179,234 research outputs found
Of cattle, sand flies and men : a systematic review of risk factor analyses for South Asian visceral leishmaniasis and implications for elimination
Full text linkBackground: Studies performed over the past decade have identified fairly consistent epidemiological patterns of risk
factors for visceral leishmaniasis (VL) in the Indian subcontinent.
Methods and Principal Findings: To inform the current regional VL elimination effort and identify key gaps in knowledge,
we performed a systematic review of the literature, with a special emphasis on data regarding the role of cattle because
primary risk factor studies have yielded apparently contradictory results. Because humans form the sole infection reservoir,
clustering of kala-azar cases is a prominent epidemiological feature, both at the household level and on a larger scale.
Subclinical infection also tends to show clustering around kala-azar cases. Within villages, areas become saturated over a
period of several years; kala-azar incidence then decreases while neighboring areas see increases. More recently, post kalaazar
dermal leishmaniasis (PKDL) cases have followed kala-azar peaks. Mud walls, palpable dampness in houses, and peridomestic
vegetation may increase infection risk through enhanced density and prolonged survival of the sand fly vector.
Bed net use, sleeping on a cot and indoor residual spraying are generally associated with decreased risk. Poor micronutrient
status increases the risk of progression to kala-azar. The presence of cattle is associated with increased risk in some studies
and decreased risk in others, reflecting the complexity of the effect of bovines on sand fly abundance, aggregation, feeding
behavior and leishmanial infection rates. Poverty is an overarching theme, interacting with individual risk factors on multiple
levels.
Conclusions: Carefully designed demonstration projects, taking into account the complex web of interconnected risk
factors, are needed to provide direct proof of principle for elimination and to identify the most effective maintenance
activities to prevent a rapid resurgence when interventions are scaled back. More effective, short-course treatment
regimens for PKDL are urgently needed to enable the elimination initiative to succeed
Natural infection of Phlebotomus argentipes with Leishmania and other trypanosomatids in a visceral leishmaniasis endemic region of Nepal.
No full textMonitoring Leishmania infection in sand flies is important for understanding the eco-epidemiology of kala-azar and assessing the impact of the recently launched kala-azar control programme in the Indian subcontinent. We applied a PCR technique that targets rRNA genes to estimate the natural incidence of Leishmania infection in sand flies sampled in six villages of the Terai region of Nepal. Amplifications were made on 135 pools of sand flies and confirmed by sequencing. Seven pools were found to be PCR positive: in five of them we identified the rDNA signature found in Leishmania spp., whereas two other pools revealed a sequence compatible with other trypanosomatids. Different methodologies were applied to evaluate the infection rate from pools of unequal size and estimated the infection rate to range from 0.468% to 0.578% for the Leishmania group and from 0.185% to 0.279% for the non-Leishmania group. Our results highlight the diversity of flagellate infections likely to be encountered in Phlebotomus argentipes populations. Our methodology allows clear discrimination of Leishmania from other trypanosomatids and should be applied on larger insect samples or in longitudinal studies
Spatial analysis of Leishmania donovani exposure in humans and domestic animals in a recent kala azar focus in Nepal.
Full text linkVisceral leishmaniasis (VL) is a major public health problem in the Indian subcontinent where the Leishmania donovani transmission cycle is described as anthroponotic. However, the role of animals (in particular domestic animals) in the persistence and expansion of VL is still a matter of debate. We combined Direct Agglutination Test (DAT) results in humans and domestic animals with Geographic Information System technology (i.e. extraction maps and scan statistic) to evaluate the exposure to L. donovani on these 2 populations in a recent VL focus in Nepal. A Poisson regression model was used to assess the risk of infection in humans associated with, among other factors, the proportion of DAT-positive animals in the proximities of the household. The serological results showed that both humans and domestic animals were exposed to L. donovani. DAT-positive animals and humans were spatially clustered. The presence of serologically positive goats (IRR=9.71), past VL cases (IRR=2.62) and the proximity to a forest island dividing the study area (IRR=3.67) increased the risk of being DAT-positive in humans. Even if they are not a reservoir, domestic animals, and specially goats, may play a role in the distribution of L. donovani, in particular in this new VL focus
Land-atmosphere interactions in Southwest Western Australia
Full text linkThe Southwest of Western Australia (SWWA) is a region of extensive land cover change with an estimated 13 million hectares of native vegetation cleared since European settlement. Whilst previous studies have suggested meteorological and climatological implications of this change in land use, no studies have explicitly focussed on the detailed mechanisms behind the impacts of land-cover change on individual meteorological phenomena. This thesis seeks to identify the physical mechanisms inducing changes within the atmosphere by using the Regional Atmospheric Modeling System (RAMS V6.0) to simulate the impact of land use change on meteorological phenomena at different scales and evaluate these model results against high resolution atmospheric soundings, station observations, and gridded rainfall analyses where appropriate. Sensitivity tests show that land-cover change results in an increase in low-level atmospheric moisture advection associated with the southern sea-breeze due to a reduction in surface roughness. It also results in a decrease in convective precipitation associated with cold-fronts and convective clouds associated with the surface heat trough, due to an increase in wind speed, and a decrease in turbulent kinetic energy and vertically integrated moisture convergence within the PBL. Large-eddy simulations further highlight the role of land-cover change and soil moisture, as well as the contributions of surface versus entrainment fluxes on the growth of the PBL and development of convective clouds. These results are discussed within the broader context of the meteorology of the region
Quantifying institutional impacts and development synergies in water resource programs : a methodology with application to the Kala Oya basin, Sri Lanka
Full text linkThe success of development programs, including water resource projects, depends on two key factors: the role of underlying institutions and the impact synergies from other closely related programs. Existing methodologies have limitations in accounting for these critical factors. This paper fills this gap by developing a methodology, which quantifies both the roles that institutions play in impact generation and the extent of impact synergies that flows from closely related programs within a unified framework. The methodology is applied to the Kala Oya Basin in Sri Lanka in order to evaluate the impacts of three water-related programs and the roles of 11 institutions in the context of food security. The results provide considerable insights on the relative role of institutions and the flow of development synergies both within and across different impact pathways. The methodology can also be used to locate slack in impact chains and identify policy options to enhance the impact flows.Economic Theory&Research,Food&Beverage Industry,E-Business,Rural Poverty Reduction,Climate Change
Comparative study of kala-azar vector control measures in eastern Nepal.
No full textThis study was conducted to explore the most effective vector control tool among indoor residual spraying (IRS), long lasting insecticidal nets (LLINs) and ecological vector management (EVM) as a part of the regional visceral leishmaniasis elimination initiative. Alpha-cypermethrin as IRS, PermaNet as LLINs and plastering the inner walls of houses with lime as EVM were the interventions. One baseline and three follow-up entomological surveys were carried out in all arms using CDC miniature light traps (LT) and mouth aspirators. Comparisons were made between intervention arms and control arms with pre-intervention and post-intervention vector densities. Light traps were found more efficient in the collection of Phlebotomus argentipes in comparison with aspiration. Vector densities were significantly low in both IRS arm (p=0.009 in LT and p<0.001 in aspirator collections) and LLIN arm (p=0.019 in LT and p=0.023 in aspirator collections) in comparison with control arm. However, in EVM arm, there was no significant difference in P. argentipes sand fly density in comparison with control arm (p=0.785) in LT collections in follow-up surveys. Hence, IRS was found most effective control measure to decrease vector density. LLINs were also found effective and can be considered as a promising alternative vector control tool in VL elimination initiative
Effect of untreated bed nets on blood-fed Phlebotomus argentipes in kala-azar endemic foci in Nepal and India.
Full text linkObservational studies in the Indian subcontinent have shown that untreated nets may be protective against visceral leishmaniasis (VL). In this study, we evaluated the effect of untreated nets on the blood feeding rates of Phlebotomus argentipes as well as the human blood index (HBI) in VL endemic villages in India and Nepal. The study had a 'before and after intervention' design in 58 households in six clusters. The use of untreated nets reduced the blood feeding rate by 85% (95% CI 76.5-91.1%) and the HBI by 42.2% (95% CI 11.1-62.5%). These results provide circumstantial evidence that untreated nets may provide some degree of personal protection against sand fly bites
Semifields and a theorem of Abhyankar
Full text linksummary:Abhyankar proved that every field of finite transcendence degree over or over a finite field is a homomorphic image of a subring of the ring of polynomials (for some depending on the field). We conjecture that his result cannot be substantially strengthened and show that our conjecture implies a well-known conjecture on the additive idempotence of semifields that are finitely generated as semirings
Comparison of Generic and Proprietary Sodium Stibogluconate for the Treatment of Visceral Leishmaniasis in Kenya.
Full text linkOBJECTIVE: To compare the use of generic and proprietary sodium stibogluconate for the treatment of visceral leishmaniasis (kala-azar). METHODS: A total of 102 patients with confirmed kala-azar were treated in a mission hospital in West Pokot region, Kenya, with sodium stibogluconate (20 mg/kg/day for 30 days)--either as Pentostam (PSM) or generic sodium stibogluconate (SSG); 51 patients were allocated alternately to each treatment group. FINDINGS: There were no significant differences in baseline demographic characteristics or disease severity, or in events during treatment. There were 3 deaths in the PSM group and 1 in the SSG group; 2 patients defaulted in each group. Only 1 out of 80 test-of-cure splenic aspirates was positive for Leishmania spp.; this patient was in the SSG group. Follow-up after > or = 6 months showed that 6 out of 58 patients had relapsed, 5 in the SSG group and 1 in the PSM group. No outcome variable was significantly different between the two groups. CONCLUSION: The availability of cheaper generic sodium stibogluconate, subject to rigid quality controls, now makes it possible for the health authorities in kala-azar endemic areas to provide treatment to many more patients in Africa
Arkheologicheskie raskopki na gorodishe Kafir-kala (Archaeological excavation at the citadel of Kafir Kala)
No full textThe article describes the results of the excavations occurred at the citadel of Kafir Kala (Samarkand, Uzbekistan) in the 2005 season. The main attention concerns the discovery of more than hundred clay sealings dated to the end of the Sogdian period (late 7th century AD) and the Arab conquest of Samarkand, when Kafir Kala temporarily abandoned and a fire destroyed the citadel
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