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African farming systems are highly heterogeneous: between agroecological and socioeconomic environments, in the wide variability in farmers’ resource endowments and in farm management. This means that single solutions (or ‘silver bullets’) for improving farm productivity do not exist. Yet to date few approaches to understand constraints and explore options for change have tackled the bewildering complexity of African farming systems. In this paper we describe the Nutrient Use in Animal and Cropping systems – Efficiencies and Scales (NUANCES) framework. NUANCES offers a structured approach to unravel and understand the complexity of African farming to identify what we term ‘best-fit’ technologies – technologies targeted to specific types of farmers and to specific niches within their farms. The NUANCES framework is not ‘just another computer model’! We combine the tools of systems analysis and experimentation, detailed field observations and surveys, incorporate expert knowledge (local knowledge and results of research), generate databases, and apply simulation models to analyse performance of farms, and the impacts of introducing new technologies. We have analysed and described complexity of farming systems, their external drivers and some of the mechanisms that result in (in)efficient use of scarce resources. Studying sites across sub-Saharan Africa has provided insights in the trajectories of change in farming systems in response to population growth, economic conditions and climate variability (cycles of drier and wetter years) and climate change. In regions where human population is dense and land scarce, farm typologies have proven useful to target technologies between farmers of different production objectives and resource endowment (notably in terms of land, labour and capacity for investment). In such regions we could categorise types of fields on the basis of their responsiveness to soil improving technologies along soil fertility gradients, relying on local indicators to differentiate those that may be managed through ‘maintenance fertilization’ from fields that are highly-responsive to fertilizers and fields that require rehabilitation before yields can improved. Where human population pressure on the land is less intense, farm and field types are harder to discern, without clear patterns. Nutrient cycling through livestock is in principle not efficient for increasing food production due to increased nutrient losses, but is attractive for farmers due to the multiple functions of livestock. We identified trade-offs between income generation, soil conservation and community agreements through optimising concurrent objectives at farm and village levels. These examples show that future analyses must focus at farm and farming system level and not at the level of individual fields to achieve appropriate targeting of technologies – both between locations and between farms at any given location. The approach for integrated assessment described here can be used ex ante to explore the potential of best-fit technologies and the ways they can be best combined at farm level. The dynamic and integrated nature of the framework allows the impact of changes in external drivers such as climate change or development policy to be analysed. Fundamental questions for integrated analysis relate to the site-specific knowledge and the simplification of processes required to integrate and move from one level to the next. Keywords: Crop–livestock systems; Soil fertility; Smallholders; Farm types; Simulation modelling

More focus is given to mosquito larval control due to the necessity to use several control techniques together in integrated vector management programmes. Botanical products are thought to be able to provide effective, sustainable and cheap mosquito larval control tools. However, bio-larvicides like Azadirachta indica (neem) could repel adult mosquitoes from laying their eggs in the treated larval habitats. In this study the response of Anopheles gambiae s.s. mosquitoes towards varying doses of crude aqueous neem extracts was examined. Non-choice oviposition tests were used to measure the proportion of mosquitoes laying on the first or second night, or not laying at all, when compared to the control. For each individual mosquito, the number of eggs laid and/or retained in the ovary was counted to determine the relationship between wing length and egg production. Larger female mosquitoes produced larger egg batches. The results show that at a dose of 0.1 g/l, a concentration previously found to be effective at controlling mosquito larvae, the oviposition behaviour of adult female mosquitoes was not significantly affected. The results indicate that the mosquitoes would expose progeny to this neem control tool, making the use of these simple neem wood extracts effective and potentially sustainable.

Smallholder farms in sub-Saharan African exhibit substantial heterogeneity in soil fertility, and nutrient resource allocation strategies that address this variability are required to increase nutrient use efficiencies. We applied the Field-scale resource Interactions, use Efficiencies and Long-term soil fertility Development (FIELD) model to explore consequences of various manure and fertilizer application strategies on crop productivity and soil organic carbon (SOC) dynamics on farms varying in resource endowment in a case study village in Murewa District, Zimbabwe. FIELD simulated a rapid decline in SOC and maize yields when native woodlands were cleared for maize cultivation without fertilizer inputs coupled with removal of crop residues. Applications of 10 t manure ha-1 year-1 for 10 years were required to restore maize productivity to the yields attainable under native woodland. Long-term application of manure at 5 and 3 t ha-1 resulted in SOC contents comparable to zones of high and medium soil fertility observed on farms of wealthy cattle owners. Targeting manure application to restore SOC to 50-60% of contents under native woodlands was sufficient to increase productivity to 90% of attainable yields. Short-term increases in crop productivity achieved by reallocating manure to less fertile fields were short-lived on sandy soils. Preventing degradation of the soils under intensive cultivation is difficult, particularly in low input farming systems, and attention should be paid to judicious use of the limited nutrient resources to maintain a degree of soil fertility that supports good crop response to fertilizer application.

Technological interventions to address the problem of poor productivity of smallholder agricultural systems must be designed to target socially diverse and spatially heterogeneous farms and farming systems. This paper proposes a categorisation of household diversity based on a functional typology of livelihood strategies, and analyses the influence of such diversity on current soil fertility status and spatial variability on a sample of 250 randomly selected farms from six districts of Kenya and Uganda. In spite of the agro-ecological and socio-economic diversity observed across the region (e.g. 4 months year_1 of food self-sufficiency in Vihiga, Kenya vs. 10 in Tororo, Uganda) consistent patterns of variability were also observed. For example, all the households with less than 3 months year_1 of food self-sufficiency had a land:labour ratio (LLR) < 1, and all those with LLR > 1 produced enough food to cover their diet for at least 5 months. Households with LLR < 1 were also those who generated more than 50% of their total income outside the farm. Dependence on off/non-farm income was one of the main factors associated with household diversity. Based on indicators of resource endowment and income strategies and using principal component analysis, farmers' rankings and cluster analysis the 250 households surveyed were grouped into five farm types: (1) Farms that rely mainly on permanent off-farm employment (from 10 to 28% of the farmers interviewed, according to site); (2) larger, wealthier farms growing cash crops (8-20%); (3) medium resource endowment, food self-sufficient farms (20-38%); (4) medium to low resource endowment relying partly on non-farm activities (18-30%); and (5) poor households with family members employed locally as agricultural labourers by wealthier farmers (13-25%). Due to differential soil management over long periods of time, and to ample diversity in resource endowments (land, livestock, labour) and access to cash, the five farm types exhibited different soil carbon and nutrient stocks (e.g. Type 2 farms had average C, N, P and K stocks that were 2-3 times larger than for Types 4 or 5). In general, soil spatial variability was larger in farms (and sites) with poorer soils and smaller in farms owning livestock. The five farm types identified may be seen as domains to target technological innovations and/or development efforts.

Globally, tuberculosis (TB) continues to exact an unacceptably high toll of disease and death among children, particularly in the wake of the HIV epidemic. Kenya is ranked 13th among the 22 high-burden TB countries, and 5th in Africa. To determine the gender-age distribution of tuberculosis among TB suspects in western Kenya. In a cross-sectional study carried out at 10 hospitals in western Kenya, sputa from 872 TB suspects underwent microscopy and culture on solid and liquid media. The growth was identified using the Hains GenoType® Mycobacterium CM and GenoType® Mycobacterium AS kits. A questionnaire was used to collect demographic data. In total, 41.4% of the TB suspects were diagnosed with mycobacterial disease (95.8% TB cases and 4.2% NTM disease cases). Hence, 39.7% of the suspects were diagnosed with TB, 61.6% males and 38.4% females. A total of 263 (76%) of the 346 TB cases accepted to be tested for HIV infection and 41.8% (110/263) were co-infected (males, 55.5%; females, 44.5%). There was no significant difference in the TB-HIV co-infection rate between genders [OR = 1.006; 95% CI: 0.671-1.508; P = 0.979]. The majority (40.9%) of the TB/HIV cases were in the 25-34-year age bracket. In general, the prevalence of TB was significantly higher in males than females (χ2 = 10.67; P = 0.001), the majority (37.0%) being in the 25-34 age-group. Children below 15 years constituted 4.9% of the cases. A high prevalence of TB was observed in this study, males in the 25-34 age-group carrying the highest burden. There is need for more efforts and resources to increase knowledge and access TB and NTM syndromes care. [Med-Science 2018; 7(2.000): 252-6]

The deliberate planting of fast-growing N2-fixing legume monoculture species in rotation with cereal crops can be an important source of N for soil fertility replenishment. We hypothesized that mixed-species fallows have a higher potential of giving long-term residual benefits in terms of biomass, nutrients, and quality of residuals leading to long-term nutrient supply to postfallow maize (Zea mays L.) crops. To test these hypotheses, two experiments were established in farmers' fields on very fine Kandiudalfic Eutrudox soils with monoculture and mixed-species fallows. Treatments included: sesbania [Sesbania sesban (L.) Merr.], crotalaria (Crotalaria grahamiana Wight and Arn.), pigeonpea [Cajanus cajan (L.) Millsp.], siratro [Macroptilium atropurpureum (DC.) Urb.], and calliandra (Calliandra calothyrsus Meissn.) as monoculture-species fallow and mixture fallows of sesbania + crotalaria, sesbania + pigeonpea, sesbania + siratro, or sesbania + calliandra compared with continuous maize cropping with or without N fertilizer, and natural weed fallow. Total aboveground biomass ranged from 4.1 to 20.5 Mg ha-1 for monoculture and 7.8 to 23.3 Mg ha-1 for mixed-species fallows. Recyclable fallow biomass N ranged from 70 to 313 kg ha-1 and there was a positive interaction in some mixtures leading to increased N accumulation. Postfallow maize yields for fallows over five cropping seasons were 161-272% or 61-103% higher when compared with continuous maize without or with N fertilizer, respectively. Long-term postfallow effects on maize yield were linearly related to the amount of recycled fallow N yield. Thus, choice of fallow species to mix should be primarily driven by a better risk management strategy and an increased basket of multiple products and services

During participatory prototyping activities in Vihiga, western Kenya, farmers designed what they considered to be the ideal farm [Waithaka, M.M., Thornton, P.K., Herrero, M., Shepherd, K.D., 2006. Bio-economic evaluation of farmers’ perceptions of viable farms in western Kenya. Agric. Syst. 90, 243–271]: one in which high productivity is achieved through optimising crop-livestock interactions. We selected four case study crop-livestock farms of different resource endowment (Type 1–4 – excluding the poorest farmers, Type 5, who do not own livestock) and quantified all relevant physical flows through and within them. With this information we parameterised a dynamic, farm-scale simulation model to investigate (i) current differences in resource use efficiencies and degree of crop-livestock interactions across farm types; and (ii) the impact of different interventions in farm Types 3 and 4 on producing the desired shifts in productivity towards the ideal farm. Assuming no resource constraints, changes in the current farm systems were introduced stepwise, as both intensification of external input use (fertilisers and fodder) and qualitative changes in the configuration of the farms (i.e. changing land use towards fodder production, improving manure handling and/or changing cattle breeds). In 10-year simulations of the baseline, current scenario using historical weather data the wealthiest farms Type 2 achieved food self-sufficiency (FSS) in 20% of the seasons due to rainfall variability, whereas the poorer Type 4 only achieved FSS in 0 to 30% of the seasons; soil organic C decreased during the simulations at annual rates of −0.54, −0.73, −0.85 and −0.84 t C ha−1 on farms of Type 1–4, respectively; large differences in productivity and recycling efficiency between farm types indicated that there is ample room to improve the physical performance of the poorer farms (e.g. light and water use efficiency was 2–3 times larger on wealthier farms). Simulating different intensification scenarios indicated that household FSS can be achieved in all farm types through input intensification, e.g. using P fertilisers at rates as small as 15 kg farm−1 season−1 (i.e. from 7 to 28 kg ha−1). Increasing the area under Napier grass from c. 20 to 40% and reducing the area of maize, beans and sweet potato in farms of Type 3 and 4 increased their primary productivity by c. 1 t ha−1 season−1, their milk production by 156 and 45 L season−1, respectively, but decreased the production of edible energy (by 2000 and 250 MJ ha−1 season−1) and protein (by 20 and 3 kg ha−1 season−1). By bringing in a more productive cow the primary productivity increased even further in Farm Type 3 (up to 5 t ha−1 season−1), as did milk production (up to c. 1000 L season−1), edible energy (up to c. 10,000 MJ ha−1 season−1) and protein (up to c. 100 kg ha−1 season−1). The impact of livestock management on the recycling of nutrients and on the efficiency of nutrient use at farm scale can be large, provided that enough nutrients are present in or enter the system to be redistributed. An increase in N cycling efficiency through improved manure handling from 25 to 50% would increase the amount of N cycled in the case study farms of Type 1 and 2 by only ca. 10 kg season−1, and only 1–2 kg season−1 in Type 3 and 4. The various alternatives simulated when disregarding resource constraints contributed to narrow the productivity and efficiency gaps between poorer and wealthier farms. However, the feasibility of implementing such interventions on a large number of farms is questionable. Implications for system (re-)design and intensification strategies are discussed.

Initiatives on integrated vector management (IVM) approaches are increasingly undertaken as alternatives to existing vector control. An impact model of IVM is presented with performance and impact indicators at six causal steps from coverage of the intervention to impact on disease. Impacts in fields other than health are also discussed because of the emphasis in IVM on capacity building, partnerships and sustainability. A conceptual framework for evaluation of IVM is designed, based on considerations of the selection of indicators, level of inference, cluster size and method of evaluation. The framework, which is tested in three case studies, is intended as guidance for public health workers and policy-makers.

African smallholder farming systems are complex, dynamic systems with many interacting biophysical subcomponents. In these systems the major inputs and outputs are managed by human agency - the farmers. To analyse potential developmental pathways of smallholder farming systems in sub-Saharan Africa (SSA), we recognised the need for a tool that can capture the effects and consequences of decision-making on the use of resources. Here we describe and apply such a new modelling tool, developed within the NUANCES framework (Nutrient Use in ANimal and Cropping systems: Efficiencies and Scales), called NUANCES-FARMSIM (FARM SIMulator), an integrated crop - livestock model developed to analyse African smallholder farm systems. NUANCES-FARMSIM was used to analyse a representative case study farm in the highlands of Western Kenya. a site for which each of the components of FARMSIM has been thoroughly tested. We present the results of a sensitivity analysis which showed the model to be sufficiently robust to identify key management options that explain most of the variability in farm productivity, and the long-term consequences of these options for the case study farm. The analyses showed clearly that the most important decisions are those related to the interactions between the different components of the farm and therefore justify the need of integrating crop and livestock components within one modelling tool. The allocation of limited resources across the farm, and the way organic matter is recycled or redistributed within the farm determines the long-term production capacity of the system. The results of the sensitivity analyses further showed that for the case study farm in Western Kenya a strong focus on improving the reliability of the subsystem level or process descriptions will only result in minor improvement in simulating productivity at farm level.

Poor soil fertility and erratic rains are major constraints to crop production in semi-arid environments. In the smallholder farming systems of sub-Saharan Africa, these constraints are manifested in frequent crop failures and endemic food insecurity. We characterized a semi-arid smallholder farming system in south-western Zimbabwe to assess crop production, nutrient use and factors that constrain productivity. The farming system was studied using resource flow mapping, farmer interviews and calculations of crop production over three cropping seasons (2002/2003, 2003/2004 and 2004/2005) to capture variability between years. Farmers were categorized into three groups: better resourced, medium resourced and poorly resourced. Better resourced farmers produced adequate grain for basic household consumption, except in the drought year (2002/2003). Poorly resourced farmers had large grain deficits, whereas the medium resourced class had smaller deficits. Better resourced and medium resourced farmers produced adequate amounts of staple cereal in two of the seasons, while poorly resourced farmers produced inadequate amounts of food in all three seasons. All farmers produced less than 300 kg/ha of legumes per season. Lack of seed was cited as the main reason for poor legume production. Better resourced farmers used animal manure (2000-5000 kg per season) and some fertilizer on their cereal crops, while the medium resourced group used less manure (1000 kg or less) and no fertilizer. The use of manure varied strongly across the years. Poorly resourced farmers used no nutrient inputs on any of their crops. All groups had negative nitrogen balances during the three cropping seasons, although the values varied strongly between seasons. Investigation of the potential strategies for developing sustainable production systems are required to address the problems of food security in the semi-arid parts of the country and the region.

Water temperature is an important determinant in many aquatic biological processes, including the growth and development of malaria mosquito (Anopheles arabiensis and A. gambiae) immatures. Water turbidity affects water temperature, as suspended particles in a water column absorb and scatter sunlight and hence determine the extinction of solar radiation. To get a better understanding of the relationship between water turbidity and water temperature, a series of semi-natural larval habitats (diameter 0.32 m, water depth 0.16 m) with increasing water turbidity was created. Here we show that at midday (1300 hours) the upper water layer (thickness of 10 mm) of the water pool with the highest turbidity was on average 2.8 degrees C warmer than the same layer of the clearest water pool. Suspended soil particles increase the water temperature and furthermore change the temperature dynamics of small water collections during daytime, exposing malaria mosquito larvae, which live in the top water layer, longer to higher temperatures.

We studied the use of African water storage pots for point source application of Metarhizium anisopliae against the malaria vectors Anopheles gambiae s.s. and An. funestus. Clay pots were shown to be attractive resting sites for male and female An. gambiae s.s. and were not repellent after impregnation with fungus. M. anisopliae was highly infective and virulent after spray application inside pots. At a dosage of 4 x 1010 conidia/m2, an average of 95 ± 1.2% of An. gambiae s.s. obtained a fungal infection. A lower dosage of 1 x 1010 conidia/m2 infected an average of 91.5 ± 0.6% of An. gambiae s.s. and 91.8 ± 1.2% of An. funestus mosquitoes. Fungal infection significantly reduced mosquito longevity, as shown by differences between survival curves and LT50 values. These pots are suitable for application of entomopathogenic fungi against malaria vectors and their potential for sustainable field implementation is discussed.

An experiment including planted Tephrosia vogelii and Tithonia diversifolia fallow species and natural fallow was conducted at Maseno, Kenya, for assessing whether these fallows grown on a nutrient depleted land could produce sufficient green manure in six month period, whether their biomass retained on the same plots or transferred to continuously cropped plots with or without added P fertiliser could increase yield of consecutive maize crops and whether it is useful to regularly repeat these fallows on same plots. First fallow was established in randomized complete blocks with three replicates. At harvesting, biomass was recorded, then either incorporated in situ or transferred to continuous cropped plots split with and without added P fertiliser and monitored for the effect in improving consecutive maize crops. The second fallow was managed on this split plot design. The two-planted shrubs fallows produced more than 9 Mg total dry biomass and accumulated 154 to 234 kg N.ha-1, which were significantly higher compared to the production in the natural fallow. The shrubs were also superior to natural fallow for P accumulation (5-22 kg versus 2 kg.ha-1). The aboveground dry biomass harvested from planted T. vogelii and T. diversifolia and either incorporated in situ or transferred into continuously cropped plots increased maize yields by 2.5 folds compared to the unmanured crop, the control. Supplementing the organic materials with an additional 20 kg P inorganic fertilizer increased the 1st maize yield by about 40%. Productivity in the plots with T. vogelii or T. diversifolia aboveground biomass removal was low for the subsequent fallow and maize crops when compared to the performance in plots where biomass was incorporated. To achieve sustained yields of maize in depleted soils requires regular improved fallowing at least one season alternating with one season maize, and additional P inputs.

Background Long-acting artemisinin-based combination therapy (LACT) offers the potential to prevent recurrent malaria attacks in highly exposed children. However, it is not clear where this advantage will be most important, and deployment of these drugs is not rationalized on this basis. Methods To understand where post-treatment prophylaxis would be most beneficial, the relationship between seasonality, transmission intensity and the interval between malaria episodes was explored using data from six cohort studies in West Africa and an individual-based malaria transmission model. The total number of recurrent malaria cases per 1000 child-years at risk, and the fraction of the total annual burden that this represents were estimated for sub-Saharan Africa. Results In settings where prevalence is less than 10 %, repeat malaria episodes constitute a small fraction of the total burden, and few repeat episodes occur within the window of protection provided by currently available drugs. However, in higher transmission settings, and particularly in high transmission settings with highly seasonal transmission, repeat malaria becomes increasingly important, with up to 20 % of the total clinical burden in children estimated to be due to repeat episodes within 4 weeks of a prior attack. Conclusion At a given level of transmission intensity and annual incidence, the concentration of repeat malaria episodes in time, and consequently the protection from LACT is highest in the most seasonal areas. As a result, the degree of seasonality, in addition to the overall intensity of transmission, should be considered by policy makers when deciding between ACT that differ in their duration of post-treatment prophylaxis. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0839-4) contains supplementary material, which is available to authorized users.

International audience; Background The human landing catches is the gold standard method used to study the vectors of malaria and to estimate their aggressiveness. However, this method has raised safety concerns due to a possible increased risk of malaria or other mosquito-borne diseases among the mosquito collectors. The aim of this study was to evaluate the incidence of malaria attacks among mosquito collectors and to compare these results with those of non-collectors in a Senegalese village. Methods From July 1990 to December 2011, a longitudinal malaria study involving mosquito collectors and non-collectors was performed in Dielmo village, Senegal. During the study period, 4 drugs were successively used to treat clinical malaria, and long-lasting insecticide-treated nets were offered to all villagers in July 2008. No malaria chemoprophylaxis was given to mosquito collectors. Incidence of uncomplicated clinical malaria and asymptomatic malaria infection were analyzed among these two groups while controlling for confounding factors associated with malaria risk in random effects negative binomial and logistic regression models, respectively. Results A total of 3,812 person-trimester observations of 199 adults at least 15 years of age were analyzed. Clinical malaria attacks accounted for 6.3% both in collectors and non-collectors, and asymptomatic malaria infections accounted for 21% and 20% in collectors and non-collectors, respectively. A non-significant lower risk of malaria was observed in the collector group in comparison with the non-collector group after adjusting for other risk factors of malaria and endemicity level (Clinical malaria: adjusted incidence rate ratio = 0.89; 95% confidence interval = 0.65-1.22; p= 0.47). Conclusion Being a mosquito collector in Dielmo was not significantly associated with an increased risk of malaria both under holoendemic, mesoendemic and hypoendemic conditions of malaria epidemiology. This result supports the view that HLC, the most accurate method for evaluating malaria transmission, may be used without health concerns in Dielmo.

Background\ud In western Kenya, maternal mortality is a major public health problem estimated at 730/100,000 live births, higher than the Kenyan national average of 488/ 100,000 women. Many women do not attend antenatal care (ANC) in the first trimester, half do not receive 4 ANC visits. A high proportion use traditional birth attendants (TBA) for delivery and 1 in five deliver unassisted. The present study was carried out to ascertain why women do not fully utilise health facility ANC and delivery services.\ud \ud Methods\ud A qualitative study using 8 focus group discussions each consisting of 8–10 women, aged 15–49 years. Thematic analysis identified the main barriers and facilitators to health facility based ANC and delivery.\ud \ud Results\ud Attending health facility for ANC was viewed positively. Three elements of care were important; testing for disease including HIV, checking the position of the foetus, and\ud receiving injections and / or medications. Receiving a bed net and obtaining a registration card were also valuable. Four barriers to attending a health facility for ANC were evident; attitudes of clinic staff, long clinic waiting times, HIV testing and cost, although not all women felt the cost was prohibitive being worth it for the health of the child. Most women preferred to deliver in a health facility due to better management of complications. However cost was a barrier, and a reason to visit a TBA because of flexible payment. Other barriers were unpredictable labour and transport, staff attitudes and husbands’ preference.\ud \ud Conclusions\ud Our findings suggest that women in western Kenya are amenable to ANC and would be willing and even prefer to deliver in a healthcare facility, if it were affordable and accessible to them. However for this to happen there needs to be investment in health promotion, and transport, as well as reducing or removing all fees associated with antenatal and delivery care. Yet creating demand for service will need to go alongside investment in antenatal services at organisational, staffing and facility level in order to meet both current and future increase in demand.

Submitted in partial fulfillment of the requirements for the Degree of Masters in Business Administration Agricultural input organizations at best group farmers on the basis of geography and yet customers, the farmers, are the final arbiters on the financial performance of the organization. This research investigated multiple characteristics of farmers for farmer factors that may be used for targeting in the certified maize seed market of Western and Coastal Kenya. The latent class finite mixture method of cluster analysis was used to model a survey sample data of 313 observations and, therefore, to first define the farmer groups or segments in the study market and then investigate for those farmer factors that would be influential in targeting social or extension initiatives and marketing strategies to the farmers. The study found that the study market is dominated by smallholder farmers at 98%, and that the farmers may be grouped into two distinct farmer groups, the empowered smallholder farmer and the challenged smallholder farmer, with a proportion of 85% and 15% respectively. The empowered farmer has the desired positive agronomic practices but is socioeconomically challenged, while the challenged farmer has poor or negative agronomic practices and is socioeconomically adverse. Socioeconomic status and gender continued to be significant factors in the smallholder dominated market but negative or resistant agronomic practices were found to have the strongest associations. Consequently, farmers may be addressed as belonging to one of either profiles, and the empowered farmer profile may be the focus for marketing strategies design while the challenged farmer profile may be the focus for social initiatives design. Additionally, seed recycling resistant behavior should be a key factor and in the context of other factors as well.

Background The anthropophilic malaria mosquito Anopheles gambiae sensu stricto (hereafter termed Anopheles gambiae) primarily takes blood meals from humans, whereas its close sibling Anopheles arabiensis is more opportunistic. Previous studies have identified several compounds that play a critical role in the odour-mediated behaviour of An. gambiae. This study determined the effect of natural and synthetic odour blends on mosquitoes with different host preferences to better understand the host-seeking behaviour of mosquitoes and the potential of synthetic odour blends for standardized monitoring. Methods Odour blends were initially tested for their attractiveness to An. gambiae and An. arabiensis in a semi-field system with MM-X traps baited with natural and synthetic odours. Natural host odours were collected from humans, cows and chickens. The synthetic odour blends consisted of three or five previously identified compounds released with carbon dioxide. These studies were continued under natural conditions where odour blends were tested outdoors to determine their effect on species with different host preferences. Results In the semi-field experiments, human odour attracted significantly higher numbers of both mosquito species. However, An. arabiensis was also attracted to cow and chicken odours, which confirms its opportunistic behaviour. A five-component synthetic blend was highly attractive to both mosquito species. In the field, the synthetic odour blend caught significantly more An. funestus than traps baited with human odour, while no difference was found for An. arabiensis. Catches of An. arabiensis and Culex spp. contained large numbers of blood-fed mosquitoes, mostly from cows, which indicates that these mosquitoes had fed outdoors. Conclusions Different odour baits elicit varying responses among mosquito species. Synthetic odour blends are highly effective for trapping mosquitoes; however, not all mosquitoes respond equally to the same odour blend. Combining fermenting molasses with synthetic blends in a trap represents the most effective tool to catch blood-fed mosquitoes outside houses, which is essential for understanding outdoor malaria transmission. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0635-1) contains supplementary material, which is available to authorized users.

Adding a dynamic, temporal dimension to the calculation of nitrogen balances is proposed as an alternative approach to assessing the impact of crop and soil management decisions on the establishment of farmer-induced soil fertility gradients within smallholder African farms. A simulation model that operates at field scale (DYNBAL-N: DYnamic simulation of Nutrient BALances) was used to understand the mechanisms leading to differences in resource use efficiency within a farm. We focused on N balances and use efficiencies, as the advantages of increasing the complexity of the calculations by considering the dynamics of the system (relative to the widely-used static approach) are expected to be large for a highly mobile nutrient such as N. The model was tested against a wide range of maize yield data (0.2–3.4 t ha−1) from on-farm measurements undertaken in western Kenya (Vihiga, Kakamega and Teso districts), producing reasonably accurate predictions (r2 = 0.72). Simulation scenarios were selected by considering multiple sources of variability affecting the N balances for typical households in Shinyalu, western Kenya, using field data collected by means of interviews, participatory resource flow mapping, soil sampling and laboratory analysis. The simulation results indicated that the use efficiencies of the biophysical resources radiation, water and N varied across the different fields of the farms, strongly affected by management decisions and soil fertility status. N balances varied between −38.0 and 21.9 kg N ha−1 for the different crop and soil management scenarios. The main N flows explaining the magnitude and the sign of the N balances were N removal by harvest, and N losses by leaching (2.3–18.3 kg ha−1) and by soil erosion (0.6–14.9 kg ha−1). Different options for soil fertility management (N fertilisation rates, manure applications) were then explored for different field types within a farm using the model. The use efficiency of the N applied as mineral fertiliser varied between 15.2 and 48.4 kg grain kg−1 applied N for different crop and soil management scenarios. The results illustrated the advantages of including the temporal dimensions and considering the spatial variability in the calculation of nutrient balances, when realistic scenarios are analysed. These results also indicated that nutrient balances at field scale are of limited value as indicators of resource use efficiency, and that nutrient stocks and corresponding crop yields need to be taken into account.

We conducted a field study in an area of endemic malaria transmission in western Kenya to determine whether mosquitoes that feed on gametocyte-infected blood but do not become infected have reduced or enhanced fecundity in comparison to mosquitoes fed on uninfected blood. Fifteen paired membrane-feeding experiments were conducted in which two strains of Anopheles gambiae mosquitoes were simultaneously fed on either Plasmodium falciparum¿infected blood from children or uninfected control blood from adults. The presence of noninfecting gametocytes in blood increased the probability that An. gambiae would produce eggs after one blood meal by sixfold (odds ratio for control relative to infected blood group 0.16; 95% CI 0.10¿0.23). This result could not be explained by variation in blood meal size or hemoglobin content between hosts. When children cleared their infections, the difference in gravidity between mosquitoes fed on their blood and uninfected adults disappeared, suggesting this phenomenon is due to the presence of Plasmodium gametocytes in blood and not to host-specific factors such as age. This result was observed in two mosquito strains that differ in their innate fecundity, suggesting it may apply generally. To our knowledge, this is the first time that Plasmodium has been implicated as enhancing vector gravidity

Environmental management of mosquito resources is a promising approach with which to control malaria, but it has seen little application in Africa for more than half a century. Here we present a kinetic model of mosquito foraging for aquatic habitats and vertebrate hosts that allows estimation of malaria transmission intensity by defining the availability of these resources as the rate at which individual mosquitoes encounter and use them. The model captures historically observed responses of malaria transmission to environmental change, highlights important gaps in current understanding of vector ecology, and suggests convenient solutions. Resource availability is an intuitive concept that provides an adaptable framework for models of mosquito population dynamics, gene flow, and pathogen transmission that can be conveniently parameterized with direct field measurements. Furthermore, the model presented predicts that drastic reductions of malaria transmission are possible with environmental management and elucidates an ecologic basis for previous successes of integrated malaria control in Africa before the advent of DDT or chloroquine. Environmental management for malaria control requires specialist skills that are currently lacking in sub-Saharan Africa where they are needed most. Infrastructure and human capacity building in clinical, public health, and environmental disciplines should therefore be prioritized so that growing financial support for tackling malaria can be translated into truly integrated control programs.

Background: The full-scale impact of odour-baited technology on the surveillance, sampling and control of vectors of infectious diseases is partly limited by the lack of methods for the efficient and sustainable dispensing of attractants. In this study we investigated whether locally-available and commonly used textiles are efficient substrates for the release of synthetic odorant blends attracting malaria mosquitoes. Methods: The relative efficacy of (a) polyester, (b) cotton, (c) cellulose + polyacrylate, and (d) nylon textiles as substrates for dispensing a synthetic odour blend (Ifakara blend 1(IB1)) that attracts malaria mosquitoes was evaluated in western Kenya. The study was conducted through completely randomized Latin square experimental designs under semi-field and field conditions. Results: Traps charged with IB1-impregnated polyester, cotton and cellulose + polyacrylate materials caught significantly more female Anopheles gambiae sensu stricto (semi-field conditions) and An. gambiae sensu lato (field conditions) mosquitoes than IB1-treated nylon (P = 0.001). The IB1-impregnated cellulose + polyacrylate material was the most attractive to female An. funestus mosquitoes compared to all other dispensing textile substrates (P < 0.001). The responses of female An. funestus mosquitoes to IB1-treated cotton and polyester were equal (P = 0.45). Significantly more female Culex mosquitoes were attracted to IB1-treated cotton than to the other treatments (P < 0.001). Whereas IB1-impregnated cotton and cellulose + polyacrylate material attracted equal numbers of female Mansonia mosquitoes (P = 0.44), the catches due to these two substrates were significantly higher than those associated with the other substrates (P < 0.001). Conclusion: The number and species of mosquitoes attracted to a synthetic odour blend is influenced by the type of odour-dispensing material used. Thus, surveillance and intervention programmes for malaria and other mosquito vectors using attractive odour baits should select an odour-release material that optimizes the odour blend.

SUMMARYThe cumulative effect of co-infections between pathogen pairs on the haematological response of East African Short-horn Zebu calves is described. Using a longitudinal study design a stratified clustered random sample of newborn calves were recruited into the Infectious Diseases of East African Livestock (IDEAL) study and monitored at 5-weekly intervals until 51 weeks of age. At each visit samples were collected and analysed to determine the infection status of each calf as well as their haematological response. The haematological parameters investigated included packed cell volume (PCV), white blood cell count (WBC) and platelet count (Plt). The pathogens of interest included tick-borne protozoa and rickettsias, trypanosomes and intestinal parasites. Generalized additive mixed-effect models were used to model the infectious status of pathogens against each haematological parameter, including significant interactions between pathogens. These models were further used to predict the cumulative effect of co-infecting pathogen pairs on each haematological parameter. The most significant decrease in PCV was found with co-infections of trypanosomes and strongyles. Strongyle infections also resulted in a significant decrease in WBC at a high infectious load. Trypanosomes were the major cause of thrombocytopenia. Platelet counts were also affected by interactions between tick-borne pathogens. Interactions between concomitant pathogens were found to complicate the prognosis and clinical presentation of infected calves and should be taken into consideration in any study that investigates disease under field conditions.

Background The effects that artemether-lumefantrine (AL) has on gametocyte dynamics in the short-term have recently been described. However there is limited long-term longitudinal data on the effect of AL on gametocyte dynamics in asymptomatic children. Methods An epidemiological study was conducted in Kombewa, Western Kenya, in which 270 asymptomatic children aged between 12 and 47 months were enrolled. The subjects were randomized to receive either a course of AL or placebo at enrolment. Active follow-up was conducted for one year. Results The gametocyte prevalence and density dynamics throughout the study period mirrored that of the asexual forms. The proportion of initially parasitaemic subjects becoming gametocytaemic was significantly lower in the AL arm for the first 12 weeks following randomization. The geometric mean gametocyte density was lower in the AL arm for 2 weeks following randomization. None of the variables of interest had a statistically significant effect on the duration of gametocytaemia. There is no effect seen in subjects who are not parasitaemic at the time of drug administration. Conclusions The treatment of asymptomatic parasitaemic subjects with AL results in a significant reduction in the proportion of subjects who become gametocytaemic for at least 12 weeks.

Conference paper presented at the 1st African Conference on Sustainable Tourism in Strathmore University, Kenya. Literature, whether oral or written, is a reservoir for evidences of realities. Thus, Literature is a powerful tool for documenting social and historical- geographical landscapes. In this article landscapes are taken to mean natural structures that have been used as tourist sites. Perhaps the major use of literature therefore according to the understanding of this article is its potential for “revealing” the origin of the mentioned landscapes and landmarks, albeit in a fantastic manner to local and foreign tourists to such sites. To a literary scholar, this marks the symbiotic relationship between fact and fiction. It is factual because what is described is real and tangible and fictional too because the explanations often go beyond normal human understanding. Kenya is dotted with magnificent social and natural landscapes that have mapped out as tourist sites. . This article revisits the western regions of Kenya and the orature in which some of the landscapes found in these regions are to described innovatively either as contexts or texts. In the article we gather inspiration from explanatory tales that have been long narrated among the Luo and the Abaluhya, from generations to generations to archive the beliefs about the existence of these sites. We now ask ourselves; what are the artistic creations in relation to the landscapes in this region? Are there any stock characters or recurring features attached to these landscapes? To what extent can these narratives be used to market the sites? Thus, the purpose of this article is twofold to; 1) identify and carry out an eco-critical analysis of oral “texts” that are built on real landscapes in Western Kenya and 2) consider the extent to which this ecofriendly “texts” can be used to market the sites.

Background. Most odour baits for haematophagous arthropods contain carbon dioxide (CO2). The CO2 is sourced artificially from the fermentation of refined sugar (sucrose), dry ice, pressurized gas cylinders or propane. These sources of CO2 are neither cost-effective nor sustainable for use in remote areas of sub-Saharan Africa. In this study, molasses was evaluated as a potential substrate for producing CO2 used as bait for malaria mosquitoes. Methods. The attraction of laboratory-reared and wild Anopheles gambiae complex mosquitoes to CO2 generated from yeast-fermentation of molasses was assessed under semi-field and field conditions in western Kenya. In the field, responses of wild Anopheles funestus were also assessed. Attraction of the mosquitoes to a synthetic mosquito attractant, Mbita blend (comprising ammonia, L-lactic acid, tetradecanoic acid and 3-methyl-1-butanol) when augmented with CO2 generated from yeast fermentation of either molasses or sucrose was also investigated. Results. In semi-field, the release rate of CO2 and proportion of An. gambiae mosquitoes attracted increased in tandem with an increase in the quantity of yeast-fermented molasses up to an optimal ratio of molasses and dry yeast. More An. gambiae mosquitoes were attracted to a combination of the Mbita blend plus CO2 produced from fermenting molasses than the Mbita blend plus CO2 from yeast-fermented sucrose. In the field, significantly more female An. gambiae sensu lato mosquitoes were attracted to the Mbita blend augmented with CO2 produced by fermenting 500 g of molasses compared to 250 g of sucrose or 250 g of molasses. Similarly, significantly more An. funestus, Culex and other anopheline mosquito species were attracted to the Mbita blend augmented with CO2 produced from fermenting molasses than the Mbita blend with CO2 produced from sucrose. Augmenting the Mbita blend with CO2 produced from molasses was associated with high catches of blood-fed An. gambiae s.l. and An. funestus mosquitoes. Conclusion. Molasses is a suitable ingredient for the replacement of sucrose as a substrate for the production of CO2 for sampling of African malaria vectors and other mosquito species. The finding of blood-fed malaria vectors in traps baited with the Mbita blend and CO2 derived from molasses provides a unique opportunity for the study of host-vector interactions.

Background: Mosquitoes are the dominant vectors of pathogens that cause infectious diseases such as malaria, dengue, yellow fever and filariasis. Current vector control strategies often rely on the use of pyrethroids against which mosquitoes are increasingly developing resistance. Here, a push-pull system is presented, that operates by the simultaneous use of repellent and attractive volatile odorants. Method/Results: Experiments were carried out in a semi-field set-up: a traditional house which was constructed inside a screenhouse. The release of different repellent compounds, para-menthane-3,8-diol (PMD), catnip oil e.o. and delta-undecalactone, from the four corners of the house resulted in significant reductions of 45% to 81.5% in house entry of host-seeking malaria mosquitoes. The highest reductions in house entry (up to 95.5%), were achieved by simultaneously repelling mosquitoes from the house (push) and removing them from the experimental set-up using attractant-baited traps (pull). Conclusions: The outcome of this study suggests that a push-pull system based on attractive and repellent volatiles may successfully be employed to target mosquito vectors of human disease. Reductions in house entry of malaria vectors, of the magnitude that was achieved in these experiments, would likely affect malaria transmission. The repellents used are non-toxic and can be used safely in a human environment. Delta-undecalactone is a novel repellent that showed higher effectiveness than the established repellent PMD. These results encourage further development of the system for practical implementation in the field.

Aiming to translate resilience thinking theory into farming systems design practice, this paper examines fundamental properties of complex systems dynamics and their relation with the mechanisms that govern resilience and transformability in African smallholder agriculture. Agroecosystems dynamics emerge from the aggregation of diverse livelihood strategies in response to changes in the agroecosystem context, and are characterised by non-linearity, irreversibility, convergence/divergence and hysteresis. I examine a number of case studies from Africa to verify three guiding hypotheses in connection to the diversity of rural livelihood strategies: (1) diversity as alternative system regimes; (2) diversity as the result of transformability; (3) diversity determined by changing agricultural contexts. The hierarchy of constraints that determine the space for manoeuvring in agroecosystems is described through the analogy of the Matryoshka nesting dolls: each system level confines and is confined by their immediate sub- and supra-systems. Agricultural contexts, as defined by agro-ecological potential, demography and market connectivity are also dynamic and their trajectory can be described as shifts across stability domains. An example from Kenya shows that household diversity can be described as alternative system regimes, through hysteretic rather than continuous, reversible models. In some particular cases diversity emerges from divergent pathways that may have implied radical transformations in the past, as shown here for rural livelihoods in northern Cameroun. A comparative analysis of East African agroecosystems shows that thresholds in specific variables that may point to the existence of possible tipping points are rather elusive and largely site specific, requiring systematic categorisation of agricultural contexts. While agroecology needs to provide the knowledge base for the ecological intensification of smallholder landscapes, policy and market developments are needed to deal with the Matryoshka effect – or with interactions that are presumably panarchical in certain cases. Desirable shifts in farming systems can only be stimulated by working on both ends simultaneously.

The strong link between poverty, natural resources and the environment is apparent in smallholder agriculture: farmers are making repeated land use and management decisions while facing diverse resource endowments and significant environmental constraints on production. To investigate the likely effects of changes in agricultural practices on the natural resource base and on farmer welfare, we develop a bio-economic dynamic model of agricultural households in the western Kenya highlands. Our modeling framework extends economic farm household models to incorporate the dynamic nature of natural resource management and its implications for household welfare, and to permit a meaningful interface with biophysical processes through soil carbon management. Using an eight-year panel data set, the model combines econometrically estimated production and soil carbon flow equations in a dynamic programming framework. We use the model to determine the optimal management of the farming system over time in terms of the quantity of mineral fertilizer and crop residues to apply, taking into consideration initial resource endowments and prices. Understanding how soil resources respond to the combined applications of mineral and organic resources is important for improved resource allocation at the farm level and for national agricultural policy decisions.

Regular treatment with praziquantel (PZQ) is the strategy for human schistosomiasis control aiming to prevent morbidity in later life. With the recent resolution on schistosomiasis elimination by the 65th World Health Assembly, appropriate diagnostic tools to inform interventions are keys to their success. We present a discrete Markov chains modelling framework that deals with the longitudinal study design and the measurement error in the diagnostic methods under study. A longitudinal detailed dataset from Uganda, in which one or two doses of PZQ treatment were provided, was analyzed through Latent Markov Models (LMMs). The aim was to evaluate the diagnostic accuracy of Circulating Cathodic Antigen (CCA) and of double Kato-Katz (KK) faecal slides over three consecutive days for Schistosoma mansoni infection simultaneously by age group at baseline and at two follow-up times post treatment. Diagnostic test sensitivities and specificities and the true underlying infection prevalence over time as well as the probabilities of transitions between infected and uninfected states are provided. The estimated transition probability matrices provide parsimonious yet important insights into the re-infection and cure rates in the two age groups. We show that the CCA diagnostic performance remained constant after PZQ treatment and that this test was overall more sensitive but less specific than single-day double KK for the diagnosis of S. mansoni infection. The probability of clearing infection from baseline to 9 weeks was higher among those who received two PZQ doses compared to one PZQ dose for both age groups, with much higher re-infection rates among children compared to adolescents and adults. We recommend LMMs as a useful methodology for monitoring and evaluation and treatment decision research as well as CCA for mapping surveys of S. mansoni infection, although additional diagnostic tools should be incorporated in schistosomiasis elimination programs., Author Summary Schistosomiasis remains one of the most prevalent parasitic diseases in developing countries, with Schistosoma mansoni being the most widespread of the human-infecting schistosomes. For the routine surveillance of human S. mansoni infection more “field-applicable,” sensitive, and cost-effective diagnostics that replicate faecal samples over several consecutive days [the Kato-Katz (KK) method], are needed. We propose a statistical modelling framework in order to evaluate the diagnostic performance of the urine strip test for Circulating Cathodic Antigen (CCA) and single-day double KK measurements over three consecutive days for the diagnosis of S. mansoni infection in two different age groups from Uganda pre- and post- praziquantel (PZQ) treatment. We demonstrate that CCA is an appropriate tool for mapping surveys of S. mansoni infection. Our findings should allow for evaluation of the risk of potential misinterpretation with regards to diagnosis of S. mansoni infection through CCA or KK in this endemic setting pre- and post- PZQ treatment as the numbers and infection intensities are brought down, bridging existing important gaps in schistosomiasis diagnostics research. More generally, the proposed statistical analysis can reveal important biological insights from other diseases without gold standard diagnostic tools whenever longitudinal data are available.