Tuesday, March 24, 2015

CDC: HPAI H5 Viruses In The United States



Note: As I was away over the weekend, I missed this update posted late Friday on the CDC’s website.


# 9857

With several highly pathogenic H5 avian flu strains being reported in North America for the very first time, and good prospects that they will continue to spread via wild and migratory birds beyond the 10 states already reporting cases, the CDC has published a number of new guidance documents.


First a link to the H5 Summary (follow the links included for more detailed information), followed by excerpts from the CDC’s current risk assessment, after which I’ll return with a bit more.


H5 Viruses in the United States

Highly pathogenic avian influenza (HPAI) H5 infections have been reported in U.S. domestic poultry (backyard and commercial flocks), captive wild birds, and wild birds. HPAI H5 detections began in December 2014 and have continued into March 2015.

No human infections with these viruses have been detected at this time, however similar viruses have infected people in other countries and caused serious illness and death in some cases. While the public health risk posed by these domestic HPAI outbreaks is considered low at this time, it is possible that human infections with these viruses may occur.

Most human infections with avian influenza viruses have occurred after close and prolonged contact with infected birds or the excretions/secretions of infected birds (e.g., droppings, oral fluids). CDC has posted guidance for clinicians and public health professionals, and is working with state health departments and animal health colleagues to minimize public health risk.

CDC Recommends
  • As a general precaution, people should avoid wild birds and observe them only from a distance; avoid contact with domestic birds (poultry) that appear ill or have died; and avoid contact with surfaces that appear to be contaminated with feces from wild or domestic birds.
  • People who have had contact with infected bird(s) should monitor their own health for possible symptoms (for example, conjunctivitis, or flu-like symptoms).
  • People who have had contact with infected birds may also be given influenza antiviral drugs preventatively.
  • Health care providers evaluating patients with possible HPAI H5 infection should notify their local or state health departments which in turn should notify CDC. CDC is providing case-by-case guidance at this time.
  • There is no evidence that any human cases of avian influenza have ever been acquired by eating properly cooked poultry products.
  • CDC will update the public as new information becomes available.



Update: Outbreaks of Avian Influenza A H5 in U.S. Wild and Domestic Birds: Human Health Implications

CDC Risk Assessment

Most human infections with avian influenza viruses (including Asian HPAI H5 viruses and LPAI H7N9 in China) have occurred in people with direct or close contact with infected birds. Limited transmission from person-to-person has been documented rarely, after very close and prolonged contact with someone who is sick. Sustained human-to-human transmission with avian influenza has not been documented.

CDC considers the risk to people from these HPAI H5 infections in U.S. birds and poultry to be low at this time because infections with avian influenza viruses are rare and – when they occur – these viruses have not spread easily to other people. However it’s possible that human infections with HPAI viruses associated with these outbreaks in birds may occur at some time.

The U.S. Department of Interior and the USDA are the lead federal departments for outbreak investigation and control in wild birds and the USDA’s Animal and Plant Health Inspection Service (APHIS) is the lead agency for such activities in domestic birds. CDC is communicating and coordinating with state health departments on appropriate human health measures and is working with animal health colleagues to evaluate and minimize public health risk.

 (continue . . . )



Although closely related to the HPAI H5N8 viruses that have been reported in Asia and Europe, the HPAI H5N2 and H5N1 viruses detected in the United States are all reassortants, with genes contributed by both H5N8 and by North American Avian viruses.


In short order we’ve seen the arrival of H5N8, a `new’ reassorted H5N1, and a reassorted H5N2 emerge, and additional subtypes may evolve as they encounter other avian, human, or swine flu viruses.


While none of these HPAI H5 viruses have shown the ability to infect humans, they are related to viruses that have, and therefore must be watched for signs that they too are adapting to mammalian hosts. 


The risks right now from these viruses are low, but not zero.


The USDA offers the following biosecurity advice for those who may come in contact with wild birds:


Bird Enthusiasts:

Do not pick up deceased or obviously sick birds. Contact your State, tribal, or Federal natural resources agency if you find sick or dead birds.

  • Wear rubber gloves when cleaning your bird feeders.
  • Wash hands with soap and water immediately after cleaning feeders.
  • Do not eat, drink, or smoke while cleaning bird feeders.


Follow routine precautions when handling wild birds.

  • Do not handle or consume game animals that are obviously sick or found dead.
  • Do not eat, drink, or smoke while cleaning game.
  • Wear rubber gloves when cleaning game.
  • Wash hands with soap and water, or alcohol wipes, immediately after handling game.
  • Wash tools and working surfaces with soap and water and then disinfect.
  • Keep uncooked game in a separate container, away from cooked or ready-to-eat foods.
  • Cook game meat thoroughly; poultry should reach an internal temperature of 165 degree Fahrenheit to kill disease organisms and parasites.
  • To report unusual signs in birds you have seen in the wild, call 1-866-4-USDA-WS. To learn more about how you can help, visit usda.gov/birdflu.


Hon Ip said...

The HPAI H5N8 strain found in the US is not a reassorted virus. This strain is essentially the same as the A/crane/Kagoshima/KU1/2014(H5N8) that was found in Japan in December, 2014. Hon Ip.

Michael Coston said...

Thank you. Poor editing on my part. I've corrected the text.