Epidemiology of malaria in irrigated parts of Tana River County, Kenya

Irrigation schemes introduced in areas of high malaria endemicity often amplify malaria burden especially if no mitigation or adaptation measures are implemented (Renshaw et al., 1998). Thias study was conducted in Bura and Hola irrigation schemes in Tana River County to (i) understand the knowledge, attitude and practices of the community in relation to malaria control and transmission, (ii) determine malaria prevalence and the associated risk factors of infection and (iii) develop and validate a transmission model for analyzing the effects of irrigation on malaria burden. A cross sectional survey was conducted in 48 households where 160 people were screened for malaria parasites using Rapid Diagnostic Test. A deterministic model was developed and validated using field data. The community demonstrated good knowledge on causes, symptoms, transmission and control of malaria. The main malaria control measure was use of bed nets where one net was shared by two people. Only 12% of the households practice environmental management to control malaria. Treatment of malaria was mainly based on Artemether-lumefantrine (AL) which is freely available in the government health facilities. The prevalence of malaria was 5% with the clinical records showing a declining trend of malaria cases. Households located ≤5kms to the nearest facility had lower risk of malaria infection (OR=0.104, p-value=0.013) than those located >5kms. Household size was also associated with malaria infection (OR=1.685, p-value=0.022). The model predicted the observed prevalence data. The high usage of bed nets and AL could have led to the observed decrease in malaria prevalence despite the intensification of irrigated agriculture. The model developed could be used to predict the prevalence of malaria in this area enabling decision makers to implement appropriate control measures in good time

Modelling malaria transmission dynamics in irrigated areas of Tana River County, Kenya

Development of irrigation schemes is usually associated with escalation of the malaria problem. Mathematical models can be used to explain the effects of irrigation on malaria transmission dynamics. This study aimed at developing and validating a one-host one-vector deterministic model made up of a mosquito population sub-module and disease transmission sub-module. Model parameters were obtained from the literature. Data covering the year 2013 were collected and these included the amount of irrigation water per unit area of irrigated land, rainfall, temperature and prevalence of malaria from the local hospitals. The Fuzzy distribution function was used to relate rainfall and irrigation patterns with oviposition and mortality rates of acquatic stages of mosquitoes. The model was fitted to malaria prevalence data obtained from the local hospitals by varying the parameters of the Fuzzy distribution function. Parameter values that gave the least variance between predicted and observed prevalence were used. The model was implemented in MS Excel using difference equations.The model fitted the data well and predicts an upsurge in the number of malaria cases 2-3 months after the rains or active irrigation. The model could be used to predict the prevalence of malaria in this area enabling decision makers to implement appropriate control measures in good time. Data from non-irrigated areas and covering a longer period of time should be collected for more rigorous model validation and simulation of the effectiveness of various the interventions

Incidence and severity of respiratory syncytial virus pneumonia in rural Kenyan children identified through hospital surveillance

Background.Although necessary for developing a rationale for vaccination, the burden of severe respiratory syncytial virus (RSV) disease in children in resource‐poor settings remains poorly defined. Methods.We conducted prospective surveillance of severe and very severe pneumonia in children aged <5 years admitted from 2002 through 2007 to Kilifi district hospital in coastal Kenya. Nasal specimens were screened for RSV antigen by immunofluorescence. Incidence rates were estimated for the well‐defined population. Results.Of 25,149 hospital admissions, 7359 patients (29%) had severe or very severe pneumonia, of whom 6026 (82%) were enrolled. RSV prevalence was 15% (20% among infants) and 27% during epidemics (32% among infants). The proportion of case patients aged 3 months was 65%, and the proportion aged 6 months was 43%. Average annual hospitalization rates were 293 hospitalizations per 100,000 children aged <5 years (95% confidence interval, 271–371 hospitalizations per 100,000 children aged <5 years) and 1107 hospitalizations per 100,000 infants (95% confidence interval, 1012–1211 hospitalizations per 100,000 infants). Hospital admission rates were double in the region close to the hospital. Few patients with RSV infection had life‐threatening clinical features or concurrent serious illnesses, and the associated mortality was 2.2%. Conclusions.In this low‐income setting, rates of hospital admission with RSV‐associated pneumonia are substantial; they are comparable to estimates from the United States but considerably underestimate the burden in the full community. An effective vaccine for children aged >2 months (outside the age group of poor responders) could prevent a large portion of RSV disease. Severity data suggest that the justification for RSV vaccination will be based on the prevention of morbidity, not mortality

Spatial, seasonal and climatic predicitve models of Rift Valley Fever disease across Africa

Understanding the emergence and subsequent spread of human infectious diseases is a critical global challenge, especially for high-impact zoonotic and vector-borne diseases. Global climate and land-use change are likely to alter host and vector distributions, but understanding the impact of these changes on the burden of infectious diseases is difficult. Here, we use a Bayesian spatial model to investigate environmental drivers of one of the most important diseases in Africa, Rift Valley fever (RVF). The model uses a hierarchical approach to determine how environmental drivers vary both spatially and seasonally, and incorporates the effects of key climatic oscillations, to produce a continental risk map of RVF in livestock (as a proxy for human RVF risk). We find RVF risk has a distinct seasonal spatial pattern influenced by climatic variation, with the majority of cases occurring in South Africa and Kenya in the first half of an El Niño year. Irrigation, rainfall and human population density were the main drivers of RVF cases, independent of seasonal, climatic or spatial variation. By accounting more subtly for the patterns in RVF data, we better determine the importance of underlying environmental drivers, and also make space- and time-sensitive predictions to better direct future surveillance resources. This article is part of the themed issue ‘One Health for a changing world: zoonoses, ecosystems and human well-being’

Evaluation of a measles vaccine campaign by oral-fluid surveys in a rural Kenyan district: interpretation of antibody prevalence data using mixture models

We evaluated the effectiveness of a measles vaccine campaign in rural Kenya, based on oral-fluid surveys and mixture-modelling analysis. Specimens were collected from 886 children aged 9 months to 14 years pre-campaign and from a comparison sample of 598 children aged 6 months post-campaign. Quantitative measles-specific antibody data were obtained by commercial kit. The estimated proportions of measles-specific antibody negative in children aged 0–4, 5–9 and 10–14 years were 51%, 42% and 27%, respectively, pre- campaign and 18%, 14% and 6%, respectively, post-campaign. We estimate a reduction in the proportion susceptible of 65–78%, with ~85% of the population recorded to have received vaccine. The proportion of ‘weak’ positive individuals rose from 35% pre-campaign to 54% post-campaign. Our results confirm the effectiveness of the campaign in reducing susceptibility to measles and demonstrate the potential of oral-fluid studies to monitor the impact of measles vaccination campaigns

Design and operation of a prototype interaction point beam collision feedback system for the International Linear Collider

A high-resolution, intratrain position feedback system has been developed to achieve and maintain collisions at the proposed future electron-positron International Linear Collider (ILC). A prototype has been commissioned and tested with a beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization in Japan. It consists of a stripline beam position monitor (BPM) with analogue signal-processing electronics, a custom digital board to perform the feedback calculation, and a stripline kicker driven by a high-current amplifier. The closed-loop feedback latency is 148 ns. For a three-bunch train with 154 ns bunch spacing, the feedback system has been used to stabilize the third bunch to 450 nm. The kicker response is linear, and the feedback performance is maintained, over a correction range of over $\pm$60 {\mu}m. The propagation of the correction has been confirmed by using an independent stripline BPM located downstream of the feedback system. The system has been demonstrated to meet the BPM resolution, beam kick, and latency requirements for the ILC

Factors determining the use of botanical insect pest control methods by small-holder farmers in the Lake Victoria basin, Kenya

A farm survey was conducted in three representative administrative districts of the Lake Victoria Basin (LVB), Kenya to document farmers’ indigenous knowledge and the factors that influence the use of botanicals instead of synthetic insecticides in insect pest management. A total of 65 farm households were randomly sampled using stratified sampling procedure. The maximum likelihood log model was used to determine factors that influence use of botanical and synthetic insect pest control methods (PCM). Results revealed that female gender as household head (HH) and age significantly (P &lt; .001) increased the likelihood of a household using botanical PCM in the field by 0.15 and 0.021, respectively. In storage, female gender and severity of pest infestation significantly (P &lt; .001) increased the probability of a household using botanical insecticide by 0.814 and 0.738, respectively. On the contrary, education of HH (0.342) and ownership of title to land (0.512) significantly (P &lt; .001) reduced the likelihood of using botanical PCM in the field, while traditional rank (0.910) and cash rank (0.744) of the crops reduced the likelihood of using botanical insecticides in the store. With respect to synthetic pesticides, gender (3.407), area cultivated (0.295) and expected yield (5.315) significantly (P &lt; .001) reduced likelihood of their use in the field, while food rank (3.967) reduced the probability of use in storage. In storage, female gender, crop type, food and traditional rank of crops were also the most important factors determining the use of botanical control methods. In conclusion, the study established that female gender, literacy levels, wealth endowments in form of land and old age are key determinants of botanical insecticides use in small-holder farming systems in the LVB, Kenya. It is recommended that the Government of Kenya enacts policies that empower youth and female gender economically in subsistence farming with the aim of improving their educational levels and farming skills to modernize agriculture among the rural communities.Key words: Botanical, Synthetic pesticide, Insects, Pest control method, Determinants, Small-holder farmers

Developing more environmentally friendly and nutritious pea varieties

Non-Peer ReviewedPhytate is the major storage form of phosphorus in crop seeds, but is not well digested by humans and non-ruminant animals. In addition, phytate chelates several essential micronutrients which are also excreted contributing to phosphorus pollution in the environment. Environmental and nutritional concerns led to the development of cultivars with the low phytate trait. The present study is aimed at biochemical and molecular characterization of two low phytate pea mutant lines, 1-150-81 and 1-2347-144 developed at the Crop Development Centre, University of Saskatchewan in collaboration with Dr. Victor Raboy, USDA, Idaho. Biochemical characterization is in progress for the two low phytate lines, their progenitor, CDC Bronco and CDC Meadow that were grown in replicated field trials at Saskatoon and Rosthern, SK in 2010 and 2011. Samples of developing seeds were collected 7 days after pollination and at weekly intervals thereafter until maturity. The concentration of phytate-phosphorus, isomeric forms of phytatephosphorus and inorganic phosphorus in these developing cotyledons and seed coats will be assessed using colorimetric and HPLC methods. In this way, the pattern of phytate-phosphorus and inorganic phosphorus accumulation will be determined in developing seeds. Molecular characterization will include cloning, sequencing and mapping of the gene(s) associated with the low phytate trait. Molecular markers will be developed based on the gene sequences. Recombinant inbred lines (RILs) were developed from crosses between the two low phytate lines and CDC Meadow. One set of RILs was evaluated in a field trial in Saskatchewan in 2011, and will be evaluated again in 2012. The RILs will be genotyped using available microsatellite markers or SNP markers and phenotyped using colorimetric and HPLC assays. These data will then be used to identify the molecular marker(s) for the trait. The study will aid us to understand the nature of the low phytate mutation(s). Significant potential benefits that we could expect out of the project include improved bioavailability of phosphorus, iron and zinc in foods and feeds, less phosphorus excretion and environmental pollution and a substantial saving in feed costs

Large scale anisotropies on halo infall

We perform a statistical analysis of the peculiar velocity field around dark matter haloes in numerical simulations. We examine different properties of the infall of material onto haloes and its relation to central halo shapes and the shape of the large scale surrounding regions (LSSR). We find that the amplitude of the infall velocity field along the halo shape minor axis is larger than that along the major axis. This is consistent for general triaxial haloes, and for both prolate and oblate systems. We also report a strong anisotropy of the velocity field along the principal axes of the LSSR. The infall velocity field around dark matter haloes reaches a maximum value along the direction of the minor axis of the LSSR, whereas along the direction of its major axis, it exhibits the smallest velocities. We also analyse the dependence of the matter velocity field on the local environment. The amplitude of the infall velocity at high local density regions is larger than at low local density regions. The velocity field tends to be more laminar along the direction towards the minor axis of the LSSR, where the mean ratio between flow velocity and velocity dispersion is of order unity and nearly constant up to scales of 15 Mpc/h. We also detect anisotropies in the outflowing component of the velocity field, showing a maximum amplitude along the surrounding LSSR major axis.Comment: 12 pages, 9 figures, accepted for publication in Monthly Notices of the Royal Astronomical Societ

Genetic improvement of chickpea for western Canada

Non-Peer ReviewedThe chickpea crop has experienced a roller-coaster ride over the past decade in western Canada. Production rose rapidly in the late 1990’s, followed by dramatic declines in the past two years. Instability can be attributed to many factors including commodity prices, erratic weather patterns, Ascochyta blight and late maturity. This paper summarizes current research on genetic improvement of chickpea at the University of Saskatchewan, with particular emphasis on efforts to improve Ascochyta blight resistance and to develop varieties with earlier maturity. Under ‘average’ weather conditions, chickpea remains an excellent nitrogen-fixing crop for the Brown and Dark Brown soil zones