In the United States, Lyme disease is the No. 1 vector-borne disease, meaning infections transmitted by arthropod species, such as mosquitoes, ticks and blackflies. Beyond the typical fever, headache and fatigue, the disease can be debilitating for many, leaving some bedridden. Favorable conditions in the northeast make Delaware an unfortunately ideal location for the disease’s life cycle.

University of Delaware wildlife ecology graduate student Scarlet Shifflett is going down to the genetic level to understand the disease’s makeup in the state of Delaware, a Lyme disease high incidence state. 

To get to the genetic level, you must first backtrack the disease’s path to humans. Infected blacklegged ticks are public enemy No. 1 and rightfully so. Their bite causes the transmission. Also known as deer ticks, these worrisome arthropods have a less publicized accomplice — the white-footed mouse. The mice and other small mammals are the actual carriers of Lyme disease. The ticks bite the rodents. The ticks become infected. The ticks pay it forward to humans. When the population of these mice increases, so may the numbers of Delawareans with Lyme disease. 

Whether a tick bite leads to Lyme disease or not boils down to bacteria’s alleles, alternative forms of a gene that arise via mutation. Borrelia burgdorferi, the bacterium behind Lyme disease, boasts quite the genetic diversity. In particular, the animals’ outer surface protein C (ospC) alleles, responsible for causing infections in vertebrates, have Shifflett’s attention. She’s analyzing what alleles within the ospC gene are present in the First State and if they are changing over time, by location and in which species (like those white-footed mice). She’s chiefly focused on ticks in the nymph stage of their life cycle — the time when they are most likely to infect humans. 

To acquire these samples, Shifflett captures and releases mice and eastern gray squirrels, who also carry the disease, with an assist from irresistible peanut butter. She then takes an ear sample and picks off the ticks. Once the animals are tick-free, Scarlet sends them on their way. 

Shifflett then departs the field for Townsend Hall on UD’s campus, where she digs into molecular lab work, amplifying and analyzing genetic material through polymerase chain reaction (PCR) testing.

“Scarlet is a determined, critical-thinking and hard-working researcher,” said Vincenzo Ellis, assistant professor in the Department of Entomology and Wildlife Ecology, which is part of the College of Agriculture and Natural Resources.

But Shifflett isn’t conducting all of this work on her own. She’s training UD undergraduates. 

“In teaching undergraduates, I’ve learned how to explain scientific research to a more general audience. Communicating what I’m doing to others helps me better understand the material,” Shifflett said. “The research was a great way to teach undergraduates how to handle small mammals, trap them and work in a wildlife ecology lab.”

Added Ellis, “Scarlet is also dedicated to mentoring students and has trained numerous undergraduates in both laboratory and field techniques related to disease ecology.”

It’s also helpful that Shifflett was recently a UD undergraduate herself. The UD Class of 2021 wildlife ecology and conservation major came to Newark as a transfer student. Disappointed with her original university’s wildlife program, she found the small-but-mighty UD Department of Entomology and Wildlife Ecology gave her more opportunities. 

“UD’s wildlife program incorporates more natural history than most other universities,” said Shifflett, who graduated from nearby Elkton High School. “At UD, you go outside and take a lot of taxonomy courses. UD also emphasizes undergraduate research and provides a lot of opportunities.”

As she wrapped up her undergraduate studies, Shifflett made up her mind to become a wildlife disease ecologist. She’ll analyze zoonotic diseases (those transmissible from animals to humans), something the general public became all too familiar with during the pandemic. Her undergraduate research with Vincenzo Ellis led to a National Science Foundation Graduate Research Fellowship for Shifflett to pursue a master of science in wildlife ecology. 

In the spring, Shifflett will defend her master’s thesis on her research. Then — because UD is so nice, you should study thrice — she’ll remain in Newark to pursue her doctorate in entomology and wildlife ecology.