The Michigan Department of Health and Human Services (MDHHS) and Ottawa County Health Department confirmed the state’s first human infection with a mosquito-borne virus for 2020 as a county resident tested positive for Jamestown Canyon virus.

Jamestown Canyon virus is spread to people through bites from infected mosquitoes.  Most cases occur from late spring through mid-fall. Illness can develop from a few days to two weeks following a mosquito bite. While most people do not become ill, initial symptoms can include fever, headache and fatigue. In rare cases, it can cause severe disease, including infection of the brain – encephalitis – or the lining around the brain and spinal cord – meningitis.

MDHHS is releasing no further information about the resident who tested positive for confidentiality reasons.

Michigan reported its first two cases of Jamestown Canyon virus in 2018 in patients from Oakland and Menominee counties. In 2019, one case was detected in a person from Cass County.

While the virus is found throughout much of the U.S., reports have been increasing in the upper Midwest. This likely reflects increased awareness and testing, but may also be due to an increase in the presence of the virus in the environment.