Wednesday, October 05, 2005

Avian Flu Update

Here are some highlights from the New England Journal report on the current state of avian flu (Influenza A H5N1).

-Animal to human transmission: Most cases in Asia occurred from contact with live birds, despite many exposures to poultry products. There have been 57 deaths so far since December 2003. There is evidence the virus is beginning to adapt to human hosts.

-Human to human transmission: A number of seroconversions (evidence of virus exposure only on blood test) among household contacts and coworkers, but no serious illnesses directly attributable to H5N1.

-Clinical Features: May have longer incubation period than standard human influenza. Upper respiratory sympoms occasional. Diarrhea, vomiting, and bleeding from nose/gums are also possible. Watery diarrhea is common. Lower respiratory tract sympoms occur early and are very common, with bilateral chest x-ray findings and rapid progression to acute respiratory distress syndrome. Most require ventilatory support and intensive care for multiorgan failure upon admission.

-Mortality: 33%-100% in various inpatient cohorts, with a median death rate of the studies listed at 80%.

-Treatment: No vigorous studies are available. H5N1 is sensitive to oseltamivir and zanamivir in the test tube and in animal models, but there is evidence that we'd need to use higher doses and longer duration of treatment than for standard human influenza.

For more info on influenza in general, see here.

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