2023 Highlights
- Minnesota continues to be in the top 10 states nationwide for incidence of tickborne diseases like Lyme disease, anaplasmosis, and babesiosis.
- It was a moderate year for mosquito-borne diseases, with 63 cases of West Nile virus, two cases of Jamestown Canyon virus, and one case of La Crosse encephalitis reported.
- The most common travel-associated vectorborne disease in Minnesota is malaria, and MDH reported a record 90 cases for 2023.
Although Minnesota reports cases of both tickborne and mosquito-borne diseases every year, tickborne diseases are much more common. Lyme disease continues to be the most frequently reported, followed by anaplasmosis and babesiosis. In 2022, a new case definition for Lyme disease was implemented nationally, allowing Minnesota to count cases based on lab reports alone. As a result of this change case counts increased compared to previous years, but the number of reports received each year has stayed consistent. Cases of anaplasmosis dropped a little in 2023 compared to 2022, but numbers are still consistent with recent trends since the mid-2010s. Babesiosis is less commonly reported than either Lyme disease or anaplasmosis, but in 2023, Minnesota reported a record of 73 cases, surpassing the previous high of 72 cases in 2011.
Arboviruses can be transmitted by mosquitoes or ticks, and in Minnesota, the most commonly reported arboviral infections are West Nile virus (transmitted by mosquitoes) and Powassan virus (transmitted by ticks). 2023 was a busy year for arboviruses, with 63 cases of West Nile virus reported, along with 48 people that tested positive after donating blood. These reports in blood donors help us track disease activity across the state, as many people that are infected with West Nile Virus never develop symptoms. Our previous record for positive blood donor reports in a single season was set in 2012, when 33 positive donors were reported. Additionally, there were 8 cases of Powassan virus reported, two cases of Jamestown Canyon virus, and one case of La Crosse encephalitis. Both Jamestown Canyon virus and La Crosse encephalitis are transmitted by mosquitoes and are much less common than West Nile. Four cases of West Nile virus and two cases of Powassan died as a result of their illness.
Malaria is the most common travel-associated vectorborne disease reported in Minnesota, and there were 90 cases in 2023. People reported exposures in 27 countries around the world, with the majority of cases (87%) reporting exposure in Africa. Most cases of malaria reported in Minnestoa are due to Plasmodium falciparum, and while that was still the case in 2023, more cases due to other species, like Plasmodium vivax, were reported than in recent years.