Wednesday, April 29, 2015

Two CDC Updates: HPAI H5 & H3N2 Canine Flu


CDC HPAI Risk Assessment


# 9992


Although neither of these viruses have shown the ability to infect humans, they are nevertheless newly arrived pathogens in North America, are spreading with impressive speed, and are capable of further evolution.  


All of which means that – while they currently pose little threat to human health -  they need to be carefully watched.

The CDC has updated their HPAI H5 webpage, and has published an announcement on the sequencing of the canine H3N2 virus, which they say shows no overt signs of being better able to infect humans than the H3N8 canine flu.


H5 Viruses in the United States

Page last updated: April 29, 2015

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 April 2015. USDA is reporting that H5 viruses have been detected in birds in 18 U.S. states; 13 states have experienced outbreaks in poultry flocks and 5 states have detected H5 in wild birds.

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. Human infections with other 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).

While the health risk posed to the general public by these domestic HPAI outbreaks is low at this time, it is possible that human infections with these viruses may occur. CDC has guidance for clinicians and public health professionals in the United States on appropriate follow-up, preventive treatment, testing, specimen collection and processing of samples from patients who may be infected with H5 viruses and has been in close contact with state health departments from all 16 states that have detected H5 in birds.

CDC Recommendations for the Public
  • 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 on H3N2 Canine Influenza (Dog Flu) Virus

April 28, 2015 – Experts from CDC’s Influenza Division have analyzed genetic sequences of the H3N2 canine influenza A virus recently detected in the United States and found no evidence suggesting an increased potential for this virus to infect humans or cause severe disease in humans. Therefore, the risk to humans posed by this virus continues to be low and is equivalent to that associated with previously circulating H3N8 canine influenza viruses.

CDC conducts year-round surveillance and genetic analysis on circulating human and novel influenza A viruses in order to assess human health risk and prepare for vaccine virus selection. This work is based in part on an informal inventory of genetic mutations that are associated with viral characteristics like increased transmissibility or severity. While genetic analysis of the H3N2 canine flu virus did not show any of these markers, the agency will continue to analyze this virus and watch the field situation closely.

H3N2 canine flu virus is responsible for an outbreak of dog flu reported in the Chicago area according to a press release issued by Cornell University, home to the New York State Animal Diagnostic Laboratory. Dog flu is a contagious respiratory disease in dogs. Two canine influenza viruses have been identified worldwide: an influenza A H3N8 virus and an influenza A H3N2 virus. No human infections with either of these canine influenza viruses have ever been reported.

Previously, canine influenza A H3N8 viruses have been identified in U.S. dog populations. However, testing at the New York State Animal Diagnostic Laboratory and the Wisconsin Veterinary Diagnostic Laboratory showed that the dog flu virus responsible for the current outbreak in dogs is an H3N2 virus. This virus is similar to H3N2 dog flu viruses that have been detected in dogs in parts of Asia since 2007.

Updates on ongoing antigenic and phenotypic analyses will be shared when they are available. For more information on canine influenza (dog flu), please visit Key Facts about Canine Influenza.

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