First 3 Human Cases of West Nile Virus Found in DE


Delaware has it’s first 3 cases of West Nile Virus in humans – all are in New Castle County. Delaware Public Health officials say all three cases are in men aged 50 and older. They were all hospitalized due to infection from the mosquito-borne illness and it’s believed that all three contracted the illness locally – however the investigation is on-going. DNREC will increase surveillance efforts of mosquito populations in the areas of the infected men’s homes and officials add that these human cases coincide with an uptick in West Nile Virus activity in the sentinel chicken monitoring program. DPH officials say mid-August to mid-October is the peak period for disease transmissions.

Additional information from DPH:

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 or four in five 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), one 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 these severe symptoms should seek medical help immediately. Symptoms may progress to stupor, disorientation, coma, convulsions, paralysis and possibly death.  

The mosquitoes that cause WNV bite primarily from dusk (evening) to dawn (morning). However, other mosquitoes that transmit diseases such as chikungunya, dengue fever and Zika can bite during the day. Applying insect repellent for personal protection is important whenever going outdoors. Wearing light-colored, long-sleeved shirts and pants is also recommended as a deterrent against mosquito bites. DPH and the DNREC Mosquito Control Section also advise reducing outdoor activities that can cause heavy breathing or excessive perspiration, not wearing perfumes or colognes, and using mosquito repellents that may contain the ingredients DEET or Picaridin in accordance with product label instructions. Additionally, Delaware residents and landowners should eliminate an unneeded standing water on their property that might exist for four or more consecutive days and that acts as mosquito breeding habitat. 

To report suspected cases of human WNV, call the Division of Public Health Office of Infectious Disease Epidemiology toll-free at 888-295-5156.   

For information on mosquito control operations in Delaware, including contact information to request residential control service for biting mosquitoes, visit  

For more information on West Nile Virus, visit