Social effects of rabies infection in male vampire bats ( Desmodus rotundus )

Abstract

Rabies virus (RABV) transmitted by the common vampire bat ( Desmodus rotundus ) poses a threat to agricultural development and public health throughout the Neotropics. The ecology and evolution of rabies host–pathogen dynamics are influenced by two infection-induced behavioural changes. RABV-infected hosts often exhibit increased aggression which facilitates transmission, and rabies also leads to reduced activity and paralysis prior to death. Although several studies document rabies-induced behavioural changes in rodents and other dead-end hosts, surprisingly few studies have measured these changes in vampire bats, the key natural reservoir throughout Latin America. Taking advantage of an experiment designed to test an oral rabies vaccine in captive male vampire bats, we quantify for the first time, to our knowledge, how rabies affects allogrooming and aggressive behaviours in this species. Compared to non-rabid vampire bats, rabid individuals reduced their allogrooming prior to death, but we did not detect increases in aggression among bats. To put our results in context, we review what is known and what remains unclear about behavioural changes of rabid vampire bats (resumen en español, electronic supplementary material, S1).

Let's stick together: Infection enhances preferences for social grouping in a songbird species

“…Nonetheless, examples of parasite manipulation to increase host sociality are rare, with observed behavioral changes more often manifesting as host-mediated declines in sociality (Cárdenas-Canales et al, 2022;Hawley et al, 2021). Our results represent a case of a directly transmitted pathogen causing augmented rather than reduced host sociality, potentially due to host-mediated behavioral changes.…”

“…Acute infections can alter host social preferences via diverse mechanisms, mediated by the pathogen or host. While some pathogens appear to manipulate infected hosts to increase sociality in ways that benefit pathogen transmission (Klein, 2003 ; Rode et al., 2013 ), the most common host‐mediated behavioral changes during infection are sickness behaviors (e.g., lethargy and anorexia (Hart, 1988 )), which generally reduce social interactions and pathogen transmission potential (Cárdenas‐Canales et al., 2022 ; Hamilton et al., 2020 ; Lopes et al., 2016 ; Ripperger et al., 2020 ). However, social interactions may also be decreased when uninfected individuals actively avoid their infected conspecifics (Zylberberg et al., 2013 ), obscuring the true social preferences of infected hosts.…”

Opportunistic evidence of the impact of bacterial infections on social integration in vampire bats

“…The sickness behavior we observed was similar to the responses of vampire bats to simulated infections with injections of lipopolysaccharide, LPS (12,20). We quantified sickness behaviors in response to a naturally-infecting pathogen, which is less often done for vertebrates (but see 33,35,39,40) compared to studies on sickness behavior using an immune challenge (e.g., (8,(10)(11)(12)15,20,24,31,(41)(42)(43). The use of immune challenges, like LPS, allows for controlled experiments on the connection between the inflammatory and the behavioral response to infection, but naturally infecting pathogens can have different, pathogen-specific effects.…”

“…Our results should be treated with caution due to the impossibility of estimating effect sizes precisely with small sample sizes (9 infected bats with varying levels of infection severity). However, while several studies have quantified social interactions when animals are infected with, or exposed to pathogens (14,(16)(17)(18)(33)(34)(35)(36)(37)(38), to our knowledge, no studies have focused on the impact of infections on social bond formation. Our findings and effect size estimates could therefore be valuable for informing future studies that test this hypothesis in more detail.…”

“…These observations are opportunistic and sparse (only 9 infected bats), but we believe our results are valuable for two main reasons. First, effect size estimates for sickness behaviors of vertebrates in response to naturally-infecting pathogens are uncommon compared to experiments that use immune challenges (but see [51][52][53][54][55]. Second, while several studies have quantified the effect of immune challenges (infection or immunogenic antigens) on host social behavior (15,(17)(18)(19)(51)(52)(53)(54)(55)(56)(57)(58)(59), the effect of short-term infections on the formation and development of long-term social bonds development remains largely unexplored.…”