Mosquito Control

Rebecca Brandt, Manager

810 Livingston Avenue
Bay City, Michigan 48708-6380
Voice: (989) 894-4555
Fax: (989) 894-0526

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.

 

2019 West Nile Virus Bird Testing Results (By Zip Code)

 

Township or City

Zip Code

Number of Birds Tested

Birds Testing Positive

Auburn

48611


0

Bay City East/Hampton/
Portsmouth

48708

2

1

Bay City West/Monitor/
Bangor

48706

3

2

Bentley

48613

0

0

Essexville

48732

3

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


2019 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 Michigan State University's Department of Microbiology and Molecular Genetics 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 September 27, 2019, there have been 594 mosquito samples containing 18,837 female mosquitoes submitted for West Nile virus testing and an additional 343 samples containing 6,110 female mosquitoes submitted for Jamestown Canyon virus testing.  Testing results show that thirteen pools (or samples) of mosquitoes tested positive for West Nile virus.  The mosquitoes were collected in CDC traps or Light traps in the following townships (Bangor, Monitor, Hampton, Frankenlust, Portsmouth, and Bay City West).  In response, extensive control efforts have taken place in the areas 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 41 dead birds reported in Bay County.  Of those, nine birds have been suitable for testing - six tested negative, but three have tested positive for West Nile virus (WNV).  A press release regarding the first Bay County WNV positive sample was issued on Friday, July 12, 2019.  Both positive birds came from the City of Bay City and one was from Monitor Township.

A weekly summary of arbovirus (arthropod-borne virus) activity, including West Nile virus in Michigan can be found here.  To date, 9 Michigan residents (1 Barry County, 2 Berrien, 1 Calhoun, 1 Cass, 3 Kalamazoo, and 1 Van Buren) have been infected with Eastern Equine encephalitis (EEE) with 4 EEE fatalities.  Additionally, 2 Michigan residents (1 Genesee and 1 Washtenaw) were infected with a California group virus and West Nile virus (WNV) has sickened 8 Michigan residents (1 Bay, 1 City of Detroit, 1 Genesee, 1 Macomb, 1 Marquette, 1 Oakland, and 2 Wayne).  Additionally, routine testing of the blood supply identified WNV in 5 Michigan blood donors (1 city of Detroit, 1 Kent, 1 Oakland, 1 Sanilac, and 1 Ottawa).

A final snapshot of 2018 West Nile Virus activity in Michigan showed that there were 159 mosquito pools testing positive for West Nile virus infection, 197 West Nile Virus bird cases, 104 human cases of West Nile with 8 fatalities, 1 human case of Eastern Equine Encephalitis, and 12 asymptomatic (no WNV symptoms) human blood donors.

Steps people should take to protect themselves from mosquitoes include: 

  1. 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.
  2. Stay indoors when mosquitoes are most active (dusk and dawn).
  3. Wear long sleeves and pants when weather permits.
  4. Have secure, intact screens on windows and doors to keep mosquitoes out.

Updated 10/7/2019