A blogger with the moniker Mike the Mad Biologist has written short critique of ideas from Ewald (and covered by Wendy Orent in several articles); seems to hinge largely on flu being transmissible before symptoms.
Evolution, Tradeoffs, Ignoring Biology, and Influenza
Doesn’t seem arguments are real substantial; not helped by what seems to me a rather curious quote re a colleague referring to "those stupid fucking natural history facts." Main one of these facts being again related to flu being transmissible before symptoms (tho as Orent notes, h5n1 is not transmissible – or darn near not transmissible – in humans). I’ve just added comment: Is flu just as contagious during asymptomatic phase. as when symptoms evident (and those with bad cases become immobile)? What of 1918 flu? Just coincidence it evolved – Ewald argues – during Western Front conditions? (And human flu otherwise not major problem; if it could readily evolve to high virulence, shouldn’t it do so more often, and even stay that way?) And why are regular bird flus "mild", yet crowd poultry in "disease factories" and get a flurry of highly pathogenic flus evolving? To me – a birder not biologist – latter seem to be neatly explained by ideas Orent writes of. (Any other theories able to explain these latter facts? Poultry farms would seem "good", accidental experiments that help confirm Ewald’s theory.)