Helminth–microparasite co‐infection in wildlife: lessons from ruminants, rodents and rabbits

Abstract

SummaryCo-infection is now recognized as the natural state of affairs in most hosts and co-infecting parasites interact in a variety of ways that can impact host health and parasite fitness. Interactions between helminths and microparasites have captured particular attention in this regard owing to the ubiquity of helminth infections in many host populations. The mechanistic underpinnings and health implications of co-infection are typically studied in laboratory and clinical settings, but recently studies of wild species have begun to tackle similar issues. Case studies from three wild mammal groups-ruminants, rodents and rabbits-serve to highlight how wild studies are contributing to the broader co-infection literature. This work suggests that wildlife research can generate new and unique insights about helminth-microparasite co-infection that are fostered in part by studying parasite interactions in a natural context. For this reason, increased integration of wild studies with research in human, laboratory and veterinary animal populations can help pave the way towards a more complete understanding of the issue of co-infection.

Interactions among symbionts operate across scales to influence parasite epidemics

“…Because all symbionts require host resources for survival, growth and reproduction (Stearns 1992;Roff 1992), they may exhibit some niche overlap and high sensitivity to the availability of that niche when they coinfect the same host individual. The resulting interactions among coinfecting parasites are well documented in plants (Tollenaere et al 2015), wild animals (Ezenwa 2016) and humans (Griffiths et al 2014). Early arriving symbionts can influence the success of later arriving symbionts by impacting host fitness (Randall et al 2013) or altering host immunity (Lello et al 2004;Graham 2008;Cobey & Lipsitch 2013).…”

“…The resulting interactions among coinfecting parasites are well documented in plants (Tollenaere et al . ), wild animals (Ezenwa ) and humans (Griffiths et al . ).…”

“…Similarly, the sequence of arrival into the host population may influence which symbiont interactions can influence parasite growth or reproduction within hosts, which may slow or accelerate epidemics of coinfecting parasites (Susi et al . ; Ezenwa ). Yet the degree to which symbiont interactions and epidemics are driven by parasite phenology remains untested.…”

Exposure and susceptibility drive reinfection with gastrointestinal parasites in a social primate

“…Coinfections with multiple parasites, commonly observed across the animal kingdom (Rynkiewicz, Pedersen, & Fenton, ) but less frequently incorporated in wildlife health studies, may also predict susceptibility to infections (Ezenwa, ; Graham, ). While infections can be the result of individual immune physiology (Ezenwa et al, ; Vaumourin, Vourc'h, Gasqui, & Vayssier‐Taussat, ), GI nematode infections can increase susceptibility to micro‐ and macroparasites via immunosuppressive effects or be protective against infections with other GI nematode taxa due to cross‐immunity or competition among the pathogens (Cox, ; Vaumourin et al, ).…”

Editorial—One Health Special Issue—Parasite Immunology

“…Vanessa Ezenwa discusses “Helminth‐microparasite co‐infection in wildlife: lessons from ruminants, rodents and rabbits,” and demonstrates that studies in wildlife populations have unique contributions to make to understanding the dynamics of coinfection in other populations, including man and domestic animals . This review illustrates vividly the benefits of bridging the divide between studies of wildlife ecologists and biomedical scientists.…”