How are geographically affected areas and areas at risk of West Nile virus (WNV) transmission defined? When is an alert for potential human WNV infection triggered?
The WNV risk assessment tool provides operational guidance to assist the countries in determining the risk of human transmission of WNV on their territory. Using the information gathered through the surveillance mechanisms they can ascertain the level of risk within an area. Seven possible risk levels are defined. For each risk level, the tool outlines the questions to be answered and suggests obligatory and desirable surveillance activities, as well as public health response measures. In addition, the report offers key facts about WNV and description of surveillance systems used.
The epidemiology and transmission cycle of the WNV is complex and assessing the risk of WNV being transmitted to humans is not always straightforward. Risk assessment at local, national and EU level can help the timely implementation of preparedness activities, control measures, as well as provide information to decision makers.