Projects

1. Ecology and control of IR malaria vectors

Ecology of malaria mosquitoes is a neglected topic, mainly because it is hard to obtain good quality data on mosquitoes. I am interested in taking advantage of new quantitative approaches, that integrate multiple types of data and deal with unobserved processes, to overcome some of these difficulties and understand how to take advantage of the mosquito ecology to improve malaria control. One of my main projects is on the ecology of insecticide resistant (IR) malaria vectors:

Mosquito ecology using data from a clinical trial

lionsInsecticides are the most widespread strategy against malaria. These are encountered in various forms including indoor residual sprays and insecticide-treated bednets, currently the most effective tool we have against malaria. One of the most prominent challenges is therefore the increasing levels of IR in mosquito vectors across Africa. Despite the gravity of this impending threat, the extent and consequences of IR for public health remain unpredictable – and they will continue to be so, if we don’t  first understand how current and novel ‘resistance busting’ strategies affect IR mosquito ecology. Recently, we found that although IR mosquitoes, don’t die immediately after contact with insecticides, their lifespan is reduced with great consequences for malaria transmission (Viana et al. 2016 PNAS). But these delayed mortality effects are likely to be transient, so we must continue search for new control tools. In a project funded by MRC, I am looking at how a new ‘resistance busting’ bednet impacted IR mosquitoes during a large-scale clinical trial in Burkina Faso (implemented by AvecNet). Specifically,

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    In this project, I am developing state-space population models to reconstruct unobserved vector life history and population dynamics to:

    1. Determine how the ecology of IR mosquitoes modulates their transmission potential and susceptibility to control measures.
    2. Quantify the impacts of current and novel control methods on mosquito life history and demography under natural settings and test the hypothesis that IR mosquitoes are unaffected by current front line strategies
    3. Model the population dynamics of IR malaria vectors and use model predictions to design optimal deployment of intervention methods.

Main collaborators: Heather Ferguson, Jason Matthiopoulos

2. Disease reservoirs and cross-species transmission

I have various ongoing projects – and I am always on the lookout for more opportunities! – to find ways to identify disease reservoirs, quantify cross-species transmission and determine their drivers, particularly of multi-host pathogens that infect wildlife. Some of these projects include:

Canine viruses in the Serengeti

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Three of the most prominent canine virus in the Serengeti are rabies, canine distemper virus (CDV) and canine parvovirus (CPV). These are pathogens typically associated with domestic dogs, however, in last decades several outbreaks have been recorded in wild carnivores around the world. In the Serengeti, CDV and CPV are well known to infect lions and other wildlife. For example, in 1994 a CDV outbreak killed 30% of the lion population in the Serengeti. Recently using Bayesian state-space models to combine 30 years of CDV serological data of in domestic dogs and lions in the Serengeti, with 20 years of dog vaccination history we found changing patterns of CDV infection: from a potential dog reservoir up to mid 90’s to a maintenance community involving wildlife and the broader Tanzanian domestic dog population (Viana et al 2015 PNAS). This study also showed that large-scale vaccination is effective at reducing CDV infection in dogs, but it does not fully prevent infection in lions. What about CPV, a disease with prevalence of >60%? Specifically,

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    Using similar approaches as to those used to understand CDV dynamics, we are interested in:

    1. Whether domestic dogs from the villages surrounding the Serengeti Park are the reservoir of CPV to the wildlife, or if wildlife can maintain it independently of dogs.
    2. Whether dog vaccination is an effective control strategy for domestic dogs, and ultimately lions and other wildlife.
    3. The co-infection dynamics of CPV and CDV in domestic dogs, and how this changes with vaccination.

Main collaborators: Abdelkader Behdenna, Sarah Cleaveland, Dan Haydon, Tiziana Lembo, Jason Matthiopoulos

Vampire bat viruses in Peru

VampBat

Vampire bats are widespread throughout Latin America and their range continues to expand due to intensification of livestock rearing, which provides a novel and abundant food resource. Their unique diet creates many opportunities for pathogen transmission from bats to livestock and humans. As a consequence, vampire bats are culled across much of Latin America, but the effects of culling on bat-associated pathogens are impossible to predict without better understanding of their natural transmission dynamics.

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    I am working with the Streicker group on this system in Peru to develop approaches to:

    1. Determine whether vampire bats are an independent reservoir of bat influenza H17N10 and H18N11 or incidentally infected by other bats.
    2. Identify and quantify the host (e.g. roost structure overlap, genetic relatedness) and environmental (deforestation and agricultural intensification) factors that contribute to cross-species transmission of bat influenza.
    3. Determine the impact of bat culling by evaluating how rates of influenza and rabies infection change with bat colony size and culling history.

Main collaborators: Daniel Streicker, Abdelkader Behdenna, Victoria Estacio.

Influenza in Mongolian horses

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Influenza viruses cause serious public health and economic concerns. In particular, the H3N8 subtype of equine influenza virus (EIV) causes considerable damage to the horse industry around the world. But H3N8 is also prevalent in wild birds (avian influenza, AIV) and there are well-documented cases of cross-species transmission from birds to mammals. Mongolia is a unique setting to study AIV cross-species jumps in horses as it is a point of convergence for many migratory birds across Asia, and supports a large semi-nomadic horse population.

Main collaborators: Pablo Murcia, Abdelkader Behdenna.

3. Data, data, data…

I am fascinated by data that can tell a story, the larger and messier, the better. So I take any opportunity I get to try make sense of the data that is presented to me. In addition to infectious diseases, I am interested in most areas of quantitative ecology, and work (or have worked) on a series of other research themes, including:

Fisheries

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Although I now focus on infectious diseases, I did my PhD on fisheries modelling. Fishing is central to the livelihood and food security of millions of people around the world. However, the removal of organisms from the marine ecosystem can greatly impact the biodiversity, stability and productivity of the ecosystems. I am interested in understanding these impacts and finding ways to maintain fishing sustainable.

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Since approximately 8% of the world total catch is discarded (with +60% discarding rate being common in certain fisheries) and the mortality rate of discarded organisms is very high, often approaching 100%, I focus in understanding how we can mitigate discards. Particularly, I use statistical modelling to understand 1) the spatio-temporal patterns of fisheries discards and its underlying drivers in order to identify adequate mitigation strategies; and 2) how we can incorporate discards data in fisheries management plans and conservation strategies. The latest is currently extremely relevant to provide a baseline to new management plans if the European Commission goes ahead with the planned ban on discards in European waters.

Miscellaneous

Identifying the ecological determinants of bacterial virulence, applying social evolution theory to fisheries management, drivers of ecological stability, intensification of the hydrological cycle, water level fluctuations in lakes due to global climatic drivers and diversity dynamics in the fossil record.

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