Study Sheds Light on Tick-Borne Infection
Posted on October 21, 2026
Bacteria from the Gulf Coast tick can be transmitted to its host within one hour of attachment before spreading rapidly to lymph nodes and internal tissues, according to new research by a recent graduate of the Frederick P. Whiddon College of Medicine.
Kevin Macaluso, Ph.D., and Chanakan “Nam” Suwanbongkot, Ph.D.
Chanakan “Nam” Suwanbongkot, Ph.D., published findings from her dissertation research in the scientific journal PLOS Pathogens, advancing understanding of how tick-borne bacteria enter the body and interact with the immune system. Her study, conducted in the laboratory of Kevin Macaluso, Ph.D., professor and chair of microbiology and immunology, used a single-tick model designed to more closely reflect how people are naturally exposed to tick-borne pathogens.
“Tick-borne diseases, including spotted fever group Rickettsia, have become an increasingly important public health concern in the United States over the past few decades,” Suwanbongkot said. “Although these diseases occur worldwide and reported cases of rickettsioses are rising, little is known about tick-to-vertebrate transmission biology.”
The Gulf Coast tick is the primary vector for Rickettsia parkeri, the bacterium that causes R. parkeri rickettsiosis. R. parkeri can cause febrile illness and a characteristic eschar — a dark, necrotic lesion that develops at the site of a tick bite.
The research findings offer new insight into the earliest stages of infection and a foundation for future research into tick-borne disease prevention.
“This work really pushes the field forward with a thorough analysis of tick transmission of a bacterial pathogen,” Macaluso said. “I was impressed by Nam’s ability to develop the bioassay and orchestrate the experiments with collaborators, all leading to an impactful publication.”
Many studies of Rickettsia infection use needles to introduce bacteria into the body, an approach that cannot fully capture the interactions among the tick, the pathogen and the host during a natural bite. To address this gap, Suwanbongkot and her collaborators developed a model using a single infected tick to study bacterial transmission and the host’s immune response at the attachment site.
Because tick saliva can influence the host’s immune response, this approach allows researchers to investigate aspects of natural transmission that needle-inoculation models may not capture. Additionally, the bacterial load delivered by the tick was substantially lower than the doses typically used in needle-inoculation studies.
The team also tracked changes in skin inflammation and immune activity over time. Although inflammation developed as ticks fed regardless of their infection status, infected skin showed a distinct immune response later in the feeding process. By six days after tick attachment, macrophages were the dominant immune cell type at the bite site, accompanied by changes in inflammatory signals consistent with a delayed pro-inflammatory response to infection.
“Dr. Suwanbongkot’s study employed a novel single-tick feeding model that reflects natural human exposure,” said Robert Barrington, Ph.D., professor of microbiology and immunology. “Her study advances our understanding of the earliest events in tick-borne infections and provides a valuable foundation for future studies aimed at preventing tick-borne disease.”
Killian Brewer, Ph.D., a 2025 graduate of the Whiddon College of Medicine who conducted research in Barrington’s laboratory, also contributed to the study. He is now a postdoctoral fellow at Vanderbilt Health.
“I’m grateful to have contributed to such a talented team, bringing together expertise in tick biology, pathogen transmission, and host immunology,” Brewer said. “It was exciting to see these perspectives come together to better understand pathogen kinetics and their interaction with the host defenses.”
Suwanbongkot graduated from the Basic Medical Sciences Graduate Program in summer 2026 and is continuing her postdoctoral research in Macaluso’s laboratory. “My Ph.D. experience was great,” she reflected. “I had the opportunity to collaborate with many outstanding scientists and learn new techniques through this project.”
Read the full study, “Spotted fever group Rickettsia infection kinetics and cutaneous host response during single tick feeding events,” in PLOS Pathogens.
