Tuesday, December 26, 2017

OIE Notified Of HPAI H5N1 In Crows - Bangladesh


Although waterfowl (ducks & geese) and gallinaceous birds (turkeys, grouse, chickens & quail) are most often associated with carriage of HPAI H5 viruses, terrestrial birds such as crows, starlings, pigeons, and sparrows are also known to carry, and shed, theses  viruses as well (see 2007’s EID Journal  Role of Terrestrial Wild Birds in Ecology of Influenza A Virus (H5N1).
As far back as 2008, we saw reports out of India of crows dying from the H5N1 virus. In 2012, and again in 2014 India saw numerous wild bird die offs that were blamed on the avian flu virus (see Media Report: H5N1 Killing Crows In Jharkhand).
While once a major hotbed of H5N1 activity, including the detection of 8 human cases, reports have become far more sporadic from Bangladesh over the past few years with only one outbreak reported in all of 2016.

This year (2017) has been only slightly more active, with 1 report of H5N1 in a poultry flock last January, quickly followed by two reports of H5N1 killing crows at the Rajshashi Medical College Campus, and again 200 miles away in Dhaka.
Today, however, the OIE is reporting two incidents in Dhaka - roughly less than 5 miles apart and on the same day (11/25/17) - involving the deaths of 63 crows.


While not exactly a unique occurrence, this is a reminder that the H5N1 virus continues to circulate in the environment, and can return to areas where it hasn't been seen in months, or even years. 

Although the incidence of terrestrial bird carriage of HPAI viruses is poorly understood and its significance remains hotly debated, recent studies and surveillance suggests their role may be greater than previously believed.   
The unexpected expansion of clade H5N8 infections to nearly 80 avian species (see ESA list of 78 affected species) last winter underscores how avian flu viruses continually evolve and adapt (see J Vet Sci: Evolution, Global Spread, And Pathogenicity Of HPAI H5Nx Clade

With the emergence of new avian flu viruses around the globe nearly every year, and an expansion of their host ranges, the research into their interactions with thousands of non-aquatic bird species has only just begun.

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