Implementation of surveillance of invasive mosquitoes in Belgium according to the ECDC guidelines

BACKGROUND: In 2012, the new guidelines for the surveillance of IMS in Europe, produced by the European Centre for Disease Prevention and Control (ECDC), were tested in Belgium. This study aimed at (1) testing the usefulness and applicability in the field of the ECDC guidelines for the surveillance of IMS in Europe and (2) surveying IMS throughout Belgium. METHODS: First, the scenarios, which Belgium is facing, were identified according to the ECDC guidelines. Second, the surveillance strategy and the methods were identified based on the guidelines and adjusted to the Belgium context. Two areas colonised by IMS and 20 potential points of entry (PoE) were selected. Mosquito Magnet Liberty Plus (CO(2)-baited) traps (23) and oviposition traps (147) were set-up, and larval sampling was performed monthly or bi-monthly from July till October 2012. Finally, the costs and workload of the surveillance activities were compared to the estimates provided by the ECDC guidelines. RESULTS: Surveillance at 20 potential PoE (complying with scenario 1) revealed that no new IMS were established in Belgium. Surveillance at two sites colonised by IMS (scenario 2) indicated that although control measures have drastically reduced the Ae. j. japonicus population this species is still present. Furthermore, Ae. koreicus is permanently established. For both scenarios, the problems encountered are discussed and recommendations are given. In addition, the actual workload was lower than the estimated workload, while the actual costs were higher than the estimated ones. CONCLUSIONS: The ECDC guidelines are helpful, applicable and efficient to implement surveillance of IMS in Belgium. Recommendations were customised to the local context (political demands, salary and investment costs, and existing expertise). The workload and costs related to the preparatory phase (i.e., planning, contacts with the PoE, writing a protocol) were found to be missing in the cost evaluation suggested in the guidelines. Updates on the occurrence of IMS in Belgium and the related risk for disease agents they can transmit will only be available once a structured and permanent surveillance system is implemented.