People: Beth Savagar, Guillaume Fournié, Bryony Jones

Peste des Petits Ruminants (PPR) is an acute infectious disease of small ruminants which is endemic across much of the developing world; throughout Africa, the Middle East and Asia. PPR causes severe morbidity and mortality, with the potential to affect 80% (1.67 billion) of the global population of small ruminants and putting the livelihoods of 300 million families at risk (FAO and OIE, 2016). In 2015, the World Organisation for Animal Health (OIE) and the Food and Agriculture Organisation (FAO) launched the PPR Global Control and Eradication Strategy (PPR GCES) which aims to eradicate PPR by 2030. A core component of this GCES is the effective implementation of mass vaccination campaigns.

This PhD project is focussed on optimising PPR vaccination campaigns through developing mathematical models of PPRV transmission in different endemic settings, to inform the design of vaccine programmes which are tailored to local contexts.

PPR-affected small ruminant populations are found in a wide range of contexts. “Flock heterogeneity” describes the differences between flocks which arise due to factors such as flock location (at multiple spatial scales), climate, religious or cultural practices, resource availability, husbandry practices and trading behaviours, amongst others. Such population heterogeneity strongly influences population-level disease dynamics, and the behaviour of epidemiological models (Bansal et al. 2007). Few studies of PPR have taken a modelling approach to investigate disease dynamics, and the effect of population heterogeneity is rarely incorporated. This project aims to address this knowledge gap by developing models which take account of the heterogeneity between flocks, at multiple scales, and examine its impact on the transmission and elimination of PPR in different small ruminant populations.

To achieve this the following questions will be addressed:

  • How does heterogeneity at the flock level impact the transmission of PPR in different endemic settings?
  • What, if any, are the implications of flock heterogeneity for the eradication of PPR, in particular with respect to the effectiveness of vaccination strategies?
  • Specifically:
    • How may heterogeneity in (i) flock dynamics (demographics) and (ii) flock mobility patterns impact PPR transmission and the effectiveness of vaccination

This PhD is supported by the RVC and APHA joint OIE Collaboration Centre for Risk Analysis and Modelling and is part of an interdisciplinary collaboration between the Royal Veterinary College (RVC), and the Animal and Plant Health Agency (APHA), principally funded by the London Interdisciplinary Doctoral Training Programme (LIDo-DTP). Dr Mark Arnold (APHA) is a co-supervisor on the project.

References:

  • FAO and OIE (2016) Peste des petits ruminants Global Eradication Programme
  • Bansal, S., Grenfell, B.T. and Meyers, L.A., 2007. When individual behaviour matters: homogeneous and network models in epidemiology. Journal of the Royal Society Interface4(16), pp.879-891

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