Environmental factors associated with the distribution of visceral leishmaniasis in endemic areas of Bangladesh: modeling the ecological niche

Abstract

BackgroundVisceral leishmaniasis (VL) is a parasitic infection (also called kala-azar in South Asia) caused by Leishmania donovani that is a considerable threat to public health in the Indian subcontinent, including densely populated Bangladesh. The disease seriously affects the poorest subset of the population in the subcontinent. Despite the fact that the incidence of VL results in significant morbidity and mortality, its environmental determinants are relatively poorly understood, especially in Bangladesh. In this study, we have extracted a number of environmental variables obtained from a range of sources, along with human VL cases collected through several field visits, to model the distribution of disease which may then be used as a surrogate for determining the distribution of Phlebotomus argentipes vector, in hyperendemic and endemic areas of Mymensingh and Gazipur districts in Bangladesh. The analysis was carried out within an ecological niche model (ENM) framework using a maxent to explore the ecological requirements of the disease.ResultsThe results suggest that VL in the study area can be predicted by precipitation during the warmest quarter of the year, land surface temperature (LST), and normalized difference water index (NDWI). As P. argentipes is the single proven vector of L. donovani in the study area, its distribution could reasonably be determined by the same environmental variables. The analysis further showed that the majority of VL cases were located in mauzas where the estimated probability of the disease occurrence was high. This may reflect the potential distribution of the disease and consequently P. argentipes in the study area.ConclusionsThe results of this study are expected to have important implications, particularly in vector control strategies and management of risk associated with this disease. Public health officials can use the results to prioritize their visits in specific areas. Further, the findings can be used as a baseline to model how the distribution of the disease caused by P. argentipes might change in the event of climatic and environmental changes that resulted from increased anthropogenic activities in Bangladesh and elsewhere.

Leishmaniasis in Sri Lanka: spatial distribution and seasonal variations from 2009 to 2016

“…Climatic changes in rainfall, humidity and atmospheric temperature influence behavioral activities and the life-cycle of vectors and reservoir hosts for leishmaniasis [35, 36]. A study in India reported that 29 °C to 31 °C was the most favorable range of the distribution of leishmaniasis, suggesting the potential of P. argentipes abundance in higher temperatures [37]. In the present study, we identified that all of the endemic regions are situated in low altitude areas less than 100 m above sea level and the mean temperature of all of these districts range between 26.5–28.5 °C.…”

Geo‐climatic factors in a newly emerging focus of zoonotic visceral leishmaniasis in rural areas of north‐eastern Iran

“…The critical role of moist condition on the development of Ph. argentipes, the single proven vector of L. donovani in Bangladesh was assumed for the fact behind this evidence (Md Abdullah, Dewan, Shogib, Rahman, & Hossain, ). Also, precipitation in the driest months was effective on the distribution of ZVL in Sinking, northwest China (Gao & Cao, ).…”

“…Relation of ZVL with warmer seasons in Spain (Perez‐Cutillas et al, ), the maximum temperature of warmest months in Greece (Giannakopoulos et al, ), the maximum temperature of warmest quarter of year in China (Gao & Cao, ), land surface temperature in Bangladesh (Md Abdullah et al, ), higher range of temperature in India (Bhunia et al, ), mean annual temperature in Ethiopia (Tsegaw et al, ), the strong positive influence of temperature on dispersion of ZVL infected dog and vectors in Sao Paulo, Brazil (da Paixão Sevá, Mao, Galvis‐Ovallos, Lima, & Valle, ) and mean annual maximum daily temperature on vector of disease in Sudan (Thomson, Elnaiern, Ashford, & Connor, ) have been reported.…”

Prediction of Cutaneous Leishmaniasis Epidemiology in Mersin Using Ecological Niche Modeling

“…Bununla birlikte, maksimum entropi (MaxEnt) içeren ekolojik niş modelleme, unsurların mevcut dağılım verilerine ihtiyaç duymaktadır. Kum sinekleri ve vektör kaynaklı hastalıkların dağılımının saptanmasında nitelikli tahmini işlevi ile bilinen yeni bir tekniktir (6,7). KL olası dağılımına etkili olduğu saptanan çevresel etmenlerden (BIO5, BIO9 ve BIO10) tümü hastalığın dağılımı ile doğru orantılı olduğu belirlenmiştir (Şekil 6a, 6b, 6c).…”