Transmission Dynamics of Mosquito-Borne Diseases: Modeling, Analysis, Prediction and Control

Mosquito-borne diseases (MBD), such as West Nile virus (WNV), dengue, and Zika virus, have become a significant global health burden for human society. Complex factors, including weather conditions, anthropogenic land use and vector-virus-host interactions, greatly affect the mosquito abundance and distribution, and the disease transmission process. In this dissertation, I will investigate the mosquito population dynamics and transmission dynamics of MBDs, and explore how these factors play roles in the MBDs. Particularly, we use WNV and Culex mosquitoes (WNV vectors) in the Region of Peel, Ontario, Canada, as an example for this study.

We first study single species population models for the mosquito and the bird respectively. For mosquitoes, we take into account the contribution of the mosquito feeding preference to the oviposition and the intraspecific competition among preadult mosquitoes. For birds, we summarize the impacts of bird species, migration and age states on the transmission of WNV and explore the influence of WNV on bird populations.

Then we establish a model to track the number of mosquitoes collected in a trap, predict mosquito trap counts and real adult mosquito population in an effective trapping zone. We consider the trapping mechanism of a CDC light trap and collecting procedure, and show how weather, mosquito and host selecting behaviors affect the trap counts.

To explore the transmission dynamics of WNV, we develop a single-season mosquito-bird model considering stormwater management ponds, temperature and precipitation. We reveal that moderate temperature and precipitation, weaker intraspecific competition will increase the mosquito population and consequently the potential for an outbreak. This work can be used to guide WNV programs in local health units where monitoring standing water and larviciding is often used to control mosquito populations and the spread of WNV.

To investigate backward bifurcation, threshold dynamics and outbreak recurrence mechanisms, we propose improved mosquito-bird compartment models. We define a new risk index to characterize the potential risk of WNV infections. We also develop the risk assessment criteria, which can be helpful to determine the risk level if there is an outbreak. Our evaluation results are generally consistent with results based on the minimum infection rate.