CSU study examines Rift Valley fever potential in Colorado livestock

A Colorado State University (CSU) study maintains the advent of Rift Valley fever in the state would deliver significant consequences for humans and livestock.

The virus is a global health concern caused by infected mosquitos and the handling of infected animal carcasses. Every 10 to 15 years, the viral disease has led to outbreaks in Africa. In the late 1990s, it spread across five African countries and infected 90,000 people, resulting in 500 deaths.

The work involved studying mosquitoes at four Northern Colorado locations, pairing livestock feedlots and sites without livestock less than 1.5 miles away, mosquitoes were collected over several months in summer 2016 and researchers subsequently analyzed blood meals to learn more about their diet.

The findings revealed Culex tarsalis mosquitoes, abundant in feedlots and at nearby sites, could serve as a vector or means of transmitting Rift Valley fever virus between livestock and humans.

“Lab studies show these mosquitoes have very high transmission rates,” Daniel Hartman, the study’s lead author and a CSU doctoral student studying microbiology, said. “We’ve now found that this mosquito is in and near feedlots. It will bite a cow and, presumably, it would bite another cow. That’s the complete transmission cycle for a virus.”

Researchers said the next step involves taking a closer look at the mosquito behavior as a means of gauging how different species could contribute to transmitting Rift Valley fever if introduced here.