Chapter 9

Niger is a landlocked country in West Africa located between 11°37 ´ and 23°23 ´ north latitude and between 00°10 ´ and 16°00 ´ east longitude, with an area of 1,267,000 square kilometers. Niger shares borders wit

Evaluating maize yield variability and gaps in two agroecologies in northern Ghana using a crop simulation model

Article purchased; Published online: 19 Oct 2017The yield gap and variability in maize under smallholder systems in two agroecologies in northern Ghana were evaluated using a decision support system for agrotechnology transfer (DSSAT). The model was used to assess (1) the potential yield of maize (YPOT), (2) water-limited exploitable maize yield (YWEX), (3) nitrogen-limited yield (YNI), (4) farmer practice maize yield (YCFP) and (5) proposed enhanced nutrient use yield (enhanced farmer practice; YEFP). Effect of supplementary irrigation was also assessed on YCFP and YEFP conditions. Yield gaps were determined as the difference between YPOT and YCFP or YEFP on the one hand, and between YWEX and YCFP or YEFP on the other hand. The yield gap based on potential yield ranged from 59% to 75% under CFP and narrowed to between 29% and 59% under EFP. With water-limited exploitable yields, the yield gap ranged from 53% to 65% under CFP, reducing to between 22% and 42% under EFP. The use of supplementary irrigation further reduced the yield gap. Improved fertiliser use and supplementary irrigation have the potential to increase yield and hence reduce the yield gap if effective policies and institutional structures are in place to provide farmers with credit facilities and farm inputs

Evaluation of the fluorescent-thin layer chromatography (f-TLC) for the diagnosis of Buruli ulcer disease in Ghana

BACKGROUND: Buruli ulcer is a tissue necrosis infection caused by an environmental mycobacterium called Mycobacterium ulcerans (MU). The disease is most prevalent in rural areas with the highest rates in West and Central African countries. The bacterium produces a toxin called mycolactone which can lead to the destruction of the skin, resulting in incapacitating deformities with an enormous economic and social burden on patients and their caregivers. Even though there is an effective antibiotic treatment for BU, the control and management rely on early case detection and rapid diagnosis to avert morbidities. The diagnosis of Mycobacterium ulcerans relies on smear microscopy, culture histopathology, and PCR. Unfortunately, all the current laboratory diagnostics have various limitations and are not available in endemic communities. Consequently, there is a need for a rapid diagnostic tool for use at the community health centre level to enable diagnosis and confirmation of suspected cases for early treatment. The present study corroborated the diagnostic performance and utility of fluorescent-thin layer chromatography (f-TLC) for the diagnosis of Buruli ulcer. METHODOLOGY/PRINCIPAL FINDINGS: The f-TLC method was evaluated for the diagnosis of Buruli ulcer in larger clinical samples than previously reported in an earlier preliminary study Wadagni et al. (2015). A total of 449 patients suspected of BU were included in the final data analysis out of which 122 (27.2%) were positive by f-TLC and 128 (28.5%) by PCR. Using a composite reference method generated from the two diagnostic methods, 85 (18.9%) patients were found to be truly infected with M. ulcerans, 284 (63.3%) were uninfected, while 80 (17.8%) were misidentified as infected or noninfected by the two methods. The data obtained was used to determine the discriminatory accuracy of the f-TLC against the gold standard IS2404 PCR through the analysis of its sensitivity, specificity, positive (+LR), and negative (–LR) likelihood ratio. The positive (PPV) and negative (NPV) predictive values, area under the receiver operating characteristic curve Azevedo et al. (2014), and diagnostic odds ratio were used to assess the predictive accuracy of the f-TLC method. The sensitivity of f-TLC was 66.4% (85/128), specificity was 88.5% (284/321), while the diagnostic accuracy was 82.2% (369/449). The AUC stood at 0.774 while the PPV, NPV, +LR, and–LR were 69.7% (85/122), 86.9% (284/327), 5.76, and 0.38, respectively. The use of the rule-of-thumb interpretation of diagnostic tests suggests that the method is good for use as a diagnostic tool. CONCLUSIONS/SIGNIFICANCE: Larger clinical samples than previously reported had been used to evaluate the f-TLC method for the diagnosis of Buruli ulcer. A sensitivity of 66.4%, a specificity of 88.5%, and diagnostic accuracy of 82.2% were obtained. The method is good for diagnosis and will help in making early clinical decisions about the patients as well as patient management and facilitating treatment decisions. However, it requires a slight modification to address the challenge of background interference and lack of automatic readout to become an excellent diagnostic tool

Isolation of Angola-like Marburg virus from Egyptian rousette bats from West Africa.

Marburg virus (MARV) causes sporadic outbreaks of severe Marburg virus disease (MVD). Most MVD outbreaks originated in East Africa and field studies in East Africa, South Africa, Zambia, and Gabon identified the Egyptian rousette bat (ERB; Rousettus aegyptiacus) as a natural reservoir. However, the largest recorded MVD outbreak with the highest case-fatality ratio happened in 2005 in Angola, where direct spillover from bats was not  shown. Here, collaborative studies by the Centers for Disease Control and Prevention, Njala University, University of California, Davis USAID-PREDICT, and the University of Makeni identify MARV circulating in ERBs in Sierra Leone. PCR, antibody and virus isolation data from 1755 bats of 42 species shows active MARV infection in approximately 2.5% of ERBs. Phylogenetic analysis identifies MARVs that are similar to the Angola strain. These results provide evidence of MARV circulation in West Africa and demonstrate the value of pathogen surveillance to identify previously undetected threats

The future of food security, environments and livelihoods in Western Africa: Four socio-economic scenarios

This working paper examines the development of regional socioeconomic scenarios for West Africa’s development, agriculture, food security and climate impacts. We present four globally consistent regional scenarios framed and outlined by regional experts who crafted narratives and determined key drivers of change. Stakeholders identified the type of actors driving change and the timeline of strategic planning as the most uncertain and most relevant factors of change affecting food security, livelihoods and environments in the region. The scenarios were linked to the IPCC community’s global Shared Socio-economic Pathways (SSPs) and quantified using two agricultural economic models, GLOBIOM and IMPACT, in interaction with drivers outlined by the SSPs and guided by semi-quantitative information from the stakeholders. The quantification of the scenarios has provided additional insights into the possible development of Western Africa in the context of a global economy as well as how the agricultural sector may be affected by climate change. The scenarios process highlights the need to combine socio-economic and climate scenarios, to base these scenarios in regional expertise, and ways to make scenarios useful for policy design. The objective of this working paper is to provide scenarios for future regional development for West Africa on the future of food security, environment, and rural livelihoods as well as offer details of the multi-stakeholder scenarios development process. Using both qualitative and quantitative scenarios we provide insights into the possible development of West Africa as well as a scalable framework for regional decision makers and the scientific community to use scenarios to build and test policies to make them more robust in the face of future uncertainty. In these scenarios, strong economic development increases food security and agricultural development. Increased crop and livestock productivity may lead to an expansion of agricultural areas within the region but productivity improvements may reduce the pressure on land elsewhere. In the context of a global economy, West Africa remains a large consumer and producer of a selection of commodities. However, the growth in population in combination with rising incomes may lead to increases in the region’s imports. For West Africa, climate change is likely to have negative effects on both crop yields and grassland productivity, and lack of investment in agriculture may exacerbate them. The aim of the regional scenarios is provide challenging contexts for policy makers to test and develop a range of national and regional policies. To date, the scenarios have been used in a number of policy design processes which include collaborations with ECOWAS priority setting, the National Plan for the Rural Sector for Burkina Faso (PNSR), and district and national level policy processes in Ghana

Diversification and agrarian change under environmental constraints in rural China: Evidence from a poor township of Beijing municipality

Working paper du GATE 2007-11This article illustrates the impact of changes related to market reforms and environmental policies on the economic structure in rural China by providing a comparative analysis of several villages in a poor township in Beijing municipality. Two main concomitant phenomena are affecting agricultural and non-agricultural choices in the studied area. First, the introduction of market mechanisms is encouraging local population to engage in new activities that are closer to local comparative advantages. Second, rural households are facing new constraints in the form of environmental protection measures, which have weakened traditional insurance channels provided by forest resources and cattle stock. Drawing on household-level survey data and interviews with village heads conducted in ten villages of Labagoumen township in December 2003, this article analyzes households decisions in response to market reforms and environmental constraints. We find large disparities both between villages and households in the diversification process and discuss the reasons of observed inertia in the region, most households still heavily relying on corn production