In a guideline published on its website, the Directorate-General for Health (DGS) states that, given the detection of the invasive species Aedes albopictus in different parishes and municipalities in mainland Portugal, it is important to strengthen prevention and control mechanisms aimed at reducing the abundance or eliminating this species of mosquito.

According to the DGS, the most recent detections of the invasive mosquito in Portugal correspond to risk level 1 (yellow), on a scale of 0 to 3, defined according to the different scenarios regarding the presence of Aedes mosquitoes and detection of cases of disease, as defined in the National Plan for the Prevention and Control of Vector-Borne Diseases.

“Based on the entomological analyses of the REVIVE network, no presence of pathogenic agents has been verified in mosquitoes to date, nor have any autochthonous cases of diseases for which the vector is competent been reported”, it highlights.

Vector prevention and control activities involve the involvement of different sectors, namely local authorities, tourism, hotels, the environment, veterinary services, agriculture, industry, and commerce, among others, complementing the efforts of the health sector in the prevention and control of diseases transmitted by the Aedes albopictus and Aedes aegypti mosquitoes, such as dengue fever, chikungunya, zika, yellow fever, all of which are mandatory to be notified, and infection by the heartworm parasite.

Vector control of Aedes albopictus involves interventions in the mosquito's life cycle, which includes the aquatic phase (eggs, larvae, and pupae) and terrestrial phase (adult phase of the mosquito).

Physical environmental intervention is the primary method of vector control, requiring multisectoral interventions in the identification and elimination of breeding sites (places and containers that may serve as habitat for mosquito eggs and larvae) and the application of larvicides and adulticides may also be necessary, according to the level of risk assessed by public health services.

In areas where mosquitoes of the Aedes genus have been confirmed (Level 1), the location and mapping, preferably with georeferencing, of places where the existence of breeding sites may pose a risk for the multiplication of mosquitoes must be ensured.

Local authorities are responsible for mapping public and private structures that may be suitable places for the existence of breeding sites, spread throughout their area of ​​intervention.

People involved in vector prevention and control actions must wear clothing that covers the entire body and use repellents.

Whenever there is a change in the Risk Level, the Public Health services network is responsible for communicating this change and promoting appropriate measures with partner entities, based on this Guideline and other documents that may be issued by the DGS.

“Mosquito-borne diseases are an emerging global public health problem that could constitute an emergency in Portugal and across borders,” says the DGS, highlighting that “the increase in international mobility of people, goods and animals, combined with climate change, are factors that contribute to the expansion of invasive mosquitoes and the consequent occurrence of cases of disease.”

The presence of invasive Aedes mosquitoes in Portugal began with the detection of Aedes aegypti in Madeira in 2005. The species Aedes albopictus was introduced to the mainland in 2017 in the North (Penafiel), in 2018 in the Algarve (Loulé), and in 2022 in the Alentejo (Mértola).