Summertime means mosquitos—and mosquito bites. In some parts of the southernmost United States and the Gulf Coast, mosquitos are a year-round nuisance.

Mosquitos can be much more than just a nuisance – they can spread viral, bacterial, or parasitic diseases to anyone, young and old, through their bites. People most at risk for mosquito-borne viruses live in tropical or rural areas, including areas with heavy rainfall, near lakes, streams, ponds or marshes. Also at risk: Anyone who travels to Mexico, Puerto Rico, Central America, South America, the Caribbean, West and Central Africa, and certain Pacific Islands where these diseases occur more frequently.

A new mosquito-borne disease recently making the news is the Keystone virus, which recently was diagnosed in a Florida resident after he went to a clinic with a fever and rash. It’s the first case of the virus that has been confirmed in a human being, though doctors believe there are others who have been infected.

Keystone, like the Zika virus, is hard to detect and diagnose. The most common symptoms are a rash and mild fever. In the most extreme cases, Keystone can cause encephalitis, or inflammation of the brain.

Though Keystone is the most recent virus to gain attention, many other mosquito-borne illnesses have plagued humans throughout history.

Malaria, Dengue, Chikungunya, Zika and West Nile virus all can cause symptoms such as:

• High fever
• Headache
• Joint and muscle pain
• Vomiting
• Diarrhea
• Yellowing of the skin and whites of the eyes (jaundice)

These mosquito-borne viruses are especially dangerous to people older than 65. Without vaccines to prevent these diseases, the best protection is to avoid getting bitten in the first place.

Mosquitos can be kept at bay by:

• Installing and maintaining screens on windows and doors.
• Using a mosquito net over your bed while you sleep if you have open windows in your house.
• Wearing long-sleeved shirts, hats, and pants when going outdoors.
• Using an Environmental Protection Agency (EPA)-registered insect repellent when outside (be sure to follow the directions on the can or bottle).

You can also help control the mosquito population in and around your home. Standing, stagnant water is prime breeding ground for mosquitos, so empty sources of standing water around your yard and house, including in old tires, shoes, gardening equipment and flower pots. Change the water in bird baths, pet water bowls and children’s pools frequently. Eliminate or dry out puddles that form around your yard and house.

Being aware of your health and your surroundings is the best way to avoid getting very sick or helping spread Keystone or other mosquito-borne illnesses. Please call your doctor if you are not feeling well, or have recently traveled to an area that has been affected by these diseases. Always see your doctor at least once a year for a complete physical exam to keep you healthy.