Malaria hotspot areas in a highland Kenya site are consistent in epidemic and non-epidemic years and are associated with ecological factors

BACKGROUND: Malaria epidemics in highland areas of East Africa have caused considerable morbidity and mortality in the past two decades. Knowledge of "hotspot" areas of high malaria incidence would allow for focused preventive interventions in resource-poor areas, particularly if the hotspot areas can be discerned during non-epidemic periods and predicted by ecological factors. METHODS: To address this issue, spatial distribution of malaria incidence and the relationship of ecological factors to malaria incidence were assessed in the highland area of Kipsamoite, Kenya, from 2001–2004. RESULTS: Clustering of disease in a single geographic "hotspot" area occurred in epidemic and non-epidemic years, with a 2.6 to 3.2-fold increased risk of malaria inside the hotspot, as compared to outside the area (P < 0.001, all 4 years). Altitude and proximity to the forest were independently associated with increased malaria risk in all years, including epidemic and non-epidemic years. CONCLUSION: In this highland area, areas of high malaria risk are consistent in epidemic and non-epidemic years and are associated with specific ecological risk factors. Ongoing interventions in areas of ecological risk factors could be a cost-effective method of significantly reducing malaria incidence and blunting or preventing epidemics, even in the absence of malaria early warning systems. Further studies should be conducted to see if these findings hold true in varied highland settings

Assessing climate and health curriculum in graduate public health education in the United States

Climate change has been identified as both a challenge and an opportunity for public health. The onus to prepare the next generation of public health practitioners lies heavily on schools and programs of public health. This article (i) assesses the status of climate change and health curricula in accredited schools of public health in the United States and (ii) proposes strategies to better train professionals so they are more informed and prepared to mitigate, manage, and respond to the health impacts of climate change. Course offerings and syllabi listed in online course catalogs from 90 nationally accredited schools of public health were evaluated with the purpose of identifying the extent of climate change education in graduate programs. Only 44 public health institutions were found to offer a climate change related course at the graduate level of education. Of the 103 courses identified, approximately 50% (n = 46) are focused on this climate change and health. These courses cover a wide array of topics with an emphasis on conveying fundamental concepts. In-depth assessment revealed a need for integrating learning opportunities that build practical skills useful in a hands-on public health practice environment. This assessment indicates the limited availability of climate-health course offerings available to graduate students in accredited schools. The findings are used to propose an educational framework to integrate climate change into public health curricula. The proposed framework, while rooted in existing directives, adopts a tiered approach that can be readily applied by institutions training the next generation of public health leaders

Environmental, socio-demographic and behavioural determinants of malaria risk in the western Kenyan highlands: a case–control study

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73660/1/j.1365-3156.2009.02370.x.pd

A country bug in the city: urban infestation by the Chagas disease vector Triatoma infestans in Arequipa, Peru

BACKGROUND:Interruption of vector-borne transmission of Trypanosoma cruzi remains an unrealized objective in many Latin American countries. The task of vector control is complicated by the emergence of vector insects in urban areas.METHODS:Utilizing data from a large-scale vector control program in Arequipa, Peru, we explored the spatial patterns of infestation by Triatoma infestans in an urban and peri-urban landscape. Multilevel logistic regression was utilized to assess the associations between household infestation and household- and locality-level socio-environmental measures.RESULTS:Of 37,229 households inspected for infestation, 6,982 (18.8%95% CI: 18.4 - 19.2%) were infested by T. infestans. Eighty clusters of infestation were identified, ranging in area from 0.1 to 68.7 hectares and containing as few as one and as many as 1,139 infested households. Spatial dependence between infested households was significant at distances up to 2,000 meters. Household T. infestans infestation was associated with household- and locality-level factors, including housing density, elevation, land surface temperature, and locality type.CONCLUSIONS:High levels of T. infestans infestation, characterized by spatial heterogeneity, were found across extensive urban and peri-urban areas prior to vector control. Several environmental and social factors, which may directly or indirectly influence the biology and behavior of T. infestans, were associated with infestation. Spatial clustering of infestation in the urban context may both challenge and inform surveillance and control of vector reemergence after insecticide intervention.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]

Topography-derived wetness indices are associated with household-level malaria risk in two communities in the western Kenyan highlands

<p>Abstract</p> <p>Background</p> <p>Transmission of <it>Plasmodium falciparum </it>generally decreases with increasing elevation, in part because lower temperature slows the development of both parasites and mosquitoes. However, other aspects of the terrain, such as the shape of the land, may affect habitat suitability for <it>Anopheles </it>breeding and thus risk of malaria transmission. Understanding these local topographic effects may permit prediction of regions at high risk of malaria within the highlands at small spatial scales.</p> <p>Methods</p> <p>Hydrologic modelling techniques were adapted to predict the flow of water across the landscape surrounding households in two communities in the western Kenyan highlands. These surface analyses were used to generate indices describing predicted water accumulation in regions surrounding the study area. Households with and without malaria were compared for their proximity to regions of high and low predicted wetness. Predicted wetness and elevation variables were entered into bivariate and multivariate regression models to examine whether significant associations with malaria were observable at small spatial scales.</p> <p>Results</p> <p>On average, malaria case households (n = 423) were located 280 m closer to regions with very high wetness indices than non-malaria "control" households (n = 895) (t = 10.35, p < 0.0001). Distance to high wetness indices remained an independent predictor of risk after controlling for household elevation in multivariate regression (OR = 0.93 [95% confidence interval = 0.89–0.96] for a 100 m increase in distance). For every 10 m increase in household elevation, there was a 12% decrease in the odds of the house having a malaria case (OR = 0.88 [0.85–0.90]). However, after controlling for distance to regions of high predicted wetness and the community in which the house was located, this reduction in malaria risk was not statistically significant (OR = 0.98 [0.94–1.03]).</p> <p>Conclusion</p> <p>Proximity to terrain with high predicted water accumulation was significantly and consistently associated with increased household-level malaria incidence, even at small spatial scales with little variation in elevation variables. These results suggest that high wetness indices are not merely proxies for valley bottoms, and hydrologic flow models may prove valuable for predicting areas of high malaria risk in highland regions. Application in areas where malaria surveillance is limited could identify households at higher risk and help focus interventions.</p

Global city densities: Re-examining urban scaling theory

Understanding scaling relations of social and environmental attributes of urban systems is necessary for effectively managing cities. Urban scaling theory (UST) has assumed that population density scales positively with city size. We present a new global analysis using a publicly available database of 933 cities from 38 countries. Our results showed that (18/38) 47% of countries analyzed supported increasing density scaling (pop ~ area) with exponents ~⅚ as UST predicts. In contrast, 17 of 38 countries (~45%) exhibited density scalings statistically indistinguishable from constant population densities across cities of varying sizes. These results were generally consistent in years spanning four decades from 1975 to 2015. Importantly, density varies by an order of magnitude between regions and countries and decreases in more developed economies. Our results (i) point to how economic and regional differences may affect the scaling of density with city size and (ii) show how understanding country- and region-specific strategies could inform effective management of urban systems for biodiversity, public health, conservation and resiliency from local to global scales.200 word statement of contribution: Urban Scaling Theory (UST) is a general scaling framework that makes quantitative predictions for how many urban attributes spanning physical, biological and social dimensions scale with city size; thus, UST has great implications in guiding future city developments. A major assumption of UST is that larger cities become denser. We evaluated this assumption using a publicly available global dataset of 933 cities in 38 countries. Our scaling analysis of population size and area of cities revealed that while many countries analyzed showed increasing densities with city size, about 45% of countries showed constant densities across cities. These results question a key assumption of UST. Our results suggest policies and management strategies for biodiversity conservation, public health and sustainability of urban systems may need to be tailored to national and regional scaling relations to be effective

Local topographic wetness indices predict household malaria risk better than land-use and land-cover in the western Kenya highlands

Abstract Background Identification of high-risk malaria foci can help enhance surveillance or control activities in regions where they are most needed. Associations between malaria risk and land-use/land-cover are well-recognized, but these environmental characteristics are closely interrelated with the land's topography (e.g., hills, valleys, elevation), which also influences malaria risk strongly. Parsing the individual contributions of land-cover/land-use variables to malaria risk requires examining these associations in the context of their topographic landscape. This study examined whether environmental factors like land-cover, land-use, and urban density improved malaria risk prediction based solely on the topographically-determined context, as measured by the topographic wetness index. Methods The topographic wetness index, an estimate of predicted water accumulation in a defined area, was generated from a digital terrain model of the landscape surrounding households in two neighbouring western Kenyan highland communities. Variables determined to best encompass the variance in this topographic wetness surface were calculated at a household level. Land-cover/land-use information was extracted from a high-resolution satellite image using an object-based classification method. Topographic and land-cover variables were used individually and in combination to predict household-level malaria in the communities through an iterative split-sample model fitting and testing procedure. Models with only topographic variables were compared to those with additional predictive factors related to land-cover/land-use to investigate whether these environmental factors improved prediction of malaria based on the shape of the land alone. Results Variables related to topographic wetness proved most useful in predicting the households of individuals contracting malaria in this region of rugged terrain. Other variables related to human modification of the environment also demonstrated clear associations with household malaria. However, these land-cover/land-use variables failed to produce unambiguous improvements in statistical predictive models controlling for important topographic factors, with none improving prediction of household-level malaria more than 75% of the time. Conclusions Topographic wetness values in this region of highly varied terrain more accurately predicted houses at greater risk of malaria than did consideration of land-cover/land-use characteristics. As such, those planning control or local elimination strategies in similar highland regions may use topographic and geographic characteristics to effectively identify high-receptivity regions that may require enhanced vigilance.http://deepblue.lib.umich.edu/bitstream/2027.42/112551/1/12936_2010_Article_1410.pd

Health status of southern Arizona border counties: a Healthy Border 2010 midterm review Situación de salud de los condados de la frontera sur de Arizona: examen a mitad de período del programa "Frontera saludable 2010"

OBJECTIVE: The region on the United States (US) side of the US-Mexico border consists of 44 counties in four states; populations on both sides of the border have similar health problems. Healthy Border 2010: An Agenda for Improving Health on the US-Mexico Border (HB 2010) is a binational agenda of health promotion and disease prevention for individuals in the region. This study reports on the health status of the four southern Arizona border counties. METHODS: Data on health indicators for Cochise, Pima, Santa Cruz, and Yuma Counties were collected from the Arizona Department of Health Services Vital Records and Statistics. Progress was calculated as a percentage made toward or away from the 2010 target. Comparisons were made between the border counties and Arizona. RESULTS: Progress toward the HB 2010 targets varied among the border counties. All border counties made progress toward the targets with the cervical cancer, hepatitis A, and teenage birthrate objectives. Most border counties moved toward the goals for breast cancer, diabetes mortality, tuberculosis, motor vehicle crashes, infant mortality from congenital abnormalities, and prenatal care. Border counties moved away from the target with the human immunodeficiency virus and infant mortality objectives. CONCLUSIONS: Assessment of the HB 2010 objectives provided a comprehensive description of the health status of the population. Although the southern Arizona border counties have shown improvement in some areas, monitoring is still needed to identify the disparities that remain.<br>OBJETIVO: La región estadounidense de la frontera entre México y los Estados Unidos consta de 48 condados distribuidos en cuatro estados, y las poblaciones que viven a uno y otro lado de la frontera tienen problemas de salud similares. El programa binacional "Frontera saludable 2010" está destinado a las poblaciones de la región y se propone mejorar la situación sanitaria en la frontera entre México y los Estados Unidos mediante actividades de promoción de la salud y prevención de enfermedades. Este estudio es un informe sobre la situación sanitaria de los cuatro condados de la frontera sur de Arizona. MÉTODOS. Los datos acerca de los indicadores de salud de los condados de Cochise, Pima, Santa Cruz y Yuma se obtuvieron del registro civil y estadísticas del Departamento de Servicios de Salud de Arizona. Se calculó el progreso mediante un porcentaje que refleja la cercanía o la lejanía del objetivo propuesto para el año 2010. Se compararon los datos correspondientes a los condados fronterizos con los del estado de Arizona. RESULTADOS: El progreso hacia los objetivos del programa "Frontera saludable 2010" no fue uniforme en los distintos condados fronterizos. Los cuatro condados lograron avances hacia los objetivos propuestos en materia de cáncer cervicouterino, hepatitis A y tasa de natalidad entre las adolescentes. La mayoría de los condados fronterizos están más próximos a cumplir con los objetivos en materia de cáncer de mama, mortalidad por diabetes, tuberculosis, colisiones de vehículos automotores, mortalidad infantil por anomalías congénitas y atención prenatal. Sin embargo, ninguno de los cuatro condados se está acercando al objetivo propuesto en cuanto al virus de la inmunodeficiencia humana y la mortalidad infantil. CONCLUSIONES: La evaluación de los objetivos del programa "Frontera saludable 2010" brindó una descripción integral de la situación de salud de la población. Aunque los condados de la frontera sur de Arizona han logrado avances en algunos aspectos, sigue siendo necesario mantener la vigilancia con el fin de detectar las disparidades aún presentes