Current Disease Ecology Thoughts

In the recently published article from researchers Molentze and Streicker, 2020, the authors provide findings and supportive reasoning regarding their acceptance of the notion that “special” animal reservoirs of zoonotic viruses should not be attributed to a previously perceived, distinct ecological or immunological relationship between animal taxa and viruses. The authors explain their disagreement in the theory that animal groups, such as rats and bats, specifically, have been widely considered by others to exhibit a higher fitness as viral reservoirs for potentially zoonotic diseases as a result of their physiology, evolutionary history, or, again, their ecological tendencies as Han et al., 2016, have formerly outlined. Furthermore, Han et al. primarily focused on the animal reservoirs and their global distribution, even concluding that the most species-rich orders (Rodentia and Chiroptera) probably appear to harbor the highest diversity of zoonoses. Although Molentze and Streicker reported, “Animal orders of established importance as zoonotic reservoirs including bats and rodents were unexceptional, maintaining numbers of zoonoses that closely matched expectations for mammalian groups of their size”. Ouch.

Olival et al., 2017 concentrated on investigated the actual zoonotic pathogens, reflecting in the author’s more specific discussion of host traits that might predict total viral richness within each mammal species. The authors also express the likeness of bats to be uniquely suited as the reservoir for more zoonotic viruses than any other taxa, due to some distinct behavioral and physiological traits they possess.

In response to this data, I personally (in total honesty) am slow to the reception of a paper with such a strong title associated with such a complex subject matter as seen in Molentze and Streicker’s paper, Viral zoonotic risk is homogenous among taxonomic orders of mammalian and avian reservoir hosts. I find the topic, still, vastly understudied to support such an aggressive statement, despite their extensive data analysis/cross examination within numerous viral families in relation to different animal taxa. However, I do view this study as a valuable addition in the ongoing study of zoonotic disease ecology and think the points raised within this paper should certainly be considered in future research directions (as I do believe this must be studied far more extensively to make such a bold statement).

I also look forward to responses and further research related to this study, especially in the public health surveillance aspect, as it appears we might need to consider widening the scope of suspected animals in zoonoses. This also adds insightful information in the important goal of properly refining strategies in order to successfully identify viruses prior to their emergence within the human population.

I still have a few residual doubts regarding the lack of viral richness in certain animal taxa, as evolution remains to be a force to be reckoned with, especially within the persistence and transmission of viral pathogens. Therefore, in my humble opinion, I find it highly unlikely for certain animals groups not to have participated in the evolution of viral zoonoses.