BOISE — West Nile virus has likely contributed to the deaths of at least three people in Idaho this summer, state health officials said Friday, and at least 54 people have been sickened by the disease.
A man from Elmore County and a Lincoln County woman, both over the age of 70, recently died after contracting West Nile virus, Department of Health and Welfare spokesman Tom Shanahan said. Neither of their names were released.
"It's kind of like the flu — when people get older, the flu can bring them down while a younger person would recover," Shanahan said. "West Nile can be the same."
Rocco Magliozzi, 12, of Norwood, Mass., died July 28 at a Boise hospital after contracting both West Nile virus — a mosquito-borne virus — and Rocky Mountain spotted fever — a tick-borne virus, Shanahan said. Officials believe the boy was bitten by both insects while attending summer camp in southern Idaho.
It's not clear which disease caused the boy's death, Shanahan said, though it was likely a combination of both. Rocky Mountain spotted fever is typically more severe than West Nile, he said.
Of the more than 50 people who have tested positive for West Nile infection this year, six became so seriously ill that they required hospitalization. Most of the cases have been in southern and south-central Idaho, though in the past few days human and animal cases have been reported in eastern Idaho as well.
It's the first year that Idaho officials know of any West Nile-related fatalities, and it's still early in the mosquito season, Shanahan said.
"Idaho is one of the last states to actually get West Nile. What we're seeing now is that in other states, after West Nile became established they saw the number of human cases rise, kind of peaking after the second or third year," he said.
West Nile virus was discovered in New York in 1999 and was noticed in Idaho in significant numbers in 2004. Now it is part of the local ecosystem, said Dr. Leslie Tengelsen, deputy state epidemiologist.
Nationally, Florida and the Gulf Coast are hot spots for West Nile virus, though in recent years a growing number of cases have occurred in Western states, said Tom Skinner, a spokesman for the Centers for Disease Control and Prevention.
"A lot of factors go into why we might see more mosquitoes in a given area than another," Skinner said. "But I don't know that West Nile virus has been around long enough for us to establish any norms as far as what to expect. It's safe to say, however, that it's entrenched here in the United States as a part of our lives and every year we're going to see infections."
About 80 percent of people infected with West Nile virus never realize they've been infected, Shanahan said. Those who do begin to feel sick usually notice the symptoms between five and 15 days after being bitten by an infected mosquito, suffering headache, fever, body aches and sometimes a rash. Less than 1 percent of those infected will develop a serious illness, Shanahan said, with disorientation, tremors, paralysis or death.
After a person has recovered from West Nile virus, it's assumed that they develop immunity to the disease, Skinner said, though that immunity may wane over time.