The 2025 season was a landmark year for mosquito-borne illness in the Twin Cities, with data showing significant trends:
West Nile Virus (WNV): In 2025, the Twin Cities metro experienced a record-breaking year with 47 human cases, the highest ever recorded in the district. The primary vector, Culex tarsalis, thrives in the agricultural-to-suburban transition zones of Carver and Scott Counties.
Cattail Mosquitoes (Coquillettidia perturbans): Unlike other species, these emerge in one massive brood, typically around the July 4th holiday. They are exceptionally aggressive and, following the heavy rains of recent years, their populations in the metro reached their highest levels since 2020.
Invasive Species Alert: 2025 marked the first documented appearance of Aedes aegypti in the Twin Cities. While currently considered eradicated by the Metropolitan Mosquito Control District (MMCD), their presence underscores the warming trend making the metro more hospitable to southern vectors.
Minnesota consistently ranks among the top states for tick-borne diseases, with the NW/SW metro serving as a high-exposure zone due to its “Wooded-Urban” interface.
Lyme Disease: Transmitted by the Blacklegged Tick (Deer Tick), Lyme disease is highly endemic here. Hennepin County alone sees hundreds of confirmed cases annually, with thousands more estimated.
Anaplasmosis & Babesiosis: These “co-infections” are frequently transmitted by the same deer ticks that carry Lyme. In Carver and Scott Counties, where large wooded tracts meet residential lawns, the risk of multi-pathogen exposure from a single bite is a primary medical concern.
Powassan Virus: A rare but severe viral brain infection. While cases are few, the virus is present in the local deer tick population and can be transmitted much faster (within minutes of attachment) than Lyme disease.
