West Nile Virus Testing Results
Background
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 will most likely continue throughout the future in Bay County.
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.
Dead Bird Reporting
Bay County Mosquito Control will be logging reports of dead birds (i.e., bird's location, including address, crossroads, and township; we'll also ask for the name of the person reporting the bird and a phone number). While we are interested in collecting information about dead birds as part of our efforts to understand West Nile Virus (WNV), we will ONLY be collecting dead crows, blue jays, and ravens in good condition (no maggots or odor). Specimens that appear to have been dead for less than 24 hours and are in good condition will be tested for WNV. According to the Michigan Department of Community Health, other bird species (robins were recently implicated) also play a role in the persistence of WNV, but these species eventually clear the infection, and do not succumb to disease as often. Birds will be collected from approximately May 15 through October 1.
Homeowners should report dead birds to Bay County Mosquito Control at (989) 894-4555. Species other than crows, blue jays, and ravens can be disposed of in the regular trash or buried. When handling birds, avoid bare-handed contact. Instead, turn a plastic shopping bag inside-out and scoop up the bird with the bag. Place the bagged carcass in an outdoor garbage can for disposal. We will not pick up live birds. Bay County Mosquito Control will test crows, blue jays, and ravens in our lab using a VectorTest kit. The results will be forwarded to the Michigan Department of Health and Human Services and posted on the Emerging Diseases website www.michigan.gov/emergingdiseases.
For help in identifying birds, Cornell University has an on-line bird guide.
We will not be involved in submitting any mammals. However, should you find a sick or dead mammal displaying symptoms of West Nile virus (clinical signs prior to death may include uncoordinated flying or walking, weakness, lethargy, tremors, and abnormal head posture), please log onto the Emerging Diseases website (www.michigan.gov/emergingdiseases) and fill in the report. DNR staff will monitor the website year round. Evidence of die-offs or unusual illness events in wildlife may prompt further investigation by DNR biologists. Questions about sick or dead wildlife can be directed to your local DNR office. In the Saginaw Bay area, the closest field office would be the Bay City Customer Service Center at 3580 State Park Drive, Bay City, MI 48706 (989) 684-9141.
2022 West Nile Virus Bird Testing Results (By Zip Code)
| Township or City | Zip Code | Number of Birds Tested | Birds Testing Positive |
| Auburn | 48611 | 0 | 0 |
| Bay City East/Hampton/
Portsmouth | 48708 | 0 | 0 |
| Bay City West/Monitor/
Bangor | 48706 | 1 | 0 |
| Bentley | 48613 | 0 | 0 |
| Essexville | 48732 | 0 | 0 |
| Kawkawlin | 48631 | 0 | 0 |
| Linwood | 48634 | 0 | 0 |
| Midland (Auburn) | 48642 | 0 | 0 |
| Munger | 48747 | 0 | 0 |
| Pinconning | 48650 | 0 | 0 |
| Rhodes | 48652 | 0 | 0 |
2022 Stats for West Nile Virus and Other Mosquito-Transmitted Diseases
Adult female mosquitoes are collected in a variety of traps: New Jersey Light Traps, CDC Traps, and Gravid Traps. The WNV mosquito season will run from May 15 through October 1.
Some mosquitoes may be tested in-house by Bay County Mosquito Control staff, but most will be submitted to the Michigan Department of Health and Human Services (MDHHS) for analysis. This year Culex species will be tested for West Nile virus and St. Louis Encephalitis; Coquillettidia perturbans species will be tested for Eastern Equine encephalitis; lastly, Anopheles species and spring Aedes mosquito species will be tested for Jamestown Canyon virus.
As of June 24, 2022, there have been 179 mosquito samples containing 4,816 female mosquitoes submitted to be tested for West Nile virus/St. Louis encephalitis/Eastern Equine encephalitis/Jamestown Canyon Virus testing. All samples have been tested and Jamestown Canyon virus was detected in one sample - one pool of 18 Anopheles punctipennis female mosquitoes collected from Kawkawlin Township on June 13. In response to any positive pools collected throughout the summer, extensive control efforts will take place in the areas where positive mosquitoes were collected to reduce adult and larval mosquito populations.
Besides mosquitoes, we also test birds (crows and blue jays), with results shown in the table above. To date, there have been 7 dead birds reported in Bay County. Of those, one was suitable for testing from zip code 48706 and tested negative for WNV.
A weekly summary of arbovirus (arthropod-borne virus) activity, including West Nile virus in Michigan can be found here. No data is available yet for 2022
A final snapshot of 2021 West Nile Virus activity in Michigan showed that WNV sickened 46 Michigan residents; 6 more were infected with Jamestown Canyon virus. Eastern Equine encephalitis virus (EEE) infected 1 Michigan resident from Oakland County. Nine horses (1 Barry, 1 Gladwin, 1 Genesee, 1 Ingham, 2 Livingston, 1 Otsego, 2 Shiawassee), one deer (Livingston), five birds (1 Dickinson, 3 Iron, 1 Marquette) and one mosquito pool (Barry) tested positive for (EEE). Seven horses (1 Genesee, 1 Kent, 1 Lenawee, 1 Midland, 1 Montcalm, 1 Sanilac, 1 Van Buren), one moose from Marquette County, one deer from Cass County, one deer from Kent County, one bovid from Calhoun County, one squirrel from Macomb County, and forty-one birds tested positive for WNV.
Steps people should take to protect themselves from mosquitoes include:
- When outdoors, use insect repellent containing DEET, picaridin, or oil of lemon eucalyptus on exposed skin and/or clothing. Always follow the directions on the product label.
- Stay indoors when mosquitoes are most active (dusk and dawn).
- Wear long sleeves and pants when weather permits.
- Have secure, intact screens on windows and doors to keep mosquitoes out.
Updated 6/24/2022