HCDCP together with the National School of Public Health, Universities, local authorities and subcontractors, conducts active vector surveillance from June to October to detect WNV circulation in mosquitoes.
Italy	▪ A national plan for surveillance on imported and autochthonous human vector-borne disease (chikungunya, dengue and WND) integrating human and veterinary surveillance is prepared annually.   ▪ Any suspected evidence of virus circulation in animals or vectors is notified to the public health authorities.	▪ Probable and confirmed human cases are notified in real time using a password-protected web-based system.   ▪ In the affected area, local health authorities implement an active surveillance at risk population.   ▪ Passive surveillance on human neurological cases is set up in the whole region where the affected area is located.   ▪ Measures for the safety of blood products are taken in line with the EU directive for blood safety.	▪ A web-based national animal disease notification system allows the notification of animal diseases.   ▪ Passive surveillance in equidae in the whole country.   ▪ Random IgM screening in horses living in non-affected areas.   ▪ Bird surveillance focuses on WNV detection in resident target species; immunological response among poultry of rural farms and migratory birds; and bird mortality.	▪ Entomological surveillance is systematically implemented during the period of vector activity in affected areas.
United Kingdom	▪ A national contingency plan for integrated surveillance and control of vector-borne disease has been prepared.   ▪ Monthly meetings between human and animal health risk assessors to share information.   ▪ Any suspect or confirmed cases would be notified to all relevant authorities.	▪ WNV in humans is a notifiable disease in Scotland, but not in the rest of the UK. It is however, a notifiable organism in England, Wales and Scotland (not Northern Ireland).   ▪ Human cases of autochthonous WNV infection should be reported to National Surveillance Centres by the diagnostic laboratories.   ▪ Measures for the safety of blood products are taken in line with the EU directive for blood safety.	▪ WNF, as a cause of equine encephalomyelitis, is a notifiable disease of equidae in the UK.   ▪ There is no active surveillance of horses or other equidae. Monitoring relies on passive surveillance and testing of horses with neurological signs.   ▪ There is no systematic WNV active surveillance of wild birds in the UK, however a passive surveillance system is in place between April and October.	▪ Some targeted surveillance for mosquitoes are carried out by PHE in areas with suitable habitat.

AGES: Austrian Agency for Health and Food Safety; ECDC: European Centre for Disease Prevention and Control; EFSA: The European Food Safety Agency; EU: European Union; HCDCP: Hellenic Center for Disease Control and Prevention; OIE: World Organization for Animal Health; PHE: Public Health England; TESSY: The European Surveillance System; UK: United Kingdom; WNF: West Nile fever; WNV: West Nile virus.