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Toxoplasma gondii is a protozoan parasite capable of infecting any warm-blooded species and can increase risk-taking in intermediate hosts. Despite extensive laboratory research on the effects of T. gondii infection on behaviour, little is understood about the effects of toxoplasmosis on wild intermediate host behavior. Yellowstone National Park, Wyoming, USA, has a diverse carnivore community including gray wolves (Canis lupus) and cougars (Puma concolor), intermediate and definitive hosts of T. gondii, respectively. Here, we used 26 years of wolf behavioural, spatial, and serological data to show that wolf territory overlap with areas of high cougar density was an important predictor of infection. In addition, seropositive wolves were more likely to make high-risk decisions such as dispersing and becoming a pack leader, both factors critical to individual fitness and wolf vital rates. Due to the social hierarchy within a wolf pack, we hypothesize that the behavioural effects of toxoplasmosis may create a feedback loop that increases spatial overlap and disease transmission between wolves and cougars. These findings demonstrate that parasites have important implications for intermediate hosts, beyond acute infections, through behavioural impacts. Particularly in a social species, these impacts can surge beyond individuals to affect groups, populations, and even ecosystem processes. Wolf behavioural, spatial, and serological data over 26 years show that wolf territory overlap with areas of high cougar density is a significant predictor of T. gondii infection. Further, infection increases the likelihood that wolves make high-risk decisions such as dispersing and becoming a pack leader. [ABSTRACT FROM AUTHOR]

Sex‐based differences in physiology, behaviour and demography commonly result in differences in disease prevalence. However, sex differences in prevalence may reflect exposure rather than transmission, which could affect disease control programmes. One potential example is chronic wasting disease (CWD), which has been observed at greater prevalence among male than female deer.We used an age‐ and sex‐structured simulation model to explore harvest‐based management of CWD under three different transmission scenarios that all generate higher male prevalence: (1) increased male susceptibility, (2) high male‐to‐male transmission or (3) high female‐to‐male transmission.Both female and male harvests were required to limit CWD epidemics across all transmission scenarios (approximated by R0), though invasion was more likely under high female‐to‐male transmission.In simulations, heavily male‐biased harvests controlled CWD epidemics and maintained large host populations under high male‐to‐male transmission and increased male susceptibility scenarios. However, male‐biased harvests were ineffective under high female‐to‐male transmission. Instead, female‐biased harvests were able to limit disease transmission under high female‐to‐male transmission but incurred a trade‐off with smaller population sizes.Synthesis and applications. Higher disease prevalence in a sex or age group may be due to higher exposure or susceptibility but does not necessarily indicate if that group is responsible for more disease transmission. We showed that multiple processes can result in the pattern of higher male prevalence, but that population‐level management interventions must focus on the sex responsible for disease transmission, not just those that are most exposed. [ABSTRACT FROM AUTHOR]