Thermal inactivation of avian influenza virus in poultry litter as a method to decontaminate poultry houses

Authors: STEPHENS, CHRIS - Orise Fellow; Spackman, Erica

Submitted to: Preventive Veterinary Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/2017
Publication Date: 9/15/2017
Citation: Stephens, C., Spackman, E. 2017. Thermal inactivation of avian influenza virus in poultry litter as a method to decontaminate poultry houses. Preventive Veterinary Medicine. 145:73–77. https://doi.org/10.1016/jpreventmed.2017.06.012.
DOI: https://doi.org/10.1016/j.prevetmed.2017.06.012

Interpretive Summary: Cleaning poultry houses after an outbreak of bird flu carries some risk of spreading virus. If the house can be decontaminated prior to cleaning, safety will be improved drastically. Heat can be used to kill the virus and requires minimal labor. We evaluated different temperatures for the time needed to kill bird flu in wet and dry litter. The temperature range was 50-120F in 10 degree increments. This wide range was tested because maximal temperatures that can be practically maintained vary by house style and weather conditions. It was found that moisture level did not affect inactivation times. At 80F and above the virus was killed in 1 day. At 50F-70F it could take 2-5 days. Because of unknowns in the field, adding at least 1 day to treatment times is recommended. We also attempted to correlate a test for the genetic material of the virus to inactivation, but the test would detect killed virus, therefore can not be used for testing heat treated poultry houses. This information will provide a guideline for decontaminating farms after a bird flu incident and will improve safety for the clean-up and recovery process.

Technical Abstract: Removal of contaminated material from a poultry house during recovery from an avian influenza virus (AIV) outbreak is costly and labor intensive. Because AIV is not environmentally stable, heating poultry houses may provide an alternative disinfection method. The objective was to determine the time necessary to inactivate AIV in poultry litter at temperatures achievable in a poultry house. Low pathogenic (LP) AIV inactivation was evaluated between 10.0'–48.9'C, at ~5.5'C intervals and highly pathogenic (HP) AIV inactivation was evaluated between 10.0'–43.3'C, at ~11'C intervals. Samples were collected at numerous time points for each temperature. Virus isolation in embryonating chicken eggs was con-ducted to determine if viable virus was present. Each sample was also tested by real-time RT-PCR. Low pathogenicity AIV was inactivated at 1 day at 26.7'C or above. At 10.0, 15.6 and 21.1'C, inactivation times increased to 2–5 days. Highly pathogenic AIV followed a similar trend; the virus was inactivated after1 day at 43.3'C and 32.2'C, and required 2 and 5 days for inactivation at 21.1'C and 10.0'C respectively. While low pathogenicity AIV appeared to be inactivated at a lower temperature than high pathogenicity AIV, this was not due to any difference in the strains, but due to fewer temperature points being evaluated for high pathogenicity. Endpoints for detection by real-time RT-PCR were not found even weeks after the virus was inactivated. This provides a guideline for the time required, at specific temperatures to inactivate AIV in poultry litter and likely on surfaces within the house. Heat treatment will provide an added level of safety to personnel and against further spread by eliminating infectious virus prior to cleaning a house.