Document Type


Date of Award


Degree Name

Master of Science (MS)


Basic Biomedical Science

First Advisor

Jose Pietri


The human body louse (Pediculus humanus humanus) is a host-specific hematophagous ectoparasite that frequently infests populations experiencing a breakdown of hygienic conditions. Body lice are vectors for several bacterial human pathogens, including Borrelia recurrentis (relapsing fever), Rickettsia prowazekii (epidemic typhus) and Bartonella quintana (trench fever) (Badiaga & Brouqui 2012, Amanzougaghene et al. 2020). Today, louse-borne relapsing fever and epidemic typhus are largely geographically restricted to small foci in East Africa. However, B. quintana is a re-emerging and underappreciated pathogen throughout the globe, especially in urban environments (Mai 2022). Transmission of B. quintana is known to occur via inoculation of infectious body louse feces into abraded skin or mucous membranes of a human host. However, there is debate in the field over whether the pathogen can be transmitted transovarially from infected female lice to their progeny, which could significantly influence disease transmission cycles. To address this question, we performed a series of experiments that examined the surface and interior of lice eggs produced by orally infected females, as well as the hemolymph of those females, for the presence of B. quintana. Additionally, human infection with B. quintana is associated with alcoholism and homelessness and can coincide with elevated circulating levels of cytokine IL-10 and the inflammatory marker neopterin. Hematophagous arthropods are capable of responding physiologically and immunologically to a variety of biomolecules present in the blood of their hosts. Therefore, we sought to investigate whether ingestion of alcohol, its metabolic product acetaldehyde, IL-10 or neopterin could affect innate immunity and infection in the body louse. Furthermore, minimal research has been conducted on the immune system of the body louse in response to bacterial challenge. More specifically, there is no prior research on the effect of the human pathogen Borrelia recurrentis on the louse immune system. We addressed this knowledge gap by orally administering varying concentrations of B. recurrentis to body lice via and analyzing the expression of immune genes. Lastly, we investigated the infectious dose of Borrelia recurrentis required for body lice to become stably infected. These findings have implications for understanding, mitigating, and preventing pathogen transmission by the body louse.

Subject Categories

Entomology | Immunology and Infectious Disease | Microbiology


Arthropod vectors, Bartonella quintana, Body lice, Borrelia recurrentis, Disease Transmission, Innate Immunity

Number of Pages



University of South Dakota

Available for download on Friday, May 16, 2025