Iceland's Mosquito-Free Status Ends as New Species Discovered

For generations, Iceland has been celebrated as one of the world's few mosquito-free havens, a distinction attributed to its harsh, unpredictable climate. However, this unique status has now ended with the confirmed discovery of three mosquitoes in the country's southwest. This development, occurring amid record-breaking heat, highlights how rapidly changing global climate patterns are redrawing ecological boundaries and enabling species migration into new territories.

The mosquitoes, identified as Culiseta annulata, a species known for its cold resistance, were found in Kjós, a glacial valley north of Reykjavík, between Thursday, October 16, and Saturday, October 18, 2025. Insect enthusiast Björn Hjaltason made the initial discovery while using wine-soaked ropes to observe moths. He subsequently sent the specimens—two females and one male—to the Icelandic Institute of Natural History, where entomologist Matthías Alfreðsson confirmed their identity.

Historical Context of Mosquito-Free Zones

Historically, Iceland and Antarctica were considered the only two places on Earth entirely free of mosquitoes. Scientists attribute Iceland's long-standing mosquito-free status to its unique climate, characterised by frequent freeze-thaw cycles that prevented mosquito larvae from maturing. The island's isolation, separated by hundreds of miles of ocean, also acted as a natural barrier against mosquito migration.

Climate Change and Vector Expansion: A Global Concern

While the exact pathway of the mosquitoes' arrival in Iceland remains unconfirmed, theories suggest they may have arrived via ships or cargo containers. Experts are cautious about directly linking this singular event to climate change, but acknowledge that warming temperatures are likely to enhance the potential for other mosquito species to establish themselves in Iceland if they arrive. Iceland is reportedly warming at four times the rate of the rest of the Northern Hemisphere, leading to collapsing glaciers and the presence of warmer-water fish species. This broader trend of rising global temperatures is enabling insects and parasites to expand into regions where they previously could not survive.

Implications for Kenya's Public Health Landscape

In Kenya, the expansion of vector-borne diseases due to climate change is a pressing public health concern. Malaria, dengue fever, and Rift Valley fever are already prevalent, and changing weather patterns exacerbate their spread. Rising temperatures and erratic rainfall create more breeding grounds for mosquitoes and accelerate their life cycles, leading to increased disease transmission.

Kenya faces an estimated 3.3 million malaria cases annually, with 75% of the population at risk. The disease is endemic in fourteen counties, primarily in the Lake Victoria and coastal regions. Climate change has already led to malaria outbreaks in previously unaffected highland areas of Kenya. The emergence of invasive mosquito species, such as Anopheles stephensi, which thrives in urban environments and is resistant to some insecticides, further complicates malaria control efforts in East Africa.

Government and Stakeholder Response in Kenya

The Kenyan government, through initiatives like the Kenya National Adaptation Plan (NAP) 2015-2030 and the Kenya Climate Change and Health Strategy (2024-2028), is working to address the health impacts of climate change. These strategies emphasise cross-sectoral collaboration, improved surveillance, and climate-resilient health infrastructure. However, experts stress the need for increased funding, public health education, and robust early warning systems to effectively mitigate the growing threat of vector-borne diseases.

Evidence/Data Box

• Mosquitoes Discovered in Iceland: Three Culiseta annulata specimens (two females, one male) found between October 16-18, 2025.
• Iceland's Warming Rate: Four times faster than the rest of the Northern Hemisphere.
• Kenyans at Malaria Risk: 75% of the population (approximately 3.3 million cases in 2023).
• Key Malaria Vectors in Kenya: Anopheles gambiae complex and Anopheles funestus, primarily transmitting Plasmodium falciparum.

Unanswered Questions and Future Outlook

The long-term establishment of Culiseta annulata in Iceland remains to be seen, with scientists monitoring whether the species can survive the country's winter. The exact mechanism of their arrival also requires further investigation. For Kenya, the ongoing challenge lies in strengthening public health systems to cope with the expanding geographical range and increased intensity of vector-borne diseases. Continued investment in research, surveillance, and integrated vector management programmes will be crucial in safeguarding public health against the evolving threats posed by climate change.

What to watch next: The survival rate of the newly discovered mosquito population in Iceland through the upcoming winter and further research into the potential for other mosquito species to establish themselves in the country. In Kenya, monitoring the spread of invasive species like Anopheles stephensi and the effectiveness of climate adaptation strategies in mitigating vector-borne disease outbreaks will be critical.