Mosquito-Transmitted Disease in Bay County
Bay County Mosquito Control's primary goal is to protect public health from diseases transmitted by mosquitoes, which is why mosquito control began in the Saginaw Valley in the late 1970s. We continue to monitor for a variety of mosquito-borne diseases including West Nile Virus, St. Louis encephalitis, Eastern Equine encephalitis, Jamestown Canyon Virus, and other California group viruses.
West Nile Virus
West Nile encephalitis is a mosquito-transmitted disease first documented in North America during the summer of 1999. The strain of West Nile virus (WNV) circulating in the U.S. causes significant mortality in exotic and native bird species, especially in the American crow. WNV was first isolated in 1937 in the West Nile province of Uganda, Africa. Epidemics have occurred in Africa, Europe, the Middle East, and most recently in Israel during 2000 and in the U.S. in 2002, 2003, and 2004, and 2012. West Nile infections continued during the 2005-2017 seasons, and will most likely continue during 2019 (see table below for Bay County data).
The chance of anyone becoming infected with WNV is very low (less than 1% of mosquitoes are infected). If infected, you would most likely show no symptoms or mild symptoms. Mild symptoms include fever, headache, body aches, mild rash, and swollen lymph glands. Severe symptoms may include severe fever, stiff neck, confusion, muscle weakness, and coma. If you develop severe symptoms, contact your health care provider.
Human vaccines are still being developed and may be available in the future. There is currently a single dose vaccine available for horses. For Bay County's West Nile Virus surveillance statistics, as well as surveillance data for other mosquito-transmitted diseases, click here or for WNV statistics for Michigan, click here.
Eastern Equine Encephalitis
Eastern Equine Encephalitis (EEE) is carried by certain types of mosquitoes in Michigan, the primary vector being Culiseta melanura. Although this species of mosquito isn't currently evident in Bay County, other species of mosquitoes here could possibly become infected with EEE. It is a potentially serious disease that can affect anyone, but children and people over age 60 are more likely to get the more severe form of EEE illness. EEE is found primarily in areas with swamps and bogs. The risk of bites from infected mosquitoes is highest for people who work or play outdoors in these areas. Wearing insect repellent when outdoors (especially at dawn and dusk) is important to prevent EEE.
EEE is also a serious disease in horses. Protecting horses with approved EEE vaccines is an important prevention measure.
Click the link to see more coverage on EEE in Michigan:https://www.michigan.gov/emergingdiseases/0,4579,7-186-76711_77442---,00.html
Jamestown Canyon Virus
Jamestown Canyon Virus (JCV) is spread to people by infected mosquitoes, and has been found in infected mosquitoes in Bay County. The virus is found throughout much of the United States, but most cases are reported from the upper Midwest. Most cases occur from late spring through mid-fall. Fever, headache, and fatigue are common symptoms with Jamestown Canyon virus disease. Jamestown Canyon virus can rarely cause severe disease, including infection of the brain (encephalitis) or the lining around the brain (meningitis). There are no vaccines to prevent or medicines to treat Jamestown Canyon virus infection. Reduce your risk of infection by avoiding mosquito bites.
St. Louis Encephalitis
Saint Louis Encephalitis (SLE) is a viral disease spread to people by the bite of an infected Culex species mosquito. Most people infected with SLE virus have no apparent illness. Initial symptoms of those who become ill include fever, headache, nausea, vomiting, and tiredness. Severe neuroinvasive disease (often involving encephalitis, an inflammation of the brain) occurs more commonly in older adults. In rare cases, long-term disability or death can result. There are no vaccines to prevent nor medications to treat SLE. Care is based on symptoms. SLE-positive mosquitoes have been detected in counties neighboring Bay County.
California Encephalitis Virus/La Crosse Encephalitis
California serogroup viruses (CAL) found in the United States include California encephalitis virus, Jamestown Canyon virus, Snowshoe hare virus, and Trivitattus virus. Almost all recognized California serogroup virus (CAL) disease cases are caused by La Crosse encephalitis virus.
La Crosse encephalitis virus (LACV) is maintained in a cycle between Aedes triseriatus (the eastern treehole mosquito) and vertebrate hosts (especially small mammals such as chipmunks and squirrels) in deciduous forest habitats (i.e., forests with trees that lose their leaves each year). Humans can become infected with LACV from the bite of an infected mosquito, however humans rarely, if ever, develop high enough concentrations of LACV in their bloodstreams to infect feeding mosquitoes. Humans are therefore considered “dead-end” or incidental hosts for LACV.
Monitoring for Zika is done by using traps to collect any of the vector species, namely Aedes aegypti or Aedes albopictus, neither of which has been found in this area. Zika virus is spread by mosquitoes that breed in containers. Although these mosquito species are not currently in our area, it is important to remember, to dump water from containers such as bird baths, tarps, and buckets at least once each week and scrub the containers to get rid of any mosquito eggs left behind.
The Centers for Disease Control and Prevention, World Health Organization and the Michigan Department of Health and Human Services are all excellent resources for keeping up with the ever-changing face of Zika.
The following links offer additional information on Zika: