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Avian Influenza A(H5N1): Information for Health Care Providers

Go to: Background | Clinical Information | At Risk Populations in NYC | Testing | Patient Management and Treatment | Prevention | Equity in Care

Update on Avian Influenza in New York City

There have been no known cases of human-to-human transmission of avian influenza A(H5N1) reported at this time, and the risk of infection is low for the public. No human A(H5N1) infections have been reported in NYC or New York State.

In NYC, people at greatest risk of exposure to A(H5N1)-infected birds include people who work at live bird markets or with wild birds.

Action Items for Clinicians

Background

Avian influenza A viruses are widespread in wild and domestic birds worldwide. Since 2021, clade 2.3.4.4b of the highly pathogenic avian influenza (HPAI) A(H5N1) virus has been circulating in North America. HPAI viruses (including some H5 and H7 subtypes) can cause severe disease in birds and some mammals. The HPAI subtype of greatest concern is A(H5N1), of which there have been a small number of human cases in the U.S.

People with occupational exposures to A(H5N1)-infected animals or their contaminated environments or products (such as poultry and dairy farm workers) may be at increased risk of infection.

Clinical Information

The most common presenting sign reported among people in the U.S. infected with A(H5N1) has been conjunctivitis.

Other signs and symptoms of A(H5N1) virus infection may include:

  • Low-grade fever
  • Cough
  • Sore throat
  • Nasal congestion
  • Myalgia
  • Headaches
  • Fatigue
  • Shortness of breath or difficulty breathing

Infection with influenza viruses, including A(H5N1), may not result in fever. Less common symptoms include diarrhea, nausea, and vomiting. Infections can also be asymptomatic.

At-Risk Populations in NYC

In NYC, people who work with water birds and poultry may be at higher risk of exposure to A(H5N1) than the general public. Risk of infection with A(H5N1) tends to coincide with the spring and fall migratory seasons as birds that are infected pass through the NYC area.

People who have a greater exposure risk are those who work with:

  • Water birds
    • Parks staff
    • Wildlife rehabilitators
    • Zoo staff
  • Poultry
    • Live bird market staff and inspectors
    • Community garden staff who have chickens on their site
    • People who own live domesticated poultry birds such as chickens

Compared to other mammals, cats and dairy cows are especially susceptible to infection with A(H5N1) viruses. A(H5N1) has been detected in a very small number of mammals in NYC, including wildlife (raccoons and skunks) and domestic pets (indoor cats that consumed raw pet food).

People with close, prolonged, and unprotected exposure to A(H5N1)-infected mammals, such as the individuals below, may also be at risk:

  • Veterinarians
  • Veterinary staff
  • Animal shelter staff

H5N1 virus may also be present in the feces of infected birds and animals, or any surface or water sources (such as ponds) contaminated with their feces or possibly other bodily fluids.

Learn more about avian influenza prevention for animal healthcare providers.

Infection Prevention and Control

If A(H5N1) infection is suspected, immediately isolate the patient and implement standard, contact, and airborne precautions with eye protection when providing care.

Appropriate infection control measures include:

  • Gloves
  • Gown
  • Respiratory protection (such as fit-tested N95)
  • Eye protection (such as goggles or face shield)
  • Placing the patient with confirmed or suspected A(H5N1) in an airborne infection isolation room; if not available, place a face mask on the patient and isolate them in an examination room with the door closed.

Testing and Precautions

  • All people hospitalized with influenza A, especially people managed in an intensive care unit (ICU), should have respiratory specimens subtyped for seasonal influenza viruses (H1, H3); see below for more guidance on testing.
  • Patients with signs or symptoms of acute respiratory illness or conjunctivitis who have been exposed to a known or suspected A(H5N1)-infected bird or animal should be tested for avian influenza as soon as possible after symptom onset. Call the Health Department Provider Access Line at 866-692-3641 if caring for a patient with suspected A(H5N1).
  • Healthcare providers should follow standard, contact, and airborne precautions when caring for patients suspected of having A(H5N1) infection.

Specimen Collection

Collect specimens using swabs with an aluminum or plastic shaft and a synthetic tip (e.g., polyester or Dacron®). Place swab specimens in vials with sterile viral transport medium (VTM) or universal transport medium (UTM).

For patients with acute respiratory symptoms: 

  • Collect three swabs
    • A nasopharyngeal swab, a nasal swab, and a throat swab: The nasal and throat swabs should be combined into one vial of VTM or UTM.
    • Place the nasopharyngeal swab in one vial and the combined nasal and throat swabs in second vial. A total of two vials with VTM or UTM should be submitted.

For patients with conjunctivitis, with or without respiratory symptoms:

  • Collect two specimens
    • A conjunctival swab: collect the conjunctival swab from both conjunctivae separately if there is bilateral conjunctivitis
    • A nasopharyngeal swab
  • Place the conjunctival swab(s) in one vial and the nasopharyngeal swab in a second vial. All vials should contain VTM or UTM.

Specimens should be refrigerated for up to 72 hours after collection and transported on ice packs. For specimens that will not be tested until more than 72 hours after collection, specimens must be frozen and transported on dry ice.

Testing Process

Most commercially available clinical influenza tests are designed only to detect influenza or influenza A, while some tests can differentiate influenza A seasonal subtypes H3 and H1. Commercially available tests are unable to differentiate avian influenza A(H5).

When testing a person for influenza A (H5):

  • If positive for influenza A, attempt subtyping for H1 and H3, which indicate infection with a seasonal virus, if feasible.
  • If the influenza A subtyping does not detect H1 or H3, it is referred to as “unsubtypeable,” and additional testing at NYC Public Health Laboratory may be indicated. Contact the NYC Public Health Laboratory for this testing. NOTE: Low viral load may impact the ability to determine subtype.
  • If a patient tests positive for seasonal influenza subtypes H1 or H3, testing for H5 is not indicated unless exposure history suggests H5 exposure.
  • If subtyping for seasonal influenza is not feasible via in-house or commercial testing, submit to the NYC Public Health Laboratory for subtyping.

If H5 infection is highly suspected, testing for H5 at the NYC Public Health Laboratory should be performed on influenza A-positive specimens, in lieu of seasonal subtyping.

Call the Health Department Public Health Laboratory at 212-671-5890 to coordinate specimen submission and transport.

Patient Management and Treatment

Antiviral treatment is recommended as soon as possible for all patients suspected of A(H5N1) infection based on clinical presentation and exposure.

Currently circulating avian influenza, A(H5N1) viruses are generally susceptible to antiviral medicines recommended for management of seasonal influenza. Treatment should not be delayed while awaiting laboratory testing results. Antiviral prophylaxis may also be recommended for close contacts of individuals with confirmed or probable A(H5N1) infection, such as those residing in the same household.

Initiate oseltamivir as soon as possible for symptomatic persons with confirmed, probable, or suspected A(H5N1) infection. Combination antiviral treatment (e.g., oseltamivir and baloxavir) can be considered for patients with more severe disease, particularly pneumonia, or outpatients who do not require hospitalization, but who are immunocompromised.

Contact the Health Department Provider Access Line at 866-692-3641 for consultation regarding management of patients and contacts with suspected A(H5N1) infection.

Prevention

Advise patients who work with birds and mammals with known or suspected A(H5N1) infection to use appropriate personal protective equipment and to receive the seasonal influenza vaccine during influenza season.

The seasonal influenza vaccine does not protect against A(H5N1) infection; however, it is important to get vaccinated to reduce the risk of seasonal influenza. Seasonal flu vaccination may also reduce the risk of an individual being coinfected with both seasonal and avian influenza viruses, a rare situation which could lead to genetic reassortment and the possible creation of a new influenza strain that could pose greater public health risk.

Learn more about influenza information for providers and immunization information for providers.

Reporting Requirements

Providers should immediately report any suspected human cases of A(H5N1) infections to the NYC Health Department.

Equity in Care

People who work within live animal markets, handle poultry products, or have close contact with animals may be at higher risk of exposure to A(H5N1) viruses. For some individuals, factors such as limited language access, lack of insurance, concerns about immigration status, or experiences of discrimination can delay care. We encourage providers to review the resources below to ensure patients receive equitable access to care:

Additional Resources

More Information