As the summer peaks and mosquito season begins, health authorities have identified the first human case of West Nile fever this season in Texas.

The Dallas County Health and Human Services Department (DCHHS) confirmed Monday that a man was diagnosed with West Nile neuroinvasive disease (WNND), a severe form of the illness transmitted by mosquitos infected with West Nile virus.

"We are reporting the first human case of West Nile virus of the 2023 season. WNV is transmitted to humans by the bite of an infected mosquito, and people should be careful when going out outside to enjoy outdoor activities," said Dr. Philip Huang, DCHHS director, reported NBC.

West Nile fever is the leading cause of mosquito-borne disease in the U.S. The virus affected 1,126 people in the country last year, causing 90 deaths.

Symptoms of West Nile fever

Although the severity of the infection and symptoms vary, watch out for these signs:

  • Fever
  • Headache and body aches
  • Tiredness
  • Nausea and vomiting
  • Diarrhea
  • Skin rash on the trunk of the body
  • Swollen lymph glands

Around 80% of people infected with the virus may not show any symptoms. Most people recover from West Nile fever completely but fatigue and weakness may last for weeks.

In more severe cases, the virus can infect the brain and spinal cord, disrupt normal functioning, and lead to encephalitis, meningitis, paralysis and even death.

Who is at risk of a serious infection?

According to the Centers for Disease Control and Prevention (CDC) about one out of 150 people with West Nile virus can develop a serious infection. People over 60 years of age and patients with certain medical conditions, such as cancer, diabetes, hypertension and kidney disease and those who underwent organ transplants are at a greater risk of developing a serious infection.


There is currently no vaccine or specific drugs to treat the infection. Health experts recommend proper rest, taking fluids and over-the-counter medications for reducing the symptoms. However, patients with serious infections need to be hospitalized for supportive treatment and pain relief.


The symptoms of West Nile fever usually appear three to 14 days after a person is bitten by an infected mosquito, which gets the virus from infected birds. The mosquitos, however, do not transmit the virus from one person to another.

A person infected with West Nile virus may transmit it to others through a blood transfusion or an organ transplant. But, since the donated blood undergoes testing for the virus in the U.S., it is considered safe.


Health officials remind people to stick to the 4 Ds to avoid mosquito bites.

  • Avoid being outdoors during Dusk and Dawn when infected mosquitos are most active
  • Dress in long sleeves, and pants when outside. Use mosquito repellents on thin clothing for extra precaution.
  • Ensure your mosquito repellent has DEET
  • Drain standing water in your yard and neighborhood that can breed mosquitos