MS05 - MEPI-07

Recent Trends in Mathematics of Vector-borne Diseases and Control (Part 2)

Wednesday, July 16 at 10:20am

SMB2025 Follow

Note: this minisymposia has multiple sessions. The other sessions are: Part-1, and Part-3.

Abba Gumel (University of Maryland), Alex Safsten, Arnaja Mitra (both University of Maryland)

Description:

Vector-borne diseases, such as malaria, dengue, Lyme disease, leishmaniasis, and West Nile virus, constitute over 17% of all infectious diseases of humans, with malaria (which causes in excess of 600,000 deaths annually, mostly in children under the age of five) being the most important of these diseases. These vectors are typically controlled by using insecticide-based control measures, and their lifecycle (and those of the pathogens they vector) are greatly affected by changes in local climatic conditions, such as temperature, precipitation, and humidity. This minisymposium brings together researchers to discuss the recent advances in modeling the spread and control of vector-borne diseases. Some of the topics to be discussed include whether or not the recent quest to eradicate malaria is feasible using currently-available insecticides-based control resources, assessing the impact of insecticide and drug resistance on vector population abundance and the intensity of the disease they cause, assessing the potential for alternative biocontrol measures (such as sterile insect technique and the use of Wolbachia infection-based measures and the release of gene drives, such as CRISPR-Cas9) to control vector species, assessing the impact of climate change on the distribution and abundance of vector species etc.

Katharine Gurski

Howard University

"Building a Model for Seasonal Malaria Chemoprevention and Drug Resistance"

Seasonal malaria chemoprevention has been shown to cut clinical malaria episodes by up to 75% in high-risk areas. However, when chemoprevention is given in an area with drug-resistant parasites, there is a risk of the long-term growth of drug-resistance outweighing the benefits of the immediate reduction in deaths of children. We aim to study this situation with data driven pharmacokinetics and pharmacodynamics, experimental data on gametocyte growth within an infected human, gametocyte decay within a treated human, and the probabilities of infecting a mosquito who bites either an infected or treated human by modeling gametocyte transmission. We formulate a model by considering arbitrarily distributed sojourn for various disease stages and chemoprevention. We consider the lessened effectiveness of treatment on drug-resistant parasites. With the use of gamma distributions fit to data, the system can be reduced to a system of ODEs, with non-trivial characteristics which are only captured by non-exponential distributions for disease stages and susceptibility.

Yves Dumont

French Agricultural Research Centre for International Development

"Reducing nuisances or minimizing epidemiological risks: which is the best choice with the Sterile Insect Technique?"

The sterile Insect Technique (SIT) is a promising biological control method against vectors of human diseases, like mosquitoes. SIT can be used either to reduce the nuisance (mosquito bites), or to reduce the epidemiological risk. Depending on the objective, the releases strategy is not the same. Since SIT is an autocidal method, it takes time to notice any effect. Reducing nuisances requires a significant reduction in the wild mosquito population. This generally requires mass releases and, consequently, the production of large numbers of sterile mosquitoes, and, time. When SIT is used to reduce the epidemiological risk, it is preferable to release sterile males only because sterile females may transmit viruses during blood meal on humans. Even if sexing methods have become increasingly efficient, allowing males to be separated from females, it is important to estimate the maximum number of sterile females per release, without, however, increasing the epidemiological risk. In this presentation, I will present some theoretical results and illustrate some of them with numerical simulations in order to discuss the best strategies depending on whether we want to reduce the nuisance, or the epidemiological risk, with SIT.

Alex Safsten

University of Maryland

"Leveraging inter-species competition to improve the effectiveness of the sterile insect technique"

Mosquitos top the list of the deadliest animals in the world due to the diseases they carry and transmit to humans, including malaria, West Nile virus, and dengue, with malaria being the most important vector-borne disease of mankind. Existing methods of mosquito control heavily rely on using chemical insecticides to kill them. Unfortunately, however, in the context of malaria for instance, the heavy and widespread use of these insecticides in endemic areas has resulted in widespread resistance to all the chemical compounds currently used in vector control. This necessitates the use of alternative methods for vector control. The sterile insect technique (SIT), which entails the periodic mass release of sterilized male mosquitoes into an environment where adult female mosquitoes are abundant, is one of the main promising approaches being proposed. The eggs laid by females that mated with sterile male mosquitoes will not hatch, thereby potentially reducing the population of the wild mosquitoes in the environment. I will present an ODE model of SIT and several strategies eliminating disease-carrying mosquitoes including using optimal and feedback control for adjusting the rate of release of sterile males as the wild population is reduced and leveraging interspecies competition from less-harmful species. I will also present a PDE model of SIT which demonstrates the spatio-temporal dynamics of SIT and allows for the development of strategies for, e.g., inducing counter invasions of non-disease-carrying mosquitoes that have recently been pushed out of their historical ranges by their disease-carrying cousins.

Zhoulin Qu

University of Texas San Antonio

"Multistage spatial model for informing release of Wolbachia-infected mosquitoes as disease control"

Malaria remains one of the leading causes of infectious disease mortality worldwide, disproportionately affecting young children and vulnerable populations. Its transmission is shaped by complex interactions between host immunity, vector dynamics, and environmental seasonality. In this talk, I will introduce a mathematical modeling framework that captures age-structured malaria transmission in both year-round and highly seasonal settings. The model integrates the development of immunity through repeated exposure and accounts for the nonlinear feedback between immunity and disease spread. I will discuss how we use this framework to explore the timing and design of vaccination strategies, particularly in environments with strong seasonal variation. Along the way, I’ll highlight key modeling challenges, share insights from our sensitivity analysis, and reflect on how mathematical tools can inform more effective and context-specific malaria control interventions.

#SMB2025 Follow

Annual Meeting for the Society for Mathematical Biology, 2025.