Social Network Predicts Exposure to Respiratory Infection in a Wild Chimpanzee Group

Abstract

Respiratory pathogens are expected to spread through social contacts, but outbreaks often occur quickly and unpredictably, making it challenging to simultaneously record social contact and disease incidence data, especially in wildlife. Thus, the role of social contacts in the spread of infectious disease is often treated as an assumption in disease simulation studies, and few studies have empirically demonstrated how pathogens spread through social networks. In July-August 2015, an outbreak of respiratory disease was observed in a wild chimpanzee community in Kibale National Park, Uganda, during an ongoing behavioral study of male chimpanzees, offering a rare opportunity to evaluate how social behavior affects individual exposure to socially transmissible diseases. From May to August 2015, we identified adult and adolescent male chimpanzees displaying coughs and rhinorrhea and recorded 5-m proximity data on males (N = 40). Using the network ktest, we found significant relationships between male network connectivity and the distribution of cases within the network, supporting the importance of short-distance contacts for the spread of the respiratory outbreak.Additionally, chimpanzees central to the network were more likely to display clinical signs than those with fewer connections. Although our analyses were limited to male chimpanzees, these findings underscore the value of social connectivity data in predicting disease outcomes and elucidate a potential evolutionary cost of being social.

Respiratory Disease Risk of Zoo-Housed Bonobos Is Associated with Sex and Betweenness Centrality in the Proximity Network

“…Nevertheless, respiratory disease is a major cause of morbidity and mortality in both captive and wild primate populations and thus a prominent threat to general primate welfare [ 40 , 42 , 43 , 54 , 55 , 56 ]. To date, only two studies have investigated the link between SNA measures and the occurrence of respiratory disease in primates [ 57 , 58 ]. One study found no association between the social network and respiratory disease in mountain gorillas ( Gorilla beringei beringei ) [ 57 ], while another study showed that in chimpanzees, males with higher strength in a proximity network had a higher chance of showing symptoms of respiratory disease, indicating the vital role of the social-proximity network in the spread of the pathogen in the group [ 58 ].…”

“…To date, only two studies have investigated the link between SNA measures and the occurrence of respiratory disease in primates [ 57 , 58 ]. One study found no association between the social network and respiratory disease in mountain gorillas ( Gorilla beringei beringei ) [ 57 ], while another study showed that in chimpanzees, males with higher strength in a proximity network had a higher chance of showing symptoms of respiratory disease, indicating the vital role of the social-proximity network in the spread of the pathogen in the group [ 58 ]. However, this study focused solely on adult males and did not investigate the role of females and juveniles, which can also be important mediators of the spread of pathogens throughout the group [ 58 ].…”

Linking parasitism to network centrality and the impact of sampling bias in its interpretation

“…Having observed a positive association between social network and geohelminth infection, we then tested the impact of sampling bias on these results, by including/excluding certain age-sex classes from the analysis. For various reasons, numerous studies have focused on specific age-sex classes rather than the whole social group (Hamilton et al, 2020; Roberts and Roberts, 2020; Sandel et al, 2021; Webber et al, 2016). Through targeted removal of network subsets and subsequent reanalysis, we demonstrated that the original relationship observed using the whole group network becomes insignificant, both in classical statistical terms (i.e., loss of statistical significance) and in absolute quantitative terms, as the model parameter estimates were in some cases considerably lower, to the point where we could not conclude from randomisation tests that the observed effects of sociality on parasitism were different from those expected to arise by chance.…”

“…Having observed a positive association between the social network and geohelminth infection, we then tested the impact of sampling bias on these results, by including/excluding certain age-sex classes from the analysis. Numerous studies have focused on specific age-sex classes rather than the whole social group (Hamilton et al, 2020;Roberts and Roberts, 2020;Sandel et al, 2021;Webber et al, 2016).…”

One Health Perspectives on New Emerging Viral Diseases in African Wild Great Apes

“…In the same way that pathogens are transmitted from great apes to people, the reverse also occurs, mainly in respiratory diseases [42]. In fact, communities close to NHPs have developed simultaneous outbreaks of respiratory diseases caused by different viruses of human origin [43].…”