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Canada Logs First Domestic West Nile Virus Case of 2025

Toronto’s first domestic infection this year underscores persistent seasonal risk for mosquito-transmitted West Nile virus; health officials note limited treatment options, no vaccine

Overview

  • An adult in Toronto with no travel history became the first Canadian to acquire West Nile virus domestically this season, according to the Public Health Agency of Canada.
  • West Nile virus spreads when mosquitoes bite infected birds and then humans, with most cases asymptomatic and up to two percent leading to serious neuroinvasive illness.
  • There is no vaccine or antiviral treatment for West Nile virus, making supportive care and rehabilitation the only options for those who develop severe symptoms.
  • Public health authorities recommend using insect repellents containing DEET or Icaridine, wearing long clothing after dusk and eliminating standing water to curb mosquito breeding.
  • PHAC data show low rates of West Nile infection among Canadian mosquitoes, keeping overall human risk low despite annual variation in case counts.