Researchers call for systemic approach to eliminate infectious diseases

Studying infectious diseases requires a systems biology perspective in which scientists consider more than just the human aspects. That is the argument expressed in a study published recently in PLOS Neglected Tropical Diseases, led by Prof. Toine Pieters (History of Pharmacy). Pieters: “As long as we continue to focus entirely on humans, it will be virtually impossible to completely eliminate these types of infectious diseases. That most likely includes COVID-19 too.”

Based on a systematic literature study, the authors claim that we have a far too reductionist view of zoonoses: diseases that transfer from animals to humans. The study was conducted before COVID-19 appeared on the scene, but it has become unexpectedly relevant today. “We focused specifically on leprosy in this publication, but the same arguments apply to other zoonoses like COVID-19,” Pieters emphasises.

Squirrels with leprosy

There is still much that is not known about leprosy, including how the disease is transmitted, but there are still hundreds of thousands of new cases of leprosy reported around the world each year, mostly outside of Europe

“With leprosy, it’s essential to understand that the disease isn’t only transmitted from one human to another”, Pieters explains. “We’ve long known that armadillos carry leprosy, and a recent study has found leprosy DNA in squirrels on the British islands as well.”

Animals as carriers

The authors plead for much more thorough research into animals as carriers and transmitters of these types of infectious diseases. “Leprosy is fairly easy to treat today,” Pieters adds. “But it’s troublesome that we haven’t managed to completely eliminate the disease so far.” The researchers suspect that animals may play an important role in the spread of the disease. “We believe that it is key to take a systems biology perspective. That also applies to COVID-19, by the way: it was transmitted to us via animals, and I believe it’s likely we won’t get rid of it until we include animals in our approach as well.”

Publication

Reservoirs and transmission routes of leprosy; A systematic review
Thomas Ploemacher*, William R. Faber, Henk Menke*, Victor Rutten*, Toine Pieters*
PLoS Negl Trop Dis 14(4), 2020. DOI 10.1371/journal.pntd.0008276

*Authors affiliated with Utrecht University.