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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Exotic & Emerging Avian Viral Diseases Research » Research » Publications at this Location » Publication #428932
Research Project: Control Strategies to Prevent and Respond to Diseases Outbreaks Caused by Avian Influenza Viruses

Location: Exotic & Emerging Avian Viral Diseases Research

Title: Caustic egg washes with a chlorine rinse inactivate avian influenza virus on eggshells

Author
item CHO, ANDREW - Orise Fellow
item Jones, Deana
item Spackman, Erica

Submitted to: Journal of Applied Poultry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2025
Publication Date: 4/12/2026
Citation: Cho, A., Jones, D.R., Spackman, E. 2026. Caustic egg washes with a chlorine rinse inactivate avian influenza virus on eggshells. Journal of Applied Poultry Research. Volume 35, Issue 3. https://doi.org/10.1016/j.japr.2026.100710.
DOI: https://doi.org/10.1016/j.japr.2026.100710

Interpretive Summary: In very rare cases, low levels of bird flu may contaminate eggs shells. Because eggs from infected hens are immediately removed from the food supply and infected hens stop laying soon after infection, it's unlikely that these eggs would ever enter the food supply. However, because eggs in the U.S. are routinely washed with sanitizers prior to packaging we tested these washes to determine whether they could inactivate the virus on egg shells. Unwashed fresh eggs from table egg laying hens were artificially contaminated with bird flu then were washed in a manner to simulate to routine practices in the egg industry. Five commercial egg wash products were tested along with a standard final rinse with chlorine. We found that the washes could consistently reduce the amount of virus on egg shells by a factor of about 100,000, which is more than the average amount of virus that could be found on eggshells. The effectiveness of these washes at inactivating bird flu provide an additional layer of protection against contamination on egg shells.

Technical Abstract: Although unlikely, highly pathogenic avian influenza virus (HPAIV) could potentially contaminate the surface of table eggs laid soon after hens are infected. The risk to consumers is largely mitigated because hens cease laying soon after infection and potentially contaminated eggs from infected flocks are removed from the food supply. However, the risk is never zero. Sanitizing washes consisting of a caustic wash (pH 11) followed by a 100-200 ppm chlorine rinse are routinely applied to table eggs in the U.S., therefore the objective of this study was to evaluate the effect of these washes on avian influenza virus (AIV) infectivity. To simulate industrial procedures, five commercial caustic eggs washes and a chlorine rinse were applied to artificially contaminated unwashed (nest run) fresh eggs from commercial table egg layers. Virus was quantified immediately after washing or after a 5-minute “contact time” and reduced the virus titer an average of 5.1 log10 50% egg infectious doses (EID50) or 5.3 log10 EID50, respectively. When the caustic washes were tested without the chlorine rinse, the reduction in titer varied among washes from 3.1 log10 EID50 to 6.8 log10 EID50 and may be due to different egg wash formulations. The 100 ppm chlorine rinse alone reduced the titer by 4.1 log10 EID50 with 5 min contact time. The titer reduction from physical washing alone with viral transport medium was 2.0 log10 EID50. These results support that the caustic washes and the chlorine rinse provide an additional layer of protection against HPAIV contamination from entering the food supply.