The tiger mosquito is already present in 120 municipalities in the Basque Country, and the Department of Health will maintain active surveillance until November

The tiger mosquito is expanding in the Basque Country, aided by warm autumn temperatures, an insect that is already present in 120 municipalities in more than 90 municipalities counted in November 2025. To cope with the spread, the Basque Government's Department of Health keeps the monitoring and control programme active until mid-November.

This invasive species is a public health concern because it is capable of transmitting diseases such as dengue, zika and chikungunya . Although the risk of infection in the Basque Country is very low, 37 imported cases of these diseases have been recorded this year, that is, people who have contracted the disease outside the Basque Country.

Of the 37 cases detected so far this year, 23 have been in Bizkaia, eight in Gipuzkoa and six in Álava. The tiger mosquito was first detected in the Basque Country in 2014 and since then no cases of infection have been recorded there.

The tiger mosquito is already present in 120 municipalities in the Basque Country.

The monitoring programme developed by the Department of Health in collaboration with Neiker and the municipalities began in July and will continue until mid-November. In this year's campaign, more than 3,300 egg tablets or obitranps have been analysed in 47 municipalities: 13 in Álava, 21 in Bizkaia and 13 in Gipuzkoa.

The results show that the tiger mosquito is present in 120 municipalities, of which 81 are already settled, 45 in Bizkaia, 34 in Gipuzkoa and two in Álava, and 39 other municipalities have detected the insect, although it cannot yet be said to be based there.

The spread has been remarkable compared to 2025. In November last year, the tiger mosquito was present in 90 municipalities, settled in 72, and was detected to have entered 19 others.

In addition, the Department of Health has five sentinel surveillance points for early detection of the insect's presence and activity throughout the year: Bilbao, Trapagaran, Gernika-Lumo, Donostia and Irun.

The tiger mosquito is black and has a white line on its head and chest that tends to sting during the day, and it is common for it to sting several times in a row, and its bites can be painful.

In the event of a sting, the Department of Health recommends washing the area with soap and water and applying cold to relieve inflammation and itching. It is important not to scratch to avoid infection. If the reaction is very strong, it causes discomfort or respiratory disturbances, health personnel must be consulted.

In order to avoid bites, it is recommended to wear long-sleeved clothing, long trousers and closed shoes, as well as authorised repellents. In the case of minors and pregnant women, physical measures such as the use of mosquito nets should be prioritised.

On the other hand, those who return from areas where these viruses are transmitted should take special care to avoid mosquito bites within 15 days of the end of their journey, in case of fever, pain or discomfort they should go to the health centre as soon as possible.

Tiger mosquito control is part of the "One Health" approach, which recognizes the link between human, animal and environmental health.