Genetic variation in parasite avoidance, yet no evidence for constitutive fitness costs.

Behavioral avoidance of parasites is a widespread strategy among animal hosts and in human public health. Avoidance has repercussions for both individual and population-level infection risk. Although most cases of parasite avoidance are viewed as adaptive, there is little evidence that the basic assumptions of evolution by natural selection are met. This study addresses this gap by testing whether there is a heritable variation in parasite avoidance behavior. We quantified behavioral avoidance of the bacterial parasite Serratia marcescens for 12 strains of the nematode host Caenorhabditis elegans. We found that these strains varied in their magnitude of avoidance, and we estimated the broad-sense heritability of this behavior to be in the range of 11%-26%. We then asked whether avoidance carries a constitutive fitness cost. We did not find evidence of one. Rather, strains with higher avoidance had higher fitness, measured as population growth rate. Together, these results direct future theoretical and empirical work to identify the forces maintaining genetic variation in parasite avoidance.

Pathogen disgust is associated with interpersonal bias among healthcare professionals.

Background and objectives: Pathogen avoidance is a fundamental motive that shapes many aspects of human behavior including bias against groups stereotypically linked to disease (e.g. immigrants, outgroup members). This link has only been examined in convenience samples and it is unknown how pathogen avoidance processes operate in populations experiencing prolonged and heightened pathogen threat such as healthcare professionals. We examined whether healthcare professionals demonstrate the same link between pathogen disgust and intergroup bias as has been documented among the general population. Methodology: Participants (N = 317; 210 healthcare professionals) were recruited using snowball sampling to take an online survey. Participants completed the Three Domain Disgust Scale to assess pathogen, sexual and moral disgust. Participants then rated their perceptions of a fictitious immigrant group ('Krasneeans') and the degree to which they endorsed group-binding moral values. Results: Compared to control participants, healthcare professionals reported lower levels of pathogen disgust, but not sexual or moral disgust. However, regardless of profession, higher pathogen disgust was associated with viewing Krasneeans as less likeable and more unclean. Additionally, regardless of profession, higher pathogen disgust was associated with greater endorsement of group-binding moral values, although healthcare professionals reported greater overall endorsement of group-binding moral values than did control participants. Conclusions and implications: Although healthcare professionals demonstrated lower levels of pathogen disgust, they nevertheless exhibited largely the same relationship between pathogen disgust and interpersonal biases as did control participants. One practical implication of this association is that pathogen avoidance motives may contribute to inequitable patient treatment in healthcare settings.

Heightened religiosity proactively and reactively responds to the COVID-19 pandemic across the globe: Novel insights from the parasite-stress theory of sociality and the behavioral immune system theory.

According to the parasite-stress theory of sociality and the behavioral immune system theory, heightened religiosity serves an anti-pathogen function by promoting in-group assortative sociality. Thus, highly religious countries/territories could have better control of the COVID-19 (proactively avoids disease-threat), and heightened COVID-19 threat could increase religiosity (reactively responds to disease-threat). As expected, country-level religiosity (religion-related online searches (Allah, Buddhism, Jesus, etc.) and number of total religions/ethnoreligions) negatively and significantly predicted COVID-19 severity (a composite index of COVID-19 susceptibility, reproductive rate, morbidity, and mortality rates) (Study 1a), after accounting for covariates (e.g., socioeconomic factors, ecological factors, collectivism index, cultural tightness-looseness index, COVID-19 policy response, test-to-case ratio). Moreover, multilevel analysis accounting for daily- (e.g., time-trend effect, season) and macro-level (same as in Study 1a) covariates showed that country-level religious searches, compared with the number of total religions/ethnoreligions, were more robust in negatively and significantly predicting daily-level COVID-19 severity during early pandemic stages (Study 1b). At weekly level, perceived coronavirus threat measured with coronavirus-related searches (corona, covid, covid-19, etc.), compared with actual COVID-19 threat measured with epidemiological data, showed larger effects in positively predicting religious searches (Study 2), after accounting for weekly- (e.g., autocorrelation, time-trend effect, season, religious holidays, major-illness-related searches) and macro-level (e.g., Christian-majority country/territory and all country-level variables in Study 1) covariates. Accordingly, heightened religiosity could proactively and reactively respond to the COVID-19 pandemic across the globe.

Effects of anxiety sensitivity, disgust, and intolerance of uncertainty on the COVID stress syndrome: a longitudinal assessment of transdiagnostic constructs and the behavioural immune system.

Excessive fear and worry in response to the COVID-19 pandemic (e.g., COVID stress syndrome) is prevalent and associated with various adverse outcomes. Research from the current and past pandemics supports the association between transdiagnostic constructs-anxiety sensitivity (AS), disgust, and intolerance of uncertainty (IU)-and pandemic-related distress. Recent research suggests a moderating effect of disgust on the relationship of AS-physical concerns and COVID-19-related distress, suggesting that transdiagnostic constructs underlie individual differences in activation of the behavioral immune system (BIS). No previous study has examined the independent and conjoint effects of pre-COVID-19 AS-physical concerns, disgust propensity (DP), disgust sensitivity (DS), and IU in this context; thus, we did so using longitudinal survey data (N = 3,062 Canadian and American adults) with simple and moderated moderations controlling for gender, mental health diagnosis, and COVID-19 diagnosis. Greater AS-physical concerns, DP, and DS predicted more severe COVID stress syndrome assessed one month later. Either DP or DS further amplified the effect of AS-physical concerns on COVID stress syndrome, except danger and contamination fears. IU did not interact with AS-physical concerns and DS or DP. Theoretical and clinical implications pertaining to delivery of cognitive behavioural therapy for pandemic-related distress are discussed.

Reciprocal Interactions Between Gut Microbiota and Host Social Behavior.

Animals harbor an extensive, dynamic microbial ecosystem in their gut. Gut microbiota (GM) supposedly modulate various host functions including fecundity, metabolism, immunity, cognition and behavior. Starting by analyzing the concept of the holobiont as a unit of selection, we highlight recent findings suggesting an intimate link between GM and animal social behavior. We consider two reciprocal emerging themes: (i) that GM influence host social behavior; and (ii) that social behavior and social structure shape the composition of the GM across individuals. We propose that, throughout a long history of coevolution, GM may have become involved in the modulation of their host's sociality to foster their own transmission, while in turn social organization may have fine-tuned the transmission of beneficial endosymbionts and prevented pathogen infection. We suggest that investigating these reciprocal interactions can advance our understanding of sociality, from healthy and impaired social cognition to the evolution of specific social behaviors and societal structure.

The Body Odor Disgust Scale (BODS): Development and Validation of a Novel Olfactory Disgust Assessment.

Disgust plays a crucial role in the avoidance of pathogen threats. In many species, body odors provide important information related to health and disease, and body odors are potent elicitors of disgust in humans. With this background, valid assessments of body odor disgust sensitivity are warranted. In the present article, we report the development and psychometric validation of the Body Odor Disgust Scale (BODS), a measure suited to assess individual differences in disgust reaction to a variety of body odors. Collected data from 3 studies (total n = 528) show that the scale can be used either as a unidimensional scale or as a scale that reflects two hypothesized factors: sensitivity to one's own body odors versus those of others. Guided by our results, we reduced the scale to 12 items that capture the essence of these 2 factors. The final version of the BODS shows an excellent internal consistency (Cronbach's αs > 0.9). The BODS subscales show convergent validity with other general disgust scales, as well as with other olfactory functions measures and with aspects of personality that are related to pathogen avoidance. A fourth study confirmed the construct validity of the BODS and its measurement invariance to gender. Moreover, we found that, compared with other general disgust scales, the BODS is more strongly related to perceived vulnerability to disease. The BODS is a brief and valid assessment of trait body odor disgust sensitivity.