Image Credit: Andrew DuBois, CC BY-NC 2.0, Image Cropped
Behavioural fever reduces ranaviral infection in toads (2019) Sauer et al, Functional Ecology, https://doi.org/10.1111/1365-2435.13427
Being infected with a pathogen such as a bacteria or virus can be bad for whatever organism is unfortunate enough to suffer the infection, and sometimes it’s bad enough to kill the host. Because of that, there is a strong pressure to engage in behaviors that reduce the chances of becoming infected in the first place. While these behaviors can be inherited and evolve over time, others take place within the lifetime of the infected individual itself, making it a ‘plastic’ response (see the “Did You Know” from our previous breakdown for the difference between plasticity and evolution).
One plastic response is that of a behavioral fever. In organisms that cannot regulate their own body temperature, like reptiles and amphibians, this behavior involves moving from an area with low temperature to one with a higher temperature, ideally limiting the damage that a pathogen can do or even killing it outright. Because this behavioral fever is so dependent on temperature, it is important to know how climate change may impact emerging infectious disease.
Many organisms are vulnerable to a wide array of diseases and parasites throughout the course of their lives, but could scavengers help reduce that vulnerability? (Image Credit: The High Fin Sperm Whale, CC BY-SA 4.0, Image Cropped)
Do scavengers prevent or promote disease transmission? The
effect of invertebrate scavenging on Ranavirus transmission (2019) Le Sage et al., Functional Ecology, https://doi.org/10.1111/1365-2435.13335
As intimate as the host-parasite relationship is, it is important to keep in mind that it is embedded within a complex web of other interactions within the local ecological community. To add to this complexity, all of these interactions can feed back on and effect the host-parasite relationship. One ubiquitous part of all communities is the scavenger, an organism that feeds on dead and decomposing organisms. The authors of this paper wanted to investigate how scavengers affect disease transmission in local communities.
This question in interesting because it can easily go either way, depending on the community in question. Scavengers could lower disease transmission by eating infected organisms, thus removing contagious elements from the environment. However, scavengers could also increase transmission by promoting the spread of contagious elements in the community via their own waste after they consume infected tissues.