Population Dynamics, Invasion, and Biological Control of Environmentally Growing Opportunistic Pathogens

Abstract

In this chapter, we analyze environmentally growing opportunistic diseases, which are a growing threat to human health, food production, and wildlife. The traditional treatment methods for opportunist diseases often fail because environmentally growing opportunist pathogens can utilize outside-host environmental resources for growth and can reside indefinitely in the environmental reservoirs. Moreover, environmental growth may promote high virulence because the trade-off between virulence and transmission can be weak or absent. Moreover, as multicellular organisms are a relatively rich resource compared to the surrounding environment, transition from free-living organism into an opportunist pathogen is a potential pathway through which novel, obligate pathogens emerge. We show that the environmental growth strategy can profoundly change the epidemiological dynamics because the pathogen faces environmental variability and outside-host food web interactions such as competition, predation, and parasitism. The contrasting evolutionary challenges between the outside-host environment and host immune responses likely play an important role in the epidemiological dynamics. Understanding the conditions that promote or hinder the spread of already existing, as well as the invasion of novel, environmentally growing opportunistic diseases is the key for controlling this class of infectious diseases. This chapter aims to give the reader a view on the studies made so far regarding environmentally growing opportunist diseases and present ideas on how the outside-host abiotic and biotic environment could be utilized in pathogen control.