Research themes
A central theme of my research is to understand why, when, and where animals become infected with pathogens, to predict and prevent spillover of zoonoses to humans. I combine field and theoretical approaches, incorporating data from individual to population levels, to identify mechanisms driving transmission and inform intervention strategies. I am especially interested in how environmental and ecological disturbances contribute to the emergence and spread of infectious diseases in humans, and I strive to translate my research into conservation and management outcomes for wildlife. Read about my work below.
The Ecology of ebolavirus (Bombali virus) in Kenyan molossid bats
Disease outbreaks caused by viruses of the genera ebolavirus present a major public health issue in sub-Saharan Africa. Despite more than 45 years of research and continued outbreaks of Ebola virus disease, the reservoirs of Zaire ebolavirus and other ebolaviruses remain unknown. In 2016 and 2018, a new ebolavirus (Bombali virus) was identified in the excreta and organs of free-tailed bats in Sierra Leone and Kenya (species: Mops condylurus and Chaerephon pumilus), supporting the role of bats as putative ebolavirus hosts. Whether these bats can sustain transmission of ebolavirus over time (i.e., whether they are true reservoirs) remains unclear.
We are undertaking a collaborative and multidisciplinary investigation into the ecology and disease ecology of M. condylurus and C. pumilus in Kenya, to elucidate the plausibility – and dynamics – of sustained ebolavirus infection in these populations.
We are undertaking a collaborative and multidisciplinary investigation into the ecology and disease ecology of M. condylurus and C. pumilus in Kenya, to elucidate the plausibility – and dynamics – of sustained ebolavirus infection in these populations.
We have synthesized published information on ebolavirus and free-tailed bat ecology, to hypothesize ecological traits needed for virus circulation and maintenance. We are now collecting ecological data to fill gaps in data needed to test these hypotheses, leveraging established bat-virus monitoring in Kenya where Bombali virus has been documented. We will then integrate empirical data on roosting dynamics - obtained through longitudinal capture, banding, and ratio-tracking efforts - with matched data on excretion of Bombali virus, to mathematically explore the plausibility of sustained transmission in M. condylurus and C. pumilus over time and space. Some examples of specific ecological traits that will be explored are shown below:
meta-population dynamicsM. condylurus and C. pumilus typically roost in buildings in human-modified landscapes. Roost sizes are smaller than what has been predicted to allow filoviruses persistence in single, isolated roosts. Meta-population dynamics (movement between roosts) may play a key role in filovirus ecology. We will use empirical information from tagged bats to estimate rates of roost switching, and to construct ecologically reasonable meta-population models to represent pathogen spread between roost buildings. |
Variable birth pulsesBirth pulses impact on the spread and maintenance of pathogens by introducing susceptible individuals (juveniles) into the population. M. condylurus and C. pumilus have two and five birth pulses per year respectively, where the interval between consecutive births shortens with increasing latitude. We will build on existing birth pulse models for bats to explore how variation in birthing may impact locations where viral maintenance is possible/likely in these species. |
Multi-species circulation Roost sharing is common between M. condylurus and C. pumilus. Viral RNA sequenced from M. condylurus samples have shown high similarity to viral RNA sequenced from C. pumilus, suggesting that cross-species transmission is plausible, and that viral circulation may involve multiple hosts. We will use empirical information on roost density and sharing, matched with virus sequencing from individual bats, to empirically investigate the plausibility of a single-species vs multi-species host-virus system. |
Simulations of virus invasion and spread within bat populations, under plausible roosting and ecological scenarios, will be important for inferring disease dynamics in these putative hosts. As one of few studies to systematically evaluate the general ecology and roosting patterns of Kenyan free-tailed bats, this study will also provide valuable ecological information on bat reproduction and habitat preferences, with practical applications for conservation and conflict management.
Evaluating the ecology and risk of coronaviruses from bats in East Africa
In the past two decades, three coronaviruses with origins in bats have emerged to cause serious and widespread disease outbreaks in humans, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19 disease. Despite the rapidly growing interest in bat coronaviruses, our knowledge of the ecology and transmission of these viruses is still low, hindering risk assessment and predictive capacity for human disease outbreaks.
We are investigating bat infection dynamics of diverse coronaviruses in a strategic global hotspot for bat species diversity and disease spillover – East Africa.
We aim to launch a longitudinal monitoring campaign that links the sampling of individual bats with collection of metadata on bat ecology, bat health, and environmental conditions, to identify novel coronaviruses in East African bats that may pose risks to human health, and understand drivers of risk.
We are investigating bat infection dynamics of diverse coronaviruses in a strategic global hotspot for bat species diversity and disease spillover – East Africa.
We aim to launch a longitudinal monitoring campaign that links the sampling of individual bats with collection of metadata on bat ecology, bat health, and environmental conditions, to identify novel coronaviruses in East African bats that may pose risks to human health, and understand drivers of risk.
Flying-fox ecology and transmission dynamics of Hendra virus
Hendra virus is a bat-borne henipavirus that emerged in 1994 to cause lethal disease in horses and humans in eastern Australia. Increasing cases of spillover in recent decades has co-occurred with observations of dramatic ecological shifts in host flying-fox populations, spurred by wide-spread land clearing in south-eastern Australia. Bats are shifting from a nomadic ecology - where individuals move across the landscape and form large roosts in response to ephemeral foraging opportunities - to residency - where individuals continuously occupy a single roost in an area with predictable food sources. As a result, roosting habitat has shifted from forest remnants with dense tree roost habitat, to urban areas with more sparse tree roost habitat.
We undertook a multidisciplinary investigation into the patterns and mechanistic drivers of Hendra virus infection in Australian flying-foxes, focusing on altered roost structure as a driver of virus transmission and spillover in a time of urbanization and rapid ecological change.
This project contributed substantial new datasets on Hendra virus excretion patterns (in prep) and flying-fox roost structure (Lunn et al. 2021a; Lunn et al. 2021b), combined with mathematical exploration of infection dynamics (Lunn et al. 2021c), and conceptual models of host-pathogen interaction (Lunn et al. 2019). Collectively, this research presents compelling evidence that spatial structure and bat aggregation may be a missing piece to our understanding of shedding and spillover risk from bat roosts. These findings have direct implications for the refinement of management strategies to mediate Hendra virus exposure risk, particularly in the context of urbanization. More broadly, the tools and insights outlined in this research can be applied to predicting risks in changing environments and ecosystems across bat-virus systems globally.
We undertook a multidisciplinary investigation into the patterns and mechanistic drivers of Hendra virus infection in Australian flying-foxes, focusing on altered roost structure as a driver of virus transmission and spillover in a time of urbanization and rapid ecological change.
This project contributed substantial new datasets on Hendra virus excretion patterns (in prep) and flying-fox roost structure (Lunn et al. 2021a; Lunn et al. 2021b), combined with mathematical exploration of infection dynamics (Lunn et al. 2021c), and conceptual models of host-pathogen interaction (Lunn et al. 2019). Collectively, this research presents compelling evidence that spatial structure and bat aggregation may be a missing piece to our understanding of shedding and spillover risk from bat roosts. These findings have direct implications for the refinement of management strategies to mediate Hendra virus exposure risk, particularly in the context of urbanization. More broadly, the tools and insights outlined in this research can be applied to predicting risks in changing environments and ecosystems across bat-virus systems globally.
Landscapes of risk? bat-human interactions in a context of human behaviour change
Human dwellings in Kenya have changed from traditional mud buildings (pictured) to western style buildings with large structural beams and ceilings. Unfortunately, spaces in ceilings, and between beams and walls, create inviting spaces for free-tailed bats to roost. The change to building practices may be increasing interactions between bats and humans, and creating opportunity for spillover. While in Kenya I procured and ground truthed detailed land cover maps from fine-scale remote sensing data, to map high-risk bat-human interfaces along an urban-rural gradient, and to identify landscape-level attributes of bat-human exposure risk in Kenya. Watch this space for updates on findings and suggestions for One Health land-use planning.