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April 14, 2004 -- A 79-year-old Ohio man may be the first human case of
West Nile virus infection this year.
The Ohio Department of Health on April 9 reported that the man is a "probable
case of West Nile virus." No other medical information is being released.
"We're waiting for confirmation from the CDC," Ohio Department
of health spokesperson Kristopher Weiss tells WebMD.
The man lives in Scioto County in southern Ohio. Weiss says warm spring
weather there has prompted mosquito activity.
Last year, Ohio reported 108 probable cases of West Nile virus infection:
84 cases of West Nile encephalitis/meningitis and 24 cases of West Nile
fever. Of these 108 cases, Weiss says, 94 remain "probable."
West Nile Spread Through Mosquitoes
West Nile virus is carried by wild birds. Mosquitoes that bite infected
birds can infect humans with the virus. It's uncommon, however, for human
cases to appear so early in the mosquito season. Usually a period of "amplification"
is needed as the pool of West-Nile-carrying mosquitoes builds up over time.
Typically, human West Nile virus infections in the U.S. peak in late summer
and early fall.
Grant L. Campbell, MD, PhD, chief of epidemiology for the CDC's arbovirus
disease branch in Ft. Collins, Colo., is in charge of tracking the West
Nile virus in the U.S. He says it seems too early for human cases to be
appearing as far north as Ohio.
"The Ohio report doesn't convince me yet that human cases have started
to occur this year," Campbell tells WebMD.
Last year, the U.S. West Nile epidemic claimed 262 lives. There were 2,863
cases of brain or nervous-system infection with the virus, the most serious
manifestation of West Nile virus infection. Overall, there were nearly
10,000 reported cases of West Nile infection.
However, only people who get ill are reported to the CDC. It's thought
that eight out of 10 people infected with the virus never get any symptoms
at all. However, West Nile disease is much more likely in people over the
age of 50.
California May Get Hit
Last year's epidemic affected 46 of the 48 contiguous U.S. states. West
Nile virus has been spreading westward since its 1999 introduction in New
York, but there have been relatively few cases west of the Rocky Mountains.
That may change this year.
Campbell says the CDC is keeping a close eye on California because it hasn't
seen much West Nile activity. The portents, however, are ominous. A dead
crow and two live house finches already have tested positive for the virus
in the past few weeks.
Because West Nile virus is spread by mosquitoes, the CDC is continuing
its "Fight the Bite" campaign. People are urged to get rid of
any potential mosquito breeding sites near their homes. These include discarded
tires and other water-holding containers such as clogged roof gutters and
unused flowerpots. It's also advised that during mosquito season, people
wear protective clothing and DEET-containing mosquito repellent.
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