Health officials in Maricopa County, Arizona (aka the Phoenix area) reports a more than 62 percent increase in human West Nile virus (WNV) cases to date in 2026, according to county data.
They have seen 52 WNV cases to date, which compares to 32 cases during the same period in 2025, or a 62.5 percent increase.
Five deaths were reported so far in 2026.
In all of 2025, Maricopa County saw 56 cases and seven deaths. In all of 2024, 21 cases and two deaths were reported in the county.
Nationally through July 28, 113 WNV cases were reported in 23 states, with 61 cases reported in Arizona.
West Nile virus in the US: 20 years ago in NYC
West Nile virus is typically spread through the bite of an infected mosquito. Most people infected don’t show symptoms, but about 1 in 5 may develop a flu-like illness with fever, headache, and body aches. In rare cases—about 1 in 150—the virus can cause severe complications like encephalitis or meningitis, which might lead to paralysis, long-term disability, or death. Older adults, people with underlying health conditions, and those with weakened immune systems are at higher risk for severe illness.
Public health officials urge all residents and visitors to remember the 4Rs (Repel, Remove, Repair, Remind) to prevent mosquito-borne diseases:
Repel: Use EPA-registered insect repellents (e.g., those containing DEET) when outdoors.
Remove: Get rid of standing water around your home and yard to prevent mosquitoes from breeding.
Repair: Patch up or replace damaged window and door screens.
Remind: Educate your friends, family, and neighbors about these safety measures.