A proposal for a cross-disciplinary approach to epidemics and invasion biology

An international team of scientists has proposed a cross-disciplinary approach to biosecurity that may benefit both invasion biologists, who study the spread of non-native species, and epidemiologists, who study human infectious pathogens. 

The scientists present a detailed review of the parallels between the two general disciplines involved and outline how working together can advance ecological and human health. Their work appears in the July issue of BioScience.

Invasion biologists primarily focus on "free-living, conspicuous macroscopic species, whose spread is observable and easy to track," the authors note. They study alien species movement from one place to another, affecting both the ecology and human health. 

In contrast, the authors write, "invasion dynamics of parasites and pathogens have received less attention," although these human infections could also be seen as a biological invasion. The continuing global coronavirus SARS-CoV-2 crisis, they point out, emphasizes the need for an interdisciplinary approach to biosecurity. 

Current Science Daily spoke with the lead author of the article, Dr. Montserrat Vilà, a professor in the Estación Biológica de Doñana (EBD-CSIC) and the Department of Plant Biology and Ecology at the University of Seville, Spain.

Parallels and differences of approach

Vilà explained the most important parallels between a biological invasion and a human epidemic: "Many invasive species provide habitat, or are vectors or reservoirs of human parasites or pathogens, and this is an area that requires the greatest research focus." 

Vilà emphasized that the study of biological invasions has a well-developed theoretical background: "I think that the discipline of invasion biology offers outstanding hypotheses worth testing for epidemics beyond the focus on a particular pathogen or parasite. I refer to species traits, biotic interactions, recipient system characteristics, and the importance of historical factors."

Commenting on the differences between the disciplines, she said that "the main differences involve the type of organisms studied: microscopic (that is, viruses, bacteria, protozoa) for epidemics, and macroscopic (plants, animals) for biological invasions."

Vilà also noted "the differences in the biological complexity of the 'recipient' of these organisms, the human body for parasites and pathogens, and the ecosystems for invaders."

"This means that the speed of an epidemic is generally faster than that of a biological invader, which has longer generation periods and disperses more slowly compared to how infected humans interact and move."

"All these differences boil down to the use of different technologies, terminologies, and scientific approaches to investigate one or the other," Vilà said.

Pandemic lessons

The COVID-19 epidemic has influenced her approach as an invasion biologist.

"COVID-19 has made me think about the importance of human behavior, social sciences, and the media in understanding invasions and how people perceive them," she said. "Scientifically, there is much to explore in terms of modeling and forecasting biological invasions using methods developed in epidemics – and vice versa."

Specifically, Vilà said, "Collaboration between experts and stakeholders from different fields (for example, health sciences, environment sciences, and social sciences) are needed to link multiple aspects related to the origin, prevention, treatment, socioeconomic, and environmental impacts of any invasion or epidemic."

Vilà cited as an example an initiative from the Spanish National Research Council (CSIC) called the Interdisciplinary Global Health Platform. 

"This and other initiatives are pivotal to addressing the major challenges and finding solutions to the COVID-19 pandemic from different perspectives," she said.

The BioScience review came about, Vilà said, from a collaboration between two sister projects on the impact of biological invasions and ecosystems now and in the near future: InvasiBES and AlienScenarios.

"We realized in these projects that we did not have sufficient expertise on microbial ecology, and so we invited internationally known scientists working in parasite ecology and zoonosis to join us," she said.

"The paper was written during the lock-out and personally helped me to organize and understand the overload of information on COVID-19 and pandemics," Vilà said. "It was challenging to get out of our comfort zone but intellectually very rewarding at the end. Some of us participate at the IPBES Invasive Alien Species Assessment and there the invasion-epidemic interface will become an important issue of global concern."

Ensuring biosecurity

The BioScience review concludes with a call for collaboration: 

"Invasion biology has accumulated over recent decades many insights that could help improve the way we deal with pathogens and the diseases they cause, but crossing this disciplinary bridge requires more tangible collaborations and concrete policy initiatives. Scientists, governments, and institutions should promote the cross-disciplinary approach to further advance in understanding the increasing threats of these novel entities and improve prevention and response measurements."

"We need to keep in mind that our health and that of animals, plants, and the environment are interrelated," Vilà said. "Thus, we need to take a biosecurity approach to prevent, manage, and reduce the impacts of both biological invasions and emerging infection diseases."