(NewsNation) — Dr. Anthony Fauci was briefly hospitalized with West Nile virus. As he recovers at home, questions about how the illness is contracted and how severe it is swirl in states that see high cases of mosquito-borne illnesses.

Fauci, the former director of the National Institute of Allergy and Infectious Diseases who headed up the federal response to the COVID-19 pandemic, is expected to make a full recovery after being hospitalized for nearly two weeks.

What is West Nile virus?

The West Nile virus is the leading cause of mosquito-borne illnesses in the continental U.S., commonly spread to people when they are bit by an infected mosquito. Cases of West Nile occur during mosquito season, which starts in the summer and continues through fall.

Most people who contract West Nile virus don’t feel sick, with only 1 in 5 infected people developing a fever and other symptoms, according to the Centers for Disease Control.

About 1 out of 150 infected people develop a serious, sometimes fatal, illness.

While the virus spreads during mosquito season in the summer and fall, experts warn that global warming means mosquito season is getting longer, prompting higher potential for the spread of the disease.

Symptoms of West Nile virus?

West Nile virus can cause flu-like symptoms, including:

• Nausea
• Aches and pains
• Vomiting
• Fever
• Chills
• Rash

“Less than about 1 in 150 people who get infected get a more serious form, and that involves the central nervous system. You get inflammation of the brain, and this the the membrane that lines the spinal cord, and that’s a much more serious situation there,” CBS News chief medical correspondent Dr. Jon LaPook said.

There are no vaccines to prevent West Nile or medicines to treat it. As of Aug. 20, the CDC had recorded 216 cases in 33 states this year. It’s best prevented by avoiding mosquito bites.

How to prevent West Nile virus?

The best way to avoid contracting West Nile virus is by avoiding mosquitos and taking certain simple precautions.

“They include things that you’re used to, like using repellent, making sure that you’re using long sleeves and long pants, you know, assuming it’s not 100 degrees, to reduce exposed skin,” Dr. Catherine Brown, an epidemiologist at the Massachusetts Department of Public Health said.

Brown joined “NewsNation Now” to discuss mosquito-borne illnesses as Massachusetts issues a voluntary curfew due to a rise in infections.

“We recommend that people reschedule their outdoor activity to avoid the hours between dusk and dawn, so just make sure that you shift your activity to the daytime hours,” Brown said.