Study: West Nile Virus Overwintering in Maricopa County

Jan 24, 2019

A study from Flagstaff scientists says West Nile virus now persists year-round in Maricopa County, overwintering inside birds and mosquitoes. KNAU’s Melissa Sevigny reports.

Credit CDC/James Gathany

Scientists at Northern Arizona University and the Translational Genomics Research Institute sequenced the virus’ DNA collected from mosquitoes. They identified a strain that entered Maricopa County between 2011 and 2013.

NAU’s Crystal Hepp is the lead author. She says, "That means this particular strain of West Nile virus has been existing in Maricopa County since that time, which means it hasn’t been annually imported, it’s actually been established in the area."

Hepp says that may be because the virus is found in a type of mosquito that doesn’t hibernate in Arizona’s mild winters. Her goal is to identify “hot spots” in Maricopa County to target for prevention efforts, such as mosquito fogging. West Nile virus has no vaccine or treatment and in rare cases it can be fatal. There were 26 human cases in Arizona last year.