New Grant from The Royal Society!
The Royal Society just awarded us a one-year Challenge Grant of £96K to study strategies for topical vaccination of bats against viruses. The grant forms new collaborations with Tonie Rocke and Jorge Osorio from USGS-NWHC and the University of Wisconsin, respectively and strengthens existing collaborations with Nestor Falcon and Carlos Shiva from the Cayetano Heredia University Vet School and William Valderrama from RENACE in Peru. We’ll be pairing biomarker experiments in wild bats with statistical and mathematical models to evaluate if and how vaccination could be an effective tool for vampire bat rabies prevention and control. This project represents an important step to ev
PhD studentships available to work at the MRC-University of Glasgow Centre for Virus Research
If you’re interested in joining the group as a PhD student, have a look at the CVR PhD Program. There are eligibility requirements related to nationality and residency, but if you qualify and are keen to apply, feel free to contact me first with a description of your experience and research interests. Applications are due January 6 2017.
Contagious Thinking Podcast and article from CVR on vampire bat rabies
From Connor Bamford and Josie Bellhouse: “For the Contagious Thinking podcast #12, we spoke with University of Glasgow’s Dr Daniel Streicker – a Wellcome Trust fellow and 2015 National Geographic Emerging Explorer – and Dr Julio Benavides – a postdoc in Daniel’s lab and recent recipient of the George Baer Latin American Investigator Award from the international group, ‘Rabies in the Americas’, about their work on trying to understand the spread of vampire bat rabies in Peru.”
Listen here: https://soundcloud.com/user-28288327/rabies-riding-the-wave-to-the-pacific-coast
Or read the blog post: http://cvr.academicblogs.co.uk/rabies-riding-the-wave-to-the-pacific-coast/
2 new grants this week to study infectious disease dynamics in vampire bats
NSF Dissertation Improvement Grant: “Consequences of resource heterogeneity for immune defense, connectivity, and rabies dynamics in vampire bats” to Dan Becker
Dan Becker was awarded $19k from the US National Science for expanding his work on how resource provisioning affects health and disease transmission in vampire bats. The new grant will allow Dan to develop new studies focusing on how livestock intensification in Latin America affects antiviral immunity, bat population genetic structure and the spread of rabies. Collaborators are Daniel Streicker and Sonia Altizer.
CONCYTEC Basic Research Grant: “The role of the vampire bat in the transmission of bacteria resistant to antibiotics used in humans and livestock”
A new grant from the Peruvian Council of Science, Technology and Technological Innovation and the has awarded our team, composed of researchers from the University of Glasgow and Cayetano Heredia University in Lima (UPCH), Peru a grant of S/.400,000 (= £80,000) to study whether antibiotic resistant bacteria are transmitted between vampire bats and livestock. Collaborators are Julio Benavides and Daniel Streicker (Glasgow) and Carlos Shiva and Nestor Falcon (UPCH).
New causes of mass mortality in modern bats
By reviewing the literature on causes of mass mortality in bats from 1790-2015, we found changes in the reasons that bats are dying in large numbers. While in the past, intentional persecution (killing, poisoning etc.) was a big factor, collisions with wind turbines and the disease white-nose syndrome in North America now lead the reported causes of mass death in bats. Interestingly, we found very little evidence for other viral or bacterial diseases causing large die-offs.
The absence of viral or bacterial infectious diseases associated with die offs is somewhat surprising given that bats often live in dense aggregations which should be ideal for disease spread. So, is disease-induced mortality really uncommon in bats? I think there are a few possibilities. First, perhaps many bat infections occur endemically at low prevalence rather than in epidemics that cause large scale die offs? If that were the case, bats could be dying from viral or bacterial infections, but since deaths occur over months or years rather than days, we fail to take notice. Rabies virus is a good example there – no die offs, but individuals certainly die of infection. On the other hand, could bats be somehow “special” in not actually showing disease at the individual-host level? This is commonly argued for other viruses like Nipah, Hendra and Ebola, where it is suggested that exceptional immune systems or ancient co-evolved relationships with viruses could protect bats at the individual level in a way that is somehow different from other host species.
Teasing apart these explanations requires a lot of work. We need long term monitoring to look at sublethal effects of infections on bats and longer term effects of infection on lifespan and we need tools to be able to actually measure the health of these bats beyond very crude measures of alive, dead or nearly dead in the field. We need experimental infection studies that replicate natural conditions of exposure and infection. All of these things are costly, but necessary if we are to fully understand bat mortality and the relationship between bats and their natural pathogens.
O’Shea, T., Cryan, P., Hayman, D., Plowright, R., Streicker, D.G. (2016) Multiple mortality events in bats: a global review Mammal Review DOI: 10.1111/mam.12064
Check out the USGS Press release for this paper here
“Livestock-dense habitat functions as an ecological trap for vampire bats: immunological evidence”
4 January 2016
Society for Integrative & Comparative Biology Annual Meeting
Oregon Convention Center
Portland, Oregon, USA
Urbanization and agriculture cause declines for many wildlife, but some species benefit from human-provided food. The abundance and predictability of these provisioned resources can affect wildlife behavior and physiology and in turn alter infectious disease dynamics. Specifically, host condition and immune defense responses to resource shifts are key to understanding whether provisioning amplifies or dampens pathogen transmission. We here tested relationships between provisioning, host condition, and immunity through a cross-sectional study of vampire bats (Desmodus rotundus) in Peru and Belize. This hematophagous species has potentially benefited from intensification of livestock rearing, which could reduce starvation stress and energy spent during foraging, allowing bats to invest more in immunity. We predicted that bats captured in sites of high livestock density would be in better body condition, display less chronic stress and inflammation, and have higher investment in humoral immunity. Contrary to this prediction, we found increasing livestock density was associated with poorer condition, greater levels of stress and inflammation, and lower IgG, and that these negative health impacts were more severe in reproductively active bats. We also found that although livestock intensification was associated with impaired bat health, capture success increased with livestock density. Together these results suggest livestock-dense habitats could function as ecological traps by producing source populations of immunologically impaired vampire bats. Increasing the relative abundance of such habitat could have profound impacts on bat susceptibility to zoonotic pathogens and the spatial spread of infections.
Building on our previous paper studying the different mechanisms through which different host species can arise as “key hosts” for parasite transmission, this new paper with Andy Fenton, Owen Petchy and Amy Pedersen creates a quantitative framework for partitioning R0 among many host species. This is a really exciting advance because we’re able to assess how robust estimates are to uncertainty in rates of cross-species versus within-species transmission and everything is estimated from fairly standard parasitological data. Applying this framework to my undergraduate dataset on gut parasites in small mammals confirms the existence of key hosts even for outwardly multi-host parasites (cryptic specialization) and shows in a hypothetical way, how different control measures could be more or less effective when targeting based on species specific values of R0.
Data for the paper are available here: http://dx.doi.org/10.5061/dryad.972mv
Abstract: Many parasites circulate endemically within communities of multiple host species. To understand disease persistence within these communities, it is essential to know the contribution each host species makes to parasite transmission and maintenance. However, quantifying those contributions is challenging. We present a conceptual framework for classifying multihost sharing, based on key thresholds for parasite persistence. We then develop a generalized technique to quantify each species’ contribution to parasite persistence, allowing natural systems to be located within the framework. We illustrate this approach using data on gastrointestinal parasites circulating within rodent communities and show that, although many parasites infect several host species, parasite persistence is often driven by just one host species. In some cases, however, parasites require multiple host species for maintenance. Our approach provides a quantitative method for differentiating these cases using minimal reliance on system-specific parameters, enabling informed decisions about parasite management within poorly understood multihost communities.
Change in post!
Vicky Estacio has decided to stay on at Glasgow and will join the Masters in Quantitative Methods in Biodiversity, Consevation and Epidemiology.
“Impact of human-provided food resources on infectious disease dynamics”
8 July 2015
International Association of Landscape Ecology World Congress
Portland, Oregon, USA
“Heterogeneity in patch quality buffers metapopulations from pathogen impacts”
13 August 2015
Ecological Society of America Annual Meeting
Baltimore Convention Center
Baltimore, Maryland, USA
Complex effects of dietary provisioning on wildlife disease dynamics
Becker, D., Streicker, D.G., & Altizer (2015) Linking anthropogenic resources to wildlife-pathogen dynamics: a review and meta-analysis. Ecology Letters. doi: 10.1111/ele.12428
Abstract: Urbanisation and agriculture cause declines for many wildlife, but some species benefit from novel resources, especially food, provided in human-dominated habitats. Resulting shifts in wildlife ecology can alter infectious disease dynamics and create opportunities for cross-species transmission, yet predicting host–pathogen responses to resource provisioning is challenging. Factors enhancing transmission, such as increased aggregation, could be offset by better host immunity due to improved nutrition. Here, we conduct a review and meta-analysis to show that food provisioning results in highly heterogeneous infection outcomes that depend on pathogen type and anthropogenic food source. We also find empirical support for behavioural and immune mechanisms through which human-provided resources alter host exposure and tolerance to pathogens. A review of recent theoretical models of resource provisioning and infection dynamics shows that changes in host contact rates and immunity produce strong non-linear responses in pathogen invasion and prevalence. By integrating results of our meta-analysis back into a theoretical framework, we find provisioning amplifies pathogen invasion under increased host aggregation and tolerance, but reduces transmission if provisioned food decreases dietary exposure to parasites. These results carry implications for wildlife disease management and highlight areas for future work, such as how resource shifts might affect virulence evolution.
Table 1. Representative study systems and evidence for different mechanisms that might drive relationships between food and disease.