Effects of changes in temperature on Zika dynamics and control.

When a rare pathogen emerges to cause a pandemic, it is critical to understand its dynamics and the impact of mitigation measures. We use experimental data to parametrize a temperature-dependent model of Zika virus (ZIKV) transmission dynamics and analyse the effects of temperature variability and control-related parameters on the basic reproduction number (R0) and the final epidemic size of ZIKV. Sensitivity analyses show that these two metrics are largely driven by different parameters, with the exception of temperature, which is the dominant driver of epidemic dynamics in the models. Our R0 estimate has a single optimum temperature (≈30°C), comparable to other published results (≈29°C). However, the final epidemic size is maximized across a wider temperature range, from 24 to 36°C. The models indicate that ZIKV is highly sensitive to seasonal temperature variation. For example, although the model predicts that ZIKV transmission cannot occur at a constant temperature below 23°C (≈ average annual temperature of Rio de Janeiro, Brazil), the model predicts substantial epidemics for areas with a mean temperature of 20°C if there is seasonal variation of 10°C (≈ average annual temperature of Tampa, Florida). This suggests that the geographical range of ZIKV is wider than indicated from static R0 models, underscoring the importance of climate dynamics and variation in the context of broader climate change on emerging infectious diseases.

Effects of seasonality and land use on the diversity, relative abundance, and distribution of mosquitoes on St. Kitts, West Indies.

BACKGROUND: Mosquito surveys that collect local data on mosquito species' abundances provide baseline data to help understand potential host-pathogen-mosquito relationships, predict disease transmission, and target mosquito control efforts. METHODS: We conducted an adult mosquito survey from November 2017 to March 2019 on St. Kitts, using Biogents Sentinel 2 traps, set monthly and run for 48-h intervals. We collected mosquitoes from a total of 30 sites distributed across agricultural, mangrove, rainforest, scrub and urban land covers. We investigated spatial variation in mosquito species richness across the island using a hierarchical Bayesian multi-species occupancy model. We developed a mixed effects negative binomial regression model to predict the effects of spatial variation in land cover, and seasonal variation in precipitation on observed counts of the most abundant mosquito species observed. RESULTS: There was high variation among sites in mosquito community structure, and variation in site level richness that correlated with scrub forest, agricultural, and urban land covers. The four most abundant species were Aedes taeniorhynchus, Culex quinquefasciatus, Aedes aegpyti and Deinocerites magnus, and their relative abundance varied with season and land cover. Aedes aegypti was the most commonly occurring mosquito on the island, with a 90% probability of occurring at between 24 and 30 (median = 26) sites. Mangroves yielded the most mosquitoes, with Ae. taeniorhynchus, Cx. quinquefasciatus and De. magnus predominating. Psorophora pygmaea and Toxorhynchites guadeloupensis were only captured in scrub habitat. Capture rates in rainforests were low. Our count models also suggested the extent to which monthly average precipitation influenced counts varied according to species. CONCLUSIONS: There is high seasonality in mosquito abundances, and land cover influences the diversity, distribution, and relative abundance of species on St. Kitts. Further, human-adapted mosquito species (e.g. Ae. aegypti and Cx. quinquefasciatus) that are known vectors for many human relevant pathogens (e.g. chikungunya, dengue and Zika viruses in the case of Ae. aegypti; West Nile, Spondweni, Oropouche virus, and equine encephalitic viruses in the case of Cx. quinqefasciatus) are the most wide-spread (across land covers) and the least responsive to seasonal variation in precipitation.

Cerebral cavernous malformations are driven by ADAMTS5 proteolysis of versican.

Cerebral cavernous malformations (CCMs) form following loss of the CCM protein complex in brain endothelial cells due to increased endothelial MEKK3 signaling and KLF2/4 transcription factor expression, but the downstream events that drive lesion formation remain undefined. Recent studies have revealed that CCM lesions expand by incorporating neighboring wild-type endothelial cells, indicative of a cell nonautonomous mechanism. Here we find that endothelial loss of ADAMTS5 reduced CCM formation in the neonatal mouse model. Conversely, endothelial gain of ADAMTS5 conferred early lesion genesis in the absence of increased KLF2/4 expression and synergized with KRIT1 loss of function to create large malformations. Lowering versican expression reduced CCM burden, indicating that versican is the relevant ADAMTS5 substrate and that lesion formation requires proteolysis but not loss of this extracellular matrix protein. These findings identify endothelial secretion of ADAMTS5 and cleavage of versican as downstream mechanisms of CCM pathogenesis and provide a basis for the participation of wild-type endothelial cells in lesion formation.

Spatio-temporal spillover risk of yellow fever in Brazil.

BACKGROUND: Yellow fever virus is a mosquito-borne flavivirus that persists in an enzoonotic cycle in non-human primates (NHPs) in Brazil, causing disease in humans through spillover events. Yellow fever (YF) re-emerged in the early 2000s, spreading from the Amazon River basin towards the previously considered low-risk, southeastern region of the country. Previous methods mapping YF spillover risk do not incorporate the temporal dynamics and ecological context of the disease, and are therefore unable to predict seasonality in spatial risk across Brazil. We present the results of a bagged logistic regression predicting the propensity for YF spillover per municipality (administrative sub-district) in Brazil from environmental and demographic covariates aggregated by month. Ecological context was incorporated by creating National and Regional models of spillover dynamics, where the Regional model consisted of two separate models determined by the regions' NHP reservoir species richness (high vs low). RESULTS: Of the 5560 municipalities, 82 reported YF cases from 2001 to 2013. Model accuracy was high for the National and low reservoir richness (LRR) models (AUC = 0.80), while the high reservoir richness (HRR) model accuracy was lower (AUC = 0.63). The National model predicted consistently high spillover risk in the Amazon, while the Regional model predicted strong seasonality in spillover risk. Within the Regional model, seasonality of spillover risk in the HRR region was asynchronous to the LRR region. However, the observed seasonality of spillover risk in the LRR Regional model mirrored the national model predictions. CONCLUSIONS: The predicted risk of YF spillover varies with space and time. Seasonal trends differ between regions indicating, at times, spillover risk can be higher in the urban coastal regions than the Amazon River basin which is counterintuitive based on current YF risk maps. Understanding the spatio-temporal patterns of YF spillover risk could better inform allocation of public health services.

ICU Telemedicine and Critical Care Mortality: A National Effectiveness Study.

BACKGROUND: Intensive care unit (ICU) telemedicine is an increasingly common strategy for improving the outcome of critical care, but its overall impact is uncertain. OBJECTIVES: To determine the effectiveness of ICU telemedicine in a national sample of hospitals and quantify variation in effectiveness across hospitals. RESEARCH DESIGN: We performed a multicenter retrospective case-control study using 2001-2010 Medicare claims data linked to a national survey identifying US hospitals adopting ICU telemedicine. We matched each adopting hospital (cases) to up to 3 nonadopting hospitals (controls) based on size, case-mix, and geographic proximity during the year of adoption. Using ICU admissions from 2 years before and after the adoption date, we compared outcomes between case and control hospitals using a difference-in-differences approach. RESULTS: A total of 132 adopting case hospitals were matched to 389 similar nonadopting control hospitals. The preadoption and postadoption unadjusted 90-day mortality was similar in both case hospitals (24.0% vs. 24.3%, P=0.07) and control hospitals (23.5% vs. 23.7%, P<0.01). In the difference-in-differences analysis, ICU telemedicine adoption was associated with a small relative reduction in 90-day mortality (ratio of odds ratios=0.96; 95% CI, 0.95-0.98; P<0.001). However, there was wide variation in the ICU telemedicine effect across individual hospitals (median ratio of odds ratios=1.01; interquartile range, 0.85-1.12; range, 0.45-2.54). Only 16 case hospitals (12.2%) experienced statistically significant mortality reductions postadoption. Hospitals with a significant mortality reduction were more likely to have large annual admission volumes (P<0.001) and be located in urban areas (P=0.04) compared with other hospitals. CONCLUSIONS: Although ICU telemedicine adoption resulted in a small relative overall mortality reduction, there was heterogeneity in effect across adopting hospitals, with large-volume urban hospitals experiencing the greatest mortality reductions.

Physical and social environmental characteristics of physical activity for Mexican-origin children: examining differences between school year and summer perceptions.

BACKGROUND: Colonias are substandard residential areas along the U.S.-Mexico border. Families of Mexican-origin living in colonias face health burdens characterized by environmental and socioeconomic hardships. Mexican Americans and low-income families, including colonias children, do not frequently participate in physical activity despite the known link to disease risk reduction. For colonias children, schools are the most commonly reported location for physical activity. School closures and extreme temperatures during summer months create a need to explore seasonal differences in environmental supports and barriers in this population. The purpose of this study was to examine the effect of seasonality on perceived environmental barriers, opportunities, and social support for physical activity among colonias children. As a secondary aim, mother-child discordance for each factor was analyzed. METHODS: Promotora-researchers recruited mother-child dyads (n=101 dyads, n=202 participants) from colonias in Hidalgo County, Texas. Mothers and children were separately administered surveys at two time points to capture perceived barriers, opportunities, and social support for physical activity (school-year: February-May; summertime: July-August). Summative scores for each outcome were calculated and three multilevel longitudinal models for continuous outcomes were examined; children were nested within households. Mother-child discordance was measured using Cohen's Kappa statistic. RESULTS: Physical activity barriers and environmental opportunities (household and neighborhood) increased from school-year to summer by 1.16 and 2.83 points respectively (p≤0.01), after adjusting for covariates. Significant predictors of increased barriers included household income of >$900/month and having more household members. Children of mothers with significant others who were employed part-time or full-time saw significant decreases in barriers. Mother-child agreement of barriers, environmental opportunities, and social support across seasons was slight to fair (range: median κ=0.047 to κ=0.262). CONCLUSIONS: These results suggest a complex relationship between dimensions of economic hardship (employment status, household income, etc…) and perceived opportunities and barriers of children's physical activity engagement during the school-year and summer. In this study, both barriers and opportunities increased from school-year to summer, further demonstrating that interactions among these characteristics need to be better understood and addressed when considering physical activity initiatives for colonias and other Mexican-American children, specifically during summer when school-based physical activity resources are unavailable.

Genetic status and timing of a weevil introduction to Santa Cruz Island, Galapagos.

Successful invasive species can overcome or circumvent the potential genetic loss caused by an introduction bottleneck through a rapid population expansion and admixture from multiple introductions. We explore the genetic makeup and the timing of a species introduction to Santa Cruz Island in the Galápagos archipelago. We investigate the presence of processes that can maintain genetic diversity in populations of the broad-nosed weevil Galapaganus howdenae howdenae. Analyses of combined genotypes for 8 microsatellite loci showed evidence of past population size reductions through moment and likelihood-based estimators. No evidence of admixture through multiple introductions was found, but substantial current population sizes (N0 298, 95% credible limits 50-2300), genetic diversity comparable with long-established endemics (Mean number of alleles = 3.875), and lack of genetic structure across the introduced range (F ST = 0.01359) could suggest that foundations are in place for populations to rapidly recover any loss of genetic variability. The time estimates for the introduction into Santa Cruz support an accidental transfer during the colonization period (1832-1959) predating the spurt in human population growth. Our evaluation of the genetic status of G. h. howdenae suggests potential for population growth in addition to our field observations of a concurrent expansion in range and feeding preferences towards protected areas and endemic host plants.

Child hunger and the protective effects of Supplemental Nutrition Assistance Program (SNAP) and alternative food sources among Mexican-origin families in Texas border colonias.

BACKGROUND: Nutritional health is essential for children's growth and development. Many Mexican-origin children who reside in limited-resource colonias along the Texas-Mexico border are at increased risk for poor nutrition as a result of household food insecurity. However, little is known about the prevalence of child hunger or its associated factors among children of Mexican immigrants. This study determines the prevalence of child hunger and identifies protective and risk factors associated with it in two Texas border areas. METHODS: This study uses 2009 Colonia Household and Community Food Resource Assessment (C-HCFRA) data from 470 mothers who were randomly recruited by promotora-researchers. Participants from colonias near two small towns in two South Texas counties participated in an in-home community and household assessment. Interviewer-administered surveys collected data in Spanish on sociodemographics, federal food assistance program participation, and food security status. Frequencies and bivariate correlations were examined while a random-effects logistic regression model with backward elimination was used to determine correlates of childhood hunger. RESULTS: Hunger among children was reported in 51% (n = 239) of households in this C-HCFRA sample. Bivariate analyses revealed that hunger status was associated with select maternal characteristics, such as lower educational attainment and Mexican nativity, and household characteristics, including household composition, reliance on friend or neighbor for transportation, food purchase at dollar stores and from neighbors, and participation in school-based nutrition programs. A smaller percentage of households with child hunger participated in school-based nutrition programs (51%) or used alternative food sources, while 131 households were unable to give their child or children a balanced meal during the school year and 145 households during summer months. In the random effects model (RE = small town), increased household composition, full-time unemployment, and participation in the National School Lunch Program were significantly associated with increased odds for child hunger, while participation in Supplemental Nutrition Assistance Program (SNAP) and purchasing food from a neighbor were significantly associated with decreased odds for child hunger. CONCLUSIONS: This study not only emphasizes the alarming rates of child hunger among this sample of Mexican-origin families, but also identifies economic and family factors that increased the odds for child hunger as well as community strategies that reduced the odds. It is unsettling that so many children did not participate in school-based nutrition programs, and that many who participated in federal nutrition assistance programs remained hungry. This study underscores the importance of identifying the presence of child hunger among low-income Mexican-origin children in Texas border colonias and increasing access to nutrition-related resources. Hunger-associated health inequities at younger ages among colonia residents are likely to persist across the life span and into old age.

School-based nutrition programs are associated with reduced child food insecurity over time among Mexican-origin mother-child dyads in Texas Border Colonias.

In 2011, an estimated 50.2 million adults and children lived in US households with food insecurity, a condition associated with adverse health effects across the life span. Relying solely on parent proxy may underreport the true prevalence of child food insecurity. The present study sought to understand mothers' and children's (aged 6-11 y) perspectives and experiences of child food insecurity and its seasonal volatility, including the effects of school-based and summertime nutrition programs. Forty-eight Mexican-origin mother-child dyads completed standardized, Spanish-language food-security instruments during 2 in-home visits between July 2010 and March 2011. Multilevel longitudinal logistic regression measured change in food security while accounting for correlation in repeated measurements by using a nested structure. Cohen's κ statistic assessed dyadic discordance in child food insecurity. School-based nutrition programs reduced the odds of child food insecurity by 74% [OR = 0.26 (P < 0.01)], showcasing the programs' impact on the condition. Single head of household was associated with increased odds of child food insecurity [OR = 4.63 (P = 0.03)]. Fair dyadic agreement of child food insecurity was observed [κ = 0.21 (P = 0.02)]. Obtaining accurate prevalence rates and understanding differences of intrahousehold food insecurity necessitate measurement at multiple occasions throughout the year while considering children's perceptions and experiences of food insecurity in addition to parental reports.

Convenience stores are the key food environment influence on nutrients available from household food supplies in Texas Border Colonias.

BACKGROUND: Few studies have focused on the relationship between the retail food environment and household food supplies. This study examines spatial access to retail food stores, food shopping habits, and nutrients available in household food supplies among 50 Mexican-origin families residing in Texas border colonias. METHODS: The design was cross-sectional; data were collected in the home March to June 2010 by promotora-researchers. Ground-truthed methods enumerated traditional (supercenters, supermarkets, grocery stores), convenience (convenience stores and food marts), and non-traditional (dollar stores, discount stores) retail food stores. Spatial access was computed using the network distance from each participant's residence to each food store. Data included survey data and two household food inventories (HFI) of the presence and amount of food items in the home. The Spanish language interviewer-administered survey included demographics, transportation access, food purchasing, food and nutrition assistance program participation, and the 18-item Core Food Security Module. Nutrition Data Systems for Research (NDS-R) was used to calculate HFI nutrients. Adult equivalent adjustment constants (AE), based on age and gender calorie needs, were calculated based on the age- and gender composition of each household and used to adjust HFI nutrients for household composition. Data were analyzed using bivariate analysis and linear regression models to determine the association of independent variables with the availability of each AE-adjusted nutrient. RESULTS: Regression models showed that households in which the child independently purchased food from a convenience store at least once a week had foods and beverages with increased amounts of total energy, total fat, and saturated fat. A greater distance to the nearest convenience store was associated with reduced amounts of total energy, vitamin D, total sugar, added sugar, total fat, and saturated fat. Participation in the National School Lunch Program (NSLP) was associated with lower household levels of total energy, calcium, vitamin C, sodium, vitamin D, and saturated fat. Spatial access and utilization of supermarkets and dollar stores were not associated with nutrient availability. CONCLUSIONS: Although household members frequently purchased food items from supermarkets or dollar stores, it was spatial access to and frequent utilization of convenience food stores that influenced the amount of nutrients present in Texas border colonia households. These findings also suggest that households which participate in NSLP have reduced AE-adjusted nutrients available in the home. The next step will target changes within convenience stores to improve in-store marketing of foods and beverages to children and adults.

Comparative genetic structure and demographic history in endemic galapagos weevils.

The challenge of maintaining genetic diversity within populations can be exacerbated for island endemics if they display population dynamics and behavioral attributes that expose them to genetic drift without the benefits of gene flow. We assess patterns of the genetic structure and demographic history in 27 populations of 9 species of flightless endemic Galápagos weevils from 9 of the islands and 1 winged introduced close relative. Analysis of mitochondrial DNA reveals a significant population structure and moderately variable, though demographically stable, populations for lowland endemics (F(ST) = 0.094-0.541; π: 0.014-0.042; Mismatch P = 0.003-0.026; and D((Tajima)) = -0.601 to 1.203), in contrast to signals of past contractions and expansions in highland specialists on 2 islands (Mismatch P = 0.003-0.026 and D((Tajima)) = -0.601 to 1.203). We interpret this series of variable and highly structured population groups as a system of long-established, independently founded island units, where structuring could be a signal of microallopatric differentiation due to patchy host plant distribution and poor dispersal abilities. We suggest that the severe reduction and subsequent increase of a suitably moist habitat that accompanied past climatic variation could have contributed to the observed population fluctuations in highland specialists. We propose the future exploration of hybridization between the introduced and highland endemic species on Santa Cruz, especially given the expansion of the introduced species into the highlands, the sensitivity to past climatic variation detected in highland populations, and the potentially threatened state of single-island endemics.

The development of an enzyme-linked immunosorbent assay for Trypanosoma vivax and its use in a seroepidemiological survey of the Eastern Caribbean Basin.

An enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against a South American (New World) strain of Trypanosoma vivax was developed and used for mass screening of cattle from 20 islands in the Eastern Caribbean Basin. The sensitivity and specificity of antigens prepared from a bovine-derived field strain and a murine-adapted laboratory strain of T. vivax, both of New World origin, were compared using an indirect fluorescent antibody (IFA) test, and an antigen prepared from the murine-adapted strain was subsequently used to develop an ELISA test. The results of the ELISA test were then compared with the results of a concurrently run IFA test. There was no cross-reactivity with either test using serum from a Trypanosoma theileri-infected cow. Both tests were weakly cross-reactive with sera from a T. brucei-infected steer, and the IFA test was moderately cross-reactive with several serum samples from a T. evansi-infected steer. For bovine sera collected from herds on islands in the Eastern Caribbean region, only five of 640 tested positive with the ELISA test. Thirty five of 653 sera tested were positive by IFA although the fluorescence elicited was weak as compared to that elicited by sera from known infected animals. Sera collected from 27 cattle in a region known to be free of T. vivax (OH, U.S.A) were negative with the ELISA test, whereas seven of 30 sera from a herd in French Guiana known to be infected with T. vivax were positive.(ABSTRACT TRUNCATED AT 250 WORDS)

The development of an enzyme-linked immunosorbent assay for Trypanosoma vivax and its use in a seroepidemiological survey of the Eastern Caribbean Basin

An enzyme-linked immunosorbent assay (ELISA) for IgG antibodies against a South American (New World) strain of Trypanosoma vivax was developed and used for mass screening of cattle from 20 islands in the Eastern Caribbean Basin. The sensitivity and specificity of antigens prepared from a bovine-derived field strain and a nurine-adapted laboratory strain of T. vivax, both of New World origin, were compared using an indirect fluorescent antibody (IFA) test, and an antigen prepared from murine-adapted strain was subsequently used to develop an ELISA test. The results of the ELISA test were then compared with the results of a concurrently run IFA test. There was no cross-reactivity with either test using serum from a Trypanosoma theileri-infected cow. Both tests were weakly cross-reactive with sera from a T. brucei-infected steer, and the IFA test was moderately cross-reactive with several serum samples from a T. evansi-infected steer. For bovine sera collected from herds on islands in the Eastern Caribbean region, only five of 640 tested positive with the ELISA test. Thirty five of 653 sera tested were positive by IFA although the fluorscence elicited was weak as compared to that elicited by sera from known infected animals. Sera collected from 27 cattle in a region known to be free of T. vivax (OH, U.S.A) were negative with the ELISA test, whereas seven of 30 sera from a herd in French Guiana known to be infected with T. vivax were positive. None of 45 caprine and 60 ovine sera collected from islands in the Eastern Caribbean region were positive by the IFA test, therefore an ELISA system for these species was not developed (AU)