Swine-flu Tests Spread to 50 States, Helping U.s. Track Virus
Before this week, only the Centers for Disease Control and Prevention lab in Atlanta could definitively identify cases of swine flu, formally called H1N1. As of yesterday, 78 laboratories in 44 states received diagnostic kits, said Rachel Powell, a CDC spokeswoman.
While state labs have the equipment required to screen for swine flu, they need access to chemicals that can identify proteins specific to H1N1, said Joseph Bresee, the CDCs chief influenza epidemiologist. Fast results can help authorities stop community outbreaks early, said Donald Kaye, of Drexel University College of Medicine.
“To pick up an initial case in, say, Philadelphia and then start tracking an outbreak there is a high priority,” said Kaye, a professor of medicine at the Philadelphia school and a member of the editorial board for the journal Infectious Disease News, in a telephone interview. “Testing lets you know theres a new center for the disease.”
Previously, hospitals would collect swabs from suspected patients and sent them to the CDCs reference laboratory in Atlanta, where thousands of samples are still awaiting analysis, according to the agency.
Roches Tamiflu
Involving state laboratories will speed that process, allowing authorities to shunt drugs such as Roche Holding AGs Tamiflu to affected areas, Kaye said.
The CDC said it has confirmed swine flu in 286 patients in 36 states. At least 533 schools in 24 states were closed for the flu yesterday, according to the U.S. Department of Education.
In little more than a week, the virus has spread from Mexico and the U.S. to 19 other countries, in Central America, South America, Europe, the Middle East, Asia and Oceania. World health officials are paying attention especially to outbreaks in the Southern Hemisphere, where influenza season begins in the next few months, before a swine flu vaccine is likely to be available, the Geneva-based WHO said.
Surveillance and tests, the cornerstones of epidemiology, tell scientists which patients have the disease and provide clues about how quickly it spreads, said Michael Osterholm, director of the Center for Infectious Disease and Policy, at the University of Minnesota in Minneapolis.
Strategies Working
Information derived from precise testing lets officials know whether strategies to slow the epidemic are working, Osterholm said in a telephone interview.
All except two of the New York swine flu cases confirmed by CDC laboratory tests are connected to St. Francis, and “many hundreds” more people connected with students at the school may have been infected, said Thomas Frieden, the city health commissioner, on April 29.
“If only 20 percent were in Queens, and there were more cases in Manhattan and the Bronx, confirmed quickly by testing, that would show a different picture with the same number of cases,” Osterholm said.
More Easily Transmitted
That scenario would mean that the flu was much more easily transmitted, and that it hadnt been contained, Osterholm said.
This flu is known to scientists as influenza type A, subtype H1N1. The “H” refers to hemagglutinin and the “N” to neuraminidase, the two proteins that sit on the surface of the virus. Hemagglutinin has a spike that extends from the surface that the virus uses to bind to any cell it is infecting.
Both proteins have variations, most of which occur in birds. Drugs that inhibit the neuraminidase protein, such as Tamiflu and GlaxoSmithKline Plc.s Relenza, prevent the virus from copying itself. No approved treatments target hemagglutinin.
Though type 1 hemagglutinin is relatively common, this particular flu viruss subtype is unusual, in that it contains chunks of swine protein, Drexels Kaye said. By contrast, the strains of H1N1 that have been circulating in prior flu seasons have human H1, and there isnt much overlap between the two, Kaye said.