Low Levels of Hive Stress Are Associated with Decreased Honey Activity and Changes to the Gut Microbiome of Resident Honey Bees.

Honey bees (Apis mellifera) face increasing threats to their health, particularly from the degradation of floral resources and chronic pesticide exposure. The properties of honey and the bee gut microbiome are known to both affect and be affected by bee health. Using samples from healthy hives and hives showing signs of stress from a single apiary with access to the same floral resources, we profiled the antimicrobial activity and chemical properties of honey and determined the bacterial and fungal microbiome of the bee gut and the hive environment. We found honey from healthy hives was significantly more active than honey from stressed hives, with increased phenolics and antioxidant content linked to higher antimicrobial activity. The bacterial microbiome was more diverse in stressed hives, suggesting they may have less capacity to exclude potential pathogens. Finally, bees from healthy and stressed hives had significant differences in core and opportunistically pathogenic taxa in gut samples. Our results emphasize the need for understanding and proactively managing bee health. IMPORTANCE Honey bees serve as pollinators for many plants and crops worldwide and produce valuable hive products such as honey and wax. Various sources of stress can disrupt honey bee colonies, affecting their health and productivity. Growing evidence suggests that honey is vitally important to hive functioning and overall health. In this study, we determined the antimicrobial activity and chemical properties of honey from healthy hives and hives showing signs of stress, finding that honey from healthy hives was significantly more antimicrobial, with increased phenolics and antioxidant content. We next profiled the bacterial and fungal microbiome of the bee gut and the hive environment, finding significant differences between healthy and stressed hives. Our results underscore the need for greater understanding in this area, as we found even apparently minor stress can have implications for overall hive fitness as well as the economic potential of hive products.

Overcrowded housing reduces COVID-19 mitigation measures and lowers emotional health among San Diego refugees from September to November of 2020.

Refugee communities are vulnerable to housing insecurity, which drives numerous health disparity outcomes in a historically marginalized population. The COVID-19 pandemic has only worsened the ongoing affordable housing crisis in the United States while continuing to highlight disparities in health outcomes across populations. We conducted interviewer-administered surveys with refugee and asylum seekers in San Diego County at the height of the COVID-19 pandemic to understand the social effects and drivers of COVID-19 in one of the largest refugee communities in the United States. Staff from a community-based refugee advocacy and research organization administered the surveys from September-November 2020. 544 respondents participated in the survey, which captured the diversity of the San Diego refugee community including East African (38%), Middle Eastern (35%), Afghan (17%), and Southeast Asian (11%) participants. Nearly two-thirds of respondents (65%) reported living in overcrowded conditions (> 1 individual per room) and 30% in severely crowded conditions (> 1.5 individuals per room). For each additional person per room, self-reported poor emotional health increased. Conversely, family size was associated with a lower likelihood of reporting poor emotional health. Crowded housing was significantly associated with a lower probability of accessing a COVID-19 diagnostic test, with every additional reported person per room there was approximately an 11% increase in the probability of having never accessed a COVID-19 testing. Access to affordable housing had the largest effect size and was associated with fewer people per room. Overcrowding housing is a structural burden that reduces COVID-19 risk mitigation behaviors. Improved access to affordable housing units or receiving vouchers could reduce overcrowded housing in vulnerable refugee communities.

Housing Instability and Evictions Linked to Elevated Intimate Partner and Workplace Violence Among Women Sex Workers in Vancouver, Canada: Findings of a Prospective, Community-Based Cohort, 2010-2019.

Objectives. To model the relationship of unstable housing and evictions with physical and sexual violence perpetrated against women sex workers in intimate and workplace settings. Methods. We used bivariate and multivariable logistic regression with generalized estimating equations to model the association of unstable housing exposure and evictions with intimate partner violence (IPV) and workplace violence among a community-based longitudinal cohort of cisgender and transgender women sex workers in Vancouver, Canada, from 2010 through 2019. Results. Of 946 women, 85.9% experienced unstable housing, 11.1% eviction, 26.2% IPV, and 31.8% workplace violence. In multivariable generalized estimating equation models, recent exposure to unstable housing (adjusted odds ratio [AOR] = 2.04; 95% confidence interval [CI] = 1.45, 2.87) and evictions (AOR = 2.45; 95% CI = 0.99, 6.07) were associated with IPV, and exposure to unstable housing was associated with workplace violence (AOR = 1.46; 95% CI = 1.06, 2.00). Conclusions. Women sex workers face a high burden of unstable housing and evictions, which are linked to increased odds of intimate partner and workplace violence. Increased access to safe, women-centered, and nondiscriminatory housing is urgently needed. (Am J Public Health. 2023;113(4):442-452. https://doi.org/10.2105/AJPH.2022.307207).

Drinking water and the implications for gender equity and empowerment: A systematic review of qualitative and quantitative evidence.

BACKGROUND: Safe drinking water is a fundamental human right, yet more than 785 million people do not have access to it. The burden of water management disproportionately falls on women and young girls, and they suffer the health, psychosocial, political, educational, and economic effects. While water conditions and disease outcomes have been widely studied, few studies have summarized the research on drinking water and implications for gender equity and empowerment (GEE). METHODS: A systematic review of primary literature published between 1980 and 2019 was conducted on drinking water exposures and management and the implications for GEE. Ten databases were utilized (EMBASE, PubMed, Web of Science, Cochrane, ProQuest, Campbell, the British Library for Development Studies, SSRN, 3ie International Initiative for Impact Evaluation, and clinicaltrials.gov). Drinking water studies with an all-female cohort or disaggregated findings according to gender were included. RESULTS: A total of 1280 studies were included. GEE outcomes were summarized in five areas: health, psychosocial stress, political power and decision-making, social-educational conditions, and economic and time-use conditions. Water quality exposures and implications for women's health dominated the literature reviewed. Women experienced higher rates of bladder cancer when exposed to arsenic, trihalomethanes, and chlorine in drinking water and higher rates of breast cancer due to arsenic, trichloroethylene, and disinfection byproducts in drinking water, compared to men. Women that were exposed to arsenic experienced higher incidence rates of anemia and adverse pregnancy outcomes compared to those that were not exposed. Water-related skin diseases were associated with increased levels of psychosocial stress and social ostracization among women. Women had fewer decision-making responsibilities, economic independence, and employment opportunities around water compared to men. CONCLUSION: This systematic review confirms the interconnected nature of gender and WaSH outcomes. With growing attention directed towards gender equity and empowerment within WaSH, this analysis provides key insights to inform future research and policy.

Financial navigation: Staff perspectives on patients' financial burden of cancer care.

PURPOSE: To describe perceptions of financial navigation staff concerning patients' cancer-related financial burden. METHODS: This qualitative descriptive study used a semi-structured interview guide to examine perceptions of financial navigation staff concerning patients' cancer-related financial burden. Staff who provided financial navigation support services to cancer patients were interviewed from different types of cancer programs across seven states representing rural, micropolitan, and urban settings. Interviews lasted approximately one hour, were audio recorded, and transcribed. Transcripts were double coded for thematic analysis. RESULTS: Thirty-five staff from 29 cancer centers were interviewed. The first theme involved communication issues related to patient and financial navigation staff expectations, timing and the sensitive nature of financial discussions. The second theme involved the multi-faceted impact of financial burden on patients, including stress, difficulty adhering to treatments, and challenges meeting basic, non-medical needs. CONCLUSIONS AND IMPLICATIONS FOR CANCER SURVIVORS: Cancer-related financial burden has a profound impact on cancer survivors' health and non-health outcomes. Discussions regarding cancer-related costs between cancer survivors and healthcare team members could help to normalize conversations and mitigate the multi-faceted determinants and effects of cancer-related financial burden. As treatment may span months and years and unexpected costs arise, having this discussion regularly and systematically is needed.

SYK coordinates neuroprotective microglial responses in neurodegenerative disease.

Recent studies have begun to reveal critical roles for the brain's professional phagocytes, microglia, and their receptors in the control of neurotoxic amyloid beta (Aß) and myelin debris accumulation in neurodegenerative disease. However, the critical intracellular molecules that orchestrate neuroprotective functions of microglia remain poorly understood. In our studies, we find that targeted deletion of SYK in microglia leads to exacerbated Aß deposition, aggravated neuropathology, and cognitive defects in the 5xFAD mouse model of Alzheimer's disease (AD). Disruption of SYK signaling in this AD model was further shown to impede the development of disease-associated microglia (DAM), alter AKT/GSK3ß-signaling, and restrict Aß phagocytosis by microglia. Conversely, receptor-mediated activation of SYK limits Aß load. We also found that SYK critically regulates microglial phagocytosis and DAM acquisition in demyelinating disease. Collectively, these results broaden our understanding of the key innate immune signaling molecules that instruct beneficial microglial functions in response to neurotoxic material.

The role of honey in the ecology of the hive: Nutrition, detoxification, longevity, and protection against hive pathogens.

Honey is the source of energy for the European honey bee, Apis mellifera. Beyond simple nutrition and a hedge against the seasonal, geographic, and chemical unpredictability of nectar, honey has properties that protect the hive against various stresses. Enzyme-mediated detoxification during honey ripening neutralizes potentially toxic phytochemicals, and bees that consume honey have enhanced tolerance to other ingested toxins. Catalase and antioxidant phenolics protect honey bees from oxidative damage caused by reactive oxygen species, promoting their longevity. Phytochemical components of honey and microRNAs have the potential to influence developmental pathways, with diet playing a large role in honey bee caste determination. Components of honey mediate stress response and promote cold tolerance during overwintering. Honey has a suite of antimicrobial mechanisms including osmotic pressure, low water activity, low pH, hydrogen peroxide, and plant-, honey bee-, and microbiota-derived compounds such as phytochemicals and antimicrobial peptides. Certain types of honey, particularly polyfloral honeys, have been shown to inhibit important honey bee pathogens including the bacteria responsible for American and European Foulbrood, the microsporidian Nosema ceranae, and the fungi responsible for Stonebrood. Understanding the diverse functional properties of honey has far-ranging implications for honey bee and hive health and management by beekeepers.

Economic vulnerability, violence, and sexual risk factors for HIV among female sex workers in Tijuana, Mexico.

Economic vulnerability is often reported to underlie involvement in sex work among female sex workers (FSW), but may also create urgency in women's work, limiting women's negotiating power with clients and in turn, increasing their vulnerability for violence and HIV. This study assessed economic vulnerability in relation to violence and sexual risk behaviors for HIV among a sample of FSW in Tijuana, Mexico. FSW at least 18 years of age were recruited through venue-based sampling for a survey (n = 228) and in-depth interviews (n = 50) to investigate HIV risk factors in this region. Using crude and adjusted logistic regression models, we assessed lack of financial support from others as well as reports of financial hardship separately in relation to experiencing sexual violence (e.g. by clients, police, relationship partners, in the past 6 months), physical violence (past 6 months), STI diagnosis, and inconsistent condom use (past 30 days). Qualitative interviews (n = 50), conducted with a subsample of the survey participants, were also examined for related themes. FSW who reported no financial support were more likely to report sexual violence (OR = 2.1; 95% CI:1.1-4.2). FSW who reported financial hardship were more likely to experience sexual violence (OR = 1.9; 95% CI:1.1-3.6) and physical violence (OR = 1.9; 95% CI:1.1-3.6), as well as to report past 30-day inconsistent condom use (OR = 2.4; 95%CI: 1.3-4.6) and to test positive for an STI (OR = 1.9; 95% CI:1.1-3.4). Qualitative data substantiated these findings. Findings suggest that interventions to improve economic well-being may be useful to prevent the intersecting concerns of violence and HIV among FSW.

How cancer programs identify and address the financial burdens of rural cancer patients.

PURPOSE: Financial toxicity is associated with negative patient outcomes, and rural populations are disproportionately affected by the high costs of cancer care compared to urban populations. Our objective was to (1) understand cancer programs' perceptions of rural-urban differences in cancer patients' experiences of financial hardship, (2) evaluate the resources available to cancer patients across the rural-urban continuum, and (3) determine how rural and urban health care teams assess and address financial distress in cancer patients. METHODS: Seven research teams within the Cancer Prevention and Research Control Network conducted semi-structured interviews with cancer program staff who have a role in connecting cancer patients with financial assistance services in both rural and urban counties. Interviews were audio-recorded and transcribed. We identified themes using descriptive content and thematic analysis. RESULTS: We interviewed 35 staffs across 29 cancer care programs in seven states, with roughly half of respondents from programs in rural counties. Participants identified differences in rural and urban patients' experiences of financial hardship related to distance required to travel for treatment, underinsurance, and low socioeconomic status. Insufficient staffing was an identified barrier to addressing rural and urban patients' financial concerns. CONCLUSIONS: Improved financial navigation services could mitigate the effects of financial toxicity experienced by cancer patients, particularly rural patients, throughout treatment and survivorship. Future research is needed to improve how cancer programs assess financial hardship in patients and to expand financial navigation services to better serve rural cancer patients.

Smoking and cessation behaviors in patients at federally funded health centers - United States, 2014.

BACKGROUND: Federally funded health centers (HCs) provide care to the most vulnerable populations in the U.S., including populations with disproportionately higher smoking prevalence such as those with lower incomes. METHODS: This study compared characteristics of adult HC patients, by cigarette smoking status, and assessed smoking cessation-related behaviors using 2014 Health Center Patient Survey data; analysis was restricted to adults with data on cigarette smoking status (n = 5583). Chi-square and logistic regression analyses were conducted. RESULTS: Overall, 28.1 % were current smokers and 19.2 % were former smokers. Current smokers were more likely to report fair/poor health (48.2 %) and a high burden of behavioral health conditions (e.g., severe psychological distress 23.9 %) versus former and never smokers. Most current smokers reported wanting to quit in the past 12 months (79.0 %) and receiving advice to quit from a healthcare professional (78.7 %). In a multivariable model, age <45, non-white race, COPD diagnosis, and past 3-month marijuana use were significantly associated with desire to quit. Few former smokers (15.2 %) reported using cessation treatment, though use was higher among those who quit within the previous year (30.6 %). CONCLUSIONS: Although most current smokers reported a desire to quit, low uptake of evidence-based treatment may reduce the number who attempt to quit and succeed. Given the burden of tobacco use, future efforts could focus on identifying and overcoming unique personal, healthcare professional, or health system barriers to connecting them with cessation treatments. Increasing access to cessation treatments within HCs could reduce smoking-related disparities and improve population health.

Meningeal lymphatic dysfunction exacerbates traumatic brain injury pathogenesis.

Traumatic brain injury (TBI) is a leading global cause of death and disability. Here we demonstrate in an experimental mouse model of TBI that mild forms of brain trauma cause severe deficits in meningeal lymphatic drainage that begin within hours and last out to at least one month post-injury. To investigate a mechanism underlying impaired lymphatic function in TBI, we examined how increased intracranial pressure (ICP) influences the meningeal lymphatics. We demonstrate that increased ICP can contribute to meningeal lymphatic dysfunction. Moreover, we show that pre-existing lymphatic dysfunction before TBI leads to increased neuroinflammation and negative cognitive outcomes. Finally, we report that rejuvenation of meningeal lymphatic drainage function in aged mice can ameliorate TBI-induced gliosis. These findings provide insights into both the causes and consequences of meningeal lymphatic dysfunction in TBI and suggest that therapeutics targeting the meningeal lymphatic system may offer strategies to treat TBI.

Antibody escape by polyomavirus capsid mutation facilitates neurovirulence.

JCPyV polyomavirus, a member of the human virome, causes progressive multifocal leukoencephalopathy (PML), an oft-fatal demyelinating brain disease in individuals receiving immunomodulatory therapies. Mutations in the major viral capsid protein, VP1, are common in JCPyV from PML patients (JCPyV-PML) but whether they confer neurovirulence or escape from virus-neutralizing antibody (nAb) in vivo is unknown. A mouse polyomavirus (MuPyV) with a sequence-equivalent JCPyV-PML VP1 mutation replicated poorly in the kidney, a major reservoir for JCPyV persistence, but retained the CNS infectivity, cell tropism, and neuropathology of the parental virus. This mutation rendered MuPyV resistant to a monoclonal Ab (mAb), whose specificity overlapped the endogenous anti-VP1 response. Using cryo-EM and a custom sub-particle refinement approach, we resolved an MuPyV:Fab complex map to 3.2 Å resolution. The structure revealed the mechanism of mAb evasion. Our findings demonstrate convergence between nAb evasion and CNS neurovirulence in vivo by a frequent JCPyV-PML VP1 mutation.

AIM2 inflammasome surveillance of DNA damage shapes neurodevelopment.

Neurodevelopment is characterized by rapid rates of neural cell proliferation and differentiation followed by massive cell death in which more than half of all recently generated brain cells are pruned back. Large amounts of DNA damage, cellular debris, and by-products of cellular stress are generated during these neurodevelopmental events, all of which can potentially activate immune signalling. How the immune response to this collateral damage influences brain maturation and function remains unknown. Here we show that the AIM2 inflammasome contributes to normal brain development and that disruption of this immune sensor of genotoxic stress leads to behavioural abnormalities. During infection, activation of the AIM2 inflammasome in response to double-stranded DNA damage triggers the production of cytokines as well as a gasdermin-D-mediated form of cell death known as pyroptosis1-4. We observe pronounced AIM2 inflammasome activation in neurodevelopment and find that defects in this sensor of DNA damage result in anxiety-related behaviours in mice. Furthermore, we show that the AIM2 inflammasome contributes to central nervous system (CNS) homeostasis specifically through its regulation of gasdermin-D, and not via its involvement in the production of the cytokines IL-1 and/or IL-18. Consistent with a role for this sensor of genomic stress in the purging of genetically compromised CNS cells, we find that defective AIM2 inflammasome signalling results in decreased neural cell death both in response to DNA damage-inducing agents and during neurodevelopment. Moreover, mutations in AIM2 lead to excessive accumulation of DNA damage in neurons as well as an increase in the number of neurons that incorporate into the adult brain. Our findings identify the inflammasome as a crucial player in establishing a properly formed CNS through its role in the removal of genetically compromised cells.

tRNA-derived fragments and microRNAs in the maternal-fetal interface of a mouse maternal-immune-activation autism model.

tRNA-derived small fragments (tRFs) and tRNA halves have emerging functions in different biological pathways, such as regulating gene expression, protein translation, retrotransposon activity, transgenerational epigenetic changes and response to environmental stress. However, small RNAs like tRFs and microRNAs in the maternal-fetal interface during gestation have not been studied extensively. Here we investigated the small RNA composition of mouse placenta/decidua, which represents the interface where the mother communicates with the foetus, to determine whether there are specific differences in tRFs and microRNAs during fetal development and in response to maternal immune activation (MIA). Global tRF expression pattern, just like microRNAs, can distinguish tissue types among placenta/decidua, fetal brain and fetal liver. In particular, 5' tRNA halves from tRNAGly, tRNAGlu, tRNAVal and tRNALys are abundantly expressed in the normal mouse placenta/decidua. Moreover, tRF and microRNA levels in the maternal-fetal interface change dynamically over the course of embryonic development. To see if stress alters non-coding RNA expression at the maternal-fetal interface, we treated pregnant mice with a viral infection mimetic, which has been shown to promote autism-related phenotypes in the offspring. Acute changes in the levels of specific tRFs and microRNAs were observed 3-6 h after MIA and are suppressed thereafter. A group of 5' tRNA halves is down-regulated by MIA, whereas a group of 18-nucleotide tRF-3a is up-regulated. In conclusion, tRFs show tissue-specificity, developmental changes and acute response to environmental stress, opening the possibility of them having a role in the fetal response to MIA.

PD-1 Dynamically Regulates Inflammation and Development of Brain-Resident Memory CD8 T Cells During Persistent Viral Encephalitis.

Programmed cell death-1 (PD-1) receptor signaling dampens the functionality of T cells faced with repetitive antigenic stimulation from chronic infections or tumors. Using intracerebral (i.c.) inoculation with mouse polyomavirus (MuPyV), we have shown that CD8 T cells establish a PD-1hi, tissue-resident memory population in the brains (bTRM) of mice with a low-level persistent infection. In MuPyV encephalitis, PD-L1 was expressed on infiltrating myeloid cells, microglia and astrocytes, but not on oligodendrocytes. Engagement of PD-1 on anti-MuPyV CD8 T cells limited their effector activity. NanoString gene expression analysis showed that neuroinflammation was higher in PD-L1-/- than wild type mice at day 8 post-infection, the peak of the MuPyV-specific CD8 response. During the persistent phase of infection, however, the absence of PD-1 signaling was found to be associated with a lower inflammatory response than in wild type mice. Genetic disruption and intracerebroventricular blockade of PD-1 signaling resulted in an increase in number of MuPyV-specific CD8 bTRM and the fraction of these cells expressing CD103, the αE integrin commonly used to define tissue-resident T cells. However, PD-L1-/- mice persistently infected with MuPyV showed impaired virus control upon i.c. re-infection with MuPyV. Collectively, these data reveal a temporal duality in PD-1-mediated regulation of MuPyV-associated neuroinflammation. PD-1 signaling limited the severity of neuroinflammation during acute infection but sustained a level of inflammation during persistent infection for maintaining control of virus re-infection.

CNS lymphatic drainage and neuroinflammation are regulated by meningeal lymphatic vasculature.

Neuroinflammatory diseases, such as multiple sclerosis, are characterized by invasion of the brain by autoreactive T cells. The mechanism for how T cells acquire their encephalitogenic phenotype and trigger disease remains, however, unclear. The existence of lymphatic vessels in the meninges indicates a relevant link between the CNS and peripheral immune system, perhaps affecting autoimmunity. Here we demonstrate that meningeal lymphatics fulfill two critical criteria: they assist in the drainage of cerebrospinal fluid components and enable immune cells to enter draining lymph nodes in a CCR7-dependent manner. Unlike other tissues, meningeal lymphatic endothelial cells do not undergo expansion during inflammation, and they express a unique transcriptional signature. Notably, the ablation of meningeal lymphatics diminishes pathology and reduces the inflammatory response of brain-reactive T cells during an animal model of multiple sclerosis. Our findings demonstrate that meningeal lymphatics govern inflammatory processes and immune surveillance of the CNS and pose a valuable target for therapeutic intervention.

Cutting Edge: Critical Roles for Microbiota-Mediated Regulation of the Immune System in a Prenatal Immune Activation Model of Autism.

Recent studies suggest that autism is often associated with dysregulated immune responses and altered microbiota composition. This has led to growing speculation about potential roles for hyperactive immune responses and the microbiome in autism. Yet how microbiome-immune cross-talk contributes to neurodevelopmental disorders currently remains poorly understood. In this study, we report critical roles for prenatal microbiota composition in the development of behavioral abnormalities in a murine maternal immune activation (MIA) model of autism that is driven by the viral mimetic polyinosinic-polycytidylic acid. We show that preconception microbiota transplantation can transfer susceptibility to MIA-associated neurodevelopmental disease and that this is associated with modulation of the maternal immune response. Furthermore, we find that ablation of IL-17a signaling provides protection against the development of neurodevelopmental abnormalities in MIA offspring. Our findings suggest that microbiota landscape can influence MIA-induced neurodevelopmental disease pathogenesis and that this occurs as a result of microflora-associated calibration of gestational IL-17a responses.

HIV Pre-exposure Prophylaxis Program Implementation Using Intervention Mapping.

INTRODUCTION: HIV pre-exposure prophylaxis has been proven to be an effective tool in HIV prevention. However, numerous barriers still exist in pre-exposure prophylaxis implementation. METHODS: The framework of Intervention Mapping was used from August 2016 to October 2017 to describe the process of adoption, implementation, and maintenance of an HIV prevention program from 2012 through 2017 in Houston, Texas, that is nested within a county health system HIV clinic. Using the tasks outlined in the Intervention Mapping framework, potential program implementers were identified, outcomes and performance objectives established, matrices of change objectives created, and methods and practical applications formed. RESULTS: Results include the formation of three matrices that document program outcomes, change agents involved in the process, and the determinants needed to facilitate program adoption, implementation, and maintenance. Key features that facilitated successful program adoption and implementation were obtaining leadership buy-in, leveraging existing resources, systematic evaluation of operations, ongoing education for both clinical and nonclinical staff, and attention to emergent issues during launch. CONCLUSIONS: The utilization of Intervention Mapping to delineate the program planning steps can provide a model for pre-exposure prophylaxis implementation in other settings.

Perioperative Care for Pediatric Patients With Penetrating Brain Injury: A Review.

Traumatic brain injury (TBI) continues to be the leading cause of death and acquired disability in young children and adolescents, due to blunt or penetrating trauma, the latter being less common but more lethal. Penetrating brain injury (PBI) has not been studied extensively, mainly reported as case reports or case series, due to the assumption that both types of brain injury have common pathophysiology and consequently common management. However, recommendations and guidelines for the management of PBI differ from those of blunt TBI in regards to neuroimaging, intracranial pressure (ICP) monitoring, and surgical management including those pertaining to vascular injury. PBI was one of the exclusion criteria in the second edition of guidelines for the acute medical management of severe TBI in infants, children, and adolescents that was published in 2012 (it is referred to as "pediatric guidelines" in this review). Many reviews of TBI do not differentiate between the mechanisms of injury. We present an overview of PBI, its presenting features, epidemiology, and causes as well as an analysis of case series and the conclusions that may be drawn from those and other studies. More clinical trials specific to penetrating head injuries in children, focusing mainly on pathophysiology and management, are needed. The term PBI is specific to penetrating injury only, whereas TBI, a more inclusive term, describes mainly, but not only, blunt injury.