**5. Conclusions**

MBDs have complicated transmission cycles, involving different reservoirs, competent vectors and environmental and climatic features that influence their epidemiology. Therefore, surveillance methods have to be planned according to these aspects.

In Italy, WNV and USUV are considered endemic in several Regions, whereas CHIKV, DENV and ZIKV are essentially related to infected travellers returning from endemic countries [57].

Two National Surveillance Plans regulate MDBs management in Italy: the first regarding WNV and USUV, which integrates human and veterinary surveillance and the second regarding MBDs specifically transmitted by *Aedes* mosquitoes, mainly CHIKV, DENV and ZIKV, based on the surveillance of both imported and autochthonous human cases.

In Piemonte and Liguria Regions (Northwestern Italy), a WNV multisectoral task force, including representatives of Public and Animal Health and Vector Control, was established in 2011 and then strengthened annually according to epidemiological findings. Since 2013, the working group cooperates with experts of four neighbouring Regions, sharing integrated WNV and USUV surveillance guidelines (human, entomologic and veterinary) throughout the whole Po river valley area. The main goal of this standardization has been the reduction of the transmission risk through blood transfusions, quickly implementing local preventive measures when the virus (in animals, vectors or humans) is detected in a specific Province. This allows to definitely decrease the risk of human transmission and consequently results in a significant reduction of health-care costs [58].

The active virological surveillance on mosquitoes and birds is considered an important tool to early detect virus circulation in a specific area, since it has been shown that the virus in mosquitoes and birds appears much earlier than the occurrence of clinical cases in dead-end hosts (humans and equines).

Passive surveillance of clinical cases in horses also can be considered a useful tool for the detection of WNV activity, but it will be less sensitive, and a positivity regarding the proof that the cycle of the virus is ended must be considered. Being dead-end hosts, the probability of infection is similar for horses and humans; then, an early detection tool especially in an endemic area cannot be considered. Furthermore, considering that in affected countries, vaccinations of horses are progressively adopted, it is estimated that surveillance in equidae will gradually become irrelevant [59].

During transmission season, following the detection of WNV viral trigger by the national Integrated Surveillance Plan, the NAT test was progressively introduced throughout affected Provinces of Piemonte Region. According to National legislation, it was stopped on

**Figure 5.** Flow chart for the management of WNV viral circulation trigger event in Piemonte and Liguria regions, since

In 2016, four (Alessandria, Novara, Torino and Vercelli) of the eight Provinces in the Piemonte

Since 2014, a total of 99,882 blood bags were screened by NAT (5172 in 2014; 38,623 in 2015;

MBDs have complicated transmission cycles, involving different reservoirs, competent vectors and environmental and climatic features that influence their epidemiology. Therefore,

In Italy, WNV and USUV are considered endemic in several Regions, whereas CHIKV, DENV and ZIKV are essentially related to infected travellers returning from endemic countries [57].

In 2017, blood screening was enforced in Novara, Vercelli, Cuneo and Asti Provinces.

In 2014 and 2015, only Alessandria province was involved in blood screening.

35,812 in 2016 and 20,275 in 2017). No infected blood bags were detected.

surveillance methods have to be planned according to these aspects.

Region were involved in NAT testing of blood donors.

72 Current Topics in Tropical Emerging Diseases and Travel Medicine

November 30.

2015.

**5. Conclusions**

The entomological surveillance can be a valuable additional tool also for the surveillance of MBDs caused by non-endemic viruses (CHIKV, DENV and ZIKV) in which humans are the reservoirs. Even if the syndromic surveillance on human cases is considered the most adequate approach to detect the introduction of these viruses, the presence of risk factors, as competent vectors and suitable climatic conditions, can significantly increase the potential risk for the local transmission in vectors, as happened in Emilia Romagna (2007) and Lazio (2017).

Indeed, the selection of the most suitable mosquito-trapping method and the identification of areas with major risks of introduction of exotic mosquitoes and pathogens are crucial, and surveillance should be planned in response to a recognized risk and carried out to support subsequent actions. In Piemonte and Liguria, the entomological surveillance in such sites (ports, international airports, international connection points and hospitals) revealed the presence of *A. albopictus*, competent vector of CHIKV, DENV and ZIKV, but no positive mosquito was found. In Liguria region, Genova city, this risk-based surveillance allowed to detect in 2015 the introduction of *A. koreicus*, an Asiatic mosquito which has become invasive in Europe in the recent years, proven to be an effective transmitter of Japanese encephalitis virus, *Dirofilaria immitis* and CHIKV [60]. While the origin of these specimens remains unknown, the presence of *A. koreicus* in such an important commercial and tourism hub is worrisome, as it might strongly accelerate the species' spread in Italy and in the rest of Europe, as already happened with *A. albopictus*.

Given the long-distance passive transfer of infected mosquito by trades, or movements of infected tourist and business travellers, particularly during the vectors season and the favourable transmission period, the potential risk of introduction and spread of emerging MBDs exists [61].

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In conclusion, the creation of a regional working group composed by public and animal health authorities, together with the authorities in charge of vector surveillance and control that regularly share information, is a crucial point towards the achievement of an integrated surveillance. The approach adopted in Northwestern Italy has been demonstrated a key point to promptly implement control measures and save resources, reducing the risk of MBDs human transmission.

The periodical evaluation of planned actions and their updating according to the evolving epidemiological scenario is of paramount importance for the prevention of the diseases and the maintenance of both human and animal health.

Further cost–benefit evaluations, including an accurate estimation of indirect costs, are needed to improve the knowledge of the economic context of MBDs and its mitigation, allowing to better target the Public Health response.
