The four main tenets of my work are:
1. Question-driven science
When working with students, I often feel like a broken record, because I am constantly asking them, what’s your research question? I believe that almost any issue can be solved by going back to the central research question. Lost in your data? Can’t figure out how to design your experiment? What’s your research question? Which graph to include in the paper? How to structure your manuscript? What to cover in the introduction? What to discuss in the discussion? What to put in your powerpoint? You get the idea.
2. Science for a reason
I do not do science in a bubble nor to make me feel really smart. In my work, every project I do must have the possibility, however minute, of having a positive impact on human society, conservation, the environment, or all of the above– even if it is just a drop in the proverbial bucket (as PhD theses often are- see below to read about my own contribution to the proverbial bucket).
3. Clarity first
The most important thing we do as scientists is communicating our work CLEARLY to non scientists. If no one understands what you did and what it means in the context of the world, what is the point? Which brings me to my final point…
4. There is no such thing as a ‘science person.’ Science is for everyone!
Need I say more?
1. Chagas disease risk in the Trinidad
Currently, not one island nation in the Caribbean is considered endemic for Chagas disease by the World Health Organization (WHO) or the Pan American Health Organization (PAHO). However, triatomine bugs have been found on several Caribbean islands, and a handful of studies have found patients with infected with the Chagas parasite Trypanosoma cruzi.
Our team is carrying out an extensive survey to characterize the risk of Chagas disease in Trinidad. In our first preliminary study, we found that 80% of bugs were infected with T. cruzi, and 57% of bugs had fed on humans. Read the full publication here.
2. Oil palm plantations and Chagas disease: a new disease transmission scenario in Panama?
In the past 20 years, agroindustry expansion has facilitated infectious disease outbreaks on a global scale, including outbreaks of Nipah virus, avian influenza and most recently the Ebola virus. One of the most rapidly expanding crop types in the Americas is the oil palm. In this industry, the African oil palm, a non-native species in the Americas, is planted in large monoculture crops, and oil is harvested from the palm nuts.
Often small, wild mammals such as opossums and bats, colonize the palms. Incidentally, these animals are also key hosts of Trypanosoma cruzi, the parasite that causes Chagas disease in humans. In Colombia, a study of African oil palms found kissing bugs in 47% of trees, 29% of harvested palm crops, and 41% of the bugs were infected with T. cruzi. If palm oil plantations in Panama were to have kissing bugs living in oil palms alongside small mammal species, all the components for a new Chagas disease transmission scenario would be in place.
Along with collaborator Nicole Gottdenker from the University of Georgia, we were awarded an international seed grant to collect preliminary data to evaluate if large-scale palm oil plantations in Panama are creating a new Chagas disease transmission scenario. This could have serious repercussions on public health, as it brings the vectors into regular contact with humans working and living in and around plantations, and creates a hotspot of Chagas disease transmission.
1. Integrating evidence, models and maps to enhance Chagas disease vector surveillance
In this study, we introduce an entomological surveillance app developed to increase surveillance efficacy for infestations of the triatomine bug species Triatoma infestans, the vector of the Chagas disease parasite Trypanosoma cruzi.
Taking it one step further, we investigated whether or not vector surveillance inspectors would use actually the app when given the opportunity- a critical, yet all too often neglected step in implementating new epidemiologic tools. Read the full publication here.
2. Trypanosoma cruzi Infection Does Not Decrease Survival or Reproduction of the Common Bed Bug, Cimex lectularius
In a previous study, it was found that the common bed bug, Cimex lectularius can transmit Trypanosoma cruzi, the causative agent of Chagas disease. In this follow up study, we asked, why has C. lectularius not been observed to vector T. cruzi outside of the laboratory? Read the full publication here.
3. Mathematical models of Chagas disease
I worked to develop mathematical models of Trypanosoma cruzi (etiological agent of Chagas disease) transmission as part of the NTD Modelling Consortium, funded by the Bill & Melinda Gates Foundation. The aim of this project was to use quantitative analysis to assist the World Health Organization in meeting their 2020 goals for Chagas disease.
In this work, we used a mathematical model to explore how animals that live around people (such as pets, livestock, and vermin) can increase or decrease transmission of T. cruzi to the people who live in their proximity. We found that animals slighty increase the speed of transmission to humans, but that transmission is still maintained in the absence of animals, albeit slower. For example, in a scenario with animals, nearby humans may get infected within 5 years, as opposed to 7 years without animals. This is an important finding, as some have suggested reducing animals as a way to reduce transmission. Based on our work, we disagree with this strategy, as animals affect only the speed of transmission, but not the ocurrence of transmission. To learn more, click here.
Do vectors get sick too?
My doctoral thesis was centered on how human pathogens affect their insect vectors. Every interaction between species occurs in a heterogeneous environment that presents countless contexts that shape the interaction over time and space. The consequences of these interactions can regulate populations, as they trickle down to influence the genes that an individual passes on to its offspring, and then, in turn, scale back up to influence the genetic and phenotypic composition of future populations. In my doctoral thesis, I sought to uncover how these principles play out in the interactions between an invertebrate vector of human disease and the disease agent it carries. Disease vectors are often considered in a context that is faithful to the word as it is used in physics, where the vector is viewed as public transportation that moves the pathogen between hosts, experiencing no consequences of parasite infection. However, vectors face the challenge of how to maximize individual fitness in a stochastic environment with limited resources just as all other species do, so why would they be exempt from the effects of being parasitized?
As such, I investigated the triatomine bug species Rhodnius prolixus when infected with the parasite Trypanosoma cruzi (etiological agent of Chagas disease), and co-infected with T. cruzi and its sister species, T. rangeli. I asked, does T. cruzi affect R. prolixus fitness, and under what contexts does this effect vary? I found a large range of variation in R. prolixus fitness when infected with T. cruzi, with the outcome being influenced by parasite strain, co-infection with T. rangeli, parasite dose, and the timing and order of infection. These factors did not act alone, but seemed to be dependent on one another: it was better to have a co-infection at lower T. rangeli doses, but at high T. rangeli doses, it was better to be infected with T. cruzi first, suggesting an interaction between dose, order and timing. These results illustrate the interactions across scales of both biological and spatio-temporal complexity that can be revealed when studying infectious disease through an ecological lens. Moreover, this work emphasizes the importance of taking into account the ecology of vector-borne neglected tropical diseases such as Chagas disease.
Graduate student mentorships
Doctoral thesis co-adviser, 2021-present: Rod Suepaul, Department of Environmental Science, University of the West Indies, Trinidad and Tobago
Doctoral Committee Member, 2017- present: Kaylee Arnold, Interdisciplinary Disease Ecology Across Scales (IDEAS), Odum School of Ecology, University of Georgia
Masters summer practicum supervisor, 2015: Hannelore MacDonald, Columbia University, Mailman School of Public Health
Undergraduate student mentorships
Thesis: Applying Next-Generation Sequencing to the Genetics and Ecology of Rhodnius pallescens, A Vector of Chagas Disease
Alexandra Eakes, Princeton Undergraduate Senior Thesis.
“Chagas disease ecology in Trinidad: Trypanosoma cruzi infection status and bloodmeal analysis of triatomine bugs on an island considered free of vector-borne transmission.”
**Alexandra won the Charles M. Cannon Memorial Prize for the best presentation of a senior thesis.**
Alexandra is currently a medical student at the University in Oklahoma.
Adriana Stephenson, Princeton Undergraduate Senior Thesis
“Elucidating Trypanosoma cruzi reservoirs across South and Central America: a review of over 70 years of sero-epidemiological evidence”
Adriana is currently a graduate student at the University of Pennsylvania.
Kathleen Mulligan, Princeton Undergraduate Senior Thesis
“Relationship between climate and the dengue fever vector Aedes aegypti in Machala, Ecuador”
Roberta “Birdie” Hutton, Princeton Undergraduate Senior Thesis
“Vector control and health care-seeking behavior: Chagas disease and dengue fever in Medellín, Colombia”
Birdie is currently a medical student at the Hackensack Meridian School of Medicine.
Anchal Padukone, Princeton Undergraduate Senior Thesis
“Relationships between Microhabitat Characteristics and the Abundance of a Chagas Disease Vector, Rhodnius pallescens, in Central Panama”
Anchal is currently a graduate student in the Department of Ecology and Evolutionary biology at the University of Tennesee at Knoxville.
Thomas Yetter, Princeton Undergraduate Senior Thesis
“Attraction of Chagas disease vector Rhodnius pallescens to artificial light sources”
Ryan Elliott, Princeton Undergraduate Senior Thesis
“Triatomines and trypanosomes: Fitness impacts of Trypanosoma cruzi and Trypanosoma rangeli mono- and co–infections in the triatomine vector Rhodnius prolixus”
**Ryan won the Ecology and Evolutionary Biology department prize for best laboratory thesis poster.**
Ryan went on to spend a year as a Princeton Fellow in Africa, working in the public health sector in Lisotho, and is now a medical student.
Lauren Castro, Princeton Undergraduate Senior Thesis
“Flight performance and trypanosome infection of the Chagas disease vector Rhodnius Pallescens: implications for the spatio-temporal spread of Trypanosoma cruzi in rural landscapes.”
*A part of this thesis is published in the Journal of Medical Entomology (see reference above under Castro et al.)
Lauren went on to complete a PhD in the Meyers Lab at the University of Texas at Austin, and is now a post-doc at the Los Alamos National Lab.
I am always looking to form new collaborations. If you have an idea of something you’d like to work on together, please contact me at firstname.lastname@example.org.