Identifying Diseased Areas using a Geospatially Developed Human African Trypanosomiasis Vector Habitat Classification Scheme

Human African Trypanosomiasis (HAT) is a vector-borne disease transmitted by the bite of the tsetse fly that results in high human morbidity and mortality.  There is no HAT vaccine, but biological control of the vector has been successful in reducing HAT incidence. However, in recent years the disease has re-emerged and spread. Due to insufficient knowledge of HAT endemic foci, the disease management remains challenging. Information is vital to effective disease management, but the level of underreporting of disease, most especially HAT in Nigeria, impedes progress. The information gap, such as comprehensive digital spatial epidemiological information/data, could be reduced with geo-referenced studies, lacking in some previous work.  To achieve effective deployment of control strategies, accurate knowledge of the spatial distribution of the disease is vital. The current study is based in Nigeria, and looks at part of Delta State, in which HAT has been identified.  The study utilizes a previously geospatially developed HAT vector habitat classification scheme, to explore the dynamics of HAT propagation. The goal was to map the direction and magnitude of HAT and identify HAT vulnerable/risk areas. This helped identify ‘HAT priority intervention areas’. The study highlights the significance of geospatial techniques where epidemiological data are limited, for improving understanding of HAT.   The study findings suggested HAT propagation in the study area was multidirectional, and that this may have been influenced by landscape characteristics.  The study also suggested that the study area could be regarded as highly hazardous and that the human population residing in the area could be said to be at moderate risk of HAT. The method employed in this study will facilitate efficient decision making, planning for resource allocation as well as support active HAT surveillance. Keywords: Propagation, geospatially, multidirectional, disease

Assessment and Management of Human African Trypanosomiasis Propagation using Geospatial Techniques

Human African Trypanosomiasis (HAT) is a chronic and acute vector-borne disease. The propagation of the disease has been linked to environmental factors, and understanding the vector’s habitat is vital to its control. The available medications for HAT are dated, lethal and expensive, but biological control of the vector has been successful in some endemic foci. Nevertheless, recently the disease has re-emerged and spread and its management remains demanding. To manage and control the disease effectively, precise, up-to-date and comprehensive knowledge of its spatial characteristics is essential. This study is based in HAT endemic foci of Delta State, Nigeria. The study applied a geospatially developed HAT vector habitat classification scheme to assess the vulnerability level of settlements affected by HAT.  In addition, factors influencing HAT propagation and land cover suitability for HAT Vector within HAT vector Habitat Zones were investigated and assessed in a geographic information system environment.  The aim was to present HAT endemic countries with strategy for mapping and deriving precise, timely and life saving data/information from HAT vector habitat.  The study emphasizes the importance of geospatial techniques where there are dearths of epidemiological data, for improving perceptive of HAT.  The study findings suggested propagation of HAT resulted from suitability of water bodies, shrub and less-dense forest for the HAT vector, and continued exposure of human populations to these land cover classes. Overlapping of HAT vector habitat zones within built-up areas was also a cause. This novel approach can also be used in other part of Nigeria as well as adapted to investigate other diseases. Keywords:  Trypanosomiasis, Geospatial, Propagation, Epidemiological, HA

Development of a Classification Scheme for Managing Human African Trypanosomiasis using Geospatial Techniques

Distinctive environ-climatic variables have been associated with Trypanosoma brucei gambiense spatial characteristics, signifying the importance of physical landscape in HAT propagation/risk. Nevertheless, techniques projected to classify human African trypanosomiasis (HAT) vector habitats tend to be generalised, time wasting and costly.  Despite control efforts, HAT has become resurgent in some locations. No model to acquire detailed and comprehensive HAT spatial or epidemiological data exists for the study area, meaning many of those most in need, especially those  residing in remotest parts of the region, may not be benefitting from good health care due to lack of information about them. This paper proposes a geospatial technique to explore vector habitat mapping. The goal was to develop a surveillance methodology that will facilitate quick and efficient management of HAT.  Supervised classification and fuzzy logic were integrated to classify land cover and ancillary datasets into HAT vector habitat. The importance of criteria and how they were prioritised were determined by the judgments of experts, the impact of the criteria on HAT propagation and previous studies. Spatial distribution/habitat characteristics play an important role in HAT propagation. Therefore, locations which have all or most of these criteria present are vital for HAT propagation. This study helped distinguish HAT vector habitat into different zones (breed, feed and rest), the classification scheme is expected to offer effective decision support to all stakeholders. Keywords: Geospatial, Remote Sensing, Geographic Information Systems, Fuzzy, Vecto

Assessment of Human African Trypanosomiasis Foci using Change Detection Algorithms

Environ-climatic change influences the occurrence and propagation of Human African Trypanosomiasis (HAT), focusing on two foci; Delta State and Jigawa State Nigeria where HAT has been reported. Geospatial and temporal based ground truthing exercise carried out to harvest HAT vector in Jigawa state did not yield any results; this indicates that the disease might have been phased out in the state.  In the same vein, resurging of HAT disease in the Delta State has been reported of recent. Thus, a change detection analysis was conducted in a geographic information systems (GIS) environment, to investigate the foci landscape. Using normalised difference vegetation index (NDVI), normalised difference water index (NDWI) and tasseled cap transformation (TCT), changes with a lag time of two decades was assessed for the two foci.  The analysis suggested that the landscape has changed considerably over the years that show Delta State as the potential active HAT foci as explained from the regression analysis of 0.9868 (99%) ahead of Jigawa state 0.0000 (0%) that can be regarded as non-active foci.  However, on-going programs, such as afforestation, forestation, irrigation farming and water reservoir projects may result in re-introduction of favourable landscape, thus, re-invasion of the area by the HAT vector. Therefore strategies that will maintain the present HAT-free status of the non-active foci, without adverse effect on the environment should be a government priority. To effectively reduce or control HAT propagation, integrated prevention schemes should be developed and executed.  The two HAT foci are of great economic importance; Delta State landscape is rich in hydrocarbons while Jigawa State is known for its extensive grazing and arable landscape. Keywords: Trypanosomiasis, Afforestation, Foci, HAT, Landscape, Environ-climatic, Spatial, Irrigatio

A holistic approach to Concentration Assessment of hazards in the risk assessment of landfill leachate

Risk assessment is a new research area. The risk assessment research area deals with a wide range of issues other than landfills. Examples of these issues are Radiation, Food Industry, Ecology, Epidemiology, etc. The authors have found that there are generic elements in risk assessment and these elements are independent of the subject areas mentioned above. An important example of these generic elements is the Concentration Assessment of hazards and is equally important from the perspective of landfill risk assessment. Furthermore, in the literature review of landfill risk assessment approaches, no evidence has been discovered of a holistic risk assessment methodology for landfill gas, leachate, or degraded landfill waste. A range of knowledge deficiencies has been found in the literature reviewed to date. One of these deficiencies in knowledge is the lack of a holistic procedure for carrying out Concentration Assessment. From the perspective of landfill leachate, this paper discusses the extent to which the Concentration Assessment of hazards is absent in landfill risk assessment approaches described in the literature reviewed to date, and the elements that should be added to the procedure of the Concentration Assessment in order to enhance the process of risk assessment. The paper also briefly outlines a holistic procedure for the Concentration Assessment and a corresponding computer model for the risk assessment of landfill leachate

Integrating varietal resistance with Xylopia aethiopica (Dunal) A. Richard seed extract for the management of Sitophilus zeamais Motschulsky in stored maize

In search for alternatives to synthetic pesticides in maize (Zea mays, L.) storage, an integrated weevil management scheme involving varietal resistance and Xylopia aethiopica (Dunal) A. Richard seed extract was evaluated in the laboratory. Varying rates of X. aethiopica extract were assessed on three maize varieties (Pajo White, Tsolo Yellow, and DMR-LSR-Y) with differing susceptibility to Sitophilus zeamais. The different rates of X. aethiopica extract significantly interacted with maize varietal resistance and reduced fecundity of S. zeamais and maize seed weight loss due to insect’s feeding. Treatment of seeds with extract at 1.0 ml/20 g seed caused significant (above 50%) mortality at 24 h post treatment in all varieties whereas no mortality was recorded with the control and 0.2 ml/20 g seed. DMRLSR-Y was better protected than the remaining two varieties in the integrated weevil management scheme. A repellency bioassay of the extract also revealed that the extract was strongly repellent to S. zeamais with 73% (Class IV) repellency recorded in 0.4 ml/30 cm2

Hazard Identification and Categorization for Waste Disposal Sites: Part 1 – an Integrated Approach Lacks

Risk assessment provides a proactive and logical ground for many decision-making processes. Although the approach of risk assessment nowadays is well established, it remains a relatively new research area, with increasing interest in understanding the principles that underpin the practice. In the review of computer models and literature on environmental risk assessments in general and the risk analysis of waste disposal sites in particular, the authors have determined that a comprehensive risk assessment methodology covering all modules and sub-modules for landfill leachate does not exist. The same fact holds for landfill gas and degraded landfill waste (although these are both beyond the scope of this paper). A range of knowledge deficiencies is identified in the literature. One such deficiency is the development of a strategic procedure for carrying out Hazard Identification and Categorization for risk assessment of landfill leachate, assisted with a corresponding computer model. This study, with reference to the relevant literature, discusses the extent to which the Hazard Identification and Categorization procedure is absent in landfill risk analysis approaches. The elements, which should be added to such a procedure in order to more effectively underpin landfill risk assessments, are also indicated