Temperature changes may impact disease outcomes

Temperature fluctuations and extreme weather events can impact infection rates and disease outcomes, according to a new report published in eLife.

It is well understood that interactions between pathogens and their hosts are sensitive to temperature changes, however, a new study shows that as the climate changes it will become increasingly difficult to predict the impact on host-pathogen interactions. 

The researchers examined the effects of different temperatures on various traits in a host organism and found that daily fluctuations of temperature reduced the infectivity and spore burden of the parasite compared to those kept at the constant average temperature.

However, by contrast, the infectivity of parasites after a heatwave was almost the same as the infectivity of those maintained at the constant temperature.

Moreover, the number of spores in the host increased following the three-day ‘heatwave’ when the background constant temperature was 16°C, but this burden was reduced at higher temperatures. This suggests that the effects of temperature variation differ depending on the average background temperature and whether this is close to the optimum temperature for the parasite.

‘Climate change is predicted to increase not only average temperatures but also temperature fluctuations and the frequency and intensity of extreme weather events,’ explains co-first author Pepijn Luijckx, William C. Campbell Lecturer in Parasite Biology, Trinity College Dublin, Ireland.

‘Yet although studies have quantified the effects of rising average temperatures on host and pathogen traits, the influence of variable temperature regimes such as heatwaves remains largely unknown.

‘Our findings show that temperature variation alters the outcome of host-pathogen interactions in complex ways. Not only does temperature variation affect different host and pathogen traits in a distinct way, but the type of variation and the average temperature to which it is applied also matter. This means that changing patterns of climate variation, superimposed on shifts in mean temperatures due to global warming, may have profound and unanticipated effects on disease dynamics.’