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11,000 may be infected in state
338 official cases just fraction of total since few victims get tested
By Bill Scanlon, Rocky Mountain News
August 18, 2003
The number of Coloradans infected with the mosquito-borne West Nile virus may now be in the thousands, say doctors and local health officials.
As of Friday, Colorado led the nation with 338 confirmed cases and seven fatalities. But like estimates of flu cases, the official numbers for West Nile are just the tip of the iceberg.
Kaiser Permanente of Colorado continues to get 500 calls a day from people who describe flu-like symptoms and wonder if it's West Nile, said Dr. Gray Houlton.
"I think there are thousands and thousands of people out there who've been infected and didn't know, or who got mild cases of West Nile fever," Houlton said.
But that's just a guess - no one really has a good handle on how widespread West Nile has become. That's because a blood test - the only way to confirm a case - is not commonly given unless a patient exhibits serious symptoms.
"If somebody has mild virus symptoms, to a large measure, it just doesn't matter if we do the test," Houlton said. "If it is positive, we will tell them to drink fluids, rest and take Tylenol. And if it's negative (for West Nile), we'll tell them to do exactly the same thing."
Most people who are infected never know it because they show no symptoms. Of those who do show symptoms, most will feel lousy for three to six days, with some kind of combination of nausea, vomiting, muscle aches and headaches.
One sign that it could be a more serious case - and deserving of testing - is if the person has a very stiff neck.
State health officials use a formula to determine the probable number of cases, multiplying the number of meningitis or encephalitis cases caused by West Nile by 150. That would put the estimated number of Coloradans infected by the virus at 11,100.
In northeast Colorado, doctors and health officials "hear stories continually all day long," about someone's brother or friend or boss who has many of the symptoms but chose not to be tested, said Denise Hase, executive director of the Northeast Colorado Health Department, which serves six counties that together have reported 54 cases.
Other summer viruses have hit hard, but if symptoms are mild, blood tests generally aren't ordered.
Physicians make the call, and often it comes down to "how quickly the person recovers," she said. "If it's relatively quickly, they say it's probably another virus. If they continue to have symptoms, they test for West Nile."
But among the thousands of mild cases that are never tested, "without a doubt, it could be West Nile fever," Hase said.
Colorado has more than half the official cases in the nation, which has been attributed to ideal weather conditions for mosquito breeding. Among the state's 338 cases are 74 that have resulted in complications of meningitis and encephalitis.
South Dakota, which is second with 66 cases, has 26 cases involving meningitis or encephalitis.
Texas, which is in third place with 65 cases, reports only those that involve meningitis or encephalitis.