Mosquitoes can be intensely annoying. In some cases mosquitoes can also spread disease.
While reducing annoyance and improving quality of life is important, the primary job of the Metropolitan Mosquito Control District is to reduce risk of mosquito-borne disease through mosquito surveillance and control and public education about ways to reduce risk.
Find further information below on both mosquito-borne and tick-borne diseases, as well as resources for other diseases not of concern in Minnesota.
Mosquito-borne Diseases in Minnesota
West Nile Virus
A pathogen transmitted primarily by Culex species mosquitoes. West Nile Virus is the most common mosquito-borne pathogen in Minnesota, with 43 cases reported in 2023.
La Crosse Encephalitis
A pathogen transmitted primarily by the species Aedes triseriatus, also known as the Eastern Treehole mosquito. In 2023, the MN Department of Health had one reported case of La Crosse Encephalitis.
Eastern Equine Encephalitis
A pathogen transmitted primarily through the species Culiseta melanura. No human cases have ever been recorded by the MN Department of Health.
Jamestown Canyon Virus
A pathogen that can transmit through several species of human-biting mosquitoes. In 2023, two cases of JCV were reported in Minnesota.
Dog Heartworm
Adult mosquitoes can carry heartworm larvae. When one of these mosquitoes bites an animal, the larvae are deposited on the surface of the animal's skin and enter the body through the bite.
Tick-borne Diseases in Minnesota
Lyme Disease
A pathogen transmitted by Ixodes scapularis, more commonly known as deer ticks. Lyme disease is the most common insect-borne disease in Minnesota.
Anaplasmosis
A pathogen also transmitted by deer ticks, and the second most common tick-borne diseases in Minnesota.
Babesiosis
A parasitic blood disease which uses deer ticks as hosts. As of 2024, babesiosis is rare but the number of cases per year is increasing. Unlike Lyme Disease, it does not usually cause a rash.
Alpha Gal Syndrome
Alpha-gal syndrome is a food allergy caused by the bite of a Lone Star tick, a species recently introduced to Minnesota. When a Lone Star tick bites, a sugar molecule — alpha-gal — can be passed into the body, potentially causing a mild to severe allergy to red meat and other animal products.
Resources on other mosquito- and tick-borne diseases in the United States
Mosquito-borne diseases
- Chikungunya: spread by species Aedes albopictus and Aedes aegypti. There have been no local cases of Chikungunya in the US since 2019.
- Dengue: spread primarily by Aedes aegypti, with the majority of continental US cases originating from abroad.
- St. Louis Encephalitis: spread primarily by mosquitoes of the Culex genera, with no cases reported in MN since the 1970s.
- Western Equine Encephalitis: spread by Culex and Culiseta mosquitoes, with no human cases reported in the US since the 1990s.
- Zika: spread by species Aedes albopictus and Aedes aegypti, with no local cases in the US since 2018.
Tick-borne diseases
- Powassan: spread by Ixodes scapularis, also known as a deer tick. Powassan virus is a rare pathogen in Minnesota, with only 8 cases in 2022.
- Rocky Mountain Spotted Fever: spread by Dermacentor variabilis, also known as the American dog tick or wood tick. A rare pathogen with only a few isolated cases found in Minnesota.