Diarrheal diseases in children from a water reclamation site in Mexico city.
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This study was conducted to assess the risk of enteric diseases among children living in a water reclamation area in Mexico City. A geographic information system was used to define eligible wells and surrounding homesteads. Sixty-five water samples from five wells were tested for fecal coliform bacteria per 100 mL (FC/100 mL) during visits to 750 eligible households; caretakers only in those dwellings with children under 5 years old were interviewed throughout repeated cross-sectional surveys, conducted during 1999-2000. Data on diarrheal diseases were obtained from 761 children during the rainy season and 732 children during the dry season; their guardians also provided information on drinking water supply, sanitation, and socioeconomic variables. The presence of indicator organisms in groundwater samples pointed to fecal pollution; bacterial indicators, however, did not predict the health risk. The rates of diarrhea were 10.7% in the dry season and 11.8% in the rainy season. Children 1 year old showed the highest rate of diarrhea during the dry season [odds ratio (OR) = 2.1 with 95% confidence interval (CI), 0.99-4.71], particularly those from households perceiving unpleasant taste of tap water (OR, 1.7; 95% CI, 0.97-2.92) and consuming vegetables washed only with water (OR, 2.2; 95% CI, 1.10-4.39). Lower risk was observed in individuals enjoying full-day water supply (OR, 0.5; 95% CI, 0.27-0.86) and a flushing toilet (OR, 0.3; 95% CI, 0.16-0.67), as well as those storing water in covered receptacles (OR, 0.3; 95% CI, 0.15-0.80). Rainy season data suggested that children from households perceiving a color to their water had a higher rate of diarrhea than did those without such complaint (OR, 1.8; 95% CI, 0.93-3.67); recent consumption of food sold by street vendors was also a significant risk factor (OR, 1.6; 95% CI, 0.98-2.87). Groundwater is at risk of contamination, as indicated by the presence of FC/100 mL. The endemic pattern of diarrhea, however, reflects mostly inadequate housing, sanitation, and water-related practices. Health protection policy must be discussed. (+info)
Interactions of climate change with biological invasions and land use in the Hawaiian Islands: Modeling the fate of endemic birds using a geographic information system.
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The Hawaiian honeycreepers (Drepanidae) represent a superb illustration of evolutionary radiation, with a single colonization event giving rise to 19 extant and at least 10 extinct species [Curnutt, J. & Pimm, S. (2001) Stud. Avian Biol. 22, 15-30]. They also represent a dramatic example of anthropogenic extinction. Crop and pasture land has replaced their forest habitat, and human introductions of predators and diseases, particularly of mosquitoes and avian malaria, has eliminated them from the remaining low- and mid-elevation forests. Landscape analyses of three high-elevation forest refuges show that anthropogenic climate change is likely to combine with past land-use changes and biological invasions to drive several of the remaining species to extinction, especially on the islands of Kauai and Hawaii. (+info)
A pilot study of global positioning system/geographical information system measurement of residential proximity to agricultural fields and urinary organophosphate metabolite concentrations in toddlers.
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This pilot study enrolled 20 children between the ages of 11 and 17 months in Imperial County, California to assess children's pesticide exposure and residential proximity to agricultural fields. We compared parental self-report of residential proximity to agricultural fields to measurements using global positioning system/geographical information system (GPS/GIS) technology, and we assessed the relationship between residential proximity to agricultural fields and a biomarker of organophosphate (OP) pesticide exposure. Questionnaires were administered twice, 4 weeks apart, to determine self-reported residential proximity to agricultural fields. Urine samples were collected at each contact to measure OP metabolites. Actual residential proximity to the closest agricultural field and number of fields was within 1 mile to the west were measured using GPS/GIS. Self-report of living proximity to agricultural fields agreed with GPS/GIS measurement 75% of the time during the initial interview, compared to 66% agreement during the second interview. Presence of urinary metabolites suggests that OP exposure was ubiquitous: creatinine-adjusted total urinary dimethyl values ranged from 1.60 to 516.00 microg/g creatinine, and total diethyl ranged from 2.70 to 134.84 microg/g creatinine. No association was found between urinary OP metabolites and residential to field proximity. These results suggest that initial self-report of living proximity to agricultural fields may be more accurate than follow-up self-report. Limitations in this pilot study prevent determination of whether self-report is an accurate measure of proximity. (+info)
Exposures to the Kuwait oil fires and their association with asthma and bronchitis among gulf war veterans.
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Military personnel deployed to the Persian Gulf War have reported a variety of symptoms attributed to their exposures. We examined relationships between symptoms of respiratory illness present 5 years after the war and both self-reported and modeled exposures to oil-fire smoke that occurred during deployment. Exposure and symptom information was obtained by structured telephone interview in a population-based sample of 1,560 veterans who served in the Gulf War. Modeled exposures were exhaustively developed using a geographic information system to integrate spatial and temporal records of smoke concentrations with troop movements ascertained from global positioning systems records. For the oil-fire period, there were 600,000 modeled data points with solar absorbance used to represent smoke concentrations to a 15-km resolution. Outcomes included respiratory symptoms (asthma, bronchitis) and control outcomes (major depression, injury). Approximately 94% of the study cohort were still in the gulf theater during the time of the oil-well fires, and 21% remained there more than 100 days during the fires. There was modest correlation between self-reported and modeled exposures (r = 0.48, p < 0.05). Odds ratios for asthma, bronchitis, and major depression increased with increasing self-reported exposure. In contrast, there was no association between the modeled exposure and any of the outcomes. These findings do not support speculation that exposures to oil-fire smoke caused respiratory symptoms among veterans. (+info)
A spatial analysis of obesogenic environments for children.
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In this study, we use spatial analysis techniques to explore environmental and social predictors of obesity in children. We constructed a merged database, incorporating clinical data from an electronic medical record system, the Regenstrief Medical Record System (RMRS) and societal & environmental data from a geographical information system, the Social Assets and Vulnerabilities Indicators (SAVI) Project. We used the RMRS to identify cohorts of children that were normal weight, overweight, or obese. The RMRS records were geocoded and merged into the SAVI database. Using the merged databases, we analyzed the relationships between markers of socioeconomic status and obesity outcomes in children. Our preliminary analyses show that markers of low socioeconomic status at the census tract level correlate with both overweight and obese outcomes in our study population. Utilization of geographic information systems (GIS) for the study of health epidemiology is discussed. (+info)
Timely redistribution of information for epidemiological surveillance and alert: the experience from the French communicable diseases network.
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Since 1984 the French Communicable Disease Network (FCDN) collects and analyses epidemiological information obtained online from a team of "Sentinel General Practitioners" (SGPs). It redistributes this information in the form of standardised weekly incidence estimates. These weekly estimates now appear on the Internet and are the basis for issuing alerts of influenza epidemics. We postulate that day to day estimations would be highly desirable to achieve timely detection of the actual onset of the epidemic, a need dramatically underscored by the emergence of bioterrorism. The present paper suggests the feasibility of reconstructing daily epidemiological information using local smoothing with a suitable spline function to obtain short latency alert messages. (+info)
Use of remote sensing and a geographical information system in a national helminth control programme in Chad.
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OBJECTIVE: To design and implement a rapid and valid epidemiological assessment of helminths among schoolchildren in Chad using ecological zones defined by remote sensing satellite sensor data and to investigate the environmental limits of helminth distribution. METHODS: Remote sensing proxy environmental data were used to define seven ecological zones in Chad. These were combined with population data in a geographical information system (GIS) in order to define a sampling protocol. On this basis, 20 schools were surveyed. Multilevel analysis, by means of generalized estimating equations to account for clustering at the school level, was used to investigate the relationship between infection patterns and key environmental variables. FINDINGS: In a sample of 1023 schoolchildren, 22.5% were infected with Schistosoma haematobium and 32.7% with hookworm. None were infected with Ascaris lumbricoides or Trichuris trichiura. The prevalence of S. haematobium and hookworm showed marked geographical heterogeneity and the observed patterns showed a close association with the defined ecological zones and significant relationships with environmental variables. These results contribute towards defining the thermal limits of geohelminth species. Predictions of infection prevalence were made for each school surveyed with the aid of models previously developed for Cameroon. These models correctly predicted that A. lumbricoides and T. trichiura would not occur in Chad but the predictions for S. haematobium were less reliable at the school level. CONCLUSION: GIS and remote sensing can play an important part in the rapid planning of helminth control programmes where little information on disease burden is available. Remote sensing prediction models can indicate patterns of geohelminth infection but can only identify potential areas of high risk for S. haematobium. (+info)
How old is the Hawaiian biota? Geology and phylogeny suggest recent divergence.
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This study quantifies long-term landscape changes in the Hawaiian archipelago relating to dispersal, speciation and extinction. Accounting for volcano growth, subsidence and erosion, we modelled the elevations of islands at time intervals of 0.5 Myr for the last 32 Myr; we also assessed the variation in the spacing of volcanoes during this period. The size, spacing and total number of volcanic islands have varied greatly over time, with the current landscape of large, closely spaced islands preceded by a period with smaller, more distantly spaced islands. Considering associated changes in rates of dispersal and speciation, much of the present species pool is probably the result of recent colonization from outside the archipelago and divergence within contemporary islands, with limited dispersal from older islands. This view is in accordance with abundant phylogenetic studies of Hawaiian organisms that estimate the timing of colonization and divergence within the archipelago. Twelve out of 15 multi-species lineages have diverged within the lifetime of the current high islands (last 5 Myr). Three of these, and an additional seven (mostly single-species) lineages, have colonized the archipelago within this period. The timing of colonization of other lineages remains uncertain. (+info)