DNREC encourages awareness of mosquito-borne diseases as biting mosquito season extends into fall

Recent West Nile detection in Mosquito Control Section’s sentinel chickens shows need for continued vigilance

DOVER – The detection this week of West Nile virus (WNV) in sentinel chickens monitored for mosquito-borne diseases by DNREC’s Mosquito Control Section serves notice to Delawareans that mosquitoes remain very active, especially during unseasonably warm weather the state is now experiencing, and that precautions should continue to be taken against mosquito bites that could transmit WNV.

“Concerns about mosquito-borne diseases could continue for several more weeks, with the peak period for transmission lasting into mid-October,” said Dr. William Meredith, Mosquito Control Section Administrator within the Division of Fish & Wildlife. “The possibility of mosquito-borne disease transmissions won’t subside until colder autumn temperatures set in.”

Delaware’s Division of Public Health Laboratory reported seven WNV-positive chickens from five of the Mosquito Control Section’s 20 monitoring stations throughout the state – four in New Castle County and one in Sussex County. Since late July, a total of 19 sentinel chickens have tested WNV-positive this year: 13 from New Castle County, five from Kent County, and one positive from Sussex County. Past north-to-south trends indicate Delaware could see a possible increase in WNV-positive findings in downstate sentinel chickens in the coming weeks. Eastern equine encephalitis (EEE), another mosquito-borne disease affecting both people and horses, was also found at a sentinel chicken station in southwestern New Castle County in late July. No human cases of WNV or EEE have been reported this year in Delaware.

The recent WNV findings in sentinel chickens prompted the Mosquito Control Section to increase mosquito population surveillance in areas surrounding the stations where the chickens tested positive, to take control actions including aerial spraying and residential fogging. In addition, the section encourages residents to use repellent containing DEET, to wear long sleeves and long pants outdoors, and avoid mosquito-infested areas or being outside during times of peak mosquito activity.

To reduce mosquito-breeding habitat, the Mosquito Control Section advises residents to drain or remove items that collect water, such as discarded buckets or containers, uncovered trash cans, stagnant birdbaths, unprotected rain barrels or cisterns, old tires, upright wheelbarrows, flowerpot liners, depressions in tarps covering boats, clogged rain gutters, corrugated downspout extenders, and unused swimming pools.

Mosquito Control also encourages residents to report intolerable numbers of biting mosquitoes by calling the numbers below. Staff answers phones between 8 a.m. and 4 p.m. Monday through Friday. Callers after business hours or during weekends or holidays should leave their name, phone number, address and a brief message.

  • Glasgow Office, serving New Castle County and northern Kent County including the Dover area: 302-836-2555
  • Milford Office, serving Sussex and southern Kent Counties: 302-422-1512

For more information about:

  • Mosquito biology/ecology and control – contact the Mosquito Control Section’s Dover office at 302-739-9917.
  • Reporting WNV-suspect wild birds, or for requests for mosquito relief – for upstate areas from Dover north, contact Mosquito Control’s Glasgow field office at 302-836-2555; for downstate areas south of Dover, contact Mosquito Control’s Milford field office at 302-422-1512.
  • WNV or EEE in humans and related medical issues – contact the Delaware Division of Public Health at 888-295-5156.
  • WNV or EEE in horses and equine vaccines – contact the Department of Agriculture’s Poultry and Animal Health Section at 302-698-4500 or 800-282-8685 (Delaware only).
  • For more information on West Nile Virus or Eastern equine encephalitis – visit the CDC website.

Media Contact: Joanna Wilson, DNREC Public Affairs Office, 302-739-9902


Equine vaccinations essential during peak mosquito season

DOVER – This year’s wet spring weather provided optimal conditions for mosquito breeding, and thus a large population of mosquitoes. Late summer coincides with peak mosquito season, which brings an increased risk of mosquito-borne diseases such as West Nile Virus (WNV) and Eastern Equine Encephalitis (EEE) for humans, but also for horses.

“Owners are encouraged to talk to their veterinarian about having their horses vaccinated against these viruses,” said Delaware State Veterinarian Dr. Heather Hirst. “It may take several weeks for a horse’s immune system to mount a response to the disease after the vaccine is given so owners should have their horses vaccinated as soon as possible.”

In nature, WNV and EEE are maintained in a cycle between mosquitoes and wild birds. Mosquitoes that feed on the infected wild birds may then bite humans or horses, infecting them with the viruses. Neither WNV nor EEE can be transmitted between horses or from horses to people.

Last week, the Delaware Division of Public Health Laboratory reported this year’s first finding of WNV in blood samples taken from DNREC’s sentinel chickens that are monitored for mosquito-borne diseases. The samples are collected as part of a statewide surveillance program conducted by DNREC’s Mosquito Control Section.

Delaware has not had any cases of WNV or EEE in horses, humans, or wild birds thus far in 2017. Illnesses were last seen in one Delaware horse with WNV in 2015 and two horses with EEE in 2013. However, several states south of Delaware have reported cases this year, including Virginia and South Carolina in July.

Both WNV and EEE cause severe, and sometimes fatal, infections in horses. Signs of infection in horses include fever (although not always with WNV), anorexia, head pressing, depression or personality change, wobbling or staggering, weakness, blindness, convulsions, muscle spasms in the head and neck, or hind-limb weakness. If owners notice any of these signs in their horses, they should contact their veterinarian immediately.

Horse owners can take several steps in the barn and around the farm to help protect horses from WNV and EEE. Horses should be kept inside during dawn and dusk, which are peak hours for mosquito activity. Topical insect repellents labeled for use on horses may be applied. The wind generated by fans installed in horse stalls can also help deter mosquitoes. Old tires and containers should be disposed of and standing water eliminated. Water troughs or buckets should be emptied, cleaned, and refilled every 2-3 days if possible to remove any mosquito eggs or larvae.

For more information about WNV or EEE:
• Human health questions should be directed to the Delaware Division of Public Health, (888) 295-5156, or (302) 744-4990.
• Animal health questions should be directed to the Delaware Department of Agriculture at (800) 282-8685 (Delaware only) or (302) 698-4500. Ask for the Poultry and Animal Health Section.

• Questions about the state’s mosquito control program or mosquito biology should be directed to the Delaware Department of Natural Resources and Environmental Control’s Mosquito Control Section at (302) 739-9917.

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Media Contact: Stacey Hofmann, Community Relations Officer, 302-698-4542, stacey.hofmann@delaware.gov


Horse owners urged to make sure vaccinations are up to date

DOVER – With warm weather here and mosquito season under way, Delaware horse owners are being advised to make certain their equines’ vaccinations are current to protect against the threat of two potentially fatal diseases.

Unvaccinated horses suffer most severely from both West Nile Virus and Eastern Equine Encephalomyelitis, which are spread by infected mosquitoes and can be fatal, said Delaware State Veterinarian Dr. Heather Hirst, who heads the Delaware Department of Agriculture’s Poultry and Animal Health Section. Delaware had two confirmed equine cases of EEE and six confirmed equine cases of WNV in 2013.

“Vaccination is a simple and cost-effective way of preventing these diseases – far cheaper than treating them,” Hirst said. “Horse owners should take full precautions to keep their horses safe, and be on the alert for signs of infection.”

Both horses and humans can contract WNV and EEE if bitten by a mosquito carrying the virus, but it is important to note that the viruses cannot be transmitted between horses or from horses to people. The viruses normally exist in a cycle between mosquitoes and birds, but occasionally EEE can be transmitted from mosquitoes to mammals.

The Mosquito Control Section of the Delaware Department of Natural Resources and Environmental Control monitors for both diseases statewide. DNREC began spraying for mosquitoes in mid-March, treating wooded wetlands near populated areas in all three counties.

Hirst said horse owners should contact their veterinarian immediately if they suspect their horse may be showing signs of WNV or EEE, which both may include fever (though not always with WNV), anorexia, head pressing, depression or personality change, wobbling or staggering, weakness, blindness, convulsions, muscle spasms in the head and neck, or hind-limb weakness.

Owners should consult with their veterinarians about the WNV and EEE vaccinations, as well as vaccinations for herpesvirus (rhinopneumonitis), influenza, rabies and tetanus, among others, Hirst said.

Horse owners can also help during mosquito season by keeping horses inside during dawn and dusk, which are peak mosquito times, and using topical insect repellents labeled for use on horses, Hirst said.

Beginning in June, DNREC’s Mosquito Control Section will be asking the public’s help in monitoring for the presence of WNV by reporting sick or dead wild birds of certain species that may have contracted the virus. Sick or dead crows, blue jays, cardinals, robins, hawks or owls, and clusters of five or more sick or dead wild birds of any species, should be reported to Mosquito Control’s two offices: Glasgow, for northern Kent County and New Castle County, (302) 836-2555; or Milford, for southern Kent County and Sussex County, (302) 422-1512. Bird specimens should have been dead for less than 24 hours and not appear to have died or been killed by other obvious causes.

For more information about WNV or EEE:

• Human health questions should be directed to the Delaware Division of Public Health, (888) 295-5156, or (302) 744-1033.

• Animal health questions should be directed to the Delaware Department of Agriculture at (800) 282-8685 (Delaware only) or (302) 698-4500. Ask for the Poultry and Animal Health Section.

• Questions about the state’s mosquito control program or mosquito biology should be directed to the Delaware Department of Natural Resources and Environmental Control’s Mosquito Control Section at (302) 739-9917.

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Contact:
Dan Shortridge
Chief of Community Relations
Delaware Department of Agriculture
302-698-4520