Tiger Mosquito Spreads to 11 Belgian Municipalities This Season

The tiger mosquito (Aedes albopictus) has been reported in 11 Belgian municipalities since the start of the mosquito season in early May, according to monitoring data released by Sciensano and the Institute of Tropical Medicine (ITG) on World Mosquito Day. The announcement marks the continued expansion of the invasive species, which can transmit viruses including dengue, chikungunya, and Zika.

Four municipalities reported the tiger mosquito for the first time this season: Rotselaar, Kraainem, and Kuurne in Flanders, and Aywaille in Wallonia. The remaining reports came from municipalities where the species had been detected in previous years, including Boom, Kessel-Lo, Merelbeke-Melle, Schelle, Wijnegem, and Zaventem in Flanders, and Ath in Wallonia, as VRT NWS reported.

A Species Gaining Ground

The latest figures underscore a broader trend: since citizen surveillance began in 2022, the tiger mosquito has now been observed in 40 Belgian municipalities. Field teams have confirmed the species is still present in Hoegaarden, Merelbeke-Melle, Wijnegem, and Zaventem, indicating it is increasingly establishing itself in these areas. Additional inspections in Boom and Ath confirmed the mosquito remains present there as well.

This year marks the fifth season that citizens have been able to report suspected tiger mosquito sightings through the MuggenSurveillance platform. The citizen science approach has proven essential for tracking the species, which often breeds in private gardens and urban areas where researchers cannot easily reach.

“Every reported observation provides valuable information that helps us better understand where this species is being introduced and where further surveillance may be needed,” said Javiera Rebolledo Romero, epidemiologist at Sciensano. “At the same time, the detection of tiger mosquitoes does not necessarily mean there is an immediate risk of virus transmission.”

Overwintering Populations Raise Concerns

The tiger mosquito’s ability to survive Belgian winters is a key concern for health authorities. As of 2025, the species was confirmed to overwinter in eight municipalities, including Ath, Kessel-Lo, Puurs-Sint-Amands, Wilrijk, Lebbeke, Sint-Joost-ten-Node, Wijnegem, and Hoegaarden, according to VRT NWS. In May 2026, the tiger mosquito was confirmed established in Saint-Josse-ten-Noode in Brussels after surviving the winter, as RTBF reported.

“Once tiger mosquitoes have established themselves in an area, they are much more difficult to control,” said Wim Van Bortel, entomologist at the ITG. “Early detection and targeted control measures therefore remain essential.”

The species, originally from Southeast Asia, was once only a summer visitor to Belgium, arriving as a hitchhiker in vehicles or airplanes from southern Europe. However, increased travel and milder winters driven by climate change have enabled the mosquito to establish permanent populations further north.

Public Health Implications

While the immediate risk of local virus transmission in Belgium remains low—tropical diseases are not endemic in the country—the establishment of permanent tiger mosquito populations increases the long-term risk of dengue, chikungunya, and Zika outbreaks. If a person infected abroad is bitten by a local tiger mosquito, and that mosquito then bites another person, local transmission could occur.

This scenario has not yet happened in Belgium, but neighboring France and Italy are already experiencing increasing outbreaks of tropical diseases transmitted by tiger mosquitoes, as BRUZZ noted. In 2025, citizens reported tiger mosquitoes in 10 municipalities, with five being first-time reports, according to the ITG.

Prevention and Monitoring

Belgian authorities are responding through a combination of citizen science, active field surveillance, and public awareness campaigns. The MEMO+ project, a collaboration between Sciensano and the ITG funded through the National Action Plan Environment and Health, monitors eight highway parking areas where tiger mosquitoes can enter the country via vehicles.

Citizens are urged to remove or cover objects that can hold standing water—such as buckets and flower pots—where the mosquito lays its eggs. Emptying standing water and refreshing animal drinking bowls at least once a week, scrubbing the walls of artificial containers to remove eggs, and properly covering rain barrels are among the recommended measures. Travelers returning from southern Europe are advised to check their vehicles and luggage for hitchhiking mosquitoes.

As the monitoring season continues through October, authorities stress that public participation remains crucial. “Four years of monitoring show that the tiger mosquito is not only being introduced into Belgium but is also beginning to establish itself here,” Van Bortel said. The question now is how quickly the species will continue its expansion—and whether Belgium can keep pace with the challenges it brings.