USDA Updates Mammalian Wildlife H5N1 List

 

#18,491

After several months with almost no additions, over the past week the USDA has added a dozen new mammalian wildlife detections to their Detections of Highly Pathogenic Avian Influenza in Mammals list.  

The numbers as presented, however, are a little confusing. 

The USDA chart indicates 419 total entries, up from 404 two weeks ago. The following 5 new entries were added last week:

Today's update shows 5 more added to the list, along with 2 more embedded further down on the 2nd page.

While 12 + 404 should equal 416, the chart indicates 419. 

After a bit of head scratching I discovered there are 3 `null' records at the bottom of this list, inflating the number.

After 194 submissions to this list between May and July of this year, we've seen only 23 additions over the past 21 weeks.  It is not entirely clear why we've seen this dramatic drop off in reporting, considering the massive number of livestock infected around the nation. 

It also isn't clear why the vast majority of the reports have come from northern states , although some of that may come down to differences in climate and terrain (swamps vs. forests vs. deserts). 

But mostly, it appears as if some states may be looking harder than others. While all 50 states have reported HPAI H5 in birds, only 35 have reported spillovers into mammals.   

Admittedly, mammals often die in remote and difficult to access places where their carcasses are quickly scavenged by other animals, meaning most never discovered or tested. And of course, some of these animals are likely to survive the infection, and are never tested.

But we need more surveillance of wildlife, not less.  

Particularly since spillovers to mammals could potentially lead to a more mammalian adapted virus (see Emerg. Microbes & Inf.: Marked Neurotropism and Potential Adaptation of H5N1 Clade 2.3.4.4.b Virus in Naturally Infected Domestic Cats). 

It is worth noting that of the 12 cases reported over the past two week 8 (75%) are feline. We also know that many go unreported. 

While the loss of (mostly) peridomestic animals to H5N1 may not seem terribly concerning, this is a vital link in the evolution of the virus that we simply should not ignore. 

What happens with this virus in mice, or cats, or marine mammals may prove to be just as important to the evolution of the virus as what happens in birds or cattle. 

While there may be some bliss in ignoring these spillovers, we do so at considerable risk.