Are humans spreading a virulent wildlife disease between british frog populations?

Lead Research Organisation: Queen Mary, University of London
Department Name: Sch of Biological and Chemical Sciences

Abstract

Background The U.K. is faced with an ever-increasing number of emerging pathogens and parasites of wildlife and livestock. Ascertaining if an emergent infectious disease is spreading and if that spread is mediated by human activities is a fundamental component of infectious disease risk assessment, indentified as a deliverable in NERC's 2007-2012 strategy. Theory suggests that dispersal mediated by human activities can proceed in a disorganized and irregular pattern, involving occasional long distance leaps followed by expansion from a new focus of introduction, rather than a wave-like pattern. Study system The project will make use of an exceptionally detailed and extensive contemporary record of the spread of a wildlife disease through British common frog populations. The frog, Rana temporaria, has been experiencing mass die-offs due to an invasive and non-native ranavirus FV35. Our partner, Froglife and the CASE parter, the Institute of Zoology (IoZ) have been tracking the pattern of these unusual frog mortalities since 1992: currently the data set includes nearly 5000 reports of mortality events. It comprises the largest available data set for a wildlife disease in the U.K. Evaluating the human involvement The student will be able use the database to evaluate the two main hypotheses for human-accelerated spread: spawn transplantation, and introduction into ponds by ornamental fish.The student will examine the data set for clusters of elevated risk of disease of the type predicted by each hypothesis. Of course, correlative analysis can only take a study so far. The great advantage of this system is that the student will then have access to genetic data from virus that they will isolate from dead frogs. They will be taught to use this data to challenge the preliminary interpretations. However, these genetic data can be misleading - stochastic events in constant populations can mimic patterns expected from rapid dispersal and population expansion. The student will be in a strong position to evaluate the genetic evidence, working in RAN's lab alongside a student specializing in theoretical investigation of these stochastic processes using Bayesian analysis, and a postdoc working on similar patterns in varicella-zoster virus. The project partners will provide an intimate knowledge of, and interactive access to the database (Froglife) and a link to the epidemiological community (Imperial). The CASE partner (the Institute of Zoology) has, together with Froglife, been collating the database and helping recruit the public to cooperate in the data collection. This project extends a strong working relationship between TWJG at the Institute of Zoology, and RAN at Queen Mary. They currently have two joint PhD students who have developed the techniques and approaches that will underwrite the new student's study.

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