Phoenix Becomes West Nile Virus Hot Spot

The U.S. Centers for Disease Control and Prevention (CDC) recently confirmed Maricopa County, Arizona, experienced its fifth and largest West Nile Virus (WNV) outbreak in 2021.

As of April 28, 2023, the greater Phoenix area reported 1,487 WNV cases, 1,014 (68%) hospitalizations, and 101 (7%) related fatalities.

Most identified WNV cases resulted in neuroinvasive disease and occurred among older adults.

The reason for the unprecedented WNV outbreak in 2021 remains unknown.

Since WNV was first detected in 2003, it has become endemic in Maricopa County.

In 2022, California and Colorado (204) also reported WNV cases.

The CDC says WNV is a mosquito-borne disease and is the leading domestically acquired arboviral disease. WNV can cause severe illness affecting the brain and spinal cord, with an associated case fatality rate of 10%.

As of May 4, 2023, no U.S. FDA-authorized West Nile virus vaccines exist.