The Buzz on Bites

A cheat sheet on local insect-borne diseases

By Rhea Maze

Spring and summer means more time outside, more bugs, and potentially more exposure to insect-borne diseases. We sought out local experts at the Fort Collins office of the Centers for Disease Control and Prevention for a quick primer:


West Nile virus (WNV) is the most common mosquito-borne disease in the continental United States and Colorado. It is most often spread to people via a bite from an infected mosquito. Mosquitoes become infected when they bite infected birds. Most incidents of WNV occur from June through September, with cases peaking in mid-August.

Most people do not show symptoms, but 20 percent of people who are infected with WNV will develop symptoms such as a fever, headache, body aches, joint pain, vomiting, diarrhea, or rash. Less than 1 percent will develop a serious neurologic illness, such as encephalitis or meningitis (inflammation of the brain or surrounding tissues). Anyone with symptoms of WNV should immediately seek medical care.

Though northern Colorado has recently experienced more mild fall and winter temperatures than in the past, it’s too soon to tell whether or not that might impact mosquito populations later this year. In any case, prevent bites by using insect repellent, wearing long sleeves and pants and treating your clothing with insect repellent, using screens on windows and doors, and removing standing water around your home where mosquitoes lay eggs.


The most common tick in northern Colorado is the Rocky Mountain wood tick which can transmit Colorado tick fever, Rocky Mountain spotted fever, or tularemia. All of these illnesses typically begin with fever, chills, body aches, and headaches. Rocky Mountain spotted fever and tularemia can be very serious and require treatment with antibiotics. Colorado tick fever is caused by a virus, so no specific treatment is available. If you develop any of these symptoms after a tick bite or after spending time in areas where ticks are common, immediately seek medical care.

Talk with your veterinarian about the best tick prevention products for your pets. Check your pets for ticks daily, especially after a hike or a camping trip, and check all family members after these activities.


Fleas can become infected with plague, a serious bacterial infection, after feeding on infected rodents. Rodents are very susceptible to plague, so it is best not to let your pets roam freely. Roaming pets are more likely to come in contact with plague-infected animals or fleas and could bring them into homes. If your pets become sick, take them to a veterinarian as soon as possible as they can transmit plague to you.

Prevent mosquito and tick bites

Use Environmental Protection Agency-registered insect repellents containing DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol, or 2-undecanone. Always follow product instructions.