-
Science 04/2012; 336(6080):418-9. · 31.20 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Cholera outbreaks have occurred in Burundi, Rwanda, Democratic Republic of Congo, Tanzania, Uganda, and Kenya almost every year since 1977-1978, when the disease emerged in these countries. We used a multiscale, geographic information system-based approach to assess the link between cholera outbreaks, climate, and environmental variables. We performed time-series analyses and field investigations in the main affected areas. Results showed that cholera greatly increased during El Nino warm events (abnormally warm El Ninos) but decreased or remained stable between these events. Most epidemics occurred in a few hotspots in lakeside areas, where the weekly incidence of cholera varied by season, rainfall, fluctuations of plankton, and fishing activities. During lull periods, persistence of cholera was explained by outbreak dynamics, which suggested a metapopulation pattern, and by endemic foci around the lakes. These links between cholera outbreaks, climate, and lake environments need additional, multidisciplinary study.
Emerging Infectious Diseases 11/2011; 17(11):2026-34. · 6.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Pollinosis is found more frequently in urban areas than in rural environments. This could be partly related to the different types of pollen exposure in these dissimilar areas. The objective of this study was to compare the distribution of pollen in these environments across an urbanization gradient.
Daily pollen abundances were obtained in France using Hirst-type sensors. Sampling was conducted from January to June in 2003 and 2006 in a rural area, a semi-rural area and in two urban areas, which were characterized by several urbanization criteria.
Total allergenic pollen abundance was higher in rural and semi-rural areas than in urban areas irrespective of the sampling year. Multivariate analyses showed that pollen exposures differed according to the type of area and were strongly explained by the urbanization gradient. Grass, ash, birch, alder, hornbeam, hazel and plantain pollen quantities exceeded the allergy threshold more often in rural settings than in urban areas. In urban areas, only plane pollen quantities exceeded the allergy threshold more often than in rural areas.
Allergenic pollen exposure is higher in rural areas than in urban areas, and the most abundant pollen in each area did not originated from the same taxa. This result should be taken into account in epidemiological studies comparing allergies in rural and urban areas to adapt the panel of pollen extracts for human environmental exposure. In addition, this study highlights that some ornamental trees produce a large number of allergenic pollens and provide new sources of aeroallergens.
Environmental Research 07/2011; 111(5):619-25. · 3.40 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: This meta-analysis of reports examining ticks throughout the Western Palearctic region indicates a distinct geographic pattern for Borrelia burgdorferi sensu lato prevalence in questing nymphal Ixodes ricinus ticks. The greatest prevalence was reported between the 5°E and 25°E longitudes based on an analysis of 123 collection points with 37,940 nymphal tick specimens (87.43% of total nymphs; 56.35% of total ticks in the set of reports over the target area). Climatic traits, such as temperature and vegetation stress, and their seasonality correlated with Borrelia prevalence in questing ticks. The greatest prevalence was associated with mild winter, high summer, and low seasonal amplitude of temperatures within the range of the tick vector, higher vegetation indices in the May-June period, and well-connected vegetation patches below a threshold at which rates suddenly drop. Classification of the target territory using a qualitative risk index derived from the abiotic variables produced an indicator of the probability of finding infected ticks in the Western Palearctic region. No specific temporal trends were detected in the reported prevalence. The ranges of the different B. burgdorferi sensu lato genospecies showed a pattern of high biodiversity between 4°W and 20°E, partially overlapping the area of highest prevalence in ticks. Borrelia afzelii and Borrelia garinii are the dominant species in central Europe (east of ∼25°E), but B. garinii may appear alone at southern latitudes and Borrelia lusitaniae is the main indicator species for meridional territories.
Applied and environmental microbiology 06/2011; 77(11):3838-45. · 3.69 Impact Factor
-
Anne-Cécile Normand, Bertrand Sudre,
Mallory Vacheyrou,
Martin Depner,
Inge M Wouters,
Ilka Noss,
Dick Heederik,
Anne Hyvärinen,
Jon Genuneit,
Charlotte Braun-Fahrländer,
Erika von Mutius,
Renaud Piarroux
[show abstract]
[hide abstract]
ABSTRACT: Exposure to environments rich in microorganisms such as farms has been shown to protect against the development of childhood asthma and allergies. However, it remains unclear where, and how, farm and other rural children are exposed to microbes. Furthermore, the composition of the microbial flora is poorly characterised. We tested the hypothesis that farm children are exposed indoors to substantial levels of viable microbes originating from animal sheds and barns. We also expected that environmental microbial flora on farms and in farm homes would be more complex than in the homes of rural control children.
Dust samples were collected using passive samplers in the bedrooms of the following groups of children in rural Bavaria, Germany: (i) those living on farms (n=144), (ii) those regularly exposed to farm environments but not living on farms (n=149) and (iii) those never visiting farms (n=150). For farm children, additional samples were collected in animal sheds and barns. All samples were subjected to fungal and bacterial culturing.
Detectable levels of microorganisms were more often found in samples taken from farm dwellings than from other homes. Farm dwellings also showed higher microbial levels. Microbial counts of farm dwelling samples correlated with the counts in corresponding animal sheds and barns.
Microorganisms are transported from animal sheds and barns into farm dwellings. Therefore, children living in these environments are exposed when indoors and when visiting animal sheds and barns. Indoor exposure may also contribute to the protective effect of the farm environment.
Occupational and environmental medicine 03/2011; 68(11):849-55. · 3.64 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Studies have shown a link between living on a farm, exposure to microbial components (e.g., endotoxins or beta-d-glucans), and a lower risk for allergic diseases and asthma. Due to the lack of validated sampling methods, studies of asthma and atopy have not relied on exposure assessment based on culture techniques. Our objective was therefore to compare several dust sampling methods for the detection of cultivable-microorganism exposure in stables. Sixteen French farms were sampled using four different methods: (i) active air sampling using a pump, (ii) passive dust sampling with a plastic box, (iii) dust sampling with an electrostatic dust fall collector (wipe), and (iv) dust sampling using a spatula to collect dust already settled on a windowsill. The results showed that collection of settled dust samples with either plastic boxes or wipes was reproducible (pairwise correlations, 0.72 and 0.73, respectively) and resulted in highly correlated results (pairwise correlation between the two methods, 0.82). We also found that settled dust samples collected with a plastic box correctly reflected the composition of the samples collected in the air of the stable when there was no farmer activity. A loss of microbial diversity was observed when dust was kept for 3 months at room temperature. We therefore conclude that measurement of viable microorganisms within a reasonable time frame gives an accurate representation of the microbial composition of stable air.
Applied and environmental microbiology 10/2009; 75(24):7617-23. · 3.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: During the last eight years, North and South Kivu, located in a lake area in Eastern Democratic Republic of Congo, have been the site of a major volcano eruption and of numerous complex emergencies with population displacements. These conditions have been suspected to favour emergence and spread of cholera epidemics.
In order to assess the influence of these conditions on outbreaks, reports of cholera cases were collected weekly from each health district of North Kivu (4,667,699 inhabitants) and South Kivu (4,670,121 inhabitants) from 2000 through 2007. A geographic information system was established, and in each health district, the relationships between environmental variables and the number of cholera cases were assessed using regression techniques and time series analysis. We further checked for a link between complex emergencies and cholera outbreaks. Finally, we analysed data collected during an epidemiological survey that was implemented in Goma after Nyiragongo eruption. A total of 73,605 cases and 1,612 deaths of cholera were reported. Time series decomposition showed a greater number of cases during the rainy season in South Kivu but not in North Kivu. Spatial distribution of cholera cases exhibited a higher number of cases in health districts bordering lakes (Odds Ratio 7.0, Confidence Interval range 3.8-12.9). Four epidemic reactivations were observed in the 12-week periods following war events, but simulations indicate that the number of reactivations was not larger than that expected during any random selection of period with no war. Nyiragongo volcanic eruption was followed by a marked decrease of cholera incidence.
Our study points out the crucial role of some towns located in lakeside areas in the persistence of cholera in Kivu. Even if complex emergencies were not systematically followed by cholera epidemics, some of them enabled cholera spreading.
PLoS Neglected Tropical Diseases 02/2009; 3(5):e436. · 4.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We studied the epidemiology of cholera in Katanga and Eastern Kasai, in the Democratic Republic of Congo, by compiling a database including all cases recorded from 2000 through 2005. Results show that lakes were the sources of outbreaks and demonstrate the inadequacy of the strategy used to combat cholera.
Emerging Infectious Diseases 06/2008; 14(5):798-800. · 6.79 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Studies have shown a link between living on a farm, exposure to microbial components (e.g., endotoxins or beta-d-glucans), and a lower risk for allergic diseases and asthma. Due to the lack of validated sampling methods, studies of asthma and atopy have not relied on exposure assessment based on culture techniques. Our objective was therefore to compare several dust sampling methods for the detection of cultivable-microorganism exposure in stables. Sixteen French farms were sampled using four different methods: (i) active air sampling using a pump, (ii) passive dust sampling with a plastic box, (iii) dust sampling with an electrostatic dust fall collector (wipe), and (iv) dust sampling using a spatula to collect dust already settled on a windowsill. The results showed that collection of settled dust samples with either plastic boxes or wipes was reproducible (pairwise correlations, 0.72 and 0.73, respectively) and resulted in highly correlated results (pairwise correlation between the two methods, 0.82). We also found that settled dust samples collected with a plastic box correctly reflected the composition of the samples collected in the air of the stable when there was no farmer activity. A loss of microbial diversity was observed when dust was kept for 3 months at room temperature. We therefore conclude that measurement of viable microorganisms within a reasonable time frame gives an accurate representation of the microbial composition of stable air.
