Q&A: Low vs. High pathogenic Avian Influenza
August 17, 2006 by Grace Ibay
Filed under Diseases & Conditions
A group writing project at Darren’s Problogger got me thinking about making a ‘list post’ for FluPatrol – how to’s? top ten? Hmm. This got sidetracked with the recent news about avian flu appearing in the USA , which, with a big sigh of relief, in all indications seem to be the the low-pathogenic strain… so this brings to mind the question:
What’s the difference between a low-pathogenic and highly pathogenic bird flu, and are they both the H5N1 sub-type?
Pathogenicity is the ability of a virus to produce disease. To answer this question, here’s a short summary I culled (pun intended!) from both the USDA and the CDC:
1. There are two types of H5N1 avian influenza (AI), the low-pathogenic (LPAI) or the “North American” strain, and the high-pathogenic (HPAI), or the notorious “Asian” stain.
2. Low pathogenic H5N1 is common to wild birds. It causes minor or nil symptoms, and therefore rarely fatal in birds. That’s what supposedly both the Dutch chickens and the Michigan swans carry.
3. In this form, the LPAI are not a concern for human health, although there have been documented cases of human transmission with mild symptoms like conjunctivitis and influenza-like illness. Examples of LPAI viruses that have infected humans include H7N7, H9N2, and H7N2.
4. High pathogenic H5N1 rapidly spreads and is often fatal to chickens, and turkeys, the worst cases of culling so far is happening in both Thailand and Indonesia . Humans get infected with these strains when there is direct contact with an infected bird. Examples of HPAI that have infected humans include H7N3 and H7N7 (mild infection); and H7N7 and H5N1 (fatal).
5. HPAI H5N1 is the subtype rapidly spreading in some parts of the world. To date, it has caused 138 human fatalities worldwide , 81 of whom died this year alone.
6. The low-path viruses have the potential to evolve to the high-path and this have been documented in some poultry outbreaks. Hence, the USDA requires tracking and reporting of both types of AI so that the virus doesn’t establish itself and start multiplying.
Tags: avian influenza, Center for Disease Control, H5N1, high-pathogenic AI, low-pathogenic AI, US Department of Agriculture, wild birds
Very interesting and informative list! Our list is up if you’d like to look… have a great day!
Thanks for putting this up. It is useful to have this information out there.
Here’s my list.