Variation in diurnal cortisol patterns among the Indigenous Shuar of Amazonian Ecuador.

OBJECTIVES: The hypothalamic-pituitary-adrenal (HPA) axis and its primary end product, the glucocorticoid cortisol, are major components of the evolved human stress response. However, most studies have examined these systems among populations in high-income settings, which differ from the high pathogen and limited resource contexts in which the HPA axis functioned for most of human evolution. METHODS: We investigated variability in diurnal salivary cortisol patterns among 298 Indigenous Shuar from Amazonian Ecuador (147 males, 151 females; age 2-86 years), focusing on the effects of age, biological sex, and body mass index (BMI) in shaping differences in diurnal cortisol production. Saliva samples were collected three times daily (waking, 30 minutes post-waking, evening) for three consecutive days to measure key cortisol parameters: levels at waking, the cortisol awakening response, the diurnal slope, and total daily output. RESULTS: Age was positively associated with waking levels and total daily output, with Shuar juveniles and adolescents displaying significantly lower levels than adults (p < .05). Sex was not a significant predictor of cortisol levels (p > .05), as Shuar males and females displayed similar patterns of diurnal cortisol production across the life course. Moreover, age, sex, and BMI significantly interacted to moderate the rate of diurnal cortisol decline (p = .027). Overall, Shuar demonstrated relatively lower cortisol concentrations than high-income populations. CONCLUSIONS: This study expands the documented range of global variation in HPA axis activity and diurnal cortisol production and provides important insights into the plasticity of human stress physiology across diverse developmental and socioecological settings.

Pathogen disgust sensitivity protects against infection in a high pathogen environment.

Disgust is hypothesized to be an evolved emotion that functions to regulate the avoidance of pathogen-related stimuli and behaviors. Individuals with higher pathogen disgust sensitivity (PDS) are predicted to be exposed to and thus infected by fewer pathogens, though no studies have tested this directly. Furthermore, PDS is hypothesized to be locally calibrated to the types of pathogens normally encountered and the fitness-related costs and benefits of infection and avoidance. Market integration (the degree of production for and consumption from market-based economies) influences the relative costs/benefits of pathogen exposure and avoidance through sanitation, hygiene, and lifestyle changes, and is thus predicted to affect PDS. Here, we examine the function of PDS in disease avoidance, its environmental calibration, and its socioecological variation by examining associations among PDS, market-related lifestyle factors, and measures of bacterial, viral, and macroparasitic infection at the individual, household, and community levels. Data were collected among 75 participants (ages 5 to 59 y) from 28 households in three Ecuadorian Shuar communities characterized by subsistence-based lifestyles and high pathogen burden, but experiencing rapid market integration. As predicted, we found strong negative associations between PDS and biomarkers of immune response to viral/bacterial infection, and weaker associations between PDS and measures of macroparasite infection, apparently mediated by market integration-related differences. We provide support for the previously untested hypothesis that PDS is negatively associated with infection, and document variation in PDS indicative of calibration to local socioeconomic conditions. More broadly, findings highlight the importance of evolved psychological mechanisms in human health outcomes.

Dual burden of infectious and chronic disease in low-resource U.S. communities: examining relationships between infection, adiposity, and inflammation.

BACKGROUND: Rising global obesity rates are linked with inflammation and associated morbidities. These negative outcomes are generally more common in low-resource communities within high-income countries; however, it is unclear how frequent infectious disease exposures in these settings may influence the relationship between adiposity and inflammation. AIM: We test associations between adiposity measures and distinct forms of inflammation among adults (n = 80) living in low-resource U.S. communities experiencing high levels of obesity and pathogen exposure. SUBJECTS AND METHODS: Adiposity measures included BMI and percent body fat. Inflammation measures included systemic inflammation (C-reactive protein [CRP]) and localised intestinal inflammation (faecal calprotectin [FC]). The relationship between a condition characterised by elevated inflammation (Helicobacter pylori infection) and adiposity was also considered. RESULTS: Adiposity was not significantly related to FC concentration. However, both adiposity measures were positively related with odds of CRP elevation and H. pylori infection was associated with significantly lower adiposity measures (all p < 0.05). CONCLUSION: For this disadvantaged U.S. sample, the association between adiposity and inflammation varies by the systemic/localised nature of inflammation and the likely underlying cause of inflammation. Defining these associations will improve understanding of how rising obesity rates shape long-term health inequities, with implications for more effective intervention design.

Evidence and potential drivers of neglected parasitic helminth and protist infections among a small preliminary sample of children from rural Mississippi.

INTRODUCTION: Intestinal infections with helminths (parasitic worms) and protists (single-celled eukaryotes) may be neglected health issues in low-resource communities across the United States. Because they predominantly infect school-aged children and can lead to nutritional deficiencies and developmental delays, these infections can affect lifelong health. More research is needed to understand the prevalence and risk factors of these parasitic infections in the United States. METHODS: A total of 24 children (ages 0.5-14 years) from a low-resource, rural Mississippi Delta community provided stool samples for 18s rRNA amplification and sequencing to determine infection presence. Parent/guardian interviews provided age, sex, and household size to test for associations with infection. RESULTS: Infections were found in 38% (n = 9) of the samples. 25% (n = 6) of participants were infected with helminths (platyhelminths [n = 5]; nematodes [n = 2]), while 21% (n = 5) were infected with protists (Blastocystis [n = 4]; Cryptosporidium [n = 1]). There were no associations between infection status and age, sex, or household size. Problematically, analytical methods did not allow for more specific classifications for helminth species. CONCLUSIONS: These preliminary findings suggest parasitic infections may be overlooked health issues in the rural Mississippi Delta and emphasize the need for more research on potential health outcomes within the United States.

Low prevalence of anemia among Shuar communities of Amazonian Ecuador.

OBJECTIVE: Anemia is an important global health challenge. We investigate anemia prevalence among Indigenous Shuar of Ecuador to expand our understanding of population-level variation, and to test hypotheses about how anemia variation is related to age, sex, and market integration. METHODS: Hemoglobin levels were measured in a total sample of 1650 Shuar participants (ages 6 months to 86 years) from 46 communities between 2008 and 2017 to compare anemia prevalence across regions characterized by different levels of market integration. RESULTS: Shuar anemia rates among children under 15 years (12.2%), adult women (10.5%), and adult men (5.3%) were less than half of those previously documented in other neo-tropical Indigenous populations. Anemia prevalence did not vary between more traditional and market integrated communities (OR = 0.47, p = .52). However, anemia was negatively associated with body mass index (OR = 0.47, p = .002). CONCLUSIONS: Compared to other South American Indigenous populations, anemia prevalence is relatively low among Shuar of Ecuador and invariant with market integration. Understanding this pattern can provide valuable insights into anemia prevention among at-risk populations.

Tradeoffs between immune function and childhood growth among Amazonian forager-horticulturalists.

Immune function is an energetically costly physiological activity that potentially diverts calories away from less immediately essential life tasks. Among developing organisms, the allocation of energy toward immune function may lead to tradeoffs with physical growth, particularly in high-pathogen, low-resource environments. The present study tests this hypothesis across diverse timeframes, branches of immunity, and conditions of energy availability among humans. Using a prospective mixed-longitudinal design, we collected anthropometric and blood immune biomarker data from 261 Amazonian forager-horticulturalist Shuar children (age 4-11 y old). This strategy provided baseline measures of participant stature, s.c. body fat, and humoral and cell-mediated immune activity as well as subsample longitudinal measures of linear growth (1 wk, 3 mo, 20 mo) and acute inflammation. Multilevel analyses demonstrate consistent negative effects of immune function on growth, with children experiencing up to 49% growth reduction during periods of mildly elevated immune activity. The direct energetic nature of these relationships is indicated by (i) the manifestation of biomarker-specific negative immune effects only when examining growth over timeframes capturing active competition for energetic resources, (ii) the exaggerated impact of particularly costly inflammation on growth, and (iii) the ability of children with greater levels of body fat (i.e., energy reserves) to completely avoid the growth-inhibiting effects of acute inflammation. These findings provide evidence for immunologically and temporally diverse body fat-dependent tradeoffs between immune function and growth during childhood. We discuss the implications of this work for understanding human developmental energetics and the biological mechanisms regulating variation in human ontogeny, life history, and health.

Disparities in bone density across contemporary Amazonian forager-horticulturalists: Cross-population comparison of the Tsimane and Shuar.

OBJECTIVES: This study investigates bone density across the life course among Bolivian Tsimane and Ecuadorian Shuar of Amazonia. Both groups are rural, high-fertility forager-horticulturalists, with high lifetime physical activity levels. We test whether Tsimane and Shuar bone density patterns are different from each other, and if both groups are characterized by lower osteoporosis risk compared to U.S. references. METHODS: Anthropometric and calcaneal bone density data, obtained via quantitative ultrasonometry (QUS), were collected from 678 Tsimane and 235 Shuar (13-92 years old). Population and sex differences in QUS values (estimated bone mineral density, speed of sound, broadband ultrasound attenuation) by age group were assessed using Mann-Whitney U tests. Age-related change and age at peak QUS value were determined using polynomial regressions. One-way analyses of covariance assessed population-level differences in QUS values by age group adjusting for body mass index. Participants aged 50+ years at elevated osteoporosis risk were identified using a T score < -1.8; binomial tests assessed risk compared to U.S. references. RESULTS: Shuar males and females <50 years old have QUS values 3-36% higher than Tsimane, with differences evident in adolescence. Among Tsimane and Shuar, 49 and 23% of participants aged 50+ years old, respectively, are at high risk for osteoporosis, compared to 34% of Americans; Shuar osteoporosis risk is comparable to Americans, while Tsimane risk is elevated. CONCLUSIONS: Disparate patterns in QUS values are documented for Tsimane and Shuar, with pronounced differences early in life. Potential explanations for differences include gene-environment interactions and/or degree of market integration, which influences diet, activity profiles, pathogen exposures, and other lifestyle covariates. As Tsimane osteoporosis risk is greater than in the United States, findings point to alternative risk factors for low bone density that are not readily discernible in industrialized populations.

Measuring attack on self: The need for field-friendly methods development and research on autoimmunity in human biology.

BACKGROUND: Autoimmune and inflammatory disorder (AIID) prevalence appears to be increasing in all but the world's poorest regions and countries. Autoimmune diseases occur when there is a breakdown in processes that regulate inflammation and self-recognition by immune cells. Very few field-based studies have been conducted among Indigenous populations and underserved communities with limited access to medical care. This is due, in part, to the fact that autoimmune diseases are difficult to diagnose, even in clinical settings. In remote field settings these difficulties are compounded by the absence of infrastructure necessary for sample storage and analysis, and the lack of hospital/clinic access for more invasive diagnostic procedures. Because of these limitations, little is known about the prevalence of autoimmunity outside wealthy regions and clinical settings. AIMS: The present paper discusses why AIID are of critical importance in human biology research and why more work needs to be devoted to validating, testing, and utilizing methods for detecting autoantibodies and other biomarkers related to autoimmunity in field-friendly, minimally invasively-collected samples. This paper reviews some of the methods used to diagnose AIIDs in clinical settings, and highlights methods that have been used in studies within human biology and related fields, emphasizing the invasiveness of specific methods and their feasibility in remote field settings. DISCUSSION AND CONCLUSIONS: Risk for AIID is affected by several reproductive, dietary, environmental, and genetic factors. Human biologists have unique perspectives that they can bring to autoimmunity research, and more population-based studies on autoimmunity are needed within these and related fields.

Validation of an enzyme-linked immunoassay assay for osteocalcin, a marker of bone formation, in dried blood spots.

OBJECTIVES: Investigating factors that contribute to bone loss and accretion across populations in remote settings is challenging, particularly where diagnostic tools are scarce. To mitigate this challenge, we describe validation of a commercial ELISA assay to measure osteocalcin, a biomarker of bone formation, from dried blood spots (DBS). METHODS: We validated the Osteocalcin Human SimpleStep ELISA kit from Abcam (ab1951214) using 158 matched plasma and DBS samples. Passing-Bablok regression analysis assessed the relationships between plasma and DBS osteocalcin concentrations. Dilutional linearity and spike and recovery experiments determined if the DBS matrix interfered with osteocalcin measurement, and intra- and inter-assay coefficients of variation (CVs) were calculated. Limit of detection, analyte stability, and specific forms of osteocalcin measured by the kit were also investigated. RESULTS: Mean plasma osteocalcin value was 218.2 ng/mL (range 64.6-618.1 ng/mL). Linear relationships existed between plasma and DBS concentrations of osteocalcin, with no apparent bias in plasma vs DBS concentrations. There was no apparent interference of the DBS matrix with measurement of osteocalcin in DBS. Intra-assay CV for DBS was ~8%, while average inter-assay CV was 14.8%. Limit of detection was 0.34 ng/mL. Osteocalcin concentrations were stable in DBS stored at -28°C and room temperature, but not those stored at 37°C. This ELISA kit detects total osteocalcin. CONCLUSIONS: Osteocalcin, a bone formation biomarker, can be measured from DBS. Combined with a previously validated DBS assay for TRACP-5b, a bone resorption biomarker, these assays have the potential to help researchers disentangle the many factors contributing to bone strength.

Soil-transmitted helminth infection and intestinal inflammation among the Shuar of Amazonian Ecuador.

OBJECTIVES: Little research exists documenting levels of intestinal inflammation among indigenous populations where exposure to macroparasites, like soil-transmitted helminths (STHs), is common. Reduced STH exposure is hypothesized to contribute to increased prevalence of elevated intestinal inflammation in wealthy nations, likely due to coevolutionary histories between STHs and human immune systems that favored anti-inflammatory pathways. Here, we document levels of intestinal inflammation and test associations with STH infection among the Shuar of Ecuador, an indigenous population undergoing socioeconomic/lifestyle changes that influence their hygienic environment. We predict that fecal calprotectin (FC; a measure of intestinal inflammation) will be lower in STH infected individuals and that FC will be negatively associated with infection intensity. METHODS: Stool samples to analyze FC levels and STH infection were collected from 69 Shuar participants (ages 5-75 years). Children (<15 years) and adults (15+ years) were analyzed separately to understand the role of exposure in immune system development and the intestinal inflammatory response. RESULTS: Two species of STH were present: Ascaris lumbricoides and Trichuris trichiura. The relationships between infection and intestinal inflammation were age- and species-specific. While no significant relationships were found among adults, children who were singly infected with T. trichiura had lower FC levels than uninfected children. Infection intensity was not significantly associated with FC in children or adults. CONCLUSIONS: These preliminary results provide limited support for our hypotheses, documenting tentative age- and species-specific associations between FC and infection status. Findings may point to the importance of species-specific STH exposure during immune system development.

A dried blood spot-based method to measure levels of tartrate-resistant acid phosphatase 5b (TRACP-5b), a marker of bone resorption.

OBJECTIVES: A number of basic questions about bone biology have not been answered, including population differences in bone turnover. In part, this stems from the lack of validated minimally invasive biomarker techniques to measure bone formation and resorption in field-based population-level research. The present study addresses this gap by validating a fingerprick dried blood spot (fDBS) assay for tartrate-resistant acid phosphatase 5b (TRACP-5b), a well-defined biomarker of bone resorption and osteoclast number. METHODS: We adapted a commercially available enzyme-linked immunosorbent assay (ELISA) kit from MyBiosource for the quantitative determination of TRACP-5b levels in serum and plasma for use with DBS. We used a rigorous process of assay modification and validation, including the use of a matched set of 189 adult plasma, fDBS, and venous DBS (vDBS) samples; parameters evaluated included precision, reliability, and analyte stability. RESULTS: Plasma and DBS TRACP-5b concentrations showed a linear relationship. There were no systematic differences in TRACP-5b levels in fDBS and vDBS, indicating no significant differences in TRACP-5b distribution between capillary and venous blood. Parallelism and spike-and-recovery results indicated that matrix factors in DBS do not interfere with measurement of TRACP-5b levels from DBS using the validated kit. Intra- and interassay CVs were 5.0% and 12.1%, respectively. DBS samples should preferably be stored frozen but controlled room temperature storage for up to a month may be acceptable. CONCLUSIONS: This DBS-based ELISA assay adds to the methodological toolkit available to human biologists and will facilitate research on bone turnover in population studies.

The application of knemometry to measure childhood short-term growth among the indigenous Shuar of Ecuador.

OBJECTIVES: Knemometry, the precise measurement of lower leg (LL) length, suggests that childhood short-term (e.g., weekly) growth is a dynamic, nonlinear process. However, owing to the large size and complexity of the traditional knemometer device, previous study of short-term growth among children has been restricted predominantly to clinical settings in industrialized Western nations. The aim of the present study is to address this limitation and promote broader understandings of global variation in childhood development by: (1) describing a custom-built portable knemometer and assessing its performance in the field; and (2) demonstrating the potential application of such a device by characterizing childhood short-term LL growth among the indigenous Shuar of Amazonian Ecuador. MATERIALS AND METHODS: Mixed-longitudinal LL length data were collected weekly from 336 Shuar children age 5-12 years old using the custom portable knemometer (n = 1,145 total observations). Device performance and Shuar short-term LL growth were explored using linear mixed effects models and descriptive statistics. RESULTS: The portable knemometer performed well across a range of participant characteristics and possesses a low technical error of measurement of 0.18 mm. Shuar childhood LL growth averages 0.47 mm/week (SD = 0.75 mm/week), but exhibits large between- and within-individual variation. DISCUSSION: Knemometry can be reliably performed in the field, providing a means for evaluating childhood short-term growth among genetically and ecologically diverse populations. Preliminary findings suggest that Shuar weekly LL growth is comparable in mean magnitude but likely more variable than reported for healthy Western children. Future work will further explore these patterns. Am J Phys Anthropol 160:353-357, 2016. © 2016 Wiley Periodicals, Inc.

Accelerometer-measured physical activity among older adults in urban India: Results of a study on global AGEing and adult health substudy.

OBJECTIVES: Accelerometry provides researchers with a powerful tool to measure physical activity in population-based studies, yet this technology has been underutilized in cross-cultural studies of older adults. The present study was conducted among older adults in an urban setting in India with the following three objectives: (1) to compare average activity levels obtained through different durations of monitoring (1, 3, and 7 days); (2) to document differences in physical activity patterns by sex and age; and (3) to evaluate links between measures of physical activity and anthropometrics, as well as between activity parameters and measures of household size, work status, and social cohesion. METHODS: The present study uses data from a physical activity substudy of the World Health Organization's Study on global AGEing and adult health (SAGE-PA). This study of 200 older adults (49-90 years old; 72 males, 128 females) in urban India combines 7 continuous days of ActiGraph GT3X accelerometry with anthropometric and sociodemographic data. RESULTS: Results reveal overall low activity levels, with significantly lower activity energy expenditure (AEE) among females (P < 0.05). No significant differences were documented in activity level by monitoring duration. Age was negatively correlated with AEE in men (P < 0.01) and women (P < 0.001). AEE was positively correlated with BMI in men (P < 0.01) and women (P < 0.05). Finally, women who were more socially integrated had greater AEE (P < 0.01). CONCLUSIONS: This study illustrates the utility of accelerometry for quantifying activity levels in aging populations in non-Western nations. Am. J. Hum. Biol. 28:412-420, 2016. © 2015 Wiley Periodicals, Inc.

Physical growth of the shuar: Height, Weight, and BMI references for an indigenous amazonian population.

OBJECTIVES: Information concerning physical growth among small-scale populations remains limited, yet such data are critical to local health efforts and to foster basic understandings of human life history and variation in childhood development. Using a large dataset and robust modeling methods, this study aims to describe growth from birth to adulthood among the indigenous Shuar of Amazonian Ecuador. METHODS: Mixed-longitudinal measures of height, weight, and body mass index (BMI) were collected from Shuar participants (n = 2,463; age: 0-29 years). Centile growth curves and tables were created for each anthropometric variable of interest using Generalized Additive Models for Location, Scale, and Shape (GAMLSS). Pseudo-velocity and Lambda-Mu-Sigma curves were generated to further investigate Shuar patterns of growth and to facilitate comparison with United States Center for Disease Control and Prevention and multinational World Health Organization growth references. RESULTS: The Shuar are small throughout life and exhibit complex patterns of growth that differ substantially from those of international references. Similar to other Amazonians, Shuar growth in weight compares more favorably to references than growth in height, resulting in BMI curves that approximate international medians. Several additional characteristics of Shuar development are noteworthy, including large observed variation in body size early in life, significant infant growth faltering, extended male growth into adulthood, and a markedly early female pubertal growth spurt in height. Phenotypic plasticity and genetic selection in response to local environmental factors may explain many of these patterns. CONCLUSIONS: Providing a detailed reference of growth for the Shuar and other Amazonian populations, this study possesses direct clinical application and affords valuable insight into childhood health and the ecology of human growth.

Physical function and activity among older adults in Jodhpur, India.

BACKGROUND: Physical activity impacts the ageing process; yet, few studies have examined relationships among physical activity, functional abilities and health among older adults in non-Western settings. AIM: This study tests for associations among measures of physical activity, function and self-report health conditions among 200 older adults (49--50 years old) in Jodhpur, Rajasthan, India. METHODS: Seven consecutive days of accelerometry data were used in measures of physical activity (Total Daily Energy Expenditure [TDEE], Physical Activity Level [PAL], Daily Average Activity Count [AC] and Activity Energy Expenditure [AEE]). Measures of physical function included grip strength, timed walk and daily average sit time. Participants reported if they had been diagnosed with diabetes, hypertension, arthritis and/or depression. RESULTS: All four measures of physical activity were positively associated with grip strength (p ≤ 0.05). AC was negatively associated with timed walk (p ≤ 0.05), and both AC and AEE were negatively associated with daily average sit time (p ≤ 0.05). Women who reported diagnosis of hypertension had lower PAL and AC (p ≤ 0.05). CONCLUSION: This study provides further evidence for a positive relationship between physical activity and functional ability among older adults and between physical activity and cardiovascular health among women in India.

Heterogeneous effects of market integration on sub-adult body size and nutritional status among the Shuar of Amazonian Ecuador.

BACKGROUND: Market integration (MI)-increasing production for and consumption from a market-based economy-is drastically altering traditional ways of life and environmental conditions among indigenous Amazonian peoples. The effects of MI on the biology and health of Amazonian children and adolescents, however, remain unclear. AIM: This study examines the impact of MI on sub-adult body size and nutritional status at the population, regional and household levels among the Shuar of Amazonian Ecuador. SUBJECTS AND METHODS: Anthropometric data were collected between 2005-2014 from 2164 Shuar (aged 2-19 years) living in two geographic regions differing in general degree of MI. High-resolution household economic, lifestyle and dietary data were collected from a sub-sample of 631 participants. Analyses were performed to investigate relationships between body size and year of data collection, region and specific aspects of household MI. RESULTS: Results from temporal and regional analyses suggest that MI has a significant and overall positive impact on Shuar body size and nutritional status. However, household-level results exhibit nuanced and heterogeneous specific effects of MI underlying these overarching relationships. CONCLUSION: This study provides novel insight into the complex socio-ecological pathways linking MI, physical growth and health among the Shuar and other indigenous Amazonian populations.

Determining osteoporosis risk in older Colono adults from rural Amazonian Ecuador using calcaneal ultrasonometry.

OBJECTIVE: Low bone density and osteoporosis prevalence, while well-documented in wealthy nations, are poorly studied in rural, non-clinical contexts in economically developing regions such as Latin America. This study contributes preliminary osteoporosis risk data for a rural Colono (mestizo) population from Amazonian Ecuador. METHODS: Anthropometrics were collected for 119 adult participants (74 females, 45 males [50-90 years old]). Heel bone density and T-scores were recorded using calcaneal ultrasonometry RESULTS: Approximately, 33.6% of the participants had low bone density and were at high-risk for osteoporosis. Four times as many females as males were considered high-risk. Consistent with epidemiological literature, advancing age was significantly associated with lower bone density values (P = 0.001). CONCLUSIONS: Low bone density and osteoporosis prevalence are expected to increase in this and other economically transitioning populations, yet infrastructure to monitor this changing epidemiological landscape is almost non-existent. Human biologists are uniquely positioned to contribute data from remote populations, a critical step toward initiating increased resource allocation for diagnosis and prevention.

Helicobacter pylori exposure among the Awajún of the Peruvian Amazon: Prevalence and environmental, social, and biological associations.

OBJECTIVES: Helicobacter pylori (H. pylori)-a gastric bacteria affecting almost 50% of the global population and leading to ulcers and cancer in severe cases-is a growing health concern among Indigenous populations who report a high burden of reported poor general health and gastrointestinal distress. We test hypothesized associations between H. pylori exposure patterns and environmental, social, and biological conditions among a sample of 212 Indigenous Awajún adults (112 males, 100 females, ages 18-65 years) living in the northern Peruvian Amazon. MATERIALS AND METHODS: Dried blood spots were analyzed for H. pylori-specific IgG using a recently developed enzyme-linked immunosorbent assay. Resulting seropositivity rates and antibody concentrations, proxying past exposures to H. pylori were analyzed in relation to relevant environmental (toilet type, floor material, reported water quality), social (household size and education level), and biological (age, sex, BMI, blood pressure, immune and metabolic biomarkers) factors using multivariable regression analyses. RESULTS: We found near ubiquitous seropositivity for H. pylori exposure in our sample (99.1% seropositive). In the regression analyses, elevations in H. pylori antibody concentrations were significantly higher among males compared to females (ß = 0.36, p = 0.01). No associations were found with any other factors. DISCUSSION: Anthropological research in the study communities suggests that the male bias in elevations of H. pylori antibody concentrations is related to cultural and biological factors. Future research is needed to further unravel these biocultural dynamics and determine whether elevations in H. pylori antibody concentrations have clinical relevance for gastrointestinal health outcomes in this population.

Rural Embodiment and Community Health: an Anthropological Case Study on Biocultural Determinants of Tropical Disease Infection and Immune System Development in the USA.

Purpose of Review: Biocultural methods are critically important for identifying environmental and socioeconomic factors linked with tropical disease risk and outcomes. For example, embodiment theory refers to the process by which lived experiences impact individual biology. Increased exposure to pathogens, chronic psychosocial stress, and unequal resource access are all outcomes linked with discrimination and poverty. Through lived experiences, race and socioeconomic inequality can literally become embodied-get under the skin and affect physiology-impacting immune responses and contributing to lifelong health disparities. Yet, few studies have investigated tropical disease patterns and associated immune function using embodiment theory to understand lasting physiological impacts associated with living in a high-pathogen environment. Recent Findings: Here, we use preliminary data drawn from the Rural Embodiment and Community Health (REACH) study to assess whether pathogen exposure and immune stimulation within a sample of children from the Mississippi Delta are associated with household income. We also test whether immune marker levels-assessed with enzyme-linked immunosorbent assays using dried blood spot samples-vary between the REACH sample and a similarly aged nationally representative NHANES sample. Immune marker levels did not differ significantly between REACH participants living below vs. above the federal poverty line, yet immunoglobulin E levels-a marker of macroparasite infection-were higher among REACH study participants compared to the NHANES sample. Summary: These results may suggest community-level pathogenic exposures (i.e., parasitic infections) are embodied by REACH participants with implications for long-term immune function, potentially resulting in immune aspects that differ from nationally representative samples. Supplementary Information: The online version contains supplementary material available at 10.1007/s40475-023-00282-z.