The urban structure and pedestrian injuries: A typological analysis of pedestrian crashes in the city of Hermosillo, Mexico.

OBJECTIVE: In this study, we aim to identify social typologies of pedestrian crashes considering demographics, health impacts, involved vehicle, temporality of the collision, and place of impact in Hermosillo, Mexico. METHODS: A socio-spatial analysis was performed by using local urban planning information and vehicles-pedestrian crashes records collected by the police department (N = 950) between 2014 and 2017. Multiple Correspondence Analysis and Hierarchical Cluster Analysis were used to determine typologies. Geographical distribution of typologies was obtained with spatial analysis techniques. RESULTS: The results suggest there are four typologies, which portray the physical vulnerability of pedestrians, which reflect the vulnerability to collisions associated to the variables age, gender, and street speed limits. Findings show that children are more likely to be injured during weekends in residential zones (Typology 1), while older females are more likely to be injured during the first three days of the week (Monday - Wednesday) in the downtown area (Typology 2). Injured males during the afternoon in arterial streets represented the most frequent cluster (Typology 3). Also, males were likely to be severely injured by heavy trucks during nighttime in peri-urban areas (Typology 4). These findings indicate that vulnerability and risk exposure vary according to the type of pedestrian involved in the crash, which are linked to the types of places they visit. CONCLUSIONS: The design of the built environment plays a major role in the number of pedestrian injuries particularly when it favors motor vehicles over pedestrians or non-motorized vehicles. Because traffic crashes are considered preventable events, cities must embrace a diversity of mobility modes and incorporate the appropriate infrastructures that safeguard the lives of all their travelers, especially pedestrians.

Differences in Longevity and Temperature-Driven Extrinsic Incubation Period Correlate with Varying Dengue Risk in the Arizona-Sonora Desert Region.

Dengue transmission is determined by a complex set of interactions between the environment, Aedes aegypti mosquitoes, dengue viruses, and humans. Emergence in new geographic areas can be unpredictable, with some regions having established mosquito populations for decades without locally acquired transmission. Key factors such as mosquito longevity, temperature-driven extrinsic incubation period (EIP), and vector-human contact can strongly influence the potential for disease transmission. To assess how these factors interact at the edge of the geographical range of dengue virus transmission, we conducted mosquito sampling in multiple urban areas located throughout the Arizona-Sonora desert region during the summer rainy seasons from 2013 to 2015. Mosquito population age structure, reflecting mosquito survivorship, was measured using a combination of parity analysis and relative gene expression of an age-related gene, SCP-1. Bloodmeal analysis was conducted on field collected blood-fed mosquitoes. Site-specific temperature was used to estimate the EIP, and this predicted EIP combined with mosquito age were combined to estimate the abundance of "potential" vectors (i.e., mosquitoes old enough to survive the EIP). Comparisons were made across cities by month and year. The dengue endemic cities Hermosillo and Ciudad Obregon, both in the state of Sonora, Mexico, had higher abundance of potential vectors than non-endemic Nogales, Sonora, Mexico. Interestingly, Tucson, Arizona consistently had a higher estimated abundance of potential vectors than dengue endemic regions of Sonora, Mexico. There were no observed city-level differences in species composition of blood meals. Combined, these data offer insights into the critical factors required for dengue transmission at the ecological edge of the mosquito's range. However, further research is needed to integrate an understanding of how social and additional environmental factors constrain and enhance dengue transmission in emerging regions.

Oxidative potential of metal-polluted urban dust as a potential environmental stressor for chronic diseases.

Oxidative stress (OS) associated with metals in urban dust has become a public health concern. Chronic diseases linked to general inflammation are particularly affected by OS. This research analyzes the spatial distribution of metals associated with OS, the urban dust´s oxidative potential (OP), and the occurrence of diseases whose treatments are affected by OS. We collected 70 urban dust samples during pre- and post-monsoon seasons to achieve this. We analyzed particle size distribution and morphology by scanning electron microscopy, as well as metal(loid)s by portable X-ray fluorescence, and OP of dust in artificial lysosomal fluid by using an ascorbic acid depletion assay. Our results show that the mean concentration of Fe, Pb, As, Cr, Cu, and V in pre-monsoon was 83,984.6, 98.4, 23.5, 165.8, 301.3, and 141.9 mg kg-1, while during post-monsoon was 50,638.8, 73.9, 16.7, 124.3, 178.9, and 133.5 mg kg-1, respectively. Impoverished areas with the highest presence of cardiovascular, cancer, diabetes, and respiratory diseases coincide with contaminated areas where young adults live. We identified significant differences in the OP between seasons. OP increases during the pre-monsoon (from 7.8 to 237.5 nmol AA min-1) compared to the post-monsoon season (from 1.6 to 163.2 nmol AA min-1). OP values are much higher than measured standards corresponding to contaminated soil and urban particulate matter, which means that additional sources beside metals cause the elevated OP. The results show no risk from chronic exposure to metals; however, our results highlight the importance of studying dust as an environmental factor that may potentially increase oxidative stress.

Knowledge, Attitudes, and Practices Related to Rocky Mountain Spotted Fever in Hermosillo, México.

Rocky Mountain spotted fever (RMSF) is a serious disease in northwest Mexico, particularly in low-income communities. This study aimed to evaluate RMSF-related knowledge, attitudes, and practices in an endemic urban area with a high burden of the disease. A cross-sectional study design using a non-probabilistic household survey was conducted with 400 residents in Hermosillo, Mexico. Primary themes assessed included dog and tick-related exposure, RMSF knowledge, healthcare-seeking behavior, sociodemographic data, and household information. The majority (59%) of those surveyed had heard about RMSF, although only 36% of RMSF-aware respondents knew any RMSF symptoms. Among RMSF-aware respondents, 26% did not know or were unsure of prevention strategies. Individuals in the low socioeconomic status (SES) stratum were less likely to have heard about RMSF (odds ratio [OR]: 0.39; 95% CI: 0.25-0.59), use dog collars or any other product to avoid ticks (OR: 0.40; 95% CI: 0.17-0.99), or check their dogs for ticks (OR: 0.25; 95% CI: 0.09-0.74). The likelihood of observing high numbers of free-roaming dogs in their neighborhood was four times higher in the low SES stratum (OR: 4.19; 95% CI: 2.10-8.38) than in the high SES stratum. These findings emphasize the need for an integrative community approach to improve early recognition of symptoms and knowledge of prevention strategies, particularly in low SES neighborhoods.

Lockdown, relaxation, and acme period in COVID-19: A study of disease dynamics in Hermosillo, Sonora, Mexico.

Lockdown and social distancing measures have been implemented for many countries to mitigate the impacts of the COVID-19 pandemic and prevent overwhelming of health services. However, success on this strategy depends not only on the timing of its implementation, but also on the relaxation measures adopted within each community. We developed a mathematical model to evaluate the impacts of the lockdown implemented in Hermosillo, Mexico. We compared this intervention with some hypothetical ones, varying the starting date and also the population proportion that is released, breaking the confinement. A Monte Carlo study was performed by considering three scenarios to define our baseline dynamics. Results showed that a hypothetical delay of two weeks, on the lockdown measures, would result in an early acme around May 9 for hospitalization prevalence and an increase on cumulative deaths, 42 times higher by May 31, when compared to baseline. On the other hand, results concerning relaxation dynamics showed that the acme levels depend on the proportion of people who gets back to daily activities as well as the individual behavior with respect to prevention measures. Analysis regarding different relaxing mitigation measures were provided to the Sonoran Health Ministry, as requested. It is important to stress that, according to information provided by health authorities, the acme occurring time was closed to the one given by our model. Hence, we considered that our model resulted useful for the decision-making assessment, and that an extension of it can be used for the study of a potential second wave.

Socioeconomic and Human Behavioral Factors Associated With Aedes aegypti (Diptera: Culicidae) Immature Habitat in Tucson, AZ.

Aedes aegypti (L.; Diptera: Culicidae) has been established in the southwestern United States for several decades, but relationships between humans and mosquitoes in this arid region are not well-characterized. In August 2012, the outdoor premises of 355 houses within 20 neighborhoods in Tucson, Arizona were surveyed for containers that could provide larval habitat for Ae. aegypti mosquitoes. At the same time, a knowledge, attitudes and practices (KAP) questionnaire was administered to a resident of each house surveyed for immature mosquitoes. The KAP questionnaire assessed respondents' knowledge and concerns about vector-borne illnesses as well as practices they used to avoid mosquitoes. Of the houses surveyed, 91% had at least one container present, and 64% had at least one container with standing water. On average, each house had 2.2 containers with water at the time of the survey. The overall House Index (proportion of premises surveyed with at least one container with Ae. aegypti immatures present) was 13%. Based on questionnaire responses, there was a significant positive association between the number of residents in the home and the odds of finding Ae. aegypti positive containers on the premises, while household income showed a significant negative association. The reported frequency of checking for standing water was also significantly associated with the odds of finding immatures, although the nature of this association was ambiguous. Flower pots were the principal type of container with Ae. aegypti larvae. These findings show that larval habitat is widely available even in an arid environment and city with good housing and sanitation infrastructure.

Outdoor spatial spraying against dengue: A false sense of security among inhabitants of Hermosillo, Mexico.

BACKGROUND: Government-administered adulticiding is frequently conducted in response to dengue transmission worldwide. Anecdotal evidence suggests that spraying may create a "false sense of security" for residents. Our objective was to determine if there was an association between residents' reporting outdoor spatial insecticide spraying as way to prevent dengue transmission and both their reported frequency of dengue prevention practices and household entomological indices in Hermosillo, Mexico. METHODOLOGY/PRINCIPAL FINDINGS: A non-probabilistic survey of 400 households was conducted in August 2014. An oral questionnaire was administered to an adult resident and the outer premises of the home were inspected for water-holding containers and presence of Ae. aegypti larvae and pupae. Self-reported frequency of prevention practices were assessed among residents who reported outdoor spatial spraying as a strategy to prevent dengue (n = 93) and those who did not (n = 307). Mixed effects negative binomial regression was used to assess associations between resident's reporting spraying as a means to prevent dengue and container indices. Mixed effects logistic regression was used to determine associations with presence/absence of larvae and pupae. Those reporting spatial spraying disposed of trash less frequently and spent less time indoors to avoid mosquitoes. They also used insecticides and larvicides more often and covered their water containers more frequently. Their backyards had more containers positive for Ae. aegypti (RR = 1.92) and there was a higher probability of finding one or more Ae. aegypti pupae (OR = 2.20). Survey respondents that reported spatial spraying prevented dengue were more likely to be older and were exposed to fewer media sources regarding prevention. CONCLUSIONS/SIGNIFICANCE: The results suggest that the perception that outdoor spatial spraying prevents dengue is associated with lower adoption of prevention practices and higher entomological risk. This provides some support to the hypothesis that spraying may lead to a "false sense of security". Further investigations to clarify this relationship should be conducted. Government campaigns should emphasize the difficulty in controlling Ae. aegypti mosquitoes and the need for both government and community action to minimize risk of dengue transmission.

Aedes aegypti (Diptera: Culicidae) Longevity and Differential Emergence of Dengue Fever in Two Cities in Sonora, Mexico.

Dengue virus, primarily transmitted by the Aedes aegypti (L.) mosquito, has rapidly expanded in geographic extent over the past several decades. In some areas, however, dengue fever has not emerged despite established Ae. aegypti populations. The reasons for this are unclear and have sometimes been attributed to socio-economic differences. In 2013 we compared Ae. aegypti adult density and population age structure between two cities in Sonora, Mexico: Hermosillo, which has regular seasonal dengue virus transmission, and Nogales, which has minimal transmission. Larval and pupal abundance was greater in Nogales, and adult density was only higher in Hermosillo during September. Population age structure, however, was consistently older in Hermosillo. This difference in longevity may have been one factor that limited dengue virus transmission in Nogales in 2013, as a smaller proportion of Ae. aegypti females survived past the extrinsic incubation period.

Spatio-temporal and neighborhood characteristics of two dengue outbreaks in two arid cities of Mexico.

Little is currently known about the spatial-temporal dynamics of dengue epidemics in arid areas. This study assesses dengue outbreaks that occurred in two arid cities of Mexico, Hermosillo and Navojoa, located in northern state of Sonora. Laboratory confirmed dengue cases from Hermosillo (N=2730) and Navojoa (N=493) were geocoded by residence and assigned neighborhood-level characteristics from the 2010 Mexican census. Kernel density and Space-time cluster analysis was performed to detect high density areas and space-time clusters of dengue. Ordinary Least Square regression was used to assess the changing socioeconomic characteristics of cases over the course of the outbreaks. Both cities exhibited contiguous patterns of space-time clustering. Initial areas of dissemination were characterized in both cities by high population density, high percentage of occupied houses, and lack of healthcare. Future research and control efforts in these regions should consider these space-time and socioeconomic patterns.

Knowledge and Beliefs about Dengue Transmission and Their Relationship with Prevention Practices in Hermosillo, Sonora.

BACKGROUND: Dengue is an emerging threat in the U.S.-Mexico border region. Transmission has regularly occurred in Sonora, MX since 1982 but it was not until 2014 that cities directly on the Arizona-Sonora border had local transmission. One of the closest urban areas to have regular seasonal transmission is Hermosillo, SN, MX. Developing a better understanding of the knowledge and perceptions of dengue in close geographic proximity to the border can identify areas to target for prevention and control measures. METHODS: We conducted focus groups in six neighborhoods in Hermosillo, SN, MX; three with high-dengue transmission and three with lower transmission. Awareness of dengue and experience with dengue was common. RESULTS: In all focus groups, discussants reported knowing someone personally who had past dengue infection. We further identified several key ways that the perceptions of dengue transmission could influence the effectiveness of dengue control campaigns. First, there was confusion about how dengue is transmitted. While people associated dengue with mosquitoes, multiple modes of transmission were perceived including direct person-to-person transmission. In one focus group, discussants indicated a stigma surrounding dengue infection. The necessity to maintain cleanliness in their households was identified as a primary strategy to fight dengue; however, participants also noted the limited impact and their actions may have on transmission if there is lack of community support or governmental infrastructure to control neighboring and public spaces. CONCLUSION: As dengue risk increases in the border region, more efforts should be made to clearly convey the single mode of transmission of dengue to avoid the development of stigma. More coordinated efforts should be made to not only control but also prevent dengue.