Epidemiology and clinical characteristics of drowning patients presenting to a pediatric emergency department from 2017 to 2020.

BACKGROUND: Drowning is a common mechanism of injury in the pediatric population that often requires hospitalization. The primary objective of this study was to describe the epidemiology and clinical characteristics of pediatric drowning patients evaluated in a pediatric emergency department (PED), including the clinical interventions and outcomes of this patient population. METHODS: A retrospective cohort study was conducted of pediatric patients evaluated in a mid-Atlantic urban pediatric emergency department from January 2017 to December 2020 after a drowning event. RESULTS: Eighty patients ages 0-18 were identified, representing 57 79 unintentional events and 1 intentional self-injury event. The majority of patients (50%) were 1-4 years of age. The majority (65%) of patients 4 years of age or younger were White, whereas racial/ethnic minority patients accounted for the majority (73%) of patients 5 years of age or older. Most drowning events (74%) occurred in a pool, on Friday through Saturday (66%) and during the summer (73%). Oxygen was used in 54% of admitted patients and only in 9% of discharged patients. Cardiopulmonary resuscitation (CPR) was performed in 74% of admitted patients and 33% of discharged patients. CONCLUSIONS: Drowning can be an intentional or unintentional source of injury in pediatric patients. Among the patients who presented to the emergency department for drowning, more than half received CPR and/or were admitted, suggesting high acuity and severity of these events. In this study population, outdoor pools, summer season and weekends are potential high yield targets for drowning prevention efforts.

Autonomous analysis to identify bijels from two-dimensional images.

Bicontinuous interfacially jammed emulsion gels (bijels) are novel composite materials that can be challenging to manufacture. As a step towards automating production, we have developed a machine learning tool to classify fabrication attempts. We use training and testing data in the form of confocal images from both successful and unsuccessful attempts at bijel fabrication. We then apply machine learning techniques to this data in order to classify whether an image is a bijel or a non-bijel. Our principal approach is to process the images to find their autocorrelation function and structure factor, and from these functions we identify variables that can be used for training a supervised machine learning model to identify a bijel image. We are able to categorise images with reasonable accuracies of 85.4% and 87.5% for two different approaches. We find that using both the liquid and particle channels helps to achieve optimal performance and that successful classification relies on the bijel samples sharing a characteristic length scale. Our second approach is to classify the shapes of the liquid domains directly; the shape descriptors are then used to classify fabrication attempts via a decision tree. We have used an adaptive design approach to find an image pre-processing step that yields the optimal classification results. Again, we find that the characteristic length scale of the images is crucial in performing the classification.

Rheological Behavior and in Situ Confocal Imaging of Bijels Made by Mixing.

Bijels (bicontinuous interfacially jammed emulsion gels) have the potential to be useful in many different applications due to their internal connectivity and the possibility of efficient mass transport through the channels. Recently, new methods of making the bijel have been proposed, which simplify the fabrication process, making commercial application more realistic. Here, we study the flow properties of bijels prepared by mixing alone using oscillatory rheology combined with confocal microscopy and also squeezing flow experiments. We found that the bijel undergoes a two-step yielding process where the first step corresponds to the fluidizing of the interface, allowing the motion of the structure, and the second step corresponds to the breaking of the structure. In the squeeze flow experiments, the yield stress of the bijel is observed to show a power law dependence on squeezing speed. However, when stress in excess of yield stress is plotted against shear rate, all the different squeeze flow data show a superposition.

Yersinia murine toxin is not required for early-phase transmission of Yersinia pestis by Oropsylla montana (Siphonaptera: Ceratophyllidae) or Xenopsylla cheopis (Siphonaptera: Pulicidae).

Plague, caused by Yersinia pestis, is characterized by quiescent periods punctuated by rapidly spreading epizootics. The classical 'blocked flea' paradigm, by which a blockage forms in the flea's proventriculus on average 1-2 weeks post-infection (p.i.), forces starving fleas to take multiple blood meals, thus increasing opportunities for transmission. Recently, the importance of early-phase transmission (EPT), which occurs prior to blockage formation, has been emphasized during epizootics. Whilst the physiological and molecular mechanisms of blocked flea transmission are well characterized, the pathogen-vector interactions have not been elucidated for EPT. Within the blocked flea model, Yersinia murine toxin (Ymt) has been shown to be important for facilitating colonization of the midgut within the flea. One proposed mechanism of EPT is the regurgitation of infectious material from the flea midgut during feeding. Such a mechanism would require bacteria to colonize and survive for at least brief periods in the midgut, a process that is mediated by Ymt. Two key bridging vectors of Y. pestis to humans, Oropsylla montana (Siphonaptera: Ceratophyllidae) or Xenopsylla cheopis (Siphonaptera: Pulicidae), were used in our study to test this hypothesis. Fleas were infected with a mutant strain of Y. pestis containing a non-functional ymt that was shown previously to be incapable of colonizing the midgut and were then allowed to feed on SKH-1 mice 3 days p.i. Our results show that Ymt was not required for EPT by either flea species.

Nanostructured, Fluid-Bicontinuous Gels for Continuous-Flow Liquid-Liquid Extraction.

Fluid-bicontinuous gels are unique materials that allow two distinct fluids to interact through a percolating, rigid scaffold. Current restrictions for their use are the large fluid-channel sizes (>5 µm), limiting the fluid-fluid interaction surface-area, and the inability to flow liquids through the channels. In this work a scalable synthesis route of nanoparticle stabilized fluid-bicontinuous gels with channels sizes below 500 nm and specific surface areas of 2 m2 cm-3 is introduced. Moreover, it is demonstrated that liquids can be pumped through the fluid-bicontinuous gels via electroosmosis. The fast liquid flow in the fluid-bicontinuous gel facilitates their use for molecular separations in continuous-flow liquid-liquid extraction. Together with the high surface areas, liquid flow through fluid-bicontinuous gels enhances their potential as highly permeable porous materials with possible uses as microreaction media, fuel-cell components, and separation membranes.

Are Langmuir Trough Studies Useful? Unexpected Emulsification Behavior Using Colloidal Rods.

While studies carried out in a Langmuir trough have rigorously demonstrated that, at high surface pressure, ellipsoidal particles do flip and spherocylinders (rods) can flip, much less is known about the practical situation on the surface of a droplet or bubble. We present emulsification studies using colloidal rods and find that the droplets are bridged by the rods independent of shear rate and particle concentration and are only weakly dependent on the pH of the continuous phase. In a trough, it is the low aspect ratio rods which flip and the high aspect ratio rods which form bilayers; on the surface of a droplet we found that the high aspect ratio rods always bridge whereas the shorter rods show random bridging behavior. Hence, the behavior of anisotropic particles "in action" is essentially opposite to expectations from trough studies.

An Evaluation of Removal Trapping to Control Rodents Inside Homes in a Plague-Endemic Region of Rural Northwestern Uganda.

Rodents pose a significant threat to human health, particularly in rural subsistence farming communities in Africa, where rodents threaten food security and serve as reservoirs of human pathogens, including the agents of plague, leptospirosis, murine typhus, rat-bite fever, Lassa fever, salmonellosis, and campylobacteriosis. Our study focused on the plague-endemic West Nile region of Uganda, where a majority of residents live in Uganda government-defined poverty, rely on subsistence farming for a living, and frequently experience incursions of rodents into their homes. In this study, we show that rodent removal was achieved in a median of 6 days of intensive lethal trapping with multiple trap types (range: 0-16 days). However, rodent abundance in 68.9% of homesteads returned to pretreatment levels within a median of 8 weeks (range 1-24 weeks), and at least a single rodent was captured in all homesteads by a median of 2 weeks (range 1-16 weeks) after removal efforts were terminated. Results were similar between homesteads that practiced rodent control whether or not their neighbors implemented similar strategies. Overall, intensive lethal trapping inside homes appears to be effective at reducing rodent abundance, but control was short lived after trapping ceased.

Flea-Associated Bacterial Communities across an Environmental Transect in a Plague-Endemic Region of Uganda.

The vast majority of human plague cases currently occur in sub-Saharan Africa. The primary route of transmission of Yersinia pestis, the causative agent of plague, is via flea bites. Non-pathogenic flea-associated bacteria may interact with Y. pestis within fleas and it is important to understand what factors govern flea-associated bacterial assemblages. Six species of fleas were collected from nine rodent species from ten Ugandan villages between October 2010 and March 2011. A total of 660,345 16S rRNA gene DNA sequences were used to characterize bacterial communities of 332 individual fleas. The DNA sequences were binned into 421 Operational Taxonomic Units (OTUs) based on 97% sequence similarity. We used beta diversity metrics to assess the effects of flea species, flea sex, rodent host species, site (i.e. village), collection date, elevation, mean annual precipitation, average monthly precipitation, and average monthly temperature on bacterial community structure. Flea species had the greatest effect on bacterial community structure with each flea species harboring unique bacterial lineages. The site (i.e. village), rodent host, flea sex, elevation, precipitation, and temperature also significantly affected bacterial community composition. Some bacterial lineages were widespread among flea species (e.g. Bartonella spp. and Wolbachia spp.), but each flea species also harbored unique bacterial lineages. Some of these lineages are not closely related to known bacterial diversity and likely represent newly discovered lineages of insect symbionts. Our finding that flea species has the greatest effect on bacterial community composition may help future investigations between Yersinia pestis and non-pathogenic flea-associated bacteria. Characterizing bacterial communities of fleas during a plague epizootic event in the future would be helpful.

Seasonal fluctuations of small mammal and flea communities in a Ugandan plague focus: evidence to implicate Arvicanthis niloticus and Crocidura spp. as key hosts in Yersinia pestis transmission.

BACKGROUND: The distribution of human plague risk is strongly associated with rainfall in the tropical plague foci of East Africa, but little is known about how the plague bacterium is maintained during periods between outbreaks or whether environmental drivers trigger these outbreaks. We collected small mammals and fleas over a two year period in the West Nile region of Uganda to examine how the ecological community varies seasonally in a region with areas of both high and low risk of human plague cases. METHODS: Seasonal changes in the small mammal and flea communities were examined along an elevation gradient to determine whether small mammal and flea populations exhibit differences in their response to seasonal fluctuations in precipitation, temperature, and crop harvests in areas within (above 1300 m) and outside (below 1300 m) of a model-defined plague focus. RESULTS: The abundance of two potential enzootic host species (Arvicanthis niloticus and Crocidura spp.) increased during the plague season within the plague focus, but did not show the same increase at lower elevations outside this focus. In contrast, the abundance of the domestic rat population (Rattus rattus) did not show significant seasonal fluctuations regardless of locality. Arvicanthis niloticus abundance was negatively associated with monthly precipitation at a six month lag and positively associated with current monthly temperatures, and Crocidura spp. abundance was positively associated with precipitation at a three month lag and negatively associated with current monthly temperatures. The abundance of A. niloticus and Crocidura spp. were both positively correlated with the harvest of millet and maize. CONCLUSIONS: The association between the abundance of several small mammal species and rainfall is consistent with previous models of the timing of human plague cases in relation to precipitation in the West Nile region. The seasonal increase in the abundance of key potential host species within the plague focus, but not outside of this area, suggests that changes in small mammal abundance may create favorable conditions for epizootic transmission of Y. pestis which ultimately may increase risk of human cases in this region.

Identification of risk factors for plague in the West Nile Region of Uganda.

Plague is an often fatal, primarily flea-borne rodent-associated zoonosis caused by Yersinia pestis. We sought to identify risk factors for plague by comparing villages with and without a history of human plague cases within a model-defined plague focus in the West Nile Region of Uganda. Although rat (Rattus rattus) abundance was similar inside huts within case and control villages, contact rates between rats and humans (as measured by reported rat bites) and host-seeking flea loads were higher in case villages. In addition, compared with persons in control villages, persons in case villages more often reported sleeping on reed or straw mats, storing food in huts where persons sleep, owning dogs and allowing them into huts where persons sleep, storing garbage inside or near huts, and cooking in huts where persons sleep. Compared with persons in case villages, persons in control villages more commonly reported replacing thatch roofing, and growing coffee, tomatoes, onions, and melons in agricultural plots adjacent to their homesteads. Rodent and flea control practices, knowledge of plague, distance to clinics, and most care-seeking practices were similar between persons in case villages and persons in control villages. Our findings reinforce existing plague prevention recommendations and point to potentially advantageous local interventions.

Stereotyped behaviours in children with autism spectrum disorders and atypical development as measured by the BPI-01.

OBJECTIVE: As repetitive behaviours in children with autism spectrum disorders (ASDs) can significantly interfere with one's daily functioning, continued research on these behaviours is needed. METHODS: This study examined the occurrence of repetitive motor movements in toddlers (17-37 months) with ASD and atypical development and the relationship between stereotypies and sensory impairment. RESULTS: Children with ASD (n = 13) exhibited significantly more repetitive behaviours than the non-ASD group (n = 12). Greater percentages of endorsement were evident for the ASD group on nearly all items of the Behaviour Problems Inventory-01 (BPI-01) Stereotypy subscale. More repetitive behaviours tended to co-occur with other stereotypies for the ASD group. A moderate correlation was found between stereotypy severity and sensory deficits. CONCLUSION: These findings suggest that stereotyped behaviours can be identified at very young ages, negatively affect the behavioural presentation of those with ASDs and should be considered when developing treatment plans.

Serological evidence for eastern equine encephalitis virus activity in white-tailed deer, Odocoileus virginianus, in Vermont, 2010.

Serum samples from 489 free-ranging white-tailed deer (Odocoileus virginianus) were screened for antibodies against the Eastern equine encephalitis virus (EEEV) using plaque reduction neutralization tests (PRNTs). EEEV antibodies were detected in 10.2% of serum samples. This is the first evidence that EEEV is present in Vermont. Serum was collected from deer in all 14 counties in the state, and positive EEEV sera were found in 12 (85%) of 14 counties, suggesting statewide EEEV activity in Vermont. Analysis of the spatial distribution of PRNT-positive samples revealed a random distribution of EEEV throughout the state. The results indicate widespread EEEV activity in Vermont and suggest that EEEV is not a recent introduction to the state but that EEEV activity has not been detected until now.

Evidence that rodent control strategies ought to be improved to enhance food security and reduce the risk of rodent-borne illnesses within subsistence farming villages in the plague-endemic West Nile region, Uganda.

Rodents pose serious threats to human health and economics, particularly in developing countries where the animals play a dual role as pests: they are reservoirs of human pathogens, and they inflict damage levels to stored products sufficient to cause food shortages. To assess the magnitude of the damage caused by rodents to crops, their level of contact with humans, and to better understand current food storage and rodent control practices, we conducted a survey of 37 households from 17 subsistence farming villages within the West Nile region of Uganda. Our survey revealed that rodents cause both pre- and post-harvest damage to crops. Evidence of rodent access to stored foods was reported in conjunction with each of the reported storage practices. Approximately half of the respondents reported that at least one family member had been bitten by a rat within the previous three months. Approximately two-thirds of respondents practiced some form of rodent control in their homes. The abundance of rodents was similar within homes that practiced or did not practice rodent control. Together, our results show that current efforts are inadequate for effectively reducing rodent abundance in homes.

Flea diversity as an element for persistence of plague bacteria in an East African plague focus.

Plague is a flea-borne rodent-associated zoonotic disease that is caused by Yersinia pestis and characterized by long quiescent periods punctuated by rapidly spreading epidemics and epizootics. How plague bacteria persist during inter-epizootic periods is poorly understood, yet is important for predicting when and where epizootics are likely to occur and for designing interventions aimed at local elimination of the pathogen. Existing hypotheses of how Y. pestis is maintained within plague foci typically center on host abundance or diversity, but little attention has been paid to the importance of flea diversity in enzootic maintenance. Our study compares host and flea abundance and diversity along an elevation gradient that spans from low elevation sites outside of a plague focus in the West Nile region of Uganda (~725-1160 m) to higher elevation sites within the focus (~1380-1630 m). Based on a year of sampling, we showed that host abundance and diversity, as well as total flea abundance on hosts was similar between sites inside compared with outside the plague focus. By contrast, flea diversity was significantly higher inside the focus than outside. Our study highlights the importance of considering flea diversity in models of Y. pestis persistence.

Evaluation of the infectiousness to mice of soil contaminated with Yersinia pestis-infected blood.

Plague, an often-fatal zoonotic disease caused by Yersinia pestis, is characterized by epizootic and quiescent periods. How Y. pestis is maintained during inter-epizootic periods is poorly understood, but soil has been implicated as a potential reservoir. Although previous studies have suggested that Y. pestis is able to survive in soil for weeks or months, it is unclear whether or not it is infectious to susceptible hosts. Here we investigate the potential for Y. pestis to infect mice through close contact with contaminated soil under laboratory conditions. In an attempt to approximate the natural conditions under which animals would be exposed to Y. pestis-contaminated soil, mouse cages filled with soil from a plague-endemic region were held at temperature and humidity ranges observed in ground squirrel burrows. These laboratory "burrows" were contaminated with highly bacteremic blood (>10(8) cfu/mL) to simulate the introduction of infectious material from a dying animal during an epizootic. Outbred Swiss-Webster mice with scarified skin patches were held on contaminated soil for 10 days and monitored for signs of illness. Following exposure to contaminated soil, one animal of 104 became infected with Y. pestis. None of the remaining animals seroconverted following a 21-day holding period. Under our experimental conditions, which maximized the likelihood of contact between susceptible mice and contaminated soil, transmission efficiency from soil to mice was 0.96% (95% CI 0.17, 5.25%). This suggests that although transmission of Y. pestis from contaminated soils is possible, it is not likely a major transmission route under natural conditions.

Climate predictors of the spatial distribution of human plague cases in the West Nile region of Uganda.

East Africa has been identified as a region where vector-borne and zoonotic diseases are most likely to emerge or re-emerge and where morbidity and mortality from these diseases is significant. Understanding when and where humans are most likely to be exposed to vector-borne and zoonotic disease agents in this region can aid in targeting limited prevention and control resources. Often, spatial and temporal distributions of vectors and vector-borne disease agents are predictable based on climatic variables. However, because of coarse meteorological observation networks, appropriately scaled and accurate climate data are often lacking for Africa. Here, we use a recently developed 10-year gridded meteorological dataset from the Advanced Weather Research and Forecasting Model to identify climatic variables predictive of the spatial distribution of human plague cases in the West Nile region of Uganda. Our logistic regression model revealed that within high elevation sites (above 1,300 m), plague risk was positively associated with rainfall during the months of February, October, and November and negatively associated with rainfall during the month of June. These findings suggest that areas that receive increased but not continuous rainfall provide ecologically conducive conditions for Yersinia pestis transmission in this region. This study serves as a foundation for similar modeling efforts of other vector-borne and zoonotic disease in regions with sparse observational meteorologic networks.

Modifiable risk factors for West Nile virus infection during an outbreak--Arizona, 2010.

West Nile virus (WNV) is the leading cause of mosquito-borne disease in the United States; however, risk factors for infection are poorly defined. We performed a case-control study to identify modifiable risk factors for WNV infection. Case-patients (N = 49) had laboratory evidence of recent WNV infection, whereas control-subjects (N = 74) had negative WNV serology. We interviewed participants, surveyed households, and assessed environmental data. WNV infection was associated with living in or near Water District X within Gilbert Township (adjusted odds ratio [aOR] 5.2; 95% confidence interval [95% CI] = 1.5-18.1), having water-holding containers in their yard (aOR 5.0; 95% CI = 1.5-17.3), and not working or attending school outside the home (aOR 2.4; 95% CI = 1.1-5.5). During this outbreak, WNV infection was likely primarily acquired peri-domestically with increased risk associated with potential mosquito larval habitats around the home and neighborhood.

Using wild white-tailed deer to detect eastern equine encephalitis virus activity in Maine.

Serum from 226 free-ranging white-tailed deer (Odocoileus virginianus) was screened for Eastern Equine Encephalitis Virus (EEEV) antibodies using plaque reduction neutralization tests. EEEV antibodies were detected in 7.1% of samples. This is the first time EEEV antibodies have been detected in O. virginianus populations in the state of Maine (ME). The highest percentage of EEEV positive sera was in Somerset County (19%) in central ME, and this is the first time that EEEV activity has been detected in that County. EEEV RNA was not detected in any of the 150 harvested deer brain samples submitted to the ME Department of Inland Fisheries and Wildlife as a part of screening for Chronic Wasting Disease. This suggests that screening deer brains is not an efficient method to detect EEEV activity. For each serum sample tested, the geographic location in which the deer was harvested was recorded. Significant spatial clustering of antibody-positive sera samples was not detected. Relative to seronegative deer, seropositive deer were slightly more likely to be harvested in nonforested areas compared with forested areas. Results indicate that screening of free-ranging deer sera can be a useful tool for detecting EEEV activity in ME and other parts of North America.

Landscape and residential variables associated with plague-endemic villages in the West Nile region of Uganda.

Plague, caused by the bacteria Yersinia pestis, is a severe, often fatal disease. This study focuses on the plague-endemic West Nile region of Uganda, where limited information is available regarding environmental and behavioral risk factors associated with plague infection. We conducted observational surveys of 10 randomly selected huts within historically classified case and control villages (four each) two times during the dry season of 2006 (N = 78 case huts and N = 80 control huts), which immediately preceded a large plague outbreak. By coupling a previously published landscape-level statistical model of plague risk with this observational survey, we were able to identify potential residence-based risk factors for plague associated with huts within historic case or control villages (e.g., distance to neighboring homestead and presence of pigs near the home) and huts within areas previously predicted as elevated risk or low risk (e.g., corn and other annual crops grown near the home, water storage in the home, and processed commercial foods stored in the home). The identified variables are consistent with current ecologic theories on plague transmission dynamics. This preliminary study serves as a foundation for future case control studies in the area.

An acarologic survey and Amblyomma americanum distribution map with implications for tularemia risk in Missouri.

In the United States, tickborne diseases occur focally. Missouri represents a major focus of several tickborne diseases that includes spotted fever rickettsiosis, tularemia, and ehrlichiosis. Our study sought to determine the potential risk of human exposure to human-biting vector ticks in this area. We collected ticks in 79 sites in southern Missouri during June 7-10, 2009, which yielded 1,047 adult and 3,585 nymphal Amblyomma americanum, 5 adult Amblyomma maculatum, 19 adult Dermacentor variabilis, and 5 nymphal Ixodes brunneus. Logistic regression analysis showed that areas posing an elevated risk of exposure to A. americanum nymphs or adults were more likely to be classified as forested than grassland, and the probability of being classified as elevated risk increased with increasing relative humidity during the month of June (30-year average). Overall accuracy of each of the two models was greater than 70% and showed that 20% and 30% of the state were classified as elevated risk for human exposure to nymphs and adults, respectively. We also found a significant positive association between heightened acarologic risk and counties reporting tularemia cases. Our study provides an updated distribution map for A. americanum in Missouri and suggests a wide-spread risk of human exposure to A. americanum and their associated pathogens in this region.