About

Vanessa Ezenwa is a professor in the Department of Ecology & Evolutionary Biology at Yale University. She joined the department in 2021 and is based at 266 Whitney Ave, New Haven, CT. Her research focuses on the ecology and evolution of infectious diseases, behavioral ecology, and the behavioral immune system. She teaches courses including Advanced Topics in Ecology & Evolutionary Biology, Behavioral Ecology, Ecology and Evolution of Infectious Disease, Responsible Conduct of Research, and Special Topics in the Ecology and Evolution of Infectious Diseases. Her work involves understanding the interactions between hosts, pathogens, and the environment, contributing to the broader understanding of disease dynamics and host behavior.

Research topics

• Biology
• Zoology
• Ecology
• Genetics
• Evolutionary biology
• Computational biology
• Bioinformatics

Selected publications

• How do infections impact social relationships?

  Biology Letters · 2026-03-25

  articleOpen access

  Infectious disease dynamics are both a cause and a consequence of variation in sociality. Social interaction rates can shape parasite transmission, and conversely, parasite infection can alter social interaction rates. At the core of this feedback is a trade-off: although many social interactions yield fitness benefits, parasites impose fitness costs on infected hosts and risks to uninfected partners. Both the benefits of social interaction and the costs of infection are context-dependent, dynamic and often asymmetric within dyads. We therefore hypothesize that variation in this cost-benefit trade-off explains how and why behavioural responses to parasitism differ between individuals across stages of relationship development and across different types of social relationships (parent-offspring, pair-bond, affiliative, dominance relationships). We use these hypothetical cost-benefit trade-offs to generate testable predictions about how parasites will impact the behaviour of infected and uninfected hosts across different social relationships. We also explore the potential for acute infections to have long-term social consequences by influencing the development of social relationships.

  PublisherDOI

• Environmental drivers of parasitic nematode infection in wild ungulates in the Serengeti National Park

  International Journal for Parasitology · 2026-01-01

  articleOpen access

  Parasite infections in host populations frequently display seasonal patterns that can shape host behavior, fitness, and population dynamics. Despite recognition that seasonality plays a key role in infection dynamics across numerous host-parasite systems, the drivers of seasonal infection dynamics for parasites with different life cycles are often unknown. This lack of system-specific understanding restricts our ability to predict when and why parasite infections and their cascading effects on host populations will have the greatest impact. We investigated how seasonality and environmental variables at the likely time of infection are related to the infection intensity of two parasitic nematodes with contrasting life cycles: strongyle nematodes (direct life cycle) and lungworms (indirect life cycle). We conducted the study in two free-ranging ungulate species in Serengeti National Park, Tanzania: Coke's hartebeest (Alcelaphus buselaphus) and topi (Damaliscus lunatus). We found a high prevalence of both parasites, with strongyle nematodes occurring in 95.5% of hartebeest and 93.1% of topi, and lungworms occurring in 100% of hartebeest and 99.7% of topi. Strongyle infection intensity peaked in the wet season but showed no strong association with precipitation, temperature, or animal density at the likely time of infection. In contrast, lungworm intensity peaked in the dry season and was associated negatively with precipitation and positively with animal occupancy. Our results highlight the importance of considering how parasite life cycles interact with environmental variables operating at different temporal scales, as seasonal infection patterns may emerge from processes acting at distinct times relative to parasite development and transmission. Identifying when parasite intensities are highest is critical for predicting when hosts are under the greatest ecological pressure due to parasitism.

  PublisherDOI

• Collective disruption: consequences of parasitism for collective animal behaviour

  Proceedings of the Royal Society B Biological Sciences · 2026-01-21 · 1 citations

  articleOpen accessSenior author

  Highly coordinated animal groups such as schooling fish, migrating birds and swarming insects are ubiquitous in nature, and these complex displays of collective behaviour emerge from local interactions between individuals. Although collective behaviours are known to confer benefits, they also come with the standard costs of group living, including increased risk of parasite infection. Notably, parasites can have profound effects on individual behaviour, which may in turn affect the inter-individual interactions that drive collective behaviour. Thus, given the commonness of parasites in animal populations and their widely appreciated effects on animal hosts, parasitism may be a key force shaping the ecology of collective behaviour. In this article, we use information transfer as a unifying theme to explore how the effects of parasites on individuals translate to the collective, focusing on four common collective behaviours: decision-making, collective movement, synchronization and construction. We also discuss the implications of parasite-altered collective behaviour for processes such as parasite transmission, wildlife conservation and animal culture.

  PublisherOA PDFDOI

• An innovative tool for non-invasive contact-free pathogen monitoring in animal saliva

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-02-11

  articleOpen access

  Abstract Habitat fragmentation, climate change, poaching, human-wildlife conflicts, and infectious diseases are the main threats to biodiversity conservation. They alter host-pathogen dynamics, reduce viable conservation areas, and promote genetic isolation, resulting in physiological stress among animal populations. Moreover, increased proximity between domestic and wild animals further facilitates disease spillovers exposing naïve host species and ecosystems to new pathogens. Of the more than 200 known zoonotic diseases, approximately 60% originate from animals, contributing significantly to the global infectious disease burden. Here, we describe the development of an innovative non-invasive approach for biological sampling that has been validated in mice and shelter cats. Our device consists of a disposable plastic cassette that through odor attractants lures animals to lick a filter paper. This saliva collection approach allowed for the detection of RNA viruses by RTqPCR and third-generation sequencing. RTqPCR oral swab and licked paper results showed that both methods significantly predicted serological status. Our sequencing results revealed the richness of the gene space, demonstrating the potential of this device for discovering rare or unknown species circulating in the saliva donor, enabling this player to be recognized as an environmental sentinel. This study demonstrates the feasibility of deploying this device in sheltered/captive animal settings as well as under laboratory simulations of different environments, providing necessary foundations for future field applications. Our methodology holds great potential for monitoring zoonotic pathogens in both captive and free-ranging animals, to even possibly allow proactive mitigation measures prior to spillover, without interfering with the natural animal behaviour and social structures. Visual abstract

  PublisherOA PDFDOI

• Author response for "Collective disruption: consequences of parasitism for collective animal behavior"

  2025-11-10

  peer-reviewSenior author
  PublisherDOI

• Application of Microbiome Feedback Theory to Animals: Can Parasites Drive Coexistence in Ungulate Communities?

  Integrative and Comparative Biology · 2025-06-09 · 2 citations

  articleOpen accessSenior author

  Parasites can have large impacts on host populations, but the extent to which parasite dynamics impact or respond to multi-species community structure remains uncertain. Empirical and theoretical studies within the host-microbiome feedback framework (often called plant-soil feedback) has provided strong evidence of the importance of soil pathogens to plant community structure and function. We adapt this framework to herd animals by extending the mathematics of host-microbiome feedback theory to accommodate increased likelihood of exposure to microbiomes from conspecific hosts rather than heterospecific hosts. We then integrate this framework with a model of interguild frequency dependence. Coupling this model with empirical observations, we estimate the host-specific fitness of gastro-intestinal nematodes living on ungulate species of Western USA. We find evidence that host-specific differences in nematode fitness could generate negative feedback on host fitness and contribute to coexistence of ungulates. Moreover, we find that this is more likely to be the case for pairs of ungulate species with high habitat overlap. If nematodes can indeed drive such negative feedbacks, then negative impacts of nematodes on their ungulate hosts should decline, i.e., be diluted, with increasing host diversity. While more work is necessary to confirm the underlying assumptions driving these conclusions, our work highlights the possibility that parasites play under appreciated roles in structuring animal communities.

  PublisherOA PDFDOI

• Fine-scale animal proximity detection and localization via multi-sensor biologgers

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-09-14

  preprintOpen access

  Abstract Accurately quantifying spatial interactions is central to understanding social behavior, information flow, predator-prey dynamics, and disease transmission. Proximity loggers that record received signal strength indicator (RSSI) offer a promising approach for estimating pairwise distances, particularly in environments where GPS is unavailable or imprecise. However, RSSI is often dismissed as too noisy for fine-scale inference, with performance that depends on environmental conditions, tag orientation, and between-device variability. Incorporating additional tag-measured data may improve RSSI performance and enable its use as a continuous measure of distance in variable environments. Here, we assess the utility of continuous RSSI as a fine-scale distance estimator and localization tool using a novel multi-sensor WiFi biologger (WildFi). We conducted four experiments: (1) testing how tag orientation affects RSSI-distance relationships; (2) evaluating whether environmental covariates measured by onboard sensors improve proximity estimates; (3) assessing the accuracy of trilateration-based tag localization using fixed gateway arrays; and (4) comparing RSSI- and GPS-inferred proximity in free-ranging Egyptian fruit bats ( Rousettus aegyptiacus ). While RSSI alone could predict distance with reasonable accuracy, incorporating additional tag-sensed information ( e.g. , temperature, humidity, barometric pressure) and accounting for tag-level heterogeneity significantly improved predictive accuracy. Based on RSSI predictions, we could estimate tag location with a median error of 2.6 meters, accurate enough to indirectly estimate proximity networks without tag-to-tag communication. In deployments on free-flying bats, we found that RSSI and GPS were only weakly concordant, with GPS unreliable for detecting fine-scale interactions (<50 m). In contrast, RSSI could capture both fine-scale and some long-range interactions up to ∼250m. These findings highlight RSSI’s potential as a robust metric for proximity logging, particularly when combined with multi-sensor data and pre-deployment validations. Integrating multi-sensor data streams further enhances RSSI interpretability. Future biologger designs should prioritize synergy among data streams for integrated insights into proximity and animal behavior. Data and code for peer review statement Data and code to reproduce the results of the paper are provided in a zip folder for peer review. We also provided our compiled code.

  PublisherOA PDFDOI

• Evaluating the contribution of individual variation in parasite‐mediated anorexia to trophic cascades

  Ecology · 2025-09-01

  articleSenior author

  Recent evidence suggests that parasite-mediated reductions in food intake (i.e., anorexia) in herbivores can trigger trophic cascades that increase producer biomass. This outcome assumes homogeneous host responses to parasite infection; however, individual variation in parasite-mediated anorexia is common. To understand the potential consequences of such variation, we quantified individual variation in host feeding responses to parasitism empirically using a wild herbivore-helminth system. We then evaluated the impact of ecologically relevant levels of variation in anorexia on producers using stochastic individual-based models composed of parasites, herbivores, and plants. Our empirical data showed that although higher helminth burdens were associated with lower population-level feeding rates, there was considerable individual variation in the presence and magnitude of anorexia. Our models revealed a pronounced effect of variation in anorexia prevalence but not magnitude on plants. Plant biomass increased as anorexia became prevalent in the herbivore population, and there was a strong dampening effect of anorexia prevalence on plant biomass variance, suggesting that parasite-mediated anorexia in herbivores can stabilize producer population dynamics. Interestingly, the association between higher anorexia prevalence and lower variance in plant biomass was due, in part, to negative feedback between herbivore feeding rates and helminth ingestion, suggesting that negative feedback between host behavior and parasitism, a phenomenon that can help stabilize certain host-parasite interactions, may have stabilizing effects that extend to other members of the ecological community via trophic cascades.

  PublisherDOI

• Author response for "Collective disruption: consequences of parasitism for collective animal behavior"

  2025-11-03

  peer-reviewSenior author
  PublisherDOI

• Disentangling transport and trophic effects of animal movement on environmental parasite abundance

  International Journal for Parasitology · 2025-08-26 · 2 citations

  articleOpen access

  Migratory wildlife plays an outsized role in disease transmission. Transmission risk is often assumed to be scaled with migratory host density through parasite transport effects, but in environmentally transmitted parasites, migratory hosts can also influence parasite availability via trophic effects. Trophic effects can either amplify or dampen transport effects, making the net impact of migratory hosts on resident hosts difficult to predict. We propose that the net effect is shaped by two attributes of migrant movement: intensity of use (i.e., number of migrants) and duration of use (i.e., length of stay). Using gastrointestinal nematodes (GIN) as a model, we experimentally varied transport and trophic effects of a migratory grazer wildebeest (Connochaetes taurinus) by manipulating the intensity and duration of dung addition and grazing across five treatment combinations in replicated plots, and measuring their effects on the density of infective third-stage GIN larvae in pasture. We found that: (1) higher dung addition increased GIN larvae density, (2) simulated grazing reduced the density of GIN, particularly in treatments with high dung addition, and (3) longer duration and lower intensities of use reduced GIN density for the subsequent hosts compared to treatments with single bouts of dung addition and grazing. Our results indicate that migratory hosts directly facilitate parasite spread via transport effects, while infection risk tends to decline with increasing intensity and duration of trophic interactions. Our results highlight the underappreciated role of transport and trophic interactions in shaping parasite spread in migrant-resident systems.

  PublisherDOI

Recent grants

• NRT-DESE: Interdisciplinary Disease Ecology Across Scales: from Byte to Benchtop to Biosphere

  NSF · $3.0M · 2015–2021

• Symposium: Animal Behavior and Disease Ecology: Past, Present, and Future - Princeton, New Jersey, August 9-14, 2014

  NSF · $10k · 2014–2016

• Coupled Macroparasite-Microparasite Interactions: Ecological and Evolutionary Consequences of Coinfection

  NIH · $1.8M · 2021–2025

• Collaborative Research: Immune tradeoffs during tissue regeneration in mammals

  NSF · $290k · 2014–2020

• Collaborative Research: Microparasite-Macroparasite Interactions: Dynamics of Co-infection and Implications for Disease Control

  NSF · $667k · 2010–2015

Frequent coauthors

• Anna E. Jolles

  78 shared

• Charles L. Nunn

  Duke Institute for Health Innovation

  47 shared

• Benjamín Roche

  Maladies Infectieuses et Vecteurs: Écologie, Génétique, Évolution et Contrôle

  47 shared

• Jessica L. Abbate

  42 shared

• Sonia Altizer

  University of Georgia

  41 shared

• John L. Gittleman

  University of Georgia

  38 shared

• Pierre Becquart

  Université de Montpellier

  37 shared

• Mary Poss

  Pennsylvania State University

  36 shared