State health officials are urging people to do what they can to prevent mosquito bites after the state's first case of West Nile virus since 2018 was reported this week.

The Division of Public Health (DPH) announced this week that a 69-year-old Kent County man had become infected with West Nile virus (WNV) — the state’s first case of human WNV since 2018, when 10 human WNV cases were reported, including two deaths from the illness.

An epidemiological investigation is currently ongoing to confirm any travel history or sources that could have led to transmission, officials said. To protect the patient’s privacy, no more information will be provided on the individual at this time.

“We’re sad to learn that a case of West Nile virus has been reported in Delaware,” said DPH Director Dr. Karyl Rattay. “West Nile virus can be very serious and even deadly, particularly in vulnerable populations. Please take all proper precautions when going outdoors and there is a possibility of being bitten by mosquitoes, like wearing insect repellent, especially if you are among a vulnerable population.”

The mosquitoes that cause WNV bite primarily from dusk (evening) to dawn (morning). However, other mosquitoes that cause diseases such as chikungunya, dengue fever and Zika can bite during the day. It is important to protect oneself by wearing insect repellent whenever going outdoors, officials urged.

WNV is a mosquito-borne illness that can cause serious health problems. WNV is transmitted by mosquitoes, generally in summer and fall, with a peak period for disease transmissions from mid-August to mid-October. Nearly 80 percent of people infected with WNV will not become ill. While only a little less than 20 percent of those infected with the virus will develop West Nile fever with mild symptoms (fever, headache, body aches, a skin rash on the chest or back and swollen lymph glands), 1 in 150 people infected will develop severe infection (West Nile encephalitis or meningitis).

Symptoms of severe WNV infection include headache, high fever, stiff neck, and/or tremors and muscle weakness. The elderly and those with weakened immune systems are most at risk. Anyone who experiences any of the severe symptoms is advised to seek medical help immediately. Symptoms may progress to stupor, disorientation, coma, convulsions, paralysis and possibly death.

Mosquito bite prevention tips offered

To avoid mosquito bites and reduce the risk of infection, individuals should:

  • Use Environmental Protection Agency (EPA)-registered insect repellents. Follow the manufacturer’s instructions for reapplication times.
  • If using sunscreen, apply it first and insect repellent second.
  • Adults applying repellent to children should spray the insect repellent onto their hands and then apply it to the child’s face. Do not apply insect repellent onto a child’s hands, eyes, mouth, or on cut or irritated skin.
  • Do not use insect repellent on babies younger than 2 months.
  • When outside, wear shoes, light-colored long-sleeved shirts and pants. Dress children in clothing that covers their arms and legs. Mosquito netting can protect one’s face and neck, and infants in carriages, strollers and playpens.
  • Use permethrin (an insecticide) to treat clothing and gear (such as boots, pants, socks and tents), but do not apply to skin.
  • Prevent mosquitoes from entering the house by using screens and keeping windows and doorways tightly sealed.

DNREC’s Mosquito Control section announced in July that WNV had been found in its sentinel chickens for the first time in 2021. Delawareans are being reminded that the possibility of contracting mosquito-transmitted diseases, including WNV and Eastern equine encephalitis (EEE), will continue until colder autumn temperatures in mid-October or later.

To report suspected cases of human WNV, call the DPH Office of Infectious Disease Epidemiology at 1-888-295-5156.

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 downstate areas south of Dover, contact Mosquito Control’s Milford field office at (302) 422-1512. For animal health questions, contact the Delaware Department of Agriculture’s Poultry & Animal Health Section at (302) 698-4561.

For more information on West Nile virus or Eastern equine encephalitis, visit

For more information on how to prevent West Nile virus, visit the Centers For Disease Control & Prevention’s website at