West Nile-Like Virus Weekly Update
From Patricia Doyle, PhD

From Promed
(Now that the West Nile virus (WNV) surveillance data reported to CDC through ArboNET are appearing weekly in MMWR (see part 7 below), ProMED-mail will no longer provide abstracted information from the USGS West Nile virus maps. A summary map of the current situation is reproduced in MMWR, and the more detailed USGS maps, down to county level in some categories, can be accessed by anyone requiring such detailed information. <>
The following update includes additional reports of the presence of West Nile virus in blood donations detected prior to the appearance of symptomatic cases of West Nile virus infection. If validated by further experience, the screening test now under trial in blood transfusion facilities may provide a sensitive early indicator of West Nile virus infection in the human population.
Now that the 2003 West Nile virus season is in full swing, only extensions of West Nile virus geographic range or host species and exceptional items will be posted separately from these weekly updates. - Mod.CP)
In this update:
[1] Mosquitoes (New York City - Staten Island)
[2] Human (Texas - Fort Worth)
[3] Human (Colorado)
[4] Human (South Dakota)
[5] Blood donor positive (Florida)
[6] More Blood donors positive (Colorado)
[7] MMWR West Nile virus update (17 to 23 Jul 2003)
Date: Fri 18 Jul 2003
From: Pablo Nart <>
Source: Daily News, Fri 18 Jul 2003 [edited]
New York City: West Nile Virus-infected Mosquitoes Detected in Staten Island
Mosquitoes collected in the Willowbrook Park area in Staten Island tested positive for West Nile virus, the first time the potentially fatal virus has been detected in the city this year, city health officials said yesterday. The Health Department does not plan to start spraying pesticides yet, but officials said they have stepped up surveillance for infected mosquitoes and their larvae in Staten Island.
"It is especially important that elderly New Yorkers take precautions against mosquitoes now, and continue to do so throughout the mosquito season," Health Commissioner Thomas Frieden said. In 2002, 29 cases of West Nile virus were reported in New York City, resulting in 3 deaths. The first U.S. outbreak was reported in New York City in 1999. The virus made 3873 people ill and killed 246 in 2002 in the U.S. Frieden urged New Yorkers to take the precautions against being bitten by infected mosquitoes, and he also urged people to report dead birds -- a sign they may have been infected by West Nile -- by calling 311 or by logging onto the website at: <>
[Byline: Paul Shin]
Date: Sun 20 Jul 2003
From: ProMED-mail <>
Source: Fort Worth Star-Telegram, Sun 20 Jul 2003 [edited]
Case of West Nile Virus Infection in Fort Worth
County health officials have confirmed Fort Worth's first human case of the West Nile virus in 2003. The patient, described as an elderly man who lives in the 76104 ZIP code area near the hospital district, is expected to make a full recovery, said Vanassa Joseph, a spokeswoman for the Tarrant County Health Department. Joseph said the county's lab returned the positive test results on Fri 18 Jul 2003. They will be sent to the Texas Department of Health for further confirmation. Fort Worth had one human case of West Nile virus in 2002, said Jason Lamers, a spokesman for the city's health department. No one in Fort Worth has died of the disease, he said.
[Byline: Peyton D. Woodson]
Date: Wed 23 Jul 2003
From: ProMED-mail <>
Source: Casper Star-Tribune, Associated Press report, Wed 23 Jul 2003 [edited]
Colorado: First Human Case of West Nile Infection for 2003
State officials stated on Tue 22 Jul 2003 that a 28-year-old man from northern Colorado is the first person in the state known to have contracted West Nile virus infection in 2003.
The man became ill on 6 Jul 2003 and saw his physician 5 days later, said Lori Maldonado, spokeswoman for the state Department of Public Health and Environment. Tests at state labs confirmed the presence of West Nile virus on Mon 21 Jul 2003. Officials have sent the results to the federal Centers for Disease Control and Prevention, but they were sure the test was positive.
"It is not surprising that Colorado's first human case of West Nile virus infection for 2003 would come from Weld County, because there already has been a great deal of virus activity in the area," said state epidemiologist Dr. Ned Calonge. Weld County is on Colorado's northern border, south of Cheyenne, Wyoming. Dr. Mark Wallace, director of the Weld County Health Department, said the case was no reason to panic. Only 2 people out of every 10 who are bitten by an infected mosquito experience any illness, experts say.
2 weeks ago, the CDC confirmed the nation's first human case of West Nile virus infection for 2003 in South Carolina. The seasonal infection has grown from an initial U.S. outbreak of 62 cases in 1999 to 4156 reported cases, including 284 deaths, in 2002. It has spread to all but a handful of states. The virus first showed up in Colorado in August 2002, but none of the 13 human cases detected in 2002 was fatal. The virus can be transmitted by mosquito bites that feed on infected birds. It can also be transmitted through transplanted organs and blood transfusions. (see: Colorado virus home page at
Date: 23 Jul 2003
From: ProMED-mail <>
Source: Argus Leader
West Nile strikes first human in S.D. for '03
West Nile virus has [caused illness in the first person] in South Dakota this summer, officials with the state Department of Health announced Tuesday. A Lyman County resident became sick with [encephalitis] Sunday, and tests confirmed West Nile encephalitis. The patient is hospitalized in Sioux Falls. The first confirmed bird death in Lyman County was 11 Jul 2003, 2 days before the human patient fell ill.
South Dakota is the eighth state with a confirmed case of West Nile, according to the federal Centers for Disease Control and Prevention and recent news reports. The CDC had confirmed 8 cases in 5 states as of Monday, and Colorado and Iowa recently reported new cases.
Date: Wed 23 Jul 2003
From: ProMED-mail <>
Source: Florida Times Union online, Wed 23 Jul 2003 [edited]
Florida: Blood Bank Detects West Nile Virus in Donor
Florida's largest blood bank has detected West Nile virus in a unit of donated blood. The Central Florida Blood Bank announced its finding on Tue 22 Jul 2003, underscoring the need to check donated blood for the virus that can cause potentially dangerous brain infections. The blood bank started testing for West Nile virus on 30 Jun 2003.
The donation was traced to a 36-year-old man from Rockledge in Brevard County who does not have any symptoms of a West Nile virus infection, said Mike Pratt, executive vice president of technical services for the blood bank. "We're just thrilled with this," Pratt said. "I think we got (the testing) started just under the wire, just in time for West Nile season." The Brevard County Health Department will investigate the findings to determine if anything must be done in the donor's area, officials said.
A new blood screening system developed by Roche Diagnostics was adopted by the Central Florida Blood Bank as part of a clinical trial to weed out infected blood donors who risk transmitting the encephalitis-related disease to transfusion patients. The Central Florida Blood Bank has 29 locations covering 17 counties. It provides more than 250 000 pints of blood each year and is the fourth largest independent blood bank in the country.
No human cases of West Nile have been diagnosed in Florida in 2003, but 2 children have contracted another mosquito-borne infection -- Eastern equine encephalitis.
Date: Wed 23 Jul 2003
From: ProMED-mail <>
Source: Rocky Mountain News, Sat 19 Jul 2003 [edited]
Colorado: 9 Suspected West Nile Virus-positive Blood Donors
5 more blood donors have tested positive for West Nile virus, bringing to 9 the number who will be re-tested to see whether they are false positives, the Bonfils Blood Center reported on Fri 18 Jul 2003. West Nile virus killed 284 Americans in 2002; in Colorado, 14 people who got sick tested positive for the virus, but none died.
Bonfils and 21 other blood centers nationwide began testing donors for West Nile on 1 Jul 2003, so to have so many positives in Colorado already is unsettling, officials said. That's why Bonfils and the Colorado Department of Public Health and Environment both are anxious to retest the 9 donors who have tested positive to see whether they truly have West Nile virus infection. Epidemiologists with the state health department are skeptical, but aren't ruling out that the findings are real.
Bonfils has sent blood samples to the labs with which it works and also to the state health department. The original test looks for RNA from the virus itself, but follow-up tests also could include checking to see whether the donor has developed antibodies to the virus. Results should be known within 2 weeks.
The state health department has no reports of ill Coloradans who've tested positive for West Nile this year. The West Nile season is expected to peak in August and September. In 2002, the Centers for Disease Control and Prevention reported a handful of West Nile cases that likely came from patients receiving blood from donors with the virus. Jessica Maitland, a spokeswoman for Bonfils, said the first positives in Colorado didn't come until the second week of testing in July, which gives officials some assurance that infected blood didn't get into the nation's blood supply in late June before testing began. Every unit of blood that tested positive was quarantined, Maitland said, "ensuring that the blood supply is safer than ever."
Also this week, 6 more horses have tested positive for West Nile virus, bringing the total to 10 in Colorado's second summer of dealing with the virus. The 10 horses include one each from Adams, Fremont, Larimer, Crowley, and Yuma counties and 5 from Weld County.
[Byline: Bill Scanlon]
Date: Thu 24 Jul 2003
From: ProMED-mail <>
Source: Morbidity and Mortality Weekly Report, Fri 25 Jul 2003 / 52(29);686
United States: West Nile Virus Activity; Thu 17 Jul to Wed 23 Jul 2003
This report summarizes West Nile virus (WNV) surveillance data reported to CDC through ArboNET as of 8 a.m., Mountain Daylight Time, Wed 23 Jul 2003.
During the reporting week of Thu 17 Jul to Wed 23 Jul 2003, 6 human cases of WNV infection were reported from 5 states (Iowa, Minnesota, Ohio, South Dakota, and Texas). During the same period, WNV infections were reported in 309 dead corvids (crows and related species), 69 other dead birds, 12 horses, and 144 mosquito pools.
During 2003, a total of 11 human cases of WNV infection have been reported from Texas (n = 5), Alabama (n = one), Iowa (n = one), Minnesota (n = one), Ohio (n = one), South Carolina (n = one), and South Dakota (n = one). Among these cases, 7 (64 percent) occurred among men; the median age was 70 years (range: 42 to 80 years), and the dates of illness onset ranged from 29 May to 13 Jul 2003. In addition, 551 dead corvids and 150 other dead birds with WNV infection were reported from 34 states; 55 WNV infections in horses have been reported from 16 states (Alabama, Arkansas, Colorado, Georgia, Kansas, Kentucky, Minnesota, Missouri, Nebraska, New Mexico, North Carolina, North Dakota, Oklahoma, Texas, Wisconsin, and Wyoming), and one WNV infection was reported in a dog (South Dakota). During 2003, WNV seroconversions have been reported in 56 sentinel chicken flocks from Florida, Iowa, and North Carolina. South Dakota reported 3 seropositive sentinel horses; 327 WNV-positive mosquito pools have been reported from 15 states (Colorado, Georgia, Illinois, Indiana, Kansas, Maryland, Massachusetts, Michigan, Mississippi, Nebraska, New Jersey, South Dakota, Texas, Virginia, and Wisconsin).
Additional information about WNV activity is available from CDC at <> and <>
[The positive mosquito pool in Staten Island and the suspected human case
in Colorado are additional to the figures listed in the MMWR update. - Mod.CP]
Patricia A. Doyle, PhD
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