Avian Flu Diary: An Overview of Significant HPAI H5 Related Events Over The Past 4 Weeks

#18,472

Twenty-eight days, and 66 blog entries ago, we took a look back at the previous 3 weeks of rapid-fire developments surrounding HPAI H5, and on several fronts the pace has only quickened since then.

Admittedly, H5N1 isn't the only threat we are concerned with (see DRC `Mystery Virus' investigation), but it is the most pressing, and currently the closest to home.

Over the past 4 weeks:

The number of confirmed H5 human cases in the U.S. has increased by 12, to 58 (with several more announced by states, but not yet confirmed by the CDC.) If you count serologically confirmed cases (the CDC doesn't) - and those in the pipeline - we are well over 70 cases.

The number of known infected dairy herds has grown from 473 to > 720 (a 65% increase), and a 16th State (Nevada) is now reporting cases.

Over the past 4 weeks more than 9 million birds from 78 flocks across 8 states have been infected (and lost) due to H5N1 in the United States, and Canada has reported > 50 outbreaks in poultry.

According to the Marin County Health Dept. they are investigating a second Bay Area child with suspected H5 infection, and currently no known risk exposure. If confirmed, this would become the 3rd `community' case, not linked to occupational exposure.

Hawaii reported H5 in wastewater samples on Nov 13th, and at least two outbreaks in captive and/or wild birds the following week, marking the first known detections in that state.

In case you missed them, some significant H5 events over the past 4 weeks (from oldest to newest) include:

On November 13th Canada's PHAC confirmed their H5 infected teenager was infected with genotype D1.1 (not the bovine genotype). The patient, at last report, is sill in intensive care and on a ventilator, and no risk exposure has been identified.

On Nov 20th, in Preprint: Enhanced Encephalitic Tropism of Bovine H5N1 Compared to the Vietnam H5N1 Isolate in Mice we looked research suggesting the bovine genotype is far more neurotropic in lab animals (mice) than its ancestral strains.

On Nov 22nd, the CDC Confirmed H5N1 Infection In A Child from Alameda county, California, becoming the second U.S. infection not linked to occupational exposure.

On Nov 25th California announced the first of (now 3) recalls of raw milk products due to H5 contamination.

On Nov 27th Hong Kong Conducted a Coordinated Avian Flu Drill `Amazonite'

On Dec 1st we looked at the continued expansion and spread of H5N5 in both Canada and Europe.

On Dec 2nd, in Nature: Influenza A(H5N1) Shedding in Air Corresponds to Transmissibility in Mammals we saw evidence that H5N1 is slowly becoming more transmissible.

On Dec 3rd the UK announced their intent to purchase > 5 million doses of H5N1 vaccine.

On Dec 4th PAHO issued an Epidemiological Alert urging all Member nations to `. . . ensure preparedness for a potential influenza pandemic at all levels (14, 15).'

On Dec 6th, in Science: A Single Mutation in Bovine Influenza H5N1 Hemagglutinin Switches Specificity to Human Receptors NIH researchers warned that H5 could be as little as `one mutation away' from becoming more transmissible in humans.

And those are just the highlights. We also saw evidence of H5N1 spillover into horses, WOAH's updated statement on H5N1 in Cattle, the USDA's belated Federal order to Begin a National Milk Testing Strategy for Avian Flu, among others.

While the trends are ominous, we still don't know if H5N1 is capable of adapting well enough to humans to spark a pandemic. Of course, by the time we have proof positive, it will be too late to act.

Which is why last weekend I urged that my readers begin to prepare as if another pandemic may be in the offing (see A Personal Pre-Pandemic Plan).