MS02 - ECOP-08

Ecological aspects of vector-borne disease

Monday, July 14 at 3:50pm

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Abigail Barlow (The University of Bath), n/a

Description:

Vector-borne diseases pose a major global health burden, particularly in tropical and subtropical regions, accounting for over 17% of infectious diseases and more than 700,000 deaths annually (WHO). Understanding vector ecology is essential for predicting disease spread, informing control strategies, and assessing impacts of environmental change. This mini-symposium highlights mathematical models exploring the ecological and epidemiological dynamics associated with two key vectors: mosquitoes and ticks. Mosquitoes, with their flight range, host flexibility, and blood-feeding behavior, facilitate transmission in urban and zoonotic settings. Ticks are uniquely effective at maintaining pathogen reservoirs because of long feeding periods, multiple transmission routes, and the ability to survive months to years without feeding. We will present research that integrates ecological, epidemiological, and mathematical approaches to generate new insights into the impact of vector ecology and control strategies on disease spread. We will address aspects such as vector life history, biting behaviors, host preference, and environmental drivers using methods including nonlinear dynamical systems, stochastic systems theory and structured population models.

Abby Barlow

The University of Bath

"Integrated tick management strategies in fragmented peridomestic environments"

The spirochetal bacterium Borrelia burgdorferi is a tick-borne zoonosis that circulates in various wildlife populations in temperate rural regions of Europe, North America and Asia. Humans are not usually competent for transmission, but spillover infections can lead to Lyme disease (LD). The infection is passed to human hosts via the bite of an infected tick. Ticks have multiple life stages and complex phenology. Over the last decade, there has been a sustained increase in Borrelia prevalence in wildlife in North America, leading to an increase in spillover events, often via residential areas that back onto woodland. Understanding tick ecology is essential for predicting the spread of LD, informing control strategies, and assessing impacts of environmental change. In this talk, we will discuss the development of a tick population model for a fragmented peridomestic environment. We will consider a metapopulation framework of residential patches, where humans might encounter ticks. Our principal goal is to understand the impact of deer dispersal on the tick ecological dynamics. Deer are the primary host for adult ticks and a necessary component of tick reproduction. They visit the residential patches in very small numbers (1 or 2 per hectare/ patch) and can disperse over large distances, transporting any feeding ticks in the process. Consequently, the location of the deer is inherently stochastic and the tick population dynamics are drawn into this stochasticity. Protective measures against LD often involve treating the deer population with an arcarcide-based treatment. We incorporate these features into our model by employing a hybrid modelling framework. Our results will explore the impact that deer dispersal and treatment on the tick population dynamics, in particular on the density of infected nymphs.

Folashade B. Agusto

University of Kansas

"Modeling the effect of lethal and non-lethal predation on the dynamics of ticks and tick-borne ehrlichiosis disease"

Tick-borne illnesses, including ehrlichiosis, from both endemic and emerging pathogens have shown a dramatic rise in recent years, posing an increasing public health threat in the United States. However, fewer studies have explored the cascading effects of lethal and non-lethal predation on the dynamics of tick-borne diseases. The fear induced by predators can alter prey behavior, impacting predation rates and ultimately influencing disease transmission dynamics. This study seeks to clarify the effects of both lethal and non-lethal predation through mathematical modeling of tick-borne disease dynamics. Theoretical analysis and sensitivity tests were conducted to examine how fear-driven changes in host behavior affect tick populations and disease prevalence. Stability conditions for various equilibria of the reduced model were established under constant tick fecundity and mortality rates. The study shows that the combined effects of lethal and non-lethal predation trigger a cascade: as predator attack rates rise, prey and tick populations, along with disease prevalence, decrease. Moreover, an increase in predator-induced fear further reduces prey populations, leading to a subsequent decline in tick populations.

Kyle Dahlin

Virginia Tech

"Down with the sickness: modelling the effect of disturbed blood-feeding on mosquito-borne disease transmission"

Mosquito-borne pathogens remain a major global health challenge, and transmission depends critically on mosquito blood feeding. This process involves behavioral interactions between mosquitoes and vertebrate hosts, including host defenses that can disturb feeding and increase mosquito mortality. We develop a mathematical model that treats blood feeding as a predator-prey interaction, incorporating mosquito decisions to persist or quit in response to host defense and the associated risk of mortality. The model links individual-level feeding outcomes to population-level traits, such as the average multiple biting number, the gonotrophic cycle duration, and vectorial capacity. We analyze how these traits are shaped by host defensive behavior and mosquito responses, and quantify the resulting effects on disease transmission. The results highlight how host-mosquito interactions can shape key parameters in transmission models and suggest directions for incorporating behavior into epidemiological predictions.

Christina Cobbold

The University of Glasgow

"Incorporating adult age dynamics into mosquito population models: implications for predicting abundances in changing climates"

Mosquito-borne diseases (MBDs) pose increasing threats under future climate change scenarios and an understanding of mosquito population dynamics is pivotal to predicting future risk of MBDs. Most models that describe mosquito population dynamics often assume that adult life-history is independent of adult age and yet mosquito senescence is known to affect mosquito mortality, fecundity and other key biological traits. Despite this, little is known about the effects of adult age at the level of the mosquito population, especially under varying temperature scenarios. We developed a stage-structured delayed differential equation model incorporating the effects of the abiotic environment and adult age to shed light on the complex interactions between age, temperature, and mosquito population dynamics. Taking Culex pipiens, a major vector of West Nile Virus, as our study species our results show that failing to consider mosquito senescence can lead to underestimates of future mosquito abundances predicted under climate change scenarios. Moreover at temperature extremes age-dependent mechanisms combined with the effects of density-dependent mortality on the immature stages at also act to decrease mosquito abundances, highlighting a complex interplay between adult aging dynamics and population abundance.

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Annual Meeting for the Society for Mathematical Biology, 2025.