West Coast USA - Detection & Anticipation 2005

Excerpted from ProMED-mail, Mar 5 2005, Id: 20050305.0670

[1] USA (California): Early rains boost for mosquitoes
[2] USA (Oregon): higher case numbers predicted

[1]
USA (CALIFORNIA): RAINS ARE A BOOST FOR WNV: HERE EARLIER, POSES GREATER RISK
Source: Los Angeles Times online, Mar 2 2005, byline: Hugo Martin and
Dave McKibben

This winter's record rains have created prime breeding conditions for
mosquitoes, prompting health officials to warn of a potentially
serious outbreak [of WNV in 2005]. ... One human case of the disease
was confirmed in Los Angeles County this year [2005], though just
when the virus was contracted was unclear, health officials said.

In the past week, the virus has been found in 2 dead birds in Los
Angeles County, a chicken in San Bernardino County and mosquito
larvae from a pool of stagnant water in Orange County. Those findings
indicate that the heavy rains have started the spread of the virus
earlier than last year ... Health officials won't speculate on the
potential human toll this year, but they said the risk of infection
increases with higher rainfall levels, because pools of standing
water are mosquito breeding grounds. ...

In 2004, the virus infected 829 people in California, killing 27,
most of whom lived in Southern California. ... The state could face
a more severe virus season this year because a series of winter
storms broke all-time rainfall records, dumping 39 inches in downtown
Los Angeles and 29 inches in San Bernardino since 1 July 2004. ... In
San Bernardino County, news of an infected chicken in Ontario -- the
first sign of the disease's return to the county this year --
prompted the Board of Supervisors on Tuesday to call for the creation
of a task force to drain or spray stagnant pools and educate the
public on ways to combat the spread of the virus. ... San Bernardino
County's Public Health Director, said the report of the infected
chicken in Ontario last week "indicates that mosquitoes are active
again and the cycle has begun." The infected chicken was one of
dozens kept by a local vector control district to gauge the spread of
West Nile and other diseases. The chickens usually survive the
infections.

In 2004, the virus began to kill birds and infect chickens in early
April. This year [2005], the virus began to surface in February,
signaling a longer and more dangerous virus season, said Robert Real,
field director for the West Valley Mosquito and Vector Control
District in San Bernardino County. Last month in Orange County,
officials reported 2 dead birds infected with the virus: a snowy
egret and an American crow. Last year, the West Nile virus was not
found in birds in Orange County until 31 Mar 2004. Health officials
also trapped a group of infected mosquitoes in January [2005?] at the
Riverview Golf Course on the Santa Ana River.

Hearst, the Orange County vector control spokesman, said the worst
was still to come. "The rains haven't yet had their effect," Hearst
said. "The [variety of] mosquitoes most dependent on large sources of
water are just now becoming active." Vector control officials said
the heavy winter rains would cause the wetlands and marsh areas to be
fuller than usual this year. ...

[2]
USA (OREGON): HIGHER CASE NUMBERS PREDICTED
Source: Statesman Journal online, Associated Press report, Thu 3 Mar 2005

Oregon's brush with West Nile virus last summer [2004] might have
been merely a primer for what the state will face this year [2005], a
health official said. The mosquito-borne virus, which has been
detected in 8 counties, sickened birds, horses and 5 people last year
[2004]. This year, hundreds of human cases could be diagnosed if the
virus follows the pattern seen in other states, said Emilio DeBess, a
public health veterinarian and epidemiologist with the Oregon
Department of Human Services.

DeBess will convene a summit Tuesday in Portland for public health
and hospital officials from across the state to plan how to deal with
a major outbreak. ...

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