Title: Assistant Professor, Division of Infectious Diseases and Global Medicine
Research Interests: Drivers of emergence of arboviral diseases, global health, humeral immunity to arboviruses, malaria, Ecological associations with vector-borne disease.
Drivers of Emergence of Arboviral Diseases
Dr. Amy Vittor studies factors that drive the emergence of vector-borne diseases. She conducted her doctorate on malaria and deforestation in the Peruvian Amazon, showing that a strong positive association exists between the abundance of malaria vectors and anthropogenic land use change. During her medical training, she treated patients with HIV and tuberculosis in Botswana, Kenya and Panama, and conducted malaria bed net implementation research in a United Nations Millennium Village in Ethiopia with the Earth Institute at Columbia University. Driven by a desire to better understand why arboviruses emerge where and when they do, she turned her attention to arboviral transmission. She studied dengue epidemiology in Kenya with the Centers for Disease Control and Prevention in Nairobi as a Fogarty International Clinical Fellow, and subsequently moved to Panama to examine the epidemiology of Venezuelan equine encephalitis and the emergent Madariaga encephalitis.
At present, her research continues to look at the effect of land use change on vector-borne disease, but now also includes an examination of the role of host susceptibility and the population’s prior immune history. She also attends on the infectious diseases service at the University of Florida Shands hospital.
The incidence of arthropod-borne viral diseases has been rising dramatically, with over 40% of the world’s population now at risk. Our lab is interested in investigating the drivers of mosquito-borne viral disease emergence. To this end, we examine the roles of tropical deforestation as well as host susceptibility in permitting diseases such as eastern equine encephalitis, Venezuelan equine encephalitis, Mayaro and chikungunya to take hold. These viruses are responsible for devastating encephalitides as well as debilitating arthralgic diseases. No approved treatments or vaccines for humans currently exist for these viruses. The findings from this study will aid in our understanding of where and why novel pathogens to emerge, and will also aid the development of vaccines and therapeutics.
- Host susceptibility: by studying the immune responses of a population in Panama, we study the mechanisms and extent of cross-reactive immunity to this important subset of arthropod-borne viruses, the alphaviruses. The central hypothesis being tested is that heterologous immunity is protective in alphaviral infection, mediated by antibodies acting via Fc receptor-mediated effector functions. These mechanisms act as a bridge between the adaptive humoral response and the innate immune response, and as such, have the potential to become activated quickly to prevent disease acquisition. We study these mechanisms by examining humoral and memory B cell cross-reactivity to heterologous virus.
- Deforestation: Deforestation greatly alters the breeding, abundance, and species composition of mosquitoes. This is a mediated by changes in the availability of breeding sites for the immature stages, as well as differences in resources, predation, survival, and fecundity. Whether these changes favor or disfavor vectors of disease, however, depends on the vector’s specific ecology. To examine this, we analyze associations between land use and land cover and seropositivity in small mammals as well as humans to eastern equine encephalitis and Venezuelan equine encephalitis in Panama.
- Arboviral transmission: In many regions where arboviral disease hotspots occur, laboratory facilities and technical expertise to conduct studies on transmission are lacking. We are studying a novel method for the identification of key animal reservoirs for eastern equine encephalitis and West Nile virus. We have designed a novel mosquito trap baited with wild-caught small mammals to allow for mosquitoes to enter and feed on the animal. This method allows us to measure daily viremia in the animal and to simultaneously capture vector mosquitoes. This study provides a field-based method for answering key questions pertaining to the enzootic cycles of local arboviruses.
Global Initiatives – Panama
Dr. Amy Vittor has been conducting research on emergent eastern equine encephalitis virus in Darien, Panama in collaboration with the Gorgas Memorial Institute (GMI), Panama.
South American eastern equine encephalitis virus (family Togaviridae, genus Alphavirus) typically does not cause disease in humans. In 2010, however, there was an outbreak in the Darien that affected primarily children. This virus has been known to circulate in animals in Panama for years. Why has it emerged in humans now? What is its transmission cycle? What role do deforestation and migration play in the transmission of this virus? The closely related Venezuelan equine encephalitis virus is endemic in the region; how does immunity to this virus influence the susceptibility to eastern equine encephalitis? These are the questions we are trying to answer.
We have been searching for the enzootic host of this virus, and have initial possible candidates based on field research of small mammals conducted by Dr. Blas Armien at GMI. In addition, we are defining the contribution of land use and land cover to the prevalence of eastern equine encephalitis and Venezuelan equine encephalitis in humans and animals. In the spring of 2015, we anticipate conducting mosquito vector studies and blood meal analyses to further define possible enzootic hosts. Concurrently, we are planning a field study to follow seroconversion rates in humans and to study immunological interactions between the two alphaviruses.