First described by Skuse in India in 1894, Aedes (Stegomya) albopictus has been recognized as one of the most invasive mosquito species, successfully colonizing numerous tropical and temperate regions worldwide over the last five decades. Aedes albopictus was first reported in Europe in 1979 in Albania [1], followed by Italy in 1990 [2]. Italy is currently considered the most infested country in Europe, with Ae. albopictus established over large areas and thriving particularly in urban areas [3]. Since its introduction in Italy, Ae. albopictus has steadily spread throughout Europe, particularly to most Mediterranean countries. In 2023, Ae. albopictus was established in 13 EU/EEA countries and 337 regions, while in 2013, it was established only in 8 countries and 114 European regions [4]. In Portugal, Ae. albopictus was first detected in 2017 through two different introduction events in the Algarve, the southernmost region [5], and Penafiel, in the Oporto region [6]. In 2022, this vector was detected in the Alentejo region and in late September 2023, in Lisbon [7]. The National Vector Surveillance Network-REVIVE (REde de VIgilância de VEctores), which has been running since 2008 under the auspices of the Portuguese Ministry of Health [8]. REVIVE conducts nationwide surveillance of the most important hematophagous arthropods for public health (mosquitoes, ticks and sandflies). Regular surveillance of mosquito species and screening of field-collected mosquitoes for arboviruses is conducted. Airports, ports, storage areas and certain border regions with Spain are monitored throughout the year with the involvement of local and regional authorities.
In addition to the nuisance associated with the establishment of Aedes albopictus, its ability to act as a vector for a wide range of arboviruses remains a major concern. This mosquito species has emerged as a significant global public health threat due to its ability to transmit several pathogenic flaviviruses (such as dengue, Zika and yellow fever) and alphaviruses (especially chikungunya virus). The Algarve, Lisbon and Oporto are the main tourist regions in the country, where the impact of the presence of this vector species can be a major concern due to the higher risk of incoming viremic travelers. Since 2007, cases of autochthonous transmission of chikungunya associated with Ae. albopictus have been documented in Europe [9]. Dengue has been reported in Europe since 2010, with autochthonous cases transmitted by Ae. albopictus in Croatia, France, Italy and Spain [10].
To date, local transmission of Aedes-borne viruses has not yet been detected in mainland Portugal. However, the geographic expansion of Ae. albopictus across Portugal, combined with the increasing number of international travelers, often from regions with ongoing Aedes-borne outbreaks, highlights the importance of mosquito vector surveillance and control, and raises public health concerns about the risk of increased introduction and autochthonous transmission of Aedes-borne viral infections. Here, we report a preliminary genetic analysis of the Ae. albopictus mosquitoes detected in Lisbon in 2023, using the primary barcode sequence for members of the animal kingdom, a partial sequence of the cytochrome c oxidase I (COX) gene, widely used to study the genetic relationships of Ae. albopictus [11–14] and previously used in Portuguese mosquito populations [15].