Health officials say West Nile infections climbed this week as the last county untouched by the disease reported its first case.
The state Department of Health Services says at least 714 people have been infected with the mosquito-borne illness, an increase of more than nine percent since last week.
Nineteen people have died from West Nile.
The virus has now appeared in each of the state´s 58 counties.
It was detected in dead birds found in the last remaining county, Del Norte, over the past week.
Officials say, despite its spread, the virus is expected to infect fewer people as cooler weather arrives.
But they say people still need to take precautions.
The illness is most severe for the elderly and those with weakened immune systems.