Modeling Mosquito-Borne Disease Dynamics
Background
Mosquito-borne diseases affect millions of people every year and can be a major cause of mortality in many developing countries. Understanding the factors determining the dynamics of mosquito-borne diseases is crucial for improving our ability to prevent them and improve human health.
Projects
Research and Policy in Infectious Disease Dynamics (RAPIDD): Working group on mosquito-borne diseases
RAPIDD is a program funded by homeland security and implemented through the National Institutes of Health and Fogarty International. The purpose of the program is to improve the modeling of infectious diseases in ways that advance prospects for the prevention of infectious diseases. It funds a variety of working groups that focus on specific topics relating to the modeling of infectious diseases.
The goal of our RAPIDD working group is to identify gaps in the modeling of mosquito population biology that when included in vector-borne disease models are likely to have the biggest impact on disease prevention. I am currently leading a project to evaluate the current state of modeling of mosquito-borne diseases. Our team of 7 postdoctoral researchers will be reviewing several hundred models to determine what aspects of mosquito biology are and are not included in existing models, and help identify which biological components maybe crucial for accurately modeling and predicting the dynamics of mosquito-borne diseases. Related projects will evolve out of workshops addressing specific topics relating to working group objectives.
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| Malaria transmission cycle. Models often differ in which components of the transmission cycles are included and the level biological detail associated with each component (from http://globalucf.org/Malaria.htm) |
Estimating the force of infection from longitudinal serological data: A case study with Dengue
Dengue fever (DF) and dengue hemorraghic fever (DHF) are caused by a virus transmitted to humans via mosquitoes. The disease is common in the tropics and in Africa and affects over 50 million people annually. There are 4 different serotypes of the disease and infection with one type gives lifelong immunity to only that one serotype. Dengue fever symptoms include fever, headache, muscle and joint pains and rash. In the more severe DHF, patients also show variable haemorrhagic phenomena. Currently, there is no vaccine for the disease and prevention relies on vector control.
Beginning in 1999 and continuing to today, blood samples have been taken from individuals in a cohort study in Iquitos, Peru once every 6 months. The serostatus of each individual at the time of blood draw was determined by the plaque reduction neutralization test (PRNT). From this we can identify the 6 month period of time during which and individual became infected and what serotype they were infected with.
In collaboration with Aaron King (MSU), we are using these data and Bayesian models to obtain a continuous estimate of the force of infection for each serotype over time. We will use this to (1) examine relationships between the force of infection and potential predictors (e.g., weather, mosquito population indicators), and (2) test if the probability of becoming infected with one serotype influences the probability of being infected with another.
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| Vector: Aedes aegypti | Child suffering from dengue |
Dengue simulation model for improving disease prevention strategies
The purpose of this project is to develop and test a simulation model that can be used by vector control programs, public health officials, and policy makers to inform decisions about the management of vector-borne diseases. Users will be able to modify entomological and epidemiological parameters to reflect the conditions of their individual locations and test the effects of various control strategies (e.g., insecticide treated nets, indoor insecticide sprays) on vector and disease dynamics. Currently, I am completing the sensitivity analysis and validation of the model and preparing for software release. This project is funded by the Innovative Vector Control Consortium (Bill & Melinda Gates Foundation), whose objectives are to: (1) produce improved insecticides and formulations and (2) provide improved tools for vector control decision making processes that will be used at community levels in disease endemic countries to reduce disease transmission.
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| Insecticide treated bed nets are often used to prevent people from being bitten | Health worker applies residual spray inside home to kill mosquitoes |