How do social and demographic processes control epidemic dynamics?

• Applicants: Marion Linda East, Ph.D.; Professorin Dr. Stephanie Kramer-Schadt
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Epidemiology and Medical Biometry/Statistics ; Theoretical Chemistry: Molecules, Materials, Surfaces
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 263713275

Infectious diseases are considered to be one of the five main causes of extirpation of wildlife populations. Currently there is insufficient information to determine the threat diseases pose to the viability of many wildlife populations because the fundamental processes and key transmission mechanisms underlying disease dynamics in free-ranging populations are little known. Important, yet neglected issues are the effects of individual behaviour and social rank on disease dynamics in hierarchically and spatially structured populations and the molecular, immunological and demographic factors that mediate long-term host-pathogen evolutionary dynamics within ecosystems. Ecological models are useful tools for dissecting complex dynamics into single factors that then can be used to analyse how each factor influences the dynamics of the system on ecological and evolutionary time scales. Progress in our understanding of such complex disease dynamics therefore requires the combination of adequate host-pathogen systems, detailed long-term data on demography and social status, disease resistance and immunity, pathogen strains and robust statistical and dynamic modelling approaches. Our project brings together these key components. Our study system is canine distemper virus (CDV) in spotted hyenas as the host in the Serengeti ecosystem. CDV is an important carnivore disease which is related to measles virus in humans. It has caused significant mortality in Serengeti wild carnivores, including spotted hyenas. By combining long-term data on CDV prevalence and the molecular characteristics of the prevailing strains with more than 26 years of detailed individual demographic and social data on the host, we have a unique opportunity to study demographic and disease dynamics in concert. Spotted hyenas are a particularly interesting host, as they are the most numerous large carnivore in this ecosystem, and have a hierarchical fission-fusion social structure, communal territoriality and denning, plus long-distance foraging beyond territorial boundaries when prey density is low. These factors provide an excellent system for investigating transmission pathways and factors driving disease spread. CDV infection and outbreaks among wild Serengeti carnivores have been controversially discussed and currently no model exists that considers CDV dynamics in this key carnivore species or the impact of maternal social status and spatial distribution on disease dynamics. We therefore propose to use the whole palette of ecological modelling to explore the wealth of our long-term field data set: from descriptive, statistical analyses of contact rates in a social animal and disease courses via mathematical models to individual-based spatially-explicit simulation models. This will provide new insights on disease dynamics in mixed local networks of individuals, a novel idea of great relevance to social mammals in several orders and a key contribution to epidemiological theory.

• DFG Programme: Research Grants
• International Connection: France
• Participating Persons: Dr. Olivier Gimenez; Professor Dr. Jean-Dominique Lebreton