@article {96451, title = {A Comparative Study of Body Lice and Bed Bugs Reveals Factors Potentially Involved in Differential Vector Competence for the Relapsing Fever Spirochete Borrelia recurrentis}, journal = {Infection and Immunity}, volume = {90}, year = {2022}, month = {May-19-2022}, pages = {13 pp}, abstract = {

Borrelia recurrentis is the causative agent of louse-borne relapsing fever and the only Borrelia species transmitted by an insect rather than a tick vector. While bed bugs (Cimex lectularius L.) are not established vectors of any human pathogens, a recent study reported that they may be competent vectors of B. recurrentis. However, many aspects of infection and transmission remain unclear in this possible secondary vector. Here, we carried out several quantitative laboratory studies to gain a better understanding of the host suitability of bed bugs relative to the established body louse vector as well as the factors that may affect the ability of bed bugs to transmit the pathogen. We fed bed bugs B. recurrentis and estimated the level and duration of infection in the hemolymph using live imaging. We performed quantitative PCR (qPCR) to examine whole-body spirochete levels and the occurrence of vertical transmission to progeny. We also developed an assay to compare the amounts of force required to release infectious hemolymph from recently engorged bed bugs and body lice. Finally, we analyzed humoral antibacterial activity in the hemolymph, hemolymph pH, and hemocyte activity in both insect species. Our results confirm that within 24\ h of ingestion, B. recurrentis can penetrate the midgut epithelium of bed bugs and enter the hemolymph, overcoming a major host barrier, as in body lice. Once in the hemolymph, spirochetes remain visible for at least 4 days. Moreover, we show that bed bugs are more physically susceptible to crushing than body lice, suggesting that crushing is a feasible route for the natural dissemination of B. recurrentis from the hemolymph of bed bugs, as for body lice. Nonetheless, our data also indicate that bed bugs are suboptimal hosts for B. recurrentis, as the bacterium does not appear to proliferate to high levels or stably colonize the hemolymph and exhibits pleomorphism in this environment. In particular, our data suggest that hemolymph pH and unique cellular immune responses, rather than humoral effectors, may be involved in limiting spirochete survival in bed bugs. Notably, we document the formation of extracellular DNA traps by bed bug hemocytes for the first time. For these reasons, while bed bugs may be capable of limited transmission given their ecology, vector competence is probably minimal relative to body lice. Additional mechanistic studies of human pathogen infection of bed bugs may provide much-needed insight into the biological factors that restrict their ability to act as vectors and may reveal novel mechanisms of immunity.

}, keywords = {Arthropod Vectors, Bed bug, Borrelia, Borrelia recurrentis, Cimex, competence, Hemolymph, host, lice, transmission, vector, vector-borne disease}, issn = {0019-9567, 1098-5522}, doi = {10.1128/iai.00683-21}, url = {https://journals.asm.org/doi/10.1128/iai.00683-21}, author = {Rashaun Potts and Jamie L. Scholl and Lee A. Baugh and Jose E. Pietri} } @article {96370, title = {Examination of vertical transmission of Bartonella quintana in body lice following multiple infectious blood meals}, journal = {Pathogens and Disease}, volume = {80}, year = {2022}, month = {Jan-01-2022}, pages = {5 pp}, abstract = {

Bartonella quintana is a re-emerging louse-borne pathogen. Horizontal transmission from the body louse vector (Pediculus humanus humanus) to a human host occurs through contact with infectious louse feces containing a high concentration of the bacteria. However, questions have remained about whether vertical transmission from infected vectors to their progeny, which could significantly influence the dynamics of transmission to humans, occurs in body lice. To address this subject, we performed a series of controlled laboratory experiments that examined the presence of B. quintana on the surface of and within eggs produced by female body lice that were provisioned multiple infectious blood meals to recapitulate the natural pathogen acquisition process. Our results demonstrate that B. quintana DNA can be detected from the surface of eggs by qPCR due to vertical transfer of infectious feces to the egg sheath during or after oviposition. However, viable B. quintana could not be cultured from the hemolymph of adult female lice or from within eggs that were surface sterilized, indicating a lack of true transovarial transmission. Based on this evidence, vertical transfer of B. quintana from infected adult lice to their eggs probably has a limited impact on the dynamics of transmission to humans.

}, keywords = {bartonella quintana, lice, louse, transmission, vector, vertical}, issn = {2049-632X}, doi = {10.1093/femspd/ftac028}, url = {https://academic.oup.com/femspd/article/80/1/ftac028/6634238}, author = {Lauren Kress and Rashaun Potts and Jose E. Pietri} } @article {95564, title = {Body lice and bed bug co-infestation in an emergency department patient, Ohio, USA}, journal = {IDCases}, volume = {19}, year = {2020}, month = {Jan-01-2020}, pages = {4 pp}, type = {Open Access}, abstract = {

Body lice and bed bugs are hematophagous insects that parasitize humans. Body lice are established vectors of several bacterial pathogens (e.g. Bartonella quintana, Borrelia recurrentis). Bed bugs are biologically competent vectors of some of the same agents, but their vectorial capacity for these in nature is unclear. In particular, a lack of exposure to louse-borne pathogens in bed bugs in the field could be a factor that limits their contribution to transmission. Here, we describe a case of a patient seen in an urban emergency department who was suffering from infestation with both body lice and bed bugs. Insects were collected from the patient and tested for the presence of louse-borne bacterial pathogens using 16S rRNA gene amplicon sequencing. Although no Bartonella, Borrelia, or Rickettsia were detected, this case provides evidence of ecological overlap between body lice and bed bugs and highlights several potential risk factors for co-infestation. The ecological relationships between bed bugs, body lice, and louse-borne bacteria should be further investigated in the field to determine the frequency of co-infestations and identify possible instances of pathogen infection in bed bugs.

}, keywords = {Bed bug, Cimex, Co-infestation, lice, louse}, issn = {2214-2509}, doi = {10.1016/j.idcr.2020.e00696}, url = {https://www.sciencedirect.com/science/article/pii/S2214250920300044}, author = {Jose E. Pietri and Justin A. Yax and Diing D. M. Agany and Etienne Z. Gnimpieba and Johnathan M. Sheele} } @article {95562, title = {A simplified protocol for in vitro rearing of human body lice}, journal = {Parasite}, volume = {27}, year = {2020}, month = {feb-2020}, pages = {6 pp}, abstract = {

Human body lice (Pediculus humanus) are neglected ectoparasites and pathogen vectors. Difficulties in raising and maintaining colonies of body lice in a laboratory setting remain a barrier to fundamental studies of physiology and vector-pathogen interactions in these insects. Several in vivo and in vitro rearing systems have been previously described and used by multiple research groups. However, these methods suffer from drawbacks that still complicate the rearing of body lice relative to many other commonly studied hematophagous insects. Here, a simplified protocol for raising and maintaining body lice in vitro using the commercially available Hemotek apparatus is described. This protocol draws from published methods for rearing body lice as well as other hematophagous insect species to further reduce labor, time, costs, and regulatory requirements typically associated with keeping human body lice in the laboratory. Using this protocol, the insects consistently fed on commercially available rabbit blood with little mortality, reached adulthood at a high rate, and produced a significant number of viable eggs, resulting in a 4.8-fold increase in population over a period of 40 days. The data suggest that the process described here can propagate modest populations for ongoing laboratory experiments and is a useful alternative to existing methods. The use and further optimization of in vitro rearing systems may facilitate dynamic studies of body lice by a wider range of investigators, enabling new progress in combating lice infestations, and louse-borne infections.

Re ́sume ́ \– Un protocole simplifi\é pour l\’\élevage in vitro des poux du corps de l\’homme. Les poux du corps de l\’homme (Pediculus humanus) sont des ectoparasites et des vecteurs de pathog\ènes n\églig\és. Les difficult\és \à \élever et \à maintenir des colonies de poux du corps en laboratoire restent un obstacle aux \études fondamentales en physiologie et des interactions\  vecteur-pathog\ène chez ces insectes. Plusieurs syst\èmes d\’\élevage in vivo et in vitro ont d\éj\à \ét\é d\écrits et utilis\és par\  plusieurs groupes de recherche. Cependant, ces m\éthodes souffrent d\’inconv\énients qui compliquent encore l\’\élevage des\  poux du corps par rapport \à de nombreux autres insectes h\ématophages couramment \étudi\és. Ici, un protocole simplifi\é pour\  \élever et maintenir des poux du corps in vitro en utilisant l\’appareil Hemotek, disponible dans le commerce, est d\écrit. Ce\  protocole s\’inspire des m\éthodes publi\ées pour l\’\élevage des poux du corps ainsi que d\’autres esp\èces d\’insectes h\ématophages pour r\éduire le travail, le temps, les co\ûts et les exigences r\églementaires g\én\éralement associ\ées \à la\  conservation des poux du corps dans le laboratoire. En utilisant ce protocole, les insectes se nourrissent constamment de sang\  de lapin disponible dans le commerce avec peu de mortalit\é, atteignent l\’\âge adulte avec un taux \élev\é et produisent un nombre important d\’\œufs viables, entra\înant une augmentation de 4,8 fois de la population sur une p\ériode de 40 jours. Les\  donn\ées sugg\èrent que le processus d\écrit ici peut propager des populations modestes pour des exp\ériences de laboratoire et\  est une alternative utile aux m\éthodes existantes. L\’utilisation et l\’optimisation des syst\èmes d\’\élevage in vitro peuvent faciliter\  les \études dynamiques des poux du corps par un plus large \éventail de chercheurs, permettant de nouveaux progr\ès dans la lutte contre les infestations par les poux et les infections transmises par les poux

}, keywords = {Artificial, body lice, feeding, In Vitro, method, rearing}, issn = {1776-1042}, doi = {10.1051/parasite/2020007}, url = {https://www.parasite-journal.org/articles/parasite/full_html/2020/01/parasite190151/parasite190151.html}, author = {Jose E. Pietri and Ritesh Ray} } @article {95556, title = {Case not Closed: Arguments for New Studies of the Interactions between Bed Bugs and Human Pathogens}, journal = {The American Journal of Tropical Medicine and Hygiene}, volume = {103}, year = {2020}, month = {Aug-05-2020}, pages = {619-624}, type = {Open Access}, abstract = {

Bed bugs (Cimex spp.) are common ectoparasites of humans. Their ubiquity across diverse human environments combined with their blood-feeding behavior creates an ideal interface for the transmission of pathogenic microbes. Despite this potential, the current dogma is that bed bugs are not vectors of any known infectious agents. However, this conclusion is based largely on the results of studies conducted before the advent of modern molecular biology and the resurgence of bed bugs on a global scale. More importantly, a small but compelling body of modern research suggesting that bed bugs can potentially vector some human pathogens exists but is often overlooked. This article critically examines the current classification of the bed bug as an insect that does not transmit disease agents. In doing so, it highlights key knowledge gaps that still exist in understanding the potential of bed bugs as pathogen vectors and outlines several arguments for why new research on the topic is necessary

}, issn = {0002-9637, 1476-1645}, doi = {10.4269/ajtmh.20-0121}, url = {https://www.ajtmh.org/view/journals/tpmd/103/2/article-p619.xml}, author = {Jose E. Pietri} } @article {95442, title = {Microbiome Differences between Human Head and Body Lice Ecotypes Revealed by 16S rRNA Gene Amplicon Sequencing}, journal = {Journal of Parasitology}, volume = {106}, year = {2020}, month = {Jan-020}, pages = {14-24}, abstract = {

Human head lice and body lice (Pediculus humanus) are neglected ectoparasites. Head lice continue to be prevalent in children worldwide, and insecticide resistance in these insects has complicated their treatment. Meanwhile, body lice, which are most common in the developing world, are resurging among marginalized populations in developed nations. Today, the microbiome is being increasingly recognized as a key mediator of insect physiology. However, the microbial communities that inhabit human lice have remained unknown beyond only a few species of bacteria. Knowledge of the microbiomes of head and body lice could improve our understanding of the observed physiological differences between the 2 ecotypes and potentially inform the development of novel interventions against lice infestations and louse-borne infectious diseases. Toward these goals, here we performed 16S rRNA gene amplicon sequencing to characterize the microbiomes of both head and body lice and identify patterns of interest among these communities. Our data reveal that head and body lice harbor limited but distinct communities of bacteria that include known intracellular endosymbionts (\“Candidatus Riesia pediculicola\”), extracellular bacteria that may be horizontally acquired from the host environment, and a number of taxa of known or potential public health significance. Notably, in body lice, the relative abundance of vertically transmitted endosymbionts is lower than in head lice, which is a significant driver of greater alpha diversity. Further, several differentially abundant non-endosymbiont taxa and differences in beta diversity were observed between head lice and body lice. These findings support the hypothesis that microbiome differences could contribute to the divergence between human louse ecotypes and underscore the need for future studies to better comprehend the acquisition and physiological roles of human lice microbiomes

}, keywords = {16S rRNA, Amplicon, bacteria, body louse, Gene, Head louse, Microbiome, Pathogen, sequencing}, issn = {0022-3395}, doi = {10.1645/19-132}, url = {https://bioone.org/journals/journal-of-parasitology/volume-106/issue-1/19-132/Microbiome-Differences-between-Human-Head-and-Body-Lice-Ecotypes-Revealed/10.1645/19-132.short}, author = {Diing D. M. Agany and Rashaun Potts and Jose L. Gonzalez-Hernandez and Etienne Z. Gnimpieba and Jose E. Pietri} }