A hundred cases of swine flu in the U.S.? Health officials say there are likely more. Just how many is not important, they say.
As the world faces a potential pandemic, swamped labs are not testing all possible cases. Getting an exact tally has taken a back seat to finding new outbreak hot spots or ways to limits its spread, health officials said.
"The specimens are coming in faster than they can possibly be tested," said Dr. Jeffrey P. Davis, state epidemiologist in Wisconsin, where a lab helped spot the nation's first known case, in a 10-year-old boy from San Diego.
New York, which has more cases than any other U.S. location, also has had to limit the samples it tests, said Dr. Don Weiss of that city's health department.
"Sure, we'd want to diagnose every case, but we don't have that resource," he said. Instead of trying to confirm every sign of the virus, "we're focused on where else is it going and how do we prevent it."
On Friday, the Centers for Disease Control and Prevention will start shipping kits so states can do their own swine flu tests. Until now, state labs could only rule out previously known flu strains and send suspicious samples to CDC.
With the new kits from CDC, states will be able to declare presumed swine flu cases, allowing doctors to start treatment. Medicines to fight the virus, such as Tamiflu and Relenza, must be taken within 48 hours of first symptoms to do any good.
Until now, many busy labs have been so overrun that they could do preliminary tests only on samples that meet a strict case definition or that involve people who traveled to Mexico.
"The capacity of the state laboratories to test all the swabs is being exceeded," said Dr. Paul Jarris, executive director of the Association of State and Territorial Health Officials.
Initially, labs just needed to detect the virus, he said. "Once it's in the community, it's not as important to detect every single case. You can actually treat based on the clinical picture."
Sending samples to CDC was "getting to be a challenge," said Alabama State Health Officer Don Williamson. The first eight were negative, and the state lab had 29 more to test on Wednesday, he said.
Without a confirmed case, state officials still took the precaution of ordering 1.5 million face masks and other supplies.
"We are preparing for the worst while praying for the best," Williamson said.
CDC has had to be selective, too. The agency generally can process about 100 samples a night, said Michael Shaw, associate director for laboratory science. CDC has not said how many specimens they have received for testing.
"As the number of specimens increases, the time slows down," Shaw said. "It's not just a matter of running tests. It takes time to unpack boxes, make a record of receiving, enter into the database."
The CDC added just 18 new cases to its official list on Thursday, and its acting director said it may stop doing confirmatory testing as the virus becomes more common in a community.
"We may move away from case updates," Dr. Richard Besser said. "The numbers become a little murkier, and we'll focus more on where things are occurring and what that tells us about the spread of infection."
The public may be surprised to know it's not so important to have an exact tally, or to tell a person whether he or she has the germ, said Sharon Shea. She is director of infectious disease programs at the Association of Public Health Laboratories, the network of labs that work with CDC.
"It's not what people want to hear. As an individual, you want to know what's making you sick," she said.
Each state's epidemiologist will have to decide what samples should be tested, said Scott Becker, executive director of the lab association.
The common cold and other viruses are also circulating and cause similar symptoms.
In the last two days, the Wisconsin State Laboratory of Hygiene "had a huge spike," about 150 samples of suspected swine flu cases, said its communicable disease chief, Pete Shult. Wisconsin has five probable cases awaiting CDC confirmation.
Through a fluke, his lab helped confirm the nation's first case. A private company doing a study of an experimental rapid flu test it wants to sell had agreed to send any samples that could not be typed to a more experienced lab — in this case, the Marshfield Clinic Research Foundation in Wisconsin.
The clinic, in turn, had agreed to alert the state to any flu viruses that did not match a known strain.
"I got a call on Good Friday. They had such a specimen," he said. That was from the boy in San Diego who was the first known U.S. case of swine flu.
The sample was tested on Monday, April 13, and shipped overnight to CDC, which confirmed it as the novel swine flu on Tuesday, April 14.
The San Diego boy had fallen ill on March 30. Since then, the CDC and the public health lab association have suggested that state labs go back through samples since February to look for signs of the virus. At CDC, stored samples show no earlier sign of it, Shaw said.
"That's the odd thing about this. It just appeared out of the blue the last week of March," he said.
Shult said the hunt now is "an academic exercise" and a lower priority than testing the hundreds of samples that might help contain the outbreak.
"I'm going to be trying to stay afloat" of the crush of current samples, he said.