Health Advisory HPAI Update: Assess patients with influenza-like illness for animal exposures

July 25, 2024

Action Requested 

• Be aware that there is an ongoing global outbreak of highly pathogenic avian influenza (HPAI) in wild birds, with transmission to poultry and certain mammals, including dairy cattle. There have been at least eight confirmed cases of HPAI in humans in the United States in 2024. There have been no human cases of HPAI confirmed in Washington; however, clinicians should remain vigilant for patients presenting with potential symptoms of HPAI.
  • Summer fair season increases the number of people coming into close contact with animals and may increase risk of exposure to an infected animal. 
• Consider highly pathogenic avian influenza (HPAI) H5N1 and other novel influenza virus infections in patients who present with influenza-like illness (ILI), including isolated conjunctivitis or symptoms of acute respiratory infection, and who have had recent close contact with animals known or suspected to have avian influenza A virus infection. 
• Specifically, ask patients seeking care for influenza-like illness about:
  • Exposure to cattle, pigs, poultry, or wild birds.
  • Attendance at agricultural fairs or other livestock exhibitions
  • Consumption of unpasteurized dairy products 
  • Exposure to sick or dead wildlife 
  • Contact with other animals with known or suspected avian influenza virus infection
• Clinicians should consider testing for novel influenza for patients with ILI who endorse any of the above exposures in the past ten days and have no alternative diagnosis. 
• If novel influenza infection, including HPAI H5N1, is suspected in a Snohomish County patient or healthcare facility, contact the Snohomish County Health Department immediately.
  • Call 425-339-3503 to reach the Communicable Disease program by phone.
  • Please complete and fax the Communicable Disease Report Form (PDF) and any accompanying lab reports to 425-339-8706. 
  • While working with public health, providers can also consider sending a routine influenza test that is capable of identifying influenza A, as this will likely be positive in cases of HPAI as well, which is helpful if positive particularly outside of the normal respiratory season.
• Contact the Health Department (425-339-3503) to help arrange sample collection and testing at the Washington State Public Health Laboratories. Staff can provide guidance on collecting the below samples:
  • A nasopharyngeal swab collected in viral transport medium for testing at WA PHL
  • Patients with conjunctivitis should also have a conjunctival swab collected in viral transport medium for testing at WA PHL
• Start empiric antiviral treatment as soon as possible for patients suspected to be infected with novel influenza A viruses as they have the potential to cause severe disease in humans. For more information, see the Centers for Disease Control and Prevention‘s (CDC) interim guidance on the use of antiviral medications for treatment of human infections with novel influenza A viruses associated with severe human disease.

Background

This outbreak of highly pathogenic avian influenza (HPAI) is a strain of influenza A (H5N1) which has been circulating globally in wild birds for several years. HPAI infection has been deadly for many species of birds. Cases in wild birds and poultry were first identified in Washington state in the spring of 2022. Since 2022, state agencies have detected infections in commercial and backyard poultry flocks, as well as sporadic infections of wild mammals such as skunks, raccoons, and harbor seals.

Avian influenza viruses had not previously been known to infect cattle, but in March 2024, HPAI H5N1 infection was reported in dairy cattle in Texas. The outbreak in dairy cattle has continued to spread, with outbreaks in dairy cattle now identified in at least 13 U.S. states. While outbreaks have NOT been identified in dairy cattle in Washington, infections have been identified in neighboring states, including at least 21 dairy operations in Idaho. 

Four avian influenza A(H5N1) infections in dairy workers exposed to cattle have been detected since March 2024: one in Texas, two in Michigan, and one in Colorado. Three infected workers had conjunctivitis as a sole symptom, and one had mild respiratory symptoms. Seven infections have been identified in workers exposed to infected poultry since April 28, 2022, with at least 4 of those being related to a recent outbreak at a Colorado poultry operation in July 2024. According to the U.S. Centers for Disease Control and Prevention, the current risk to the general public is low. However, it is important to understand and prepare for possible avian influenza and novel influenza infections in humans, as infections can range in severity and certain occupations are at increased risk of exposure to infected animals.

As the multistate outbreak of avian influenza A (H5N1) in dairy cattle, poultry and other animals continues and fair season begins, monitoring for novel influenza A virus infections in humans is critical to identify transmission of these viruses between animals and people. Rapid detection of, and treatment for, novel influenza A viruses and efforts to reduce transmission to other people remain important components of national efforts to prevent the emergence of new viruses that could have pandemic potential. To accomplish this, testing for influenza viruses and monitoring for novel influenza A virus infections should continue year-round.

Resources

• 2022–2024 Detections of Highly Pathogenic Avian Influenza (usda.gov)
• Clinical Overview of Evaluating and Managing Patients Exposed to Birds Infected with Avian Influenza A Viruses of Public Health Concern | Bird Flu | CDC
• H5N1 Bird Flu: Current Situation | Bird Flu | CDC
• Avian Influenza | Washington State Department of Health