Lisbon releases 30,000 sterile mosquitoes to combat Asian tiger mosquito population

To combat the spread of mosquito-borne diseases like dengue, Lisbon is releasing 30,000 sterile male Asian tiger mosquitoes on September 24, 2026. This experimental project aims to suppress wild populations through non-viable mating. Similar sterile release programs are underway in California, where climate change has extended the mosquito season to a year-round threat. Meanwhile, cities like Ahmedabad, India, are facing severe surges in pediatric dengue cases, highlighting the growing global public health urgency.

The Lisbon sterile mosquito project

• ▪The Lisbon experimental project targets the Asian tiger mosquito (Aedes albopictus) because the species can transmit public health threats including dengue, Zika, and yellow fever.
• ▪Afonso Moreira, leader of the Lisbon project, stated that releasing sterile males is only one control measure and emphasized that eliminating breeding sites remains essential.
• ▪The Lisbon sterile mosquito release project has previously released 60,000 mosquitoes in Portugal, making the September 24, 2026 release the final one of its kind for the project.
• ▪Lisbon is releasing 30,000 sterile male Asian tiger mosquitoes in the Alvalade parish on September 24, 2026, as part of an experimental public health project.

Dengue cases in California

• ▪A Centers for Disease Control and Prevention investigation identified 14 locally acquired dengue cases in Los Angeles County between August and November 2024, with six resulting in hospitalization.
• ▪Pasadena and Long Beach recorded the first locally acquired cases of dengue fever ever identified in California in 2023, followed by another cluster in Los Angeles County in 2024.

California sterile mosquito Program

• ▪The California mosquito release program uses male mosquitoes bred by the Kentucky-based company MosquitoMate that carry the naturally occurring bacterium Wolbachia to prevent wild female eggs from hatching.
• ▪In the San Gabriel Valley of California, mosquito control officials are releasing approximately 30,000 sterile male Aedes aegypti mosquitoes weekly, aiming for a total of nearly half a million.

Climate change expanding mosquito seasons

• ▪Stephen Dobson of MosquitoMate stated that the climate crisis is expanding mosquito habitats northward into regions that historically were too cold for their survival.
• ▪An analysis by Climate Central found that nearly 95% of analyzed United States cities experience an average of 18 more days per year with temperatures suitable for disease-spreading mosquitoes compared to the early 1970s.
• ▪Tristan Hallum of the San Gabriel Valley mosquito and vector control district stated that the local mosquito season has expanded from a May-to-September window to year-round treatment activity.

Mosquito-borne diseases in Ahmedabad

• ▪The Ahmedabad Municipal Corporation reported 70 cases of malaria, 22 cases of malaria falciparum, and seven cases of chikungunya across all age groups since September 1, 2026.
• ▪An eight-year-old child died from dengue in the eastern part of Ahmedabad during the first 20 days of September 2026 amid a surge in viral infections.
• ▪In Ahmedabad, India, children aged 0 to 14 years accounted for 183 of the 496 dengue cases (approximately 37%) reported to the Ahmedabad Municipal Corporation since September 1, 2026.

Debatable claims

• ▪The climate crisis is the primary driver of expanding mosquito-borne disease transmission
• ▪Eliminating breeding sites is more critical to controlling mosquito populations than releasing sterile insects
• ▪Governments should deploy sterile mosquito releases to combat climate-driven disease expansion