title: The risk of disease to great apes: simulating disease spread in orang-utan (Pongo pygmaeus wurmbii) and chimpanzee (Pan troglodytes schweinfurthii) association networks.
abstract: All great ape species are endangered, and infectious diseases are thought to pose a particular threat to their survival. As great ape species vary substantially in social organisation and gregariousness, there are likely to be differences in susceptibility to disease types and spread. Understanding the relation between social variables and disease is therefore crucial for implementing effective conservation measures. Here, we simulate the transmission of a range of diseases in a population of orang-utans in Sabangau Forest (Central Kalimantan) and a community of chimpanzees in Budongo Forest (Uganda), by systematically varying transmission likelihood and probability of subsequent recovery. Both species have fission-fusion social systems, but differ considerably in their level of gregariousness. We used long-term behavioural data to create networks of association patterns on which the spread of different diseases was simulated. We found that chimpanzees were generally far more susceptible to the spread of diseases than orang-utans. When simulating different diseases that varied widely in their probability of transmission and recovery, it was found that the chimpanzee community was widely and strongly affected, while in orang-utans even highly infectious diseases had limited spread. Furthermore, when comparing the observed association network with a mean-field network (equal contact probability between group members), we found no major difference in simulated disease spread, suggesting that patterns of social bonding in orang-utans are not an important determinant of susceptibility to disease. In chimpanzees, the predicted size of the epidemic was smaller on the actual association network than on the mean-field network, indicating that patterns of social bonding have important effects on susceptibility to disease. We conclude that social networks are a potentially powerful tool to model the risk of disease transmission in great apes, and that chimpanzees are particularly threatened by infectious disease outbreaks as a result of their social structure.
authors.affiliation: Centre for Research in Evolutionary and Environmental Anthropology, University of Roehampton, London, United Kingdom.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Carne
authors.affiliation: Centre for Research in Evolutionary and Environmental Anthropology, University of Roehampton, London, United Kingdom.
authors.forename: Stuart
authors.initials: S
authors.lastname: Semple
authors.affiliation: The Orang-utan Tropical Peatland Project, Centre for International Cooperation in Sustainable Management of Tropical Peatland, Universitas Palangka Raya, Palangka Raya, Central Kalimantan, Indonesia; Centre for Research in Animal Behaviour, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom.
authors.forename: Helen
authors.initials: H
authors.lastname: Morrogh-Bernard
authors.affiliation: School of Psychology and Neuroscience, University of St Andrews, St Andrews, Fife, United Kingdom; Cognitive Science Centre, University of Neuchâtel, Neuchâtel, Switzerland.
authors.forename: Klaus
authors.initials: K
authors.lastname: Zuberbühler
authors.affiliation: Centre for Research in Evolutionary and Environmental Anthropology, University of Roehampton, London, United Kingdom.
authors.forename: Julia
authors.initials: J
authors.lastname: Lehmann
mesh_terms: D000818:Animals; D018420:Ape Diseases / Q000635:transmission*; D003141:Communicable Diseases / Q000453:epidemiology / Q000662:veterinary*; D003198:Computer Simulation; D004198:Disease Susceptibility / Q000453:epidemiology / Q000662:veterinary*; D056727:Endangered Species; D058872:Epidemics; D007214:Indonesia / Q000453:epidemiology; D008954:Models, Biological; D002679:Pan troglodytes; D057079:Pongo; D018570:Risk Assessment; D012307:Risk Factors; D012931:Social Environment; D014454:Uganda / Q000453:epidemiology
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