Naval Medical Research Unit Six

Facial expression analysis using artificial intelligence (AI) represents an emerging approach for assessing mental health, particularly in neurocognitive disorders. This study encompassed observational investigations that assessed facial expressions in individuals aged 60 years and above. A comprehensive literature search was carried out across PubMed, Scopus, EMBASE, and Web of Science. Risk of bias and study quality were assessed using the QUADAS-2 and CLAIM tools. Descriptive analysis and meta-analysis of proportions were performed using STATA version 19. The pooled effect size (ES) was calculated using a random-effects model (DerSimonian–Laird method), and results were presented with corresponding 95% confidence intervals (CI). Six studies were analyzed, comprising a total of 433 participants aged over 60 years, representing diverse AI applications in the detection of neurocognitive disorders. The disorders evaluated included mild cognitive impairment (MCI) (37.4%), dementia (29.3%), and Alzheimer’s disease (AD) (33.3%). Most studies (83.3%) used video-based facial recordings analyzed through deep learning algorithms and emotion recognition models. The pooled meta-analysis demonstrated that AI-based facial recognition algorithms achieved a high overall detection accuracy in older adults (ES = 0.84; 95% CI: 0.77–0.91), with the best performance observed in Alzheimer’s disease (ES = 0.93; 95% CI: 0.89–0.97). AI-based facial analysis demonstrates high, robust, and non-invasive accuracy for the early and differential detection of neurocognitive disorders, including MCI, dementia-related conditions, and AD, in older adults.

The vestibular system – the organs in our inner ear that sense head motion and gravity – contribute to self-motion perception, balance control, and several reflexive responses. Maintaining robust vestibular sensation imposes a high metabolic load; consider that the human vestibular periphery has over 100,000 hair cells requiring energy to maintain depolarization and roughly 40,000 peripheral neurons requiring energy to support an average firing rate of nearly 100 action potentials per second for each neuron. Therefore, the aim of this study was to evaluate the impact of reduced oxygen (hypoxia) on the human vestibular system. To quantify the impacts of hypoxia, vestibular function was quantified using standard forced-choice psychophysical methods to determine the smallest earth-vertical (i.e., upward/downward) translation that a seated human could reliably sense. To manipulate blood oxygenation, we controlled the O2 content of the air that participants breathed using a Reduced Oxygen Breathing Device 2 (Environics). To quantify blood oxygenation and pulse rate, we used a standard fingertip pulse oximeter. We hypothesized that: (1) blood oxygenation would decrease when breathing air with lower oxygen content, (2) human vestibular thresholds would worsen with reduced blood oxygenation, and (3) vestibular degradation would increase as blood oxygenation decreases. All data were collected at an elevation of ~800’. On different days, 15 participants breathed air with 20.9% or 15.4% oxygen content to simulate 0’ and 8,000’ altitudes respectively. As predicted, blood oxygenation (SpO2) reduced from an average of 96.7% when participants breathed air with 20.9% oxygen to 91.4% when breathing air with 15.4% oxygen content ( F (1,11) = 148.27, p <.001, Generalized eta squared = 0.770). Earth-vertical translation thresholds were significantly higher when breathing 15.4% oxygen than 20.9% oxygen ( F (1,14) = 22.49, p <.001, Generalized eta squared = 0.096). The largest threshold increase (median 41%; mean 33%) was observed in the 3rd threshold test conducted 30 to 45 minutes after reducing O2 content. Further, Type II linear regression showed that thresholds degraded as blood oxygenation decreased (R = -0.29). Despite these relatively large changes in perceptual precision, subjects reported no spatial disorientation illusions. These results show that vestibular thresholds were both significantly and substantively impacted at a simulated altitude of 8,000’. The significant correlation showing increasing thresholds with decreasing SpO2 suggests that decreases in tissue oxygenation may cause an increase in vestibular thresholds. These findings are noteworthy because the mild hypoxia condition was designed to match the cabin pressurization required in the US by the FAA for commercial flights. These results suggest that many of us who have flown in a commercial jet may have temporarily experienced degraded vestibular function. Behavioral impacts remain to be understood, but vestibular precision appears to be a harbinger of human hypoxia. Support provided by the Office of Naval Research (ONR) via a Multidisciplinary University Research Initiative grant (MURI N00014-20-1-2163). This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Leishmaniasis and Carrion's disease are endemic neglected diseases in Peru. Both diseases are transmitted by phlebotomine sand flies competent for infection with Leishmania species and Bartonella bacilliformis. In Peru, 149 sand fly species have been identified. Knowledge regarding sand fly species diversity and distribution in leishmaniasis and Carrion's disease transmission areas has grown in the past 2 decades through multiple surveillance efforts in endemic regions, including unexplored low and high jungle areas. Furthermore, molecular testing approaches have been implemented to enhance surveillance of Leishmania and Bartonella species in sand fly populations from these endemic regions. This review emphasizes the importance of entomological surveillance in Peru for the characterization of sand fly species and the discovery of a great diversity of Leishmania and Bartonella species in sand fly populations from Andean and Amazonian regions.

We identified highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b in wild birds, poultry, and a lion in Peru during November 2022–February 2023 and markers associated with transmission adaptation and antiviral drug resistance. Continuous genomic surveillance is needed to inform public health measures and avoid mass animal deaths.

Uncertainty about risk of illness and the value of influenza vaccines negatively affects vaccine uptake among persons targeted for influenza vaccination. During 2016-2019, we followed a cohort of healthcare personnel (HCP) targeted for free-of-charge influenza vaccination in five Lima hospitals to quantify risk of influenza, workplace presenteeism (coming to work despite illness), and absenteeism (taking time off from work because of illness). The HCP who developed acute respiratory illnesses (ARI) (≥1 of acute cough, runny nose, body aches, or feverishness) were tested for influenza using reverse-transcription polymerase chain reaction (rt-PCR). The cohort (2968 HCP) contributed 950,888 person-days. Only 36 (6%) of 605 HCP who participated every year were vaccinated. The HCP had 5750 ARI and 147 rt-PCR-confirmed influenza illnesses. The weighted incidence of laboratory-confirmed influenza was 10.0/100 person-years; 37% used antibiotics, and 0.7% used antivirals to treat these illnesses. The HCP with laboratory-confirmed influenza were present at work while ill for a cumulative 1187 hours. HCP were frequently ill and often worked rather than stayed at home while ill. Our findings suggest the need for continuing medical education about the risk of influenza and benefits of vaccination and stay-at-home-while-ill policies.

Enterotoxigenic Escherichia coli (ETEC) are common causes of infectious diarrhea among young children of low-and middle-income countries (LMICs) and travelers to these regions. Despite their significant contributions to the morbidity and mortality associated with childhood and traveler’s diarrhea, no licensed vaccines are available. Current vaccine strategies may benefit from the inclusion of additional conserved antigens, which may contribute to broader coverage and enhanced efficacy, given their key roles in facilitating intestinal colonization and effective enterotoxin delivery. EatA and EtpA are widely conserved in diverse populations of ETEC, but their immunogenicity has only been studied in controlled human infection models and a population of children in Bangladesh. Here, we compared serologic responses to EatA, EtpA and heat-labile toxin in populations from endemic regions including Haitian children and subjects residing in Egypt, Cameroon, and Peru to US children and adults where ETEC infections are sporadic. We observed elevated IgG and IgA responses in individuals from endemic regions to each of the antigens studied. In a cohort of Haitian children, we observed increased immune responses following exposure to each of the profiled antigens. These findings reflect the wide distribution of ETEC infections across multiple endemic regions and support further evaluation of EatA and EtpA as candidate ETEC vaccine antigens.

Plasmablastic lymphoma (PBL) is a rare subtype of diffuse large B-cell lymphoma originally described in human immunodeficiency virus (HIV)-positive patients. However, recent reports have described this neoplasia in HIV-negative patients. This neoplasia usually arises in extranodal tissues, such as the gastrointestinal tract, abdominal cavity and retroperitoneum. Here a case is presented of an HIV-negative patient with a history of stage II rectal cancer for which he received chemotherapy and radiotherapy with a complete response. However, in the following years, the patient presented clinical deterioration and the presence of an exophytic mass with fistulous tracts. For this reason, the patient underwent a new biopsy of the rectum which showed a plasmablastic lymphoma of the rectum, with an extensive local compromise that presented complete remission after 6 cycles of chemotherapy with a DA-EPOCH regimen.

Transmission heterogeneity, whereby a disproportionate fraction of pathogen transmission events result from a small number of individuals or geographic locations, is an inherent property of many, if not most, infectious disease systems. For vector-borne diseases, transmission heterogeneity is inferred from the distribution of the number of vectors per host, which could lead to significant bias in situations where vector abundance and transmission risk at the household do not correlate, as is the case with dengue virus (DENV). We used data from a contact tracing study to quantify the distribution of DENV acute infections within human activity spaces (AS), the collection of residential locations an individual routinely visits, and quantified measures of virus transmission heterogeneity from two consecutive dengue outbreaks (DENV-4 and DENV-2) that occurred in the city of Iquitos, Peru. Negative-binomial distributions and Pareto fractions showed evidence of strong overdispersion in the number of DENV infections by AS and identified super-spreading units (SSUs): i.e. AS where most infections occurred. Approximately 8% of AS were identified as SSUs, contributing to more than 50% of DENV infections. SSU occurrence was associated more with DENV-2 infection than with DENV-4, a predominance of inapparent infections (74% of all infections), households with high Aedes aegypti mosquito abundance, and high host susceptibility to the circulating DENV serotype. Marked heterogeneity in dengue case distribution, and the role of inapparent infections in defining it, highlight major challenges faced by reactive interventions if those transmission units contributing the most to transmission are not identified, prioritized, and effectively treated.

The isolation of Zika virus (ZIKV) from serum of suspected human cases for diagnostic purposes can be challenging due to infrastructure constraints of laboratory testing technology. Therefore, as an alternative method, the objective of this study was to evaluate a random sample of oropharyngeal swabs for the diagnosis of ZIKV infection among patients with symptoms of arboviral and respiratory illness. The results revealed that ZIKV RNA could be detected by a reverse transcriptase polymerase chain reaction (RT-PCR) assay and isolated from oropharyngeal swabs from five of 38 samples, but serum samples from the same patients were negative for ZIKV by a variety of laboratory diagnostic approaches including RT-PCR and viral isolation followed by immunofluorescence assays. The findings suggested that the molecular detection and isolation of ZIKV in oropharyngeal swab warrants further study for consideration as an improved diagnostic procedure.