Identification of environmental parameters and risk mapping of visceral leishmaniasis in Ethiopia by using geographical information systems and a statistical approach

Abstract

Abstract. Visceral leishmaniasis (VL), a vector-borne disease strongly influenced by environmental factors, has (re)-emerged in Ethiopia during the last two decades and is currently of increasing public health concern. Based on VL incidence in each locality (kebele) documented from federal or regional health bureaus and/or hospital records in the country, geographical information systems (GIS), coupled with binary and multivariate logistic regression methods, were employed to develop a risk map for Ethiopia with respect to VL based on soil type, altitude, rainfall, slope and temperature. The risk model was subsequently validated in selected sites. This environmental VL risk model provided an overall prediction accuracy of 86% with mean land surface temperature and soil type found to be the best predictors of VL. The total population at risk was estimated at 3.2 million according to the national population census in 2007. The approach presented here should facilitate the identification of priority areas for intervention and the monitoring of trends as well as providing input for further epidemiological and applied research with regard to this disease in Ethiopia.

Visceral Leishmaniasis in Benishangul-Gumuz Regional State, Western Ethiopia: Reemerging or Emerging?

“…2 The lack of correlation of positivity rate with age, as is commonly observed in established endemic foci 15,16 (Table 1), suggests that there is no cumulative response to infection from historical exposures, and thus infection in the area is likely to be of recent origin. A similar association of Leishmania infection with farming practices, as indicated in our survey, has previously been reported by Fuller and others 17 in the Humera focus.…”

“…1 In Ethiopia, over 3.2 million people live at risk of infection with up to 4,500 new cases of kalaazar per year. 2,3 The known endemic foci are the SegenWoito valleys, lower Omo river plains, Lake Abaya area in the southwest, and Metema-Humera area in the northwest. 4 The east African region has experienced several outbreaks of kala-azar in recent years.…”

“…Parts of the Benishangul-Gumuz regional state fall under high and very high risk zones according to the kalaazar environmental factor-based risk map. 2 However, to our knowledge, there has so far been no report of kala-azar from the region although it is currently home to new small-and large-scale development programs that penetrate into formerly uninhabited or sparsely inhabited areas that attracted influxes of immigrants and shift population bases, all factors which could potentially lead to the establishment of new foci. We conducted a rapid assessment to verify if there is autochthonous transmission in the area of Benishangul-Gumuz where the kala-azar case came from so that appropriate measures could be taken for early intervention.…”

Environmental modelling of visceral leishmaniasis by susceptibility-mapping using neural networks: a case study in north-western Iran

“…To specify the input data for the prediction model, the association between VL endemicity and various factors in the literature was explored. In this regard, seven items were deduced from literature to be the critical recognition criteria (CRC) for predictive mapping of VL risk-prone areas: temperature, precipitation, proximity to rivers, altitude, presence of health-centres, land cover and presence of nomads (Sudhakar et al, 2006;Bhunia et al, 2010;Salahi-Moghaddam et al, 2010;Rajabi et al, 2012;Tsegaw et al, 2013).…”

Leishmaniasis: A Review on Parasite, Vector and Reservoir Host

“…Human imposed environmental changes result in the modification of the micro-ecology of the parasite, the vector and the reservoir host favoring the higher transmission of leishmaniasis in areas [58]. Human activities such as deforestation, agricultural development and settlements near forested areas and domestication of animals are reasons for occurrence of both zoonotic and anthroponotic transmissions of leishmaniasis [59]. Hence, control and elimination of leishmaniasis largely depends on the understanding of how leishmaniasis involves various mammalian reservoir hosts, whose epidemiological role is yet to be fully understood [60,61].…”