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Thursday, December 29, 2011

US : Novel Swine Flu Virus Now Reported in 5 States, Says CDC

Article via Medscape, a long but informative article, excerpt :

" The number of reported cases of a novel swine influenza virus has risen to 12 since July, encompassing 5 states, according to the US Centers for Disease Control and Prevention (CDC). The virus includes a gene from the human pandemic strain and affects mostly children.

The agency is taking the influenza newcomer seriously, urging public health departments, hospitals, and clinicians engaged in influenza surveillance to consider the possibility of the virus in patients presenting with influenza-like illness (ILI).

The infections in question involve a variant of the A(H3N2) virus that circulates among pigs. It contains a gene from the pandemic 2009 influenza A(H1N1) virus that codes for matrix proteins found in the viral shell.

The novel virus is worrisome enough that the CDC, the World Health Organization, and the World Organisation for Animal Health have dubbed it A(H3N2)v. The "v," which stands for "variant," distinguishes the novel virus from the seasonal A(H3N2) virus. The 2011-2012 seasonal influenza vaccine is designed to protect against this strain, the 2009 pandemic strain, and an influenza B strain.

In 3 of the 5 states where the A(H3N2)v virus has surfaced — Indiana, Pennsylvania, and Maine — patients became infected after direct or indirect contact with pigs. In Iowa and West Virginia, the other 2 states, the evidence suggests that the virus spread from human to human on a limited basis.

The CDC has not found evidence of sustained human-to-human transmission of the virus, but "all influenza viruses have the capacity to change, and it's possible this virus may become widespread," the agency states on its Web site.

One seeming bit of good news is that, so far, the A(H3N2)v virus causes illnesses that are generally no worse than those triggered by the seasonal influenza virus. Three of the 12 patients were hospitalized, but they and all the others recovered.

However, there is a bad-news chaser: The seasonal influenza vaccine for 2011-2012 is unlikely to protect people from the A(H3N2)v virus, the CDC reports. In addition, limited serologic studies indicate that young children have little preexisting immunity, although older children and adults may have limited immunity."

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