An overview of parasite-induced behavioral alterations – and some lessons from bats

Abstract

SummaryAn animal with a parasite is not likely to behave like a similar animal without that parasite. This is a simple enough concept, one that is now widely recognized as true, but if we move beyond that statement, the light that it casts on behavior fades quickly: the world of parasites, hosts and behavior is shadowy, and boundaries are ill-defined. For instance, at first glance, the growing list of altered behaviors tells us very little about how those alterations happen, much less how they evolved. Some cases of parasiteinduced behavioral change are truly manipulative, with the parasite standing to benefit from the changed behavior. In other cases, the altered behavior has an almost curative, if not prophylactic, effect; in those cases, the host benefits. This paper will provide an overview of the conflicting (and coinciding) demands on parasite and host, using examples from a wide range of taxa and posing questions for the future. In particular, what does the larger world of animal behavior tell us about how to go about seeking insights -or at least, what not to do? By asking questions about the sensory-perceptual world of hosts, we can identify those associations that hold the greatest promise for neuroethological studies of parasite-induced behavioral alterations, and those studies can, in turn, help guide our understanding of how parasite-induced alterations evolved, and how they are maintained.

Better with your parasites? Lessons for behavioural ecology from evolved dependence and conditionally helpful parasites

“…arising from the host's immune response), parasite-initiated effects (e.g. secretion of neuroactive compounds), or some combination of these factors (Hart, 2011;McCusker & Kelley, 2013;Moore, 2013;Poulin, 1995). The best approach to understanding the mechanisms underlying shifts in host phenotype will vary depending on the particular hosteparasite system in question, but we suggest a general approach here.…”

Toxoplasma gondiiinfection, from predation to schizophrenia: can animal behaviour help us understand human behaviour?

“…Another example may be the Seoul virus, which, similar to the rabies virus in dogs, is thought to increase aggressive behaviours in rats, where the resulting wounding may facilitate transmission via contact with virus present in saliva or excrement (Hinson et al, 2004;Klein et al, 2004). Other heteroxenous parasites that appear to cause their intermediate hosts to be predated upon more than expected by their definitive hosts include Plagiorynchus cylindraceu in isopods (Moore, 1983), Sarcocystis cernae in voles (Hoogenboom and Dijkstra, 1987) and Euhaplorchis californiensis in fish (Lafferty and Morris, 1996) (and see Moore, 2013).…”

Host behaviour–parasite feedback: an essential link between animal behaviour and disease ecology

“…Behavioural change due to infection can occur for a variety of reasons. Parasites may manipulate host behaviour to enhance their own fitness, or changes in host behaviour may result from immunological or pathological consequences of parasite infection [6][7][8]. On longer timescales, parasites impose selective pressures on their hosts that can drive evolutionary changes in behaviour [9,10]; and in turn, these changes in host behaviour can shape parasite population dynamics and life history including traits such as virulence and transmission mode [11].…”