Health Alert: Presumptive Positive Human Cases of Avian Influenza Under Investigation in Washington; Recommendations for Human Health Investigation and Response

This is a Health Alert from the Washington State Department of Health (DOH) regarding human cases of avian influenza under investigation in Washington.

Public health partners should be aware that four people in Washington have tested presumptive positive for avian influenza A(H5) virus, reported by the Washington State Department of Health (DOH) on October 20, 2024. Four agricultural workers tested presumptive positive for avian influenza after working with infected poultry at a commercial farm in Franklin County experiencing an outbreak of H5N1 highly pathogenic avian influenza (HPAI) in their flock. The presumptive positive samples have been forwarded to the Centers for Disease Control and Prevention (CDC) for confirmatory testing. This is an active investigation and the number of cases under investigation may change as further test results are received.

To increase provider awareness about HPAI and to facilitate prompt reporting of suspected human cases to public health, DOH has drafted a Provider Alert (PDF) for local health jurisdictions (LHJs) and Tribal Health Partners to distribute to providers in their jurisdiction.

Current Situation in Washington

LHJs and Tribal Health Partners should be aware that four people have tested presumptive positive for avian influenza A(H5) virus in Washington state in association with an outbreak in poultry. HPAI H5N1 has been reported in wild birds, backyard poultry, and commercial poultry in Washington state and any ongoing cases and outbreaks in animals will continue to increase the risk of exposure and infection among responders, agricultural workers, and others who may be exposed to infected animals. Public health partners should review available guidance and resources for the public health response to HPAI H5N1 and be prepared to provide prevention recommendations, symptom monitoring information, testing, and treatment for people exposed to avian influenza infected animals or their environments and review guidance for investigating suspected human cases of novel influenza.

Actions Requested

  • Prepare to conduct symptom monitoring of people exposed to HPAI during and for ten days following their last known exposure. Symptoms include:
    • Fever (measured) or feeling feverish/chills; cough; sore throat; difficulty breathing (shortness of breath); eye tearing, redness or irritation (conjunctivitis); headaches; runny or stuffy nose; muscle or body aches; and/or diarrhea/vomiting.
    • Note that these signs and symptoms are non-specific and overlap with those caused by other respiratory viruses, including seasonal influenza A and B viruses. Further evaluation of symptomatic people should be performed by the state or local public health agency to assess whether testing, isolation, and/or treatment is warranted.
  • Order testing for HPAI through the Washington State Public Health Laboratories (WA PHL) for individuals with a history of HPAI exposure who develop compatible symptoms.
    • Jurisdictions should consider how they would collect samples and coordinate shipment to WA PHL.
    • For each ill individual, collect nasopharyngeal swab in viral transport medium.
    • If the person has conjunctivitis (with or without respiratory symptoms), also collect a conjunctival swab in separate VTM.
    • Submit specimens following specimen testing guidance for Influenza on the WA PHL Lab Test Menu website.
    • Each swab will need a separate requisition form through Lab Web Portal.
  • Investigate suspected human cases according to the DOH Investigation Guidelines for Influenza – Novel or Unsubtypable Strain.
  • Encourage providers to report suspected novel or avian influenza cases to their Local Public Health Jurisdiction immediately.
  • Conduct appropriate clinical decision-making around care for suspected cases of avian influenza pending testing:
    • Clinicians should be encouraged to consider highly pathogenic avian influenza (HPAI) H5N1 and other novel influenza virus infections in patients who present with acute respiratory illness, isolated conjunctivitis, or influenza-like illness (ILI), and who have had recent close contact with animals known or suspected to have avian influenza A virus infection or exposure to a suspected, probable or confirmed human case of HPAI H5N1.
    • When a suspected human case of HPAI is identified, testing and treatment should be arranged. Personnel should adhere to personal protective equipment (PPE) recommendations when collecting samples, empiric antiviral treatment should be prescribed, and the patient should be encouraged to isolate at home away from their household members and not go to work or school until it is determined they do not have avian influenza A virus infection. For more information, please visit:
    • Post-exposure prophylaxis (PEP) with influenza antiviral medications can be considered for exposed persons. For more information, please visit:
    • Testing for other potential causes of acute respiratory illness should be considered depending upon the local epidemiology of circulating respiratory viruses, including SARS-CoV-2.
  • Use appropriate precautions when interacting with potentially infected persons:
    • Standard, contact, and airborne precautions are recommended for patients presenting for medical care, evaluation, or testing who have illness consistent with influenza and recent exposure to potentially infected birds or other animals. For additional guidance on infection control precautions for patients who might be infected with HPAI A(H5N1) virus, please refer to CDC’s Interim Guidance for Infection Control Within Healthcare Settings.
  • Encourage preventative actions:
    • People should avoid unprotected exposure to sick or dead wild and domesticated animals, their feces, unpasteurized milk, or anything in the environment contaminated by animals with suspected or confirmed HPAI A(H5N1) virus infection.
    • People who cannot avoid exposure to sick or dead animals or potentially contaminated environments should follow CDC guidance for recommended PPE.
    • People exposed to HPAI A(H5N1)-virus infected animals (including people wearing recommended PPE) should monitor for signs and symptoms of influenza beginning after their first exposure and for 10 days after their last exposure.
    • Backyard bird flock owners, poultry workers, dairy workers, and responders should avoid unprotected direct physical contact with sick or dead wild and domesticated animals, carcasses, feces, unpasteurized milk or litter from infected animals.
      • Workers should wear recommended PPE when in direct contact with sick or dead birds, carcasses, feces, unpasteurized milk, or litter from potentially infected animals, and when going into any buildings with sick or dead animals, carcasses, feces, or litter from potentially infected animals.
  • Report sick/dead domestic birds or livestock to the Washington State Department of Agriculture's Avian Health Program: 1-800-606-3056.
  • Report sick/dead wild birds or other wildlife online to the Washington State Department of Fish & Wildlife.

For more information on avian influenza in humans, please refer to the resources below.

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; as the name suggests, HPAI infection has been deadly for many species of birds. Cases of HPAI in wild birds and poultry were first identified in Washington state in the spring of 2022. Since 2022, WA 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. There have been no detections of HPAI H5N1 in dairy cattle in Washington state. On October 20, 2024, four presumed human cases of avian influenza under investigation were reported among poultry workers in Washington State who had direct contact with infected poultry.

Since the start of the outbreak in 2022, nine cases of avian influenza A(H5N1) infection in commercial poultry workers have been detected in Colorado, seventeen cases of avian influenza A(H5N1) infections in dairy workers exposed to dairy cattle have been detected (Texas (1), Michigan (2), Colorado (1), California (13)), and one case of avian influenza A(H5N1) infection has been detected in a person in Missouri with no known exposure to infected animals. 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 from mild to fatal and certain occupations are at increased risk of exposure to infected animals.

As the multistate outbreak of avian influenza A (H5N1) in poultry, dairy cattle, and other animals continues, 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

For questions, or to report cases, please contact your Local Health Jurisdiction.