Public asked to report sick or dead wild birds to DNREC’s Mosquito Control Section for 2018 West Nile virus monitoring

The logo for the Department of Natural Resources and Environmental ControlDOVER – DNREC’s Mosquito Control Section within the Division of Fish & Wildlife is seeking the public’s help in monitoring West Nile virus in Delaware by reporting sick or dead wild birds that may have contracted the virus. West Nile virus (WNV) is a mosquito-borne disease of considerable concern to human health and to owners of unvaccinated horses.

The Mosquito Control Section requests that the public report sick or dead birds of the following species only: crows, blue jays, cardinals, robins, hawks or owls, plus clusters of five or more sick or dead wild birds of any species. Bird specimens should have been dead for less than 24 hours and not appear to have died from other obvious causes. Mosquito Control also notes that uncollected dead wild bird specimens are very unlikely to transmit WNV to humans or pets.

“We are again tracking when and where West Nile virus might appear in Delaware this year and monitoring its possible spread throughout the state,” said Dr. William Meredith, Mosquito Control Section administrator, DNREC Division of Fish & Wildlife. “Our sampling strategy is to collect and test birds from now into late September.”

Birds collected by DNREC are processed by the Delaware Department of Agriculture’s Poultry & Animal Health Lab, and then submitted to the Division of Public Health (DPH) Laboratory for virus testing. From July through mid- to late-October, DNREC’s Mosquito Control Section also operates a statewide network of about 20 sentinel chicken stations in prime mosquito areas. The DPH lab tests blood samples from the sentinel chickens for WNV and Eastern equine encephalitis (EEE), another mosquito-borne viral disease that affects humans and horses. The results help indicate where WNV or EEE has been transmitted by mosquitoes from wild bird hosts to other animals, possibly leading to an increased risk of exposure for humans or horses. Neither WNV nor EEE can be transmitted between horses or from horses to people.

The period of greatest concern for disease transmission for WNV and EEE is late summer and early fall. WNV is transmitted to humans primarily by the common house mosquito, and possibly by the Asian tiger mosquito. The disease first appeared in Delaware in 2001. Last year, Delaware had one human case and two equine cases, with the last cases of EEE detected in two horses in 2013. Nationwide, the Centers for Disease Control (CDC) logged 2,022 reported human cases of WNV last year resulting in 121 deaths, 10 of which occurred in our region.

Four other mosquito-borne diseases of concern that can occur in Delawareans are malaria, dengue fever, and chikungunya and Zika viruses. Cases of these four diseases are almost always found in travelers returning from tropical or sub-tropical regions where these illnesses are more prevalent. None involve wild birds as hosts, but rather are transmitted by mosquitoes from person-to-person.

To report sick or dead birds, call Mosquito Control’s field offices between 8 a.m. and 4 p.m., Monday through Friday:

  • New Castle County and Kent County from Dover north, Glasgow office: 302-836-2555
  • Remainder of Kent County and Sussex County, Milford office: 302-422-1512

Residents also are encouraged to call to report intolerable numbers of biting mosquitoes and request control services. Voicemail may be left after hours, or on weekends or holidays.

For more information, call Delaware Mosquito Control’s main office at 302-739-9917, or click Delaware Mosquito Control.

For more information about West Nile virus in humans, call the Delaware Division of Public Health at 302-744-4990 or 888-295-5156.

For more information about West Nile virus in horses, Eastern equine encephalitis, or vaccines, call the Delaware Department of Agriculture’s Poultry and Animal Health Section at 800-282-8685 (Delaware only) or 302-698-4500.

Follow the Division of Fish & Wildlife on Facebook, https://www.facebook.com/DelawareFishWildlife.

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

Vol. 48, No. 146


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


DNREC Mosquito Control Section announces year’s first findings of West Nile and equine encephalitis viruses

DOVER – The Department of Natural Resources and Environmental Control’s Mosquito Control Section, in conjunction with the Delaware Division of Public Health Laboratory and the Department of Agriculture, announced today the first detection of mosquito-transmitted viruses in Delaware this year reported earlier this month. West Nile virus (WNV) was recently detected along the Delaware River in the Wilmington area and in west-central Kent County – both instances confirmed by blood samples taken from DNREC’s sentinel chickens. Eastern equine encephalitis (EEE) has also recently been detected from a sentinel chicken in southwestern New Castle County. Additionally, a WNV-positive wild crow was recently found in northwestern New Castle County. Thus far in Delaware this year, no cases of WNV or EEE have been found in humans or horses.

“These findings are not cause for alarm, but are of some concern,” said Mosquito Control Section Administrator Dr. William Meredith, Division of Fish & Wildlife. “Based on these virus-positive findings, and with mosquito season reaching its peak for transmission of mosquito-borne diseases from about mid-August into mid-October, Mosquito Control will increase its mosquito population monitoring activities in targeted areas, and continue to take appropriate control actions as warranted.”

DNREC’s Mosquito Control operates 20 monitoring stations with caged chickens statewide. The sentinel chickens are humanely kept and tended in the field. Sentinel chickens bitten by mosquitoes carrying WNV or eastern equine encephalitis (EEE) – both of which can affect humans and horses – develop antibodies that enable them to survive. Their blood is tested every two weeks for the antibodies, which indicate exposure to the mosquito-borne viruses.

The Mosquito Control Section also conducts extensive statewide monitoring to determine the types and population abundance of 19 problematic mosquito species through a statewide network of more than 30 stationary adult light trap stations. The Section also assesses larval mosquito populations by sampling aquatic habitats around the state.

There are no approved WNV or EEE vaccines for humans. The majority of humans infected with WNV will not show any symptoms; 20 percent develop a mild illness which may include fever, body and muscle aches, headache, nausea, vomiting, and rash. A small number of humans who are infected develop serious illness, particularly certain groups who are more vulnerable, such as senior citizens. Neurological symptoms including paralysis and possibly death may occur.

“The first findings of mosquito-transmitted viruses in Delaware this year serve as a good reminder for people to take common-sense precautions against mosquito bites,” Meredith said. These include wearing long-sleeved shirts and long pants when outdoors in mosquito-prone areas, applying insect repellent containing 10-30 percent DEET in accordance with all label instructions, and avoiding mosquito-infested areas or times of peak mosquito activity around dusk, dawn or throughout the night.

To reduce mosquito-breeding habitat and chances of disease transmission, residents should drain or remove from outdoor areas all 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. “The possibility of mosquito-borne disease transmissions won’t subside until cooler autumn temperatures set in, usually in mid-October and sometimes even later,” Meredith said.

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 encephalitisvisit the CDC website.

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


DNREC Mosquito Control Section’s spraying season begins with larviciding wooded wetlands

DOVER – Weather-permitting, DNREC’s Mosquito Control Section within the Division of Fish & Wildlife will begin its annual spring woodland pool spraying campaign Thursday, March 23 downstate and possibly Friday, March 24 upstate, treating wooded wetlands near select populated areas in New Castle, Kent and Sussex counties. In most years, about 10,000 forested acres that produce large numbers of early season mosquitoes are strategically sprayed, using larvicides applied by helicopter and fixed-wing aircraft.

“The amount of spraying needed is determined by where and how wet the woodlands are, and can vary from year to year, depending on location and amount of precipitation that has occurred over the past autumn, winter and early spring,” said Delaware Mosquito Control Administrator Dr. William Meredith of DNREC’s Division of Fish & Wildlife. “Up until the recent nor’easter, our woodlands were much drier than normal for this time of year, but with recent rainfall standing water is now at about 70 percent of normal levels. This means we might treat 7,000-8,000 acres statewide during the upcoming weeks, instead of our usual average of about 10,000 acres.”

Over the next few weeks, Mosquito Control will apply a bacterially-produced insecticide, Bti. “Like all insecticides used by Delaware Mosquito Control, the U.S. Environmental Protection Agency has determined that Bti, when used in accordance with EPA-approved instructions as required by federal law, can be applied without posing unreasonable risk to human health, wildlife or the environment,” Dr. Meredith said.

Aerial spraying of woodland pools must be completed before the forest canopy fills in, usually around mid-April, because foliage prevents the insecticide from reaching woodland pools and other wet spots on the forest floor containing mosquito larvae. The spring campaign marks the beginning of Delaware’s annual mosquito season, which in most years continues until mid-October or early November, depending upon when the first killing frost occurs.

“If larval stages of early season mosquitoes are not successfully controlled, an intolerable number of biting adult mosquitoes could take wing in late April and remain through late June, becoming particularly troublesome within one to two miles of their woodland pool origins, and significantly affecting quality of life and human health for residents and visitors alike,” said Dr. Meredith.

“Delaware has about 100,000 acres of wet woodlands during most springs, and it’s not possible for logistical or budgetary reasons to larvicide all woodland mosquito-producing habitats,” Dr. Meredith continued. “Targeting wet woodlands near populated areas is the best return on investment in providing mosquito relief to the most people.”

With Zika virus in the news recently, Dr. Meredith said Mosquito Control’s initial annual spray campaign is not as focused on disease control as the section’s work will be later in the season. “The mosquito species in Delaware with the potential to transmit Zika is the Asian tiger mosquito, not the spring woodland pool mosquito,” he said, adding that Asian tiger mosquitoes typically appear later in the season.

“However, now is not too early for the public to take action to reduce backyard mosquito-producing habitat for species such as the Asian tiger mosquito that are known to carry illnesses such as West Nile virus and chikungunya as well as possibly Zika,” Dr. Meredith said.

Residents are strongly encouraged to reduce mosquito-producing habitat by cleaning clogged rain gutters and downspout extenders, keeping fresh water in birdbaths, draining abandoned swimming pools and preventing or emptying standing water from containers such as scrap tires, cans, buckets, flower pot liners, unused water cisterns, children’s toys, upright wheelbarrows, uncovered trash cans, depressions in tarps covering boats or other objects stored outside.

As in the past, public notice of when and where spraying for adult mosquitoes will occur this year will be available via daily radio announcements and by calling 800-338-8181 toll-free. Interested parties may also subscribe to receive email, text or phone message notices of mosquito control spraying in their area by signing up on the Spray Zone Notification System at http://de.gov/mosquitospray.

To request localized mosquito control, please call Mosquito Control’s field offices:

  • 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 Delaware’s Mosquito Control program, please call the Dover office at 302-739-9917.

DNREC’s Mosquito Control Section provides statewide services to about 935,000 Delaware residents and 7.5 million visitors annually to maintain quality of life and protect public health by reducing the possibility of mosquito-borne illnesses such as West Nile virus, eastern equine encephalitis, chikungunya and Zika virus. Throughout the warmer months, Mosquito Control monitors and treats mosquito populations that emerge from wetland areas found throughout the state, including ditches, stormwater ponds, wet woodlands and coastal salt marshes. The Section also works year-round on water and marsh management projects designed to reduce mosquito populations, and provides the public with information on dealing with mosquitoes, from reducing backyard mosquito production to avoiding mosquito bites.

Media contact: Joanna Wilson, DNREC Public Affairs, 302-739-9902.

Vol. 47, No. 68

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Zika: Back-To-School and New Delaware Cases

DOVER, DE — School is in full swing but the official end of summer does not mean the end of mosquito season. Mosquitoes can breed and bite for another several weeks in Delaware. To prevent the spread of Zika and any mosquito-borne illness, the Division of Public Health (DPH) and Department of Natural Resources and Environmental Control (DNREC) reminds you that stopping the mosquito bite is still the best protection against disease.

Delaware now has 15 Zika cases, including four not previously announced. All cases were caused by mosquito bites while traveling abroad. There is currently no evidence that local mosquitoes are transmitting the illness. All but one of the Delaware Zika cases are in adults and none are pregnant. One of the most recent cases is in an infant who got the illness while traveling abroad. All individuals have recovered well and are showing no long-term effects at this time. Of the 15 Delaware cases, nine are in New Castle County and three each are in Kent and Sussex counties.

It is possible that someone who is traveling abroad and gets bitten by a mosquito carrying Zika virus could bring the disease back to Delaware. A returning traveler carrying Zika could be bitten by a Delaware mosquito that picks up the virus, bites another person and transmits the disease as they feed on their blood. This is likely how Zika spread to south Florida and much of Latin America and the Caribbean. The mosquito of greatest concern in Delaware for possible local transmission of Zika is the Asian tiger mosquito, commonly found where people live, work, and play.

None of the 15 Delaware individuals confirmed with Zika could locally transmit the virus if bitten by a mosquito now. After about seven days of exposure, the virus clears from the blood so the individual can no longer transmit it to others through a mosquito bite. However, it is still possible for the adults to transmit the disease sexually, and DPH has instructed any provider treating a patient with a positive test on how to prevent sexual transmission.

“At Public Health, our biggest concern remains for pregnant women because we know that a fetus infected with Zika can have devastating consequences,” said DPH Director Dr. Karyl Rattay. “We are still telling pregnant women to avoid countries where Zika transmission is active and their sexual partners to be tested if they recently traveled to those areas. If the sexual partner has confirmed Zika, the couple should abstain from sex or use condoms and other barrier methods until the baby is born.”

Women who are trying to become pregnant and have been diagnosed with Zika virus or have symptoms of Zika, should wait at least eight weeks after symptoms first appeared before trying to conceive. Men who have been diagnosed with Zika virus or have symptoms are advised to wait at least six months after symptoms first appeared before having vaginal, oral, or anal unprotected sex.

To learn more about which countries have active Zika visit the CDC’s website here. Delaware Public Health and DNREC both provide fact sheets on the Zika virus, as found here.

“Most of us think that once the kids go back to school, we don’t need to worry about mosquito bites,” said DNREC Mosquito Control Administrator William Meredith. “But mosquitoes can continue to breed and bite until the first hard frost which can be as late as November. We still need to be vigilant in protecting against bites and reducing mosquito populations.”

To reduce the risk of mosquito bites, use Environmental Protection Agency (EPA) registered insect repellents; stay in places with air conditioning or that use window or door screens to keep mosquitoes outside; sleep under a mosquito bed net if you are outside and not able to protect yourself from mosquitoes; treat clothing and gear with permethrin available in pharmacies or purchase permethrin-treated items; and wear long-sleeved shirts and long pants. And, do not allow any standing water or puddles near your home.

To learn more about how to reduce mosquitoes around your home, two videos with information about Zika virus and backyard water sanitation tips also are available on DNREC’s YouTube Channel: Zika Virus, Mosquitoes and You, and Mosquito Control & Your Backyard.

To report intolerable numbers of biting mosquitoes and request local relief, residents are encouraged to call Mosquito Control’s field offices:
• 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 Delaware’s Mosquito Control program, call the field offices or the main Dover office at 302-739-9917, or visit de.gov/mosquito.

Zika is a generally mild illness caused by a virus primarily transmitted through the bite of infected Aedes mosquitoes. About one in five people infected with the virus develop the disease, and most people who are infected do not develop symptoms. The most common symptoms of Zika virus infection are fever, rash, joint pain, and conjunctivitis (red eyes). However, while it is often mild, Zika has been linked to serious birth defects in infants whose mothers were infected during the pregnancy and rare but serious health complications in adults.

A person who is deaf, hard-of-hearing, deaf-blind or speech-disabled can call the DPH phone number above by using TTY services. Dial 7-1-1 or 800-232-5460 to type your conversation to a relay operator, who reads your conversation to a hearing person at DPH. The relay operator types the hearing person’s spoken words back to the TTY user. To learn more about TTY availability in Delaware, visit http://delawarerelay.com.

Delaware Health and Social Services is committed to improving the quality of the lives of Delaware’s citizens by promoting health and well-being, fostering self-sufficiency, and protecting vulnerable populations. DPH, a division of DHSS, urges Delawareans to make healthier choices with the 5-2-1 Almost None campaign: eat 5 or more fruits and vegetables each day, have no more than 2 hours of recreational screen time each day (includes TV, computer, gaming), get 1 or more hours of physical activity each day, and drink almost no sugary beverages.