West Nile disease -- a mosquito-borne illness -- has reached epidemic proportions in Michigan, particularly in older suburbs that ring metro Detroit and Grand Rapids, state health officials warned Wednesday.
Michigan's 80 cases this summer, including four deaths, rank the state as the sixth highest in the nation with the problem, according to the U.S. Centers for Disease Control and Prevention.
Those at the greatest risk from West Nile are people older than 50, pregnant women and people with compromised immune systems, such as kidney disease and cancer patients.
Michigan and the five other states -- Texas, South Dakota, Mississippi, Oklahoma and Louisiana -- account for 70% of the nation's West Nile cases, the CDC said Wednesday. Only Alaska and Hawaii have no reports of the disease so far.
Michigan's cases put it on track to match the state's worst West Nile outbreak in 2002, when 644 people contracted the disease and 51 died, said Dr. Dean Sienko, interim chief medical executive for the Michigan Department of Community Health, speaking Wednesday in a telephone briefing with the news media.
"This is something people need to pay attention to, particularly over the age of 50," who are most vulnerable to developing serious health problems from the disease, Sienko said.
Both he and CDC officials described the outbreak this year as an epidemic. They said cases, both in Michigan and nationwide, are likely to surpass the number reported in any year since 1999, when the disease was first reported in the U.S. near New York City's JFK International Airport.
Dry, warm weather appears to have contributed to the rising number of cases and will continue to pose problems as long as nighttime temperatures remain above 50 degrees -- ideal mosquito-breeding weather, health and science officials say.
Michigan's 80 cases required hospitalization of 62 people, and four died, all in metro Detroit, Sienko said. He said he expects the number of cases to continue to climb for another month, because it typically takes up to two weeks for symptoms to occur after a person is bitten.
The latest death, reported this week, was an 86-year-old Wayne County woman. All four Michigan deaths have been among people older than 50.
Nationwide, 1,590 West Nile cases have been reported, including 66 deaths, according to the CDC. Texas, particularly the Dallas area, accounts for nearly half of the reports. There, officials are conducting pesticide spraying in communities that have asked to be included in prevention efforts.
Spraying is considered effective, but it is less common in many states, including Michigan, because many communities say they can't afford it.
One exception is Warren, where Mayor Jim Fouts ordered spraying of the city this summer.
Fouts also has increased monitoring of sources of standing water, such as swimming pools on foreclosed properties. Owners face fines of up to $1,000 for letting stagnant water remain on their property.
Fouts said he ordered the spraying of Warren's 1,200 storm drains because he recalled several deaths and serious lingering health problems among Warren residents during the 2002 West Nile outbreak. Each spraying costs about $20,000.
"It's better to be penny-wise than pound-foolish," he said.
As many as 80% of this year's West Nile cases in Michigan have been in the tri-county area, particularly suburbs built after World War II with more densely populated communities and storm drains and street catch basins where mosquitoes breed, said Ned Walker, a Michigan State University microbiologist and West Nile expert.
Suburbs with higher numbers of West Nile cases this year include Allen Park, Berkley, Royal Oak, Westland, Redford Township and Dearborn Heights, he said.
Walker called storm drains "little mosquito factories" for the single species, Culex pipiens, also called a northern house mosquito, that "appears to be the sole carrier" of West Nile disease. He said the species likes small areas where water pools, such as tires and flowerpots, nooks of trees and gutters.
Dr. Steve Halstead, a veterinarian with the Michigan Department of Agriculture & Rural Development, said that although horses and other animals can contract the virus, Michigan has only one case so far this year, in an unvaccinated horse in Montcalm County. There is a vaccine against the virus for horses, but not for humans.
Walker said the Culex mosquito travels about a mile from its breeding grounds. Females lay 150-200 eggs in their short 21- to 28-day life cycle. Some hibernate during the winter in basements, electrical transformers and other spots, he said.
"People need to be scared somewhat," he said. "The mosquito population with this infection is at its peak right now, this week. We'll see lots more human cases."
EXPLORE: Health West Nile Virus Prevention
Edited By Cen Fox Post Team
