The Center for Disease Control is closely tracking the spread of West Nile virus and two other dangerous infections -- hantavirus pulmonary syndrome and bubonic plague.
The first two human cases of West Nile virus were confirmed in Washington last week.
The state Department of Health reported that a 70-year-old Pierce County woman was likely exposed while traveling out of state and a Yakima man in his thirties was infected in state.
The number of West Nile cases nationally is at its highest since first detected in 1999.
West Nile Virus is a mosquito-borne disease that can cause encephalitis or meningitis. Symptoms can include fever, headache, body aches, neck stiffness, stupor, disorientation, tremors, convulsions, muscle weakness, paralysis, and coma.
Texas has been hit the hardest by West Nile, with 40 deaths and more than 1,000 cases.
The death toll from HPS is now up to three. Cabins at Yosemite National Park are believed to be where six people contracted the virus.
Up to 10,000 people from around the world have stayed in the park's cabins this summer and may have been exposed.
Another person -- one of 29 volunteers for an episode of The Learning Channel's "Hoarders: Buried Alive" -- contracted HPS near Houston.
It can take six weeks for symptoms of HPS to develop, which include a headache, fever, muscle aches, shortness of breath and a cough. HPS can lead to rapid acute respiratory and organ failure.
A case of bubonic plague was confirmed in Colorado just a few days ago.
The young girl is believed to have contracted the disease from a dead squirrel on a camping trip.