West Nile virus risk assessment tool

0

• Free area
• No historical circulation of WNV

Is there any risk of WNV transmission in this area?

Obligatory:

• Human: passive surveillance
• Veterinary: passive surveillance for horses
• SoHO: standard haemovigilance, biovigilance and post-transfusion/transplantation surveillance (not specific for WNV)

Health sector

• Increase awareness amongst healthcare professionals about WNV so as it will be considered in the differential diagnosis of travellers returning from affected areas.
• Education of travellers to affected areas on how to reduce the risk.
• Ensure there are laboratory capabilities within the country for diagnosis.
• Ensure SoHo donation authorities have implemented measures to prevent transmission through travellers returning from affected areas (see WNV and blood safety introduction to a preparedness plan).

1

• Predisposed areas where the ecological conditions are suitable for WNV circulation.
• No historical circulation of WNV is known.
• The probability of a human outbreak is unknown but likely to be low.

• Is there any risk of WNV transmission in this area in the season?
• Would we detect WNV circulation if it occurred?

Obligatory:

• Human: passive surveillance
• Veterinary: passive surveillance for horses;
• SoHO: standard haemovigilance- biovigilance and post-transfusion/transplantation surveillance (not specific for WNV)

Desirable:

• Assess the risk of WNV transmission in the area.

Multi-sectoral collaboration and coordination

• Consider drafting WNV preparedness plan

• Response as level above
• Ensure there are laboratory capabilities within the country for diagnosis of WNV

• No specific action

• No specific action.

2

• Imperilled areas where the ecological conditions are suitable for WNV circulation
• Past evidence of WNV circulation
• The probability of a human outbreak is unknown.

• To what extent has the virus infected local animal populations?
• What is the prevalence of infection in animal populations?
• Are passive/active surveillance systems (including laboratory diagnostics) in place to be able to identify horse and human infections with WNV?

Obligatory:

• As above

AND:

• Ensure timely detection and reporting of human cases by passive surveillance;
• Develop and implement a surveillance plan including mosquito, bird and equid surveillance enabling the detection of WNV circulation.

Multi-sectoral collaboration and coordination

• Develop a WNV preparedness plan, including surveillance activities and an integrated vector control plan.
• Allocate resources necessary to enable emergency response (i.e. vector control, communication plan).
• Establish close and regular exchange of information between all sectors as part of the WNV preparedness plan.

Health sector

• Response as level above AND:
• to assure an appropriate level of awareness among health care professionals;
• to define roles and responsibilities, but also training courses, curricula, information and management recommendations;
• availability of national guidelines for clinical management.

Public communication

• Conduct public information campaigns during the mosquito season to strengthen use of personal protection measures against mosquito bites.

Vector management response

• As part of the WNV preparedness plan: consider preparing vector control activities if entomological indicators suggest the need.
• Allocate resources necessary to enable emergency response (i.e. vector control).
• Implement larval control as part of the integrated vector control in the event of there having been WNV circulation in the previous year.

3a

• Imperilled areas
• Current surveillance findings (i.e. mosquito or bird screening) indicating WNV epizootic activity in the area in the second part of the season (i.e. August-September-October)
• The probability of a human outbreak is low.

• What is the geographic extension of the area where WNV is circulating?
• What is the seasonal dynamic of WNV circulation?
• What is the real risk for people?

• As above

• Ensure timely detection and reporting of human cases by passive surveillance.
• As part of the surveillance plan: ensure the proper continuation of the surveillance activities.

• Response as level above
• Health sector
• Response as level above

Public communication

• Consider public information campaigns to support vector control response

Vector management response

• Response as level above;

AND:

• Implement public education programs focused on risk potential and personal protection, and emphasising residential source reduction.
• Vector control focuses on larval control.

3b

Imperilled areas

• Current surveillance findings (i.e. mosquito or bird screening) indicating WNV epizootic activity in the area, in the first part of the season (May-June-July)
• The probability of a human outbreak is low to moderate.

Idem as level above

Obligatory:

• As above

AND:

• Human: active/enhanced surveillance in the area with confirmed virus circulation.
• Ensure timely reporting of human cases by passive/active surveillance.
• As part of the surveillance plan: increase the mosquito and bird surveillance activities.

Multi-sectoral collaboration and coordination

• Response as level above

Health sector

• Response as level above

Public communication

• Response as level above
• AND:
• Implement public information on personal protection and source reduction

Vector management response

AND:

• Response as level above
• Increase effort for public information on personal protection and source reduction continued larval control
• If surveillance indicates virus circulation is increasing initiate ground adult mosquito control in areas at high risk for humans or in hot spot sites (if known)

Imperilled areas

• WNV-specific IgM detected in local non-vaccinated horse(s) or WNV isolated from local horse.
• The probability of a human outbreak is high.

Obligatory:

• As above

AND:

• Human: active/enhanced surveillance in the area with confirmed virus circulation
• Ensure timely reporting of human cases by passive/active surveillance
• As part of the surveillance plan: increase the mosquito, bird and horse surveillance activities.

Multi-sectoral collaboration and coordination

• Create/establish multi-sectoral outbreak response team

Health sector

• Response as level above
• Increase awareness among health professionals

Public communication

• Conduct public information campaigns to strengthen use of personal protection measures against mosquito bites and source reduction.

Vector management response

• Response as level above
• If surveillance indicates virus circulation is increasing, initiate ground adult control in high-risk areas for humans or in hot spot sites (if known).

5

Affected area

• At least one human case detected (i.e. probable or confirmed human case according to EU case definition).
• Outbreak ongoing

• What is the geographic extension of the ’affected area’ where WNV is being transmitted to humans?
• What is the risk of increasing numbers of human cases?

Obligatory:

• As above

• Human: active/enhanced surveillance in the area with confirmed virus circulation.
• Ensure timely reporting of human cases by passive/active surveillance.
• As part of the surveillance plan: continue the surveillance activities.

Multi-sectoral collaboration and coordination

• Regular meetings of multi-sectoral outbreak emergency response team
• Establishment of geographical boundaries of affected area.

Health sector

• Response as level above
• Increase awareness among health professionals
• Safety of SoHO: implement EU directive for blood, tissues, cells and organ safety in affected area, quantitative risk assessment of transfusions/transplantations, implement deferral policy, +/- NAT screening, +/- inactivation techniques, evaluate impact of measures implemented on blood supplies.

Public communication

• Response as level above;
• AND:
• Increase public information campaigns in order to reach most people at risk.

Vector management response

• Response as level above;
• AND:
• Intensify ground adult mosquito control with multiple applications in areas of high risk of human cases.
• Enhance risk communication.
• Monitor efficacy of spraying on target mosquito populations.