APHIS Releases Partial Epidemiology Report on Highly Pathogenic Avian Influenza

APHIS Releases Partial Epidemiology Report on Highly Pathogenic Avian Influenza June 15, 2015 – The United States Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) today released an epidemiology report outlining its initial findings through June 5 about how highly pathogenic avian influenza (HPAI) was likely entering new premises during this period of time. After conducting investigations on over 80 commercial poultry farms, APHIS analysis indicates that there are likely several ways the virus could be transmitted, including lapses in biosecurity practices and environmental factors. APHIS cannot, however, associate HPAI transmission with one factor or group of factors in a statistically significant way at this time, and will continue to update this report regularly as more analyses are completed. APHIS scientists believe wild birds were responsible for introducing HPAI into commercial poultry. While wild birds are the original pathway for the virus’ introduction into the United States, it appears the virus was spreading in other ways as well, given the number and proximity of farms affected by HPAI. For instance, the report provides evidence that a certain cluster of farms was affected by identical viruses, pointing to possible transmission among those farms. In addition, genetic analyses of the HPAI viruses suggest that independent introductions as well as transmission between farms were occurring in several States concurrently. For example, APHIS has observed the following: sharing of equipment between an infected and non-infected farm; employees moving between infected and non-infected farms; lack of cleaning and disinfection of vehicles moving between farms; and reports of rodents or small wild birds inside the poultry houses. APHIS is compiling these practices and will present these findings in a subsequent update of this report. Based on an analysis by APHIS, environmental factors may also play a part in transmitting HPAI. APHIS found that air samples collected outside of infected poultry houses contain virus particles, indicating that the virus could be transmitted by air. In addition, preliminary analysis of wind data shows a relationship between sustained high winds and an increase in the number of infected farms approximately 5 days later. APHIS is conducting additional analyses to better characterize environmental factors that may contribute to virus spread. … …