May 18, 2015
Wildlife biologist affiliated the USDA will commence trapping rodent, small mammals and free- living birds on farms in Iowa to determine whether they are possible carries of avian influenza. The project will be coupled with an epidemiologic investigation of the current epornitic of HPAI.
EGG-CITE has previously advocated a comprehensive epidemiologic survey to determine the risk factors associated with outbreaks of highly pathogenic avian influenza strain H5N2 on turkey farms and on large egg-production complexes.
Trapping rodents on a farm which has been infected with HPAI will not be very helpful since the quantum of virus shed from over 2 million hens will ensure saturation of the environment. The findings as with previous studies on pasteurellosis will not differentiate between whether the rodents acquired the infectious agent from their environment or whether they serve as shedders capable of transferring virus among farms. These objectives would be better accomplished under controlled laboratory conditions. The important questions are whether rodents or endemic passeriforms (sparrows, pigeons and crows) can be infected and if so, the duration of shedding and if not how long they may serve as potential mechanical vectors.
Turkey and egg producers representing different segments of the industry need to know the risk factors contributing to outbreaks in order to plan and implement appropriate and effective protective measures. There are currently a number of theories being advanced by poultry health professionals, wildlife biologists, owners of farms and regulatory officials. Infection of a specific type of farm is obviously subject to a range of factors possibly synergistic in action. By determining the contribution of each possible factor will requires detailed field investigation with on-site observation.
Using a mailed-out survey is guaranteed to generate a result. The validity of conclusions, if apparent, will be weaker than using trained observers using a structured questionnaire and documenting findings relating to affected and unaffected farms using a case-control approach. The results of a rigorous epidemiologic investigation should be provided to the industry as soon as possible to guide implementation of effective preventive measures which will require capital expenditure and changes in operational procedures.