Washington, Apr 28 (IANS): The largest recorded West Nile virus (WNV) outbreak in a US county occurred in Maricopa, Arizona, in 2021, according to a new report published by the Centers for Disease Control and Prevention (CDC).

In 2021, Maricopa County experienced the fifth, and largest, WNV outbreak reported in the county, with 1,487 cases, 1,014 hospitalizations, and 101 deaths, reports Xinhua news agency citing the CDC as saying.

The number of cases was more than four times that reported in the previous largest outbreak, it said.

The reason for the unprecedented WNV outbreak is unknown, but is likely multi-factorial, potentially related to increased rain, recent population growth and housing development, and changes in health care-seeking behaviour during the Covid-19 pandemic, according to the CDC.

WNV, an arthropod-borne arbovirus, is primarily transmitted through bites of infected Culex mosquitoes and is the leading cause of domestically acquired arbovirus infections in the US, according to the health body.

Public health agencies should continually review messaging to improve awareness, said the CDC, adding that human and mosquito surveillance is essential to mounting a rapid, coordinated response and limiting further spread.