Current evidence indicates that avian influenza viruses (AIVs) do not spread easily from infected birds to humans. However, infected birds can spread AIVs through their saliva, nasal secretions and excrement. Direct contact with infected poultry, live or dead, or their secretions or excretions is a major risk factor for human infection.1,2
Worker exposure to AIVs can occur when virus particles in aerosolized droplets or dust are inhaled or contact a person’s mucous membranes, such as the eyes, nose, or mouth. Droplet exposure is most likely to occur during poultry slaughtering, defeathering, butchering, and preparation for cooking. Activities leading to dust exposure include cleaning tasks (such as using a blower to remove litter from around barn roof supports or a brush to clean cages or using a mechanical bucket to scoop up litter during litter/manure removal) and catching poultry.
Worker exposure also can occur when a person touches something that has AIV on it and then touches the mouth, eyes, or nose.3,4 This indirect exposure happens when a worker touches contaminated surfaces, objects, or materials, including contaminated litter or egg collection containers.
The role of environmental contamination in AIV transmission is not well defined. A 2009 study found the length of time that AIVs survive on surfaces varies with environmental factors, but AIVs can remain infectious for long periods under routine conditions3. A more recent study found two strains of influenza A virus remained infectious on stainless steel surfaces for more than seven days.4
When outbreaks involve human cases, AIVs are not easily spread between people. Some data indicate non-sustained, human-to-human transmission of AIVs, but most of these cases involved unprotected, close, and prolonged contact between a sick patient and caregiver.
There are documented human cases linked to consuming raw, contaminated poultry blood.5 However, no evidence exists to substantiate AIV transmission through properly prepared poultry or eggs. In either case, workers would not be expected to have any greater risk of ingestion exposure to contaminated meat or eggs than would other members of the general public.
As a general rule for food safety, the safe minimum cooking temperature for poultry is 165°F.
1 World Health Organization (WHO), Avian Influenza.
2 Centers for Disease Control and Prevention (CDC), Avian Influenza: Current Situation.
3 Stallknecht, D.E. and Brown, J. D., Tenacity of Avian Influenza Viruses, Rev. Sci. Tech., 28 (1), 56-67 (2009).
4 Perry, KA, Coulliette, AD, Rose, LJ, Shams, AM, Edwards, JR, Noble-Wang, JA et al., Persistence if Influenza A (H1N1) virus on stainless steel surfaces, Appl. Environ. Microbiol. 82:3239-3242 (2016).
5 World Health Organization (WHO), Avian Influenza.