Idaho - Health Advisory: Consider avian influenza A (H5N1) in patients with dairy cattle or poultry exposure (CDH, June 16, 2026)

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Health Advisory: Consider Avian Influenza A (H5N1) in Patients with Dairy Cattle or Poultry Exposure

by Trent Young on June 16, 2026

HEALTH ALERT NETWORK – Health District 4

Advisory for Healthcare Providers: Consider Avian Influenza A (H5N1) in Patients with Dairy Cattle or Poultry Exposure

Key Messages

Local Situation: Avian Influenza A (H5N1) has been confirmed in over 80 Idaho dairy premises, including 12 in District 4 currently under ISDA quarantine.

• Clinical Suspicion: Consider H5N1 infection in patients presenting with conjunctivitis or acute respiratory illness who report recent exposure to dairy cattle, sick poultry, or contaminated environments.
• Report Immediately: Novel influenza A infections are immediately reportable. Contact CDH at 208-327-8625 to report suspected cases.
• Occupational Risk: While the risk to the general public remains low, agricultural workers and others with direct animal exposure are at increased risk.

Background and Current Situation

Due to ongoing H5N1 detections in Idaho dairy herds and continued circulation in poultry, clinicians should consider H5N1 in patients with compatible illness and relevant exposure histories.

Since its detection in U.S. dairy cattle in March 2024, H5N1 has spread to more than 1,100 dairy herds across at least 20 states. There have been 71 reported human cases in the U.S. since 2024, most associated with dairy cattle exposure and direct contact with infected animals or contaminated milk. No human cases have been reported in Idaho. Most U.S. infections have been mild and characterized by conjunctivitis, although respiratory illness and severe disease can occur. There is no evidence of sustained person-to-person transmission.

Individuals at increased risk of exposure include:

• Dairy farm workers and milkers
• Veterinarians and animal health personnel
• Farm support staff (cleaning, transport, equipment handling)
• Household contacts of exposed workers

Clinical Presentation

Mild / Typical Illness:

• Conjunctivitis (redness, irritation, discharge, foreign body sensation)
• Fever, cough, sore throat, rhinorrhea
• Fatigue, headache, myalgia, arthralgia
• Gastrointestinal symptoms

Moderate to Severe Illness:

• Shortness of breath
• Altered mental status or seizures
• Pneumonia, ARDS, sepsis, multi-organ failure

Asymptomatic Testing: Consider testing asymptomatic individuals with high-risk exposures (e.g., exposure to infected animals without recommended PPE or after a PPE breach). Collect respiratory and conjunctival specimens as recommended.

Laboratory Testing and Specimen Collection

Idaho Bureau of Laboratories (IBL) Submission:
Order Name: Influenza Subtyping
Aliases: Flu A/B PCR, Flu A subtyping, H5N1, HPAI
Commercial Lab Availability for Influenza A (H5):

• ARUP: Respiratory or conjunctival swabs
• LabCorp: Nasopharyngeal (NP) swabs only
• Quest: NP, nasal, OP, BAL, or conjunctival swabs

Standard Specimen Collection:

• Nasopharyngeal (NP) swab in one viral transport medium (VTM) tube
• Nasal and oropharyngeal (OP) swabs combined in a second VTM tube
• If conjunctivitis is present, collect a conjunctival swab in a separate VTM tube
• For severe illness, collect lower respiratory specimens (e.g., bronchoalveolar lavage or endotracheal aspirate) when feasible
• Rapid influenza diagnostic tests have limited sensitivity and should not be used to rule out H5N1 infection

Handling and Transport

• Coordinate specimen collection and submission with Central District Health before shipping.
• Store specimens:
  • 2–8°C for up to 72 hours, OR
  • ≤ −20°C for longer storage (up to 30 days)
• If frozen:
  • Do NOT thaw before testing
  • Ship on dry ice for overnight delivery
• If refrigerated, transport promptly on cold packs

Antiviral Treatment and Prophylaxis

• Do NOT delay treatment while awaiting results.
• Initiate oseltamivir 75 mg orally twice daily for 5 days for symptomatic adolescents and adults with suspected H5N1 infection. Refer to CDC guidance for pediatric dosing.
• Consider post-exposure prophylaxis for individuals with high-risk exposures, using recommended treatment dosing for 5 or 10 days, depending on the exposure scenario.

Central District Health Contact: 208-327-8625

Resources

• Avian Influenza (Bird Flu): Highly Pathogenic Avian Influenza A(H5N1) Virus: Interim Recommendations for Prevention, Monitoring, and Public Health. CDC.gov Updated December 26, 2024. Accessed January 09, 2026.
• https://www.cdc.gov/bird-flu/prevention/hpai-interim-recommendations.html
• Emergency Use Instructions (EUI) Fact Sheet for Healthcare Providers: Oseltamivir for Treatment or Post-Exposure Prophylaxis of Novel Influenza A. February 18, 2025. https://www.cdc.gov/bird-flu/media/pdfs/2024/07/Oseltamivir-EUI-HCP_1.pdf
• Avian Influenza (Bird Flu): Interim Guidance on Specimen Collection and Testing for Patients with Suspected Infection with Novel Influenza A Viruses Associated with Severe Disease or with the Potential to Cause Severe Disease in Humans. CDC .gov. Updated May 15, 2025. Accessed January 09, 2026. https://www.cdc.gov/bird-flu/php/severe-potential/index.html

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