Livestock Ectoparasites in a Warming World

Authors Wall et al. (2011) say that "the prevalence of livestock ectoparasites is the result of a complex interaction of factors such as parasite and host abundance, host susceptibility, climate and, critically, farmer husbandry and intervention strategies, all of which change seasonally in space and time." And, therefore, they state that "the effects of any climate change on disease incidence are hard to predict," whereas climate alarmists often go directly from warming to unmitigated catastrophe with respect to whatever host-parasite system they may be discussing.

In an effort to further explore the subject, Wall et al. used a detailed analysis of cutaneous myiasis in sheep -- which is spread by the blowfly Lucilia sericata in the United Kingdom -- to illustrate the great complexity of this issue. So what did they learn?

The four researchers report that "both simulation and spatial species distribution models show that the range of elevated temperatures predicted by current climate change scenarios is likely to result in an elongated blowfly season with earlier spring emergence and a higher cumulative incidence of strike." However, they hasten to add that "the models suggest that simple changes in some husbandry practices, such as shearing or trap use, could have an important effect in reducing early season ewe strike incidences," and that "practical measures exist which, with modest changes in husbandry practices, should be able to manage expected increases in strike."

The UK scientists conclude that the key message of their work is that "simple extrapolations of the known effects of temperature on ectoparasite development," in an attempt to "predict changes in disease incidence in a warmer climate," is simply "too simplistic." Quite to the contrary, they write that "attempts to predict the likely impact of climate change on disease incidence must take into account changes in farmer behavior and animal management practices as well as parasite biology." And this conclusion holds equally true for any number of afflictions of both man and beast alike.