Cases of this type of influenza H1 virus appeared to pick up more recently, with eight of the 11 cases being reported by the CDC after June 2007, the researchers noted. The cases were spotted via the CDC's routine "passive" flu surveillance systems and additional but unidentified cases may have occurred, the experts said.
The findings suggest that "all human infections with influenza viruses of animal origin, even those that appear to be clinically mild, warrant a thorough public health investigation to assess the epidemiological risk to humans," the researchers said.
At the teleconference, Besser also discussed reports of so-called swine flu parties.
"Having swine flu H1N1 parties is a big mistake," he said. "This is a new emerging infection and we are learning more each day, but how an individual person will be impacted by the infection is not something we know. It is a big mistake. It is putting individuals and children at risk and CDC does not recommend that people follow that course."
As the outbreak continues, the CDC continues to study various aspects of the health threat to gain a better understanding of the virus, how it is spread, as well as better ways to test for it, Besser said. The research under way includes: finding a rapid diagnostic test; understanding "viral shedding" (how long people can pass the virus to others); determining how the virus is transmitted in households; and learning how well antiviral drugs work, he said.
Testing has found that the swine flu virus remains susceptible to two common antiviral drugs, Tamiflu and Relenza, according to the CDC.
On Tuesday, U.S. health officials said the outbreak of swine flu appears similar to the seasonal flu in its severity, so schools across the nation should remain open and any schools that did close should reopen.'/>"/>
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