Biomedical subjects

Andy Fenton

Publications and source records attributed to Andy Fenton.

3 recordsLinked to original sources

PubMed2006

Emphasizing the ecology in parasite community ecology.

In natural systems, individuals are often co-infected by many species of parasites. However, the significance of interactions between species and the processes that shape within-host parasite communities remain unclear. Studies of parasite community ecology are often descriptive, focusing on patterns of parasite abundance across host populations rather than on the mechanisms that underlie interactions within a host. These within-host interactions are crucial for determining the fitness and transmissibility of co-infecting parasite species. Here, we highlight how techniques from community ecology can be used to restructure the approaches used to study parasite communities. We discuss insights offered by this mechanistic approach that will be crucial for predicting the impact on wildlife and human health of disease control measures, climate change or novel parasite species introductions.

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PubMed2006

Helminths as vectors of pathogens in vertebrate hosts: a theoretical approach.

Pathogens frequently use vectors to facilitate transmission between hosts and, for vertebrate hosts, the vectors are typically ectoparasitic arthropods. However, other parasites that are intimately associated with their hosts may also be ideal candidate vectors; namely the parasitic helminths. Here, we present empirical evidence that helminth vectoring of pathogens occurs in a range of vertebrate systems by a variety of helminth taxa. Using a novel theoretical framework we explore the dynamics of helminth vectoring and determine which host-helminth-pathogen characteristics may favour the evolution of helminth vectoring. We use two theoretical models: the first is a population dynamic model amalgamated from standard macro- and microparasite models, which serves as a framework for investigation of within-host interactions between co-infecting pathogens and helminths. The second is an evolutionary model, which we use to predict the ecological conditions under which we would expect helminth vectoring to evolve. We show that, like arthropod vectors, helminth vectors increase pathogen fitness. However, unlike arthropod vectors, helminth vectoring increases the pathogenic impact on the host and may allow the evolution of high pathogen virulence. We show that concomitant infection of a host with a helminth and pathogen are not necessarily independent of one another, due to helminth vectoring of microparasites, with profound consequences for pathogen persistence and the impact of disease on the host population.

Animals↗

PubMed2005

Community epidemiology framework for classifying disease threats.

Recent evidence suggests that most parasites can infect multiple host species and that these are primarily responsible for emerging infectious disease outbreaks in humans and wildlife. However, the ecologic and evolutionary factors that constrain or facilitate such emergences are poorly understood. We propose a conceptual framework based on the pathogen's between- and within-species transmission rates to describe possible configurations of a multihost-pathogen community that may lead to disease emergence. We establish 3 dynamic thresholds separating 4 classes of disease outcomes, spillover, apparent multi-host, true multihost, and potential emerging infectious disease; describe possible disease emergence scenarios; outline the population dynamics of each case; and clarify existing terminology. We highlight the utility of this framework with examples of disease threats in human and wildlife populations, showing how it allows us to understand which ecologic factors affect disease emergence and predict the impact of host shifts in a range of disease systems.

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