Influenza A Virus Biological Agent Reference Sheet (BARS)

Last updated 08/26/2024

Summary

Agent Characteristics

Risk Group: RG-2 associated with human disease, rarely serious; preventive, or therapeutic interventions often available.

Agent Type: Virus

Description: Influenza A viruses are segmented, negative-sense, single-stranded RNA viruses in the Orthomyxoviridae family. Influenza A viruses are divided based on the nature of the glycoproteins present on the envelope, haemagglutinin (HA) and neuraminidase (NA). Variation in the surface antigens allows Influenza A viruses to have a broad host range, including humans and other animals. Only three of the 16 HA subtypes (H1, H2, and H3) and two of the 9 NA subtypes (N1 and N2) have established stable human lineages since the 1918 pandemic. Pandemics, epidemics, localized outbreaks, and sporadic cases have been caused by influenza A viruses, including High Pathogenic Avian Influenza (HPAI) strains. While many strains produce mild symptoms such as headache, sore throat, cough, and sneezing, at-risk populations can experience pulmonary complications, myocarditis, and pericarditis. Secondary bacterial pneumonia after influenza is one of the leading causes of mortality worldwide.

Host Range: Includes avian, swine, and primates, including humans, and can be broader depending on strain.

Host Shedding: Blood, saliva, feces

Route of Exposure to Humans: Aerosol/inhalation, animal bites, contaminated items, direct contact, mucous membranes, and broken skin

Infectious Dose: 100-1000 viral particles for humans, varies by strain

Incubation Period: 1-7 days

Health Hazards

Signs and symptoms of infection may include:

• Flu-like symptoms (i.e., fever, headache, dehydration, weight loss, lethargy)
• Gastrointestinal symptoms (i.e., loss of appetite, nausea, vomiting, diarrhea)
• Respiratory symptoms (i.e., coughing, sneezing)

Immunizations: Available Prophylaxis*: Antiviral drugs available

*Formal medical advice is obtained during medical consultations with Cornell Health or a primary healthcare provider as needed.

Agent Viability

For more guidance on disinfection, see: disinfectant selection.

Laboratory Hazards

• High-energy-creating activities (centrifugation, sonication, high-pressure systems, vortexing, tube cap popping)
• Handling of sharps (needles, scalpels, microtome blades, broken glass, etc.)
• Splash/droplet-creating activities (shaking incubators, liquid culturing, mechanical pipetting)
• Equipment contamination
• Exposed skin/uncovered wounds

Laboratory Acquired Infection (LAI) History: Research published in 1997 describes a case in which two people showed signs of infection after exposure to experimentally infected pigs.

Laboratory Handling Guidelines

Laboratory Biosafety Level (BSL): BSL-2 or BSL-3 for highly pathogenic avian influenza.