Michael Jhung, MD, Influenza Division, National Center for Immunization and Respiratory Disease, and Deborah Nelson, Ph.D., Animal and Plant Health Inspection Service, US Department of Agriculture, provided an update on reports of highly pathogenic avian influenza and guidance from the Atlanta-based Centers for Disease Control and Prevention. The article appeared in an early release of the CDC’s Morbidity and Mortality Weekly Report (MMWR).
The authors noted that the US Department of Agriculture received 14 reports of birds infected with Asian-origin, highly pathogenic avian influenza A (HPAI) between Dec. 15, 2014 and Jan. 16, 2015. The MMWR report states although these viruses — H5N2, H5N8 and H5N1 — are not known to have caused human illnesses, their presence in North America might increase the likelihood of human infections caused by other avian influenza viruses. Viruses such as H5N1 and H5N6 viruses and H7N9 have been known to cause severe illness in humans and sometimes death.
“The 14 HPAI H5 detections, seven (H5N2), six (H5N8), and one (H5N1), occurred in five northwestern states (California, Idaho, Oregon, Utah, and Washington),” the MMRW report stated. “Outbreaks occurred in five domestic, backyard flocks, two captive wild birds, and seven wild aquatic birds. All backyard flocks were destroyed after identification of HPAI H5 virus. Of 24 persons reporting exposure to infected birds, one person developed influenza-like illness (ILI) after exposure, but subsequently tested negative for influenza.”
The report said CDC has developed testing and guidance for individuals exposed to birds infected with HPAI H5 viruses. “Until more is known about these viruses, CDC is taking a cautious approach, and recommendations are largely consistent with guidance for influenza viruses associated with severe disease in humans,” the report stated.
Canada also is on the lookout for human infections with H7N9 avian influenza. The Public Health Agency of Canada reported two cases of avian influenza A (H7N9) imported from China. The first case was reported on Jan. 26, and a second case was confirmed on Jan. 29, the agency reported.
“They are the first North Americans known to have been infected with this virus,” according to the agency. “The individuals were from British Columbia and traveled together to China. Neither required hospitalization and both have recovered.”
The agency added that the health risk posed by the H7N9 from China to Canada is considered low. Available research indicates the virus does not transmit easily among humans.
Currently, no travel restrictions have been issued in response to the confirmed cases. However, a travel health notice was posted on Jan. 16 to advise Canadian travelers on ways to minimize their risk of being exposed to avian influenza.