For years we’ve been worried about a bird influenza strain (H5N1) mutating to infect humans and permit human-to-human transmission. Now it appears that a pig flu (H1N1) has in fact adapted to humans, infecting almost a thousand in Mexico and several in the US, and causing nearly 100 deaths.
The United States government declared a public health emergency Sunday as the number of identified cases of swine flu in the nation rose to 20.
The declaration is part of a “standard operating procedure” that will make available additional government resources to combat the virus, Homeland Security Secretary Janet Napolitano said at the White House.
Additional cases of swine flu are expected to be reported in the coming days, added Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention.
Past flu pandemics have caused up to a million casualties, and the epic 1918 “Spanish” flu pandemic is estimated to have killed up 10% of young adults worldwide. However, there have been false alarms as well; a few cases in 1976 prompted massive immunizations in the US for an epidemic that never materialied, and the vaccine caused a number of adverse reactions.
Unlike earlier epidemics, however, it appears that public health services are being more proactive, both in monitoring the disease and in responding, in Mexico, with closure of gathering places such as schools. It’s thus very possible that we will avoid repeating the mistakes of past pandemics that led to mass casualties. However, this is a story to keep an eye on.
Here’s a presentation that two classmates and I did for an infectious disease class. It talks about the experience of the 1918 flu pandemic, the biology of the influenza virus, and the precautions necessary to prevent a new pandemic (bird flu in this case, but relevant to today).