Meta-analysis of effects of African population health initiatives

There are many ongoing African initiatives focused on local impacts on population health, with the goal of reducing mortality rates and increasing access to essential medical services.   In the past several years, a number of these initiatives have published analyses of impacts of their programs.  While these initiatives are programmatically different, they use the same metrics for measuring impacts (e.g., under-five mortality; access to treatment for fever, diarrhea, respiratory infections; vaccine coverage).  A database of published results has been constructed, and will be used by the student researcher to better understand different models for accomplishing health related development goals and identifying gaps in the evidence base.

Mentor: John Drake
Type of Project: Quantitative/Computer-based

Nectar, parasitism and flight in butterflies

When animals have unlimited access to food, they can often tolerate parasite infection and maintain high levels of growth and reproduction – but under food shortages, infected animals suffer more severe harm from parasites. This study examines the interactive consequences of food resources and parasitism for flight in a migratory insect, the monarch butterfly.  Migratory animals face extreme energetic demands during long migratory journeys, and some studies show that infected animals are less likely to survive long-distance migrations, in part owing to lower energy reserves of infected animals.  Monarchs are famous for undergoing a long-distance two-way bird like migration from breeding grounds as far north as Canada to wintering sites in southern Mexico.  Monarchs fuel their migration by accumulating lipid reserves from nectar resources during the fall. Monarchs are infected by a debilitating protozoan that replicates internally in caterpillars and pupae, and forms dormant spores on the outside of adults’ bodies. These parasites can lower monarch survival and reproduction, and past work showed that infected monarchs migrate less well than healthy butterflies. The proposed project test the flight performance of experimentally infected and healthy monarchs, fed different nectar diets. This study will examine the hypothesis that the flight performance of infected monarchs will suffer more under caloric restriction than the flight performance of healthy butterflies.

Mentors: Ashlew Ballew, Paola Barriga, Sonia Altizer
Type of project: Empirical, lab-based

Parasitism and Stress

Research in the Davis lab is broadly focused on animal “ecophysiology”, with study subjects ranging from birds, to butterflies, to beetles. REU students can make many contributions to these ongoing projects, with a combination of field work and laboratory experiments.  A recent thematic area involves asking, how can animals cope with the daily stressors in their lives while being parasitized? A useful study subject for these experiments is a common forest-dwelling beetle (horned passalus, pictured), which is naturally-parasitized by a seemingly benign nematode (pictured). This parasite appears to cause little outward harm to its host, but during times of duress or heightened activity, there is in fact an observable cost to being parasitized.

In the summer of 2020, an REU student will conduct an experiment that tests the behavioral and physiological reactions of parasitized and unparasitized beetles to a mild, non-lethal stressor, to further understand how parasites impact their hosts. The details of this project will depend in part on the interests of the student. The ideal applicant for these projects is someone who is OK with traipsing through chigger-infested forests, is able to work with (handle) bugs, and who is not squeamish about icky dissections.

Mentor: Andy Davis
Type of project: Empirical, Lab- or field-based

Understanding hydrogen peroxide employment by honeybees as an anti-parasitic social immunity tool

Hydrogen peroxide has immunological function across a broad suite of life on earth, and is still used in the US as a common antiseptic. Honeybees are another self-medicating social animal also known to use hydrogen peroxide manipulation – mostly in honey production; this in part makes it the only naturally occurring foodstuff to never spoil and underpins part of its medical applications in wound healing. Previous undergraduate work with UGA and Emory University investigated whether hydrogen peroxide content in honey poses a toxicity risk to a macroparasite, the small hive beetle, in addition to its antimicrobial effects. Dr Lewis Bartlett is currently trialling novel small hive beetle control methods, and this project will integrate with that work to further establish: ranges of hydrogen peroxide content in naturally occurring honey across different nectar sources, honeybee tolerance of hydrogen peroxide consumption and whether it exceeds that of other insects, and toxicity of hydrogen peroxide to juvenile and adult small hive beetles with the potential for it to be employed as a parasite control agent. The study will further be framed in the context of floral diversity and pollinator health, by determining whether different plants favour the production of honey with different antiparasitic or antiseptic properties through. The student will undertake empirical entomological toxicity trials and basic entomological rearing at the UGA honey bee lab, as well as data analysis and visualisation focussed on assessing survivorship, with the aim to produce a concise scientific publication; they will also have the opportunity to learn field skills in apicultural research if they wish. The student will also be given the option to attend (for free – including transport from Athens, meals and accommodation) a leading honeybee conference in North Georgia (https://bees.caes.uga.edu/yhc-uga-beekeeping-institute.html) as an introduction to the system in the week of May 11th – 16th, prior to the official REU start date of May 18th.

Mentor: Lewis Bartlett
Project Type: Empirical, lab- and field-based

Specific Requirements: Student cannot have a known allergy to honeybees, and must have no objection to euthanasia or experimental destruction of live insects for research purposes.

Honeybees in a hive

How parasites influence ecosystems: studying the varied effects of a trematode parasite on its environment

Historically, parasites have been primarily studied for their negative effects on human and animal health. However, the scientific community is becoming increasingly aware that parasites can have complex effects on their ecological communities (Dunn et al. 2012, Mischler et al. 2016), and in some cases can benefit the ecosystem (Davis and Prouty 2019). How parasites alter ecosystem processes and nutrient cycling remains relatively unexplored, despite calls to address this question (Raffel et al. 2008, Hatcher et al. 2012). However, this question is vital because such research could provide novel insights into both human and ecosystem health.  In addition to the direct impacts of parasites on host mortality and population growth, parasites can indirectly impact their communities and environments in subtle, but equally important ways (Buck and Ripple 2017). For example, parasites can alter ecosystem processes through changes in host physiology (Bernot and Lamberti 2008), nutrient excretion stoichiometry (Bernot 2013) and behavior (Lafferty and Ecology 1996) that have population and community-wide effects. For this project, we will investigate how a trematode parasite influences its snail host, Helisoma trivolvis, in terms of various host changes such as nutrient excretion, metabolism, respiration, foraging and behavior. The REU student will investigate these effects by comparing infected and uninfected snails in the lab. The majority of the work will be done in the lab, but there is possibility for field work and field manipulations given time and interest.

Mentors: Emlyn Resetarits and Jeb Byers
Type of project: Empirical, lab-based

Mammalian host biodiversity and filovirus spillover risk in Africa

Ebola and other filoviruses are multi-host pathogens that can infect a wide variety of species, and filovirus emergence presents a pressing threat to human health.  Presumably areas that contain large numbers of host species that are susceptible to filoviruses or that contain key reservoir species (such as bats) in high abundance are also areas where the risk of transmission from wild animals to humans is high.  However, this hypothesis has rarely been tested.  Using data on the location of past spillover events of Ebola, Marburg virus, and other filoviruses in Africa, the goal of this project will be to test what aspects of mammalian host biodiversity (e.g., variation in  mammalian species richness, phylogenetic diversity, or ecological diversity) have the greatest impact on spillover risk.  Mammalian host data will be drawn from a variety of published sources such as PanTHERIA (a species level database of mammalian trait data) and species range data compiled by the International Union for Conservation of Nature. The project will involve compiling large data sets and analyzing them using the R programming language. 

Project Mentor: Patrick Stephens
Type of Project: Quantitative/Computer-based

Population Genetics of the Lyme Disease vector, Ixodes scapularis

The tick species Ixodes scapularis (Acari: Ixodidae) is the main vector in the United States for Borrelia burgdorferi, the causative agent of Lyme Disease. Previous research has identified behavioral differences between northern and southern populations of I. scapularis with northern nymphs spending more time above leaf litter increasing the likelihood for human contact. This difference in behavior is observed despite the environment, suggesting an unknown genetic driver to these behavioral patterns. This study will expand on a pilot study using ticks from Connecticut, South Carolina, and Minnesota that identified 99,187 SNPs distributed across 14,168 polymorphic loci using triple-enzyme restriction-site-associated DNA sequences (3RAD). This illustrates that I. scapularis populations have large amounts of intra- and inter-population variation. In this upcoming study we plan to assess 27 populations across the range of I. scapularis to elucidate the genotypes driving behavioral differences and Borrelia transmission. We are also interested in microbiome disparities across this range as it could have an impact onBorrelia transmission. The student will be trained and involved across the pipeline of this study: tick ID, DNA extraction, 3RAD and 16S library prep, and bioinformatics analysis.

Project mentors: Julia Frederick and Travis Glenn
Type of project: Combination of Empirical (lab-based) and Quantitative (computer-based)



Who is at risk of getting infected in structured contact networks?

Human immunodeficiency virus transmits through networks of people linked through a
range of contacts, including sexual contact and intravenous drug use. SARS and Foot
and Mouth Disease are spread through long-distance movements of infected people
and livestock, followed by local transmission. These outbreaks demonstrate the
important role of networks to transmission of pathogens. Networks can be quantified in
many ways, and an individual’s “importance” to the population can be described with
node “centrality” statistics. Identifying which centrality statistics indicate an individual
has high vulnerability to infection could greatly enhance surveillance and prevention.
However, pathogen transmission routes and human social networks are highly variable
in their structure. For example, sexual contact networks for HIV tend to be assorted by
race. This project will investigate our ability to predict the vulnerability of individuals to
infection when networks are structured in space or social groups. These results could
help us understand when it is worthwhile to estimate node centrality for surveillance
and prevention systems.

The student selected for this project will work closely with Paige Miller (PhD student) to
write computer code (R and python) for disease simulations on networks. The project
will be supervised by Dr. John Drake (Odum School of Ecology, Director of the Center
for the Ecology of Infectious Diseases) and Dr. Chris Whalen (College of Public Health,
Director of the Global Health Institute). This is a quantitative and simulation-based
project; we will not be collecting our own data. Long hours of learning how to code and
manage data in R will be required. An interest in mathematical modeling of infectious
diseases, ecology, and human sociology is encouraged. The student is free to tailor
this project to their own interests by focusing on specific pathogens or populations!

Mentors: Paige Miller, John Drake, Chis Whalen

Development of infectious disease research and teaching software

Using computer models to study infectious diseases can be challenging for students and researchers who are not trained as modelers. To make this process easier, we have developed several software packages, implemented in the popular R language, to help individuals learn about and analyze infectious disease models both at the individual and population level. The goal of this project is to further advance this software by implementing new features, making tutorials, testing existing features, adding new features, and more. This will increase the usefulness and power of the software and will give future students and researchers better tools to learn about and analyze different infectious diseases. This project is quantitative. We will make use of the R language for all parts of this project. The project is offered by the Handel group.

Host Laboratory: Andreas Handel
Type of project: Quantitative/Computer-based

Data analysis to help inform norovirus vaccine design

Norovirus is a common cause of gastrointestinal disease. There is currently no vaccine, but several are under development. It is not clear how exactly a new norovirus vaccine should look like and to whom it should be mainly given (e.g. children or adults). Together with colleagues at Emory University, we are working on a project that analyzes different types of norovirus data to develop a comprehensive mathematical modeling framework to guide norovirus vaccine design and implementation. For this project, you will help with those analyses. The results of this analysis will allow us to better understand properties of norovirus infection and transmission and therefore will help inform the design and implementation of a future norovirus vaccine. This project is quantitative. We will make use of the R language for all analyses. The project is offered by the Handel group.

Host Laboratory: Andreas Handel
Type of project: Quantitative/Computer-based