DENVER (KDVR) — Mosquitoes are more prevalent this year than they have been in the past, and so is West Nile virus.

Dr. Daniel Pastula, an infectious disease specialist at UCHealth, said there is an increased risk of contracting the virus this year due to extra rainfall and moisture creating the ideal breeding grounds for the blood-sucking pests.

Last year, there were 206 confirmed cases in Colorado, causing 20 deaths, according to the Colorado Department of Public Health and Environment. That means the virus was deadly for nearly 10% of Coloradans who were confirmed infected.

Yet, public health officials say that less than 1% of those infected will develop serious, sometimes fatal symptoms.

Eric Aakko, the Weld County health department spokesperson, told FOX31 that it’s hard to tell just how deadly it is because research shows that the majority of people infected do not show symptoms.

“We don’t have a way of knowing how many people are — who have been infected and are asymptomatic, but that’s what the research has shown us is that around 80% or four out of five will not experience any symptoms,” Aakko said.

According to the Centers for Disease Control and Prevention, “About 1 in 5 people who are infected develop a fever and other symptoms. About 1 out of 150 infected people develop a serious, sometimes fatal, illness.”

There are no vaccines or prevention medications for West Nile virus just yet, but you can reduce your risk by wearing long-sleeved shirts and pants, especially around dusk and dawn when mosquitoes are most active, and using insect repellent.