Gavin Smith wrote:

    Dear All,

    It was asked what proof there was for Dr Sim’s statements regarding reporting of infection in small flocks, and in general with the role of intensive farming in the spread of bird flu.

    Well, there is a paper published in 2004 describing H5N1 epidemiology in Thailand. I have not re-read the paper for this post, but if I remember clearly, the authors found higher levels of infection in smaller flock sizes, the opposite of what I would have expected. There is also some discussion of the reporting of disease by different sized operations.

    The reference is:

    Tiensin T., et al. (2004). Highly Pathogenic Avian Influenza H5N1, Thailand, 2004. Emerging Infectious diseases 11(11): 1664-1672.

    and can be found at: http://www.cdc.gov/ncidod/EID/vol11no11/05-0608.htm

    Best Wishes,

    I did re-read the study. Yes, it does find more detected cases of infection in backyard flocks (83% of all cases). But this figure taken alone paints a distorted picture given the much greater number of backyard flocks in the country than commercial flocks. It also doesn’t provide a comparison of the number of infected birds per flock size (given that the backyard flocks are minute in comparison with the factory farms and that mortality rates within backyard farms are generally much lower).

    Most importantly, the study found that the proportion of factory farms infected were five times higher than for backyard farms.