Homeland Security Watch

News and analysis of critical issues in homeland security

May 6, 2009

Flu threat continues to evolve

Filed under: Biosecurity — by Philip J. Palin on May 6, 2009

A thirty-three year old Texas school teacher has been confirmed as the second US fatality of the H1N1 virus, even as public health mitigation efforts are being eased in Mexico City, Washington D.C.,  San Francisco, and elsewhere.

Late Tuesday, Secretary Napolitano explained, “the CDC [Centers for Disease Control] today modified its interim guidance regarding the closure of schools and child care facilities. As CDC announced earlier today, this particular strain is currently causing a disease similar in nature to seasonal influenza, and with the new information they’ve been able to collect, no longer recommend communities immediately close schools. Instead, teachers and students with influenza-like illness should stay home, which is consistent with what would be recommended during a typical flu season. ”

As of noon eastern on Wednesday the WHO pandemic alert remains at phase 5.  But as the number of confirmed European diagnoses increases a move to phase 6 is considered likely.  WHO standards  call for declaring phase 6 when a community-level outbreak is confirmed in two WHO regions.  Such an outbreak in Europe — in Spain or the United Kingdom — now seems likely. 

The official WHO count of laboratory confirmed cases of H1N1 infection now stands at 1516 scattered across twenty-two countries.  But the disease is in most cases presenting itself with a severity similar to seasonal flu.

Public health officials caution that the new influenza strain could still strengthen through ongoing mutation.

 A report this morning from National Public Radio underlines the unpredictability of the flu virus.  According to NPR, a possible  mutation of the H3N2 strain of seasonal flu may have emerged.  According to Canadian scientists, “In British Columbia, the H3N2 virus causes more severe cases of flu than H1N1 does,” Brunham says. “So we wonder if some of the severe cases in Mexico may have been caused by the variant H3N2 virus.”

Scientists are also concerned that H1N1 could return during the fall flu season with greater strength.  According to the Baltimore Sun,  “the worst is likely still to come. In pandemics of the past, flu that arrived in the spring hit harder come fall, when influenza season returned.”

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