State’s First 2025 Detection of West Nile Virus Found in DNREC’s Sentinel Chickens

No Human Cases of WNV Reported to Date in State; Equine Owners Urged to Vaccinate Their Animals

West Nile Virus (WNV) has been detected in Delaware for the first time for 2025 in sentinel chickens that help the Department of Natural Resources and Environmental Control (DNREC) monitor the state for mosquito-borne illnesses.

The DNREC Mosquito Control Section reported WNV detection at three different sentinel chicken flock locations in New Castle County that were sampled Aug. 11, with virus-positive confirmation of the chickens Aug. 13 from the Delaware Division of Public Health (DPH) laboratory. “The date of these detects is slightly later than our typical first detection date, historically the last week in July or first week in August – but is consistent with other WNV activity thus far this summer elsewhere in the mid-Atlantic and Northeast,” said DNREC Mosquito Control Section Administrator Tom Moran.

The Mosquito Control Section deploys small sentinel chicken flocks throughout the state during summer and early fall as surveillance strategy for certain mosquito-borne illnesses. Weekly blood samples taken from these chickens are tested for WNV and Eastern Equine Encephalitis (EEE) antibodies by the DPH lab. Sentinel chickens bitten by mosquitoes carrying WNV or EEE develop antibodies to these diseases but are otherwise unaffected.

A positive detect informs the Mosquito Control Section about which virus is circulating in the vicinity of the detection and is evidence that infected mosquitoes in the area have passed the virus to the sentinel chickens. DNREC then conducts further surveillance on which, and how many, mosquito species are present in the area of detection, as only certain species can transmit WNV and/or EEE to humans and horses. This surveillance will in turn determine any control measures to be taken by the Mosquito Control Section.

While there have been no reported WNV cases yet in humans for 2025 in the state, Delawareans are reminded that the possibility of contracting mosquito-transmitted diseases, including WNV and EEE, will continue until colder autumn temperatures arrive in mid-October. The DPH Disease Prevention and Control Section reports that Delaware had one probable case of neuroinvasive WNV in 2024 with no human WNV cases to date this year.

Most people infected with WNV do not develop symptoms, but about 20% can develop a mild illness, including fever, body and muscle aches, headache, nausea, vomiting, and rash symptoms. A small number of people can develop serious illness involving neurological problems, paralysis, and possibly death. EEE is not as prevalent as WNV but can present more severe symptoms in humans and horses.

According to the Delaware Department of Agriculture (DDA), there were six equine cases of WNV in 2024, and no EEE cases, with no cases of either disease to date recorded this year. The State Veterinarian’s Office within DDA urges horse owners to have all their equine animals vaccinated by veterinarians against both WNV and EEE. While vaccines for the mosquito-borne illnesses are highly effective in minimizing disease, horses and equines that have been vaccinated in the past will need an annual booster shot. Neither disease has a specific drug treatment, and infections in horses are fatal in 70% to 90% of EEE cases and 30% of WNV cases.

Horse owners can take several additional steps in the barn and around the farm to help protect their horses from mosquito bites. Horses should be kept inside at dawn and dusk, peak hours for mosquito activity. Topical insect repellents labeled for use on horses can also be applied. Wind generated by fans installed in horse stalls can also help deter mosquitoes. Water troughs or buckets should be emptied, cleaned, and refilled every 2-3 days to remove mosquito eggs or larvae.

Spraying to reduce mosquito populations in areas where WNV or EEE is detected may be initiated by the DNREC Mosquito Control Section as warranted, based on factors to include mosquito population levels and mosquito species present in affected areas. Residents can also contribute to lessening the chance of mosquito-borne disease transmission by eliminating mosquito habitat – by draining or removing outdoor items that collect water, such as discarded buckets or containers, uncovered trashcans, stagnant birdbaths, open rain barrels or cisterns, old tires, upright wheelbarrows, flowerpot liners, depressions in boat tarps, clogged rain gutters, corrugated downspout extenders, and unused swimming pools.

Delawareans also are reminded to take common-sense precautions to avoid mosquito bites, including wearing light-colored, long-sleeved shirts and pants when outdoors in mosquito-prone areas; applying insect repellent containing 10% to 30% diethyltoluamide (DEET) in accordance with label instructions; and avoiding mosquito-infested areas and times of peak mosquito activity around dusk, dawn and at night.

More information about mosquitoes and mosquito-borne diseases in Delaware is available from the following resources:

For mosquito biology/ecology and control, contact the DNREC Mosquito Control Section office in Dover at 302-739-9917, with more information at gov/mosquito
For requests for mosquito relief in upstate areas from Dover north, contact Mosquito Control’s Glasgow field office at 302-836-2555.
For requests for mosquito relief in downstate areas south of Dover, contact Mosquito Control’s Milford field office at 302-422-1512.
For animal health questions, contact the DDA Poultry and Animal Health Section at 302-698-4500.
To report suspected cases of human WNV, call the DPH Office of Infectious Disease Epidemiology toll-free at 888-295-5156.

For more information on West Nile virus or eastern equine encephalitis, visit the Centers for Disease Control website.

Media contacts:
DNREC: Michael Globetti, michael.globetti@delaware.gov
DDA: Stephanie Alexander, stephanie.alexander@delaware.gov
DPH: Sean Dooley, sean.dooley@delaware.gov

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Delaware Issues Tick Safety Tips as Peak Season Arrives

June marks the beginning of peak tick season in Delaware. The Delaware Division of Public Health (DPH) and the Department of Natural Resources and Environmental Control (DNREC) remind Delawareans to take proactive steps to protect themselves, their families, and pets this summer.

With warmer weather increasing outdoor activities, the risk of tick bites and tick-borne illnesses rises significantly. According to the latest Delaware Vector-Borne Disease Surveillance Report from DPH, 344 cases of Lyme disease, the most common tick-borne disease in Delaware, were reported in the state in 2024. Lyme disease is spread by blacklegged ticks (also known as deer ticks) in the Mid-Atlantic region, and symptoms can range from fever and fatigue to severe joint pain and neurological issues if left untreated. In some cases, a rash resembling a bullseye will appear near the site of the bite. Due to an increase in testing reports in the last year Alpha-gal Syndrome (AGS), another tick-borne illness, was made reportable in Delaware beginning December 2024. More than 100 cases of AGS were reported to DPH from June to December 2024.

The most common tick species in Delaware is the lone star tick. While this species does not carry the bacteria that cause Lyme disease, they can be infected with bacteria that cause yet another tick-borne disease, ehrlichiosis. Lone star ticks are also the main species associated with AGS. Another tick species commonly encountered in Delaware during the summer months is the American dog tick, which can carry bacteria that cause spotted fever rickettsiosis.

“Earlier this year, the DNREC Tick Program published a study in the Journal of Medical Entomology detailing each tick species that has been reported in Delaware,” said State Tick Biologist Dr. Ashley Kennedy of the DNREC Mosquito Control Section. “The last such report was published in 1945 and there have been a lot of changes since then – new tick introductions and new tick-borne pathogens discovered. Now we know that Delaware is home to at least 15 different tick species, possibly as many as 19 species. With all these changes, tick awareness year-round is more important than ever.”

To avoid tick bites:

Dress smart: When entering wooded or grassy areas, wear long pants, long sleeves, and tuck your pants into socks to minimize exposed skin. Light-colored clothing makes ticks easier to spot.
Avoid tick habitats: Avoid walking in tall grass, leaf litter, or in wooded or brushy areas. Walk in the center of trails
Tick repellent: Use insect repellents containing at least 20% DEET*, picaridin, or oil of lemon eucalyptus on your skin and clothing. This simple step creates an extra layer of protection.
Tick checks: After enjoying the outdoors, check yourself, your kids, and pets for ticks and immediately take a bath or shower. Ticks like to hide in warm, hidden areas, so inspect armpits, groins, and behind the knees. If you find a tick, remove it promptly using fine-tipped tweezers. Grasp the tick as close to your skin as possible and pull it out gently.
Yard care: Keep your yard tick-free by mowing the lawn regularly, removing leaf piles, and creating a buffer zone with gravel or wood chips between your lawn and wooded areas.

*When applying insect repellents, always follow the instructions on the product’s label, which provides application instructions. It is generally recommended to avoid applying repellents on a child’s face, hands, and areas that may come into contact with eyes or mouth.

“Defending yourself from ticks is not just about comfort, it’s about health,” said DPH Director Steven Blessing. “By following these simple, effective steps, you can protect yourself and your loved ones from tick bites and tick-borne illnesses, ensuring a safe and enjoyable summer.”

In case you find a tick on your person, child, or pet
In case you find a tick on yourself, your child, or your pet, you should remove it as soon as possible and seek medical treatment if you develop a fever, rash, or flu-like symptoms within 30 days of the bite. To dispose of a live tick found on the body, the Centers for Disease Control recommends flushing it down the toilet. Do not crush the tick with your fingers. After removing the tick, thoroughly clean the bite area and your hands with soap and water, rubbing alcohol, or hand sanitizer.

If you would like to bring the tick to your health care provider for identification, place it in a sealed container or put it in a capped container of rubbing alcohol. Knowing the type of tick involved in the bite can help determine which diseases you may be at risk for. Additional DNREC guidance is to save ticks in a zip-seal bag in case they are needed for future medical reference. State Tick Biologist Dr. Kennedy also suggests Delawareans take a photo of the tick after it has been removed and include it when submitting a Tick Interaction Report at de.gov/ticks to learn more about the risks associated with a tick encounter.

For tick-borne disease information, visit dhss.delaware.gov/dhss/dph/epi/tick.html. Report tick interactions at dnrec.delaware.gov/fish-wildlife/ticks/reporting/.

DNREC Mosquito Control Section Set to Spray Woodland Pool Habitats, Working to Cut Down Swarms at the Larval Stage

The DNREC Mosquito Control Section woodland pool spray campaign helps prevent emerging swarms of biting mosquitoes /DNREC photo

Annual Statewide Spring Spray Campaign Aims
to Reduce the Year’s First Mosquito Emergence

The Delaware Department of Natural Resources and Environmental Control will begin its annual spring spraying of woodland pools to control aquatic immature (larval) mosquitoes as early as Tuesday, March 18, with spray operations continuing through mid-April, weather permitting. The spring spray campaign by DNREC’s Mosquito Control Section will begin in southern Sussex County, then expand into Kent and New Castle counties over the next several weeks. Targeting these early-season woodland pool larval mosquitoes limits the emergence of biting adult mosquitoes later in the spring (typically early May) coming from these habitats.

Up to 10,000 acres of wet woodlands near select populated areas are typically treated. However, Delaware’s continuing drought conditions have resulted in much lower-than-average water present in the woodlands. All control treatments will be done via helicopter applying a liquid, bacteria-derived insecticide commonly known as Bti. As with all insecticides used by the Mosquito Control Section within the DNREC Division of Fish and Wildlife, Bti has been determined by the U.S. Environmental Protection Agency to pose no unreasonable risks to human health, wildlife or the environment when applied in accordance with product label instructions as required by federal law.

The spring woodland mosquito larvae spraying campaign marks the beginning of Delaware’s mosquito control season – which in most years continues until late October or early November. Starting in April, Mosquito Control Section activities will expand to larval and adult saltmarsh mosquitoes, other freshwater mosquitoes, and urban and suburban container-breeding mosquitoes to manage mosquito populations for improving the state’s quality of life and to protect public health.

Locations and times for scheduled mosquito spraying activity in the state can be obtained by calling toll-free 800-338-8181. Mosquito spraying announcements can also be received by email, text or voicemail by subscribing to Mosquito Control’s Spray Zone Notification System at de.gov/mosquitospray.

To request local mosquito control service for a residential area, call a Mosquito Control Section field office with coverage responsibilities as follows:

Glasgow Office, 302-836-2555, serving New Castle County and the northern half of Kent County, including Dover.
Milford Office, 302-422-1512, serving the southern half of Kent County south of Dover and all of Sussex County.

For more information about DNREC’s mosquito control efforts in Delaware, visit de.gov/mosquito.

About DNREC
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities and educates Delawareans about the environment. The DNREC Division of Fish and Wildlife conserves and manages Delaware’s fish and wildlife and their habitats, and provides fishing, hunting, wildlife viewing and boating access on more than 68,000 acres of public land. For more information, visit the website and connect with @DelawareDNREC on Facebook, Instagram, X (formerly known as Twitter) or LinkedIn.

Media Contact: Michael Globetti, michael.globetti@delaware.gov; Nikki Lavoie, nikki.lavoie@delaware.gov;

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Delaware’s First 2024 Evidence of West Nile Virus Detected in DNREC’s Sentinel Chickens

No Human Cases of WNV Reported to Date in State; Equine Owners Urged to Vaccinate Their Animals

West Nile Virus (WNV) has been detected in Delaware for the first time for 2024 in sentinel chickens that help the Department of Natural Resources and Environmental Control monitor the state for mosquito-borne illnesses, DNREC announced today. The initial WNV occurrence was found in eight sentinel chickens sampled July 22 by the DNREC Mosquito Control Section, and then tested and reported to be virus-positive by the Delaware Division of Public Health (DPH) Laboratory July 24.

The positive results came from five of the 20 sentinel chicken stations throughout the state maintained by the Mosquito Control Section – WNV-positive results came from three sentinel chicken stations in New Castle County, one in Kent County, and one in Sussex County. “Encountering eight virus-positive chickens in just one week is above the typical weekly rate for our program’s WNV findings, but perhaps reflects what seems to be an active WNV season thus far this year elsewhere in the Northeast,” said Mosquito Control Section Administrator Dr. William Meredith. While there have been no reported WNV cases yet in humans for 2024 in the state, he said, Delawareans are reminded that the possibility of contracting mosquito-transmitted diseases, including WNV and eastern equine encephalitis (EEE), will continue until colder autumn temperatures arrive in mid-October or later.

The DNREC Mosquito Control Section monitors these diseases by collecting blood samples each week starting in early July into the fall from the state’s network of outdoor-caged sentinel chickens that are humanely housed and handled. The blood samples are tested for WNV and EEE antibodies by the DPH Laboratory. Sentinel chickens bitten by mosquitoes carrying WNV or EEE develop antibodies to these diseases, but are otherwise unaffected. Mosquitoes can transmit both WNV and EEE to humans and horses.

Precautions for the public against mosquito-borne disease and illness
Most people infected with WNV do not develop symptoms, but about 20% can develop a mild illness, including fever, body and muscle aches, headache, nausea, vomiting, and rash symptoms. A small number of people can develop serious illness involving neurological problems, paralysis, and possibly death. The Public Health Lab reports that Delaware had four confirmed cases of neuroinvasive WNV in 2023, and none so far this year. EEE is not as prevalent as WNV, but can present more severe symptoms in humans and horses.

The public is reminded to take common-sense precautions to avoid mosquito bites, including wearing light-colored clothing of long-sleeved shirts and long pants when outdoors in mosquito-prone areas; applying insect repellent containing 10% to 30% diethyltoluamide (DEET) in accordance with label instructions; and avoiding mosquito-infested areas and times of peak mosquito activity around dusk, dawn and at night.

According to the Delaware Department of Agriculture (DDA), there were seven equine cases of WNV in 2023, and no EEE cases. The State Veterinarian within DDA urges horse owners to have horses and other equines vaccinated by veterinarians against WNV and EEE. While both vaccines are highly effective in minimizing disease, horses and equines that have been vaccinated in the past will need an annual booster shot. Neither disease has a specific drug treatment, and infections in horses are fatal in 70% to 90% of EEE cases and 30% of WNV cases.

Mosquito Control Section response to WNV and EEE
Spraying to reduce mosquito populations in areas where WNV or EEE is detected may be initiated by the DNREC Mosquito Control Section as warranted, based on factors to include mosquito population levels and mosquito species present in affected areas. Residents can also contribute to lessening the chance of mosquito-borne disease transmission through eliminating mosquito habitat by draining or removing outdoor items that collect water – such as discarded buckets or containers, uncovered trashcans, stagnant birdbaths, open rain barrels or cisterns, old tires, upright wheelbarrows, flowerpot liners, depressions in boat tarps, clogged rain gutters, corrugated downspout extenders, and unused swimming pools.

More information about mosquitoes and mosquito-borne diseases is available from the following resources:

For mosquito biology/ecology and control, contact the DNREC Mosquito Control section office in Dover at 302-739-9917.
- For requests for mosquito relief in upstate areas from Dover north, contact Mosquito Control’s Glasgow field office at 302-836-2555.
- For requests for mosquito relief in downstate areas south of Dover, contact Mosquito Control’s Milford field office at 302-422-1512.
For animal health questions, contact the DDA Poultry and Animal Health Section at 302-698-4500.
To report suspected cases of human WNV, call the DPH Office of Infectious Disease Epidemiology toll-free at 888-295-5156.
- For more information on West Nile virus or eastern equine encephalitis, visit cdc.gov/ncidod/dvbid/westnile/index.htm

About DNREC
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities and educates Delawareans about the environment. The DNREC Division of Fish and Wildlife, within which the Mosquito Control Section operates, conserves and manages Delaware’s fish and wildlife and their habitats, and provides fishing, hunting, wildlife viewing and boating access on more than 68,000 acres of public land owned or managed by the Division of Fish and Wildlife. For more information, visit the website and connect with @DelawareDNREC on Facebook, Instagram, X (formerly known as Twitter) or LinkedIn.

Media Contacts:
DNREC: Michael Globetti, michael.globetti@delaware.gov; Nikki Lavoie, nikki.lavoie@delaware.gov
DDA: Stacey Hofmann, stacey.hofmann@delaware.gov
DPH: Laura Matusheski, laura.matusheski@delaware.gov

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DNREC’s Mosquito Control Section Set to Spray Woodland Pools

The DNREC Mosquito Control section’s woodland pools spray campaign targets larval (immature) mosquitoes before they can emerge as biting insects that torment Delawareans and visitors alike later in spring and summer. /DNREC photo

Spring Campaign to Reduce Numbers of Year’s First Biting Mosquitoes

The Delaware Department of Natural Resources and Environmental Control will begin its annual spraying of spring woodland pools to control aquatic immature (larval) mosquitoes as early as Friday, March 15, weather permitting. The spring spray campaign by DNREC’s Mosquito Control section will begin in southern Sussex County, then expand into Kent and New Castle counties over the next several weeks. Controlling early-season woodland pool larval mosquitoes limits the emergence of biting adult mosquitoes later in the spring.

Up to 10,000 acres of wet woodlands near select populated areas will be treated with a helicopter applying the bacteria-derived insecticide Bti. As with all insecticides used by the Mosquito Control section within the DNREC Division of Fish and Wildlife, Bti has been determined by the U.S. Environmental Protection Agency to pose no unreasonable risks to human health, wildlife or the environment when applied in accordance with product label instructions as required by federal law.

The spring woodland mosquito larvae spraying campaign marks the beginning of Delaware’s mosquito control season – which in most years continues until late October or early November. Starting in April, Mosquito Control section activities will expand to larval and adult saltmarsh mosquitoes, other freshwater mosquitoes, and urban and suburban container-breeding mosquitoes to manage mosquito populations for improving the state’s quality of life and to protect public health.

To request local mosquito control service, call a Mosquito Control section field office:

Glasgow Office, 302-836-2555, serving New Castle County and the northern half of Kent County, including Dover.
Milford Office, 302-422-1512, serving the southern half of Kent County south of Dover and all of Sussex County.

For more information on DNREC’s mosquito control efforts in Delaware, visit de.gov/mosquito.

About DNREC
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities and educates Delawareans about the environment. The DNREC Division of Fish and Wildlife conserves and manages Delaware’s fish and wildlife and their habitats, and provides fishing, hunting, wildlife viewing and boating access on nearly 68,000 acres of public land owned or managed by the Division of Fish and Wildlife. For more information, visit the website and connect with @DelawareDNREC on Facebook, Instagram, X (formerly known as Twitter) or LinkedIn.

Media contacts: Michael Globetti, michael.globetti@delaware.gov; Nikki Lavoie, nikki.lavoie@delaware.gov