The effect of geo-climatic determinants on the distribution of cutaneous leishmaniasis in a recently emerging focus in eastern Iran

Mehdi Karamian,Walter Robert Taylor,Majid Shayesteh,Mohammad Amin Ghatee,Mohammad Reza Jamavar,Saeed Mohebi-Nejad,Ghasem Taheri

doi:10.1186/s13071-021-05046-0

Abstract

BackgroundCutaneous leishmaniasis (CL) has been reported in recent years in South Khorasan Province, a desert region of eastern Iran, where the main species is Leishmania tropica. Little is known of the influence of geography and climate on its distribution, and so this study was conducted to determine geo-climatic factors by using geographic information system.MethodsThe home addresses of patients with CL patients who were diagnosed and notified from 2009 to 2017 were retrieved from the provincial health center and registered on the village/town/city point layer. The effects of mean annual rainfall (MAR) and mean annual humidity (MAH), mean annual temperature (MAT), maximum annual temperature (MaxMAT), minimum annual temperature (MinMAT), mean annual number of high-velocity wind days (MAWD), mean annual frosty days (MAFD) and snowy days (MASD), elevation, soil type and land cover on CL distribution were examined. The geographical analysis was done using ArcMap software, and univariate and multivariate binary logistic regression were applied to determine the factors associated with CL.ResultsA total of 332 CL patients were identified: 197 (59.3%) male and 135 (40.7%) female. Their mean age was 29.3 ± 2.1 years, with age ranging from 10 months to 98 years. CL patients came from a total of 86 villages/towns/cities. By multivariate analysis, the independent factors associated with increased CL were urban setting (OR = 52.102), agricultural land cover (OR = 3.048), and MAWD (OR = 1.004). Elevation was a protective factor only in the univariate analysis (OR = 0.999). Soil type, MAH, MAT, MinMAT, MaxMAT, and MAFD did not influence CL distribution in eastern Iran.ConclusionsThe major risk zones for CL in eastern Iran were urban and agricultural areas with a higher number of windy days at lower altitudes. Control strategies to reduce human vector contact should be focused in these settings.Graphical abstract

Highlights

Cutaneous leishmaniasis (CL) has been reported in recent years in South Khorasan Province, a desert region of eastern Iran, where the main species is Leishmania tropica
Univariate analysis Climatic factors This analysis showed that mean annual number of high-velocity wind days (MAWD) was a factor (OR = 1.004, P = 0.043, 95% CI 1–1.008), increasing the probability of CL by 0.4%/day, whilst mean annual frosty days (MAFD), mean annual snowy days (MASD), mean annual temperature (MAT), minimum annual temperature (MinMAT), maximum annual temperature (MaxMAT), and mean annual rainfall (MAR) were not MAWD MAFD MASD MAT MinMAT MaxMAT MAR mean annual humidity (MAH)
We have shown that in South Khorasan, a mostly dry province, urban land cover was associated with the highest odds of acquiring CL, followed by agricultural land and MAWD

Summary

Introduction

Cutaneous leishmaniasis (CL) has been reported in recent years in South Khorasan Province, a desert region of eastern Iran, where the main species is Leishmania tropica. CL is the most prevalent form, and the majority of CL cases, accounting for 84% of the global burden, occur in the Middle East (Afghanistan, Iran, Iraq, Syria, Pakistan, and Yemen), North Africa (Tunisia and Algeria), and South America (Brazil, Peru, and Colombia). Leishmania tropica and L. major are the main etiological species of Old World CL, but L. aethiopica, L. infantum, and L. donovani have been isolated from CL lesions in some countries [3]. Leishmania major has a wide geographical distribution from Central Asia to the Middle East, the Mediterranean Basin, and parts of West Africa, whilst L. tropica is found mostly in the Middle East and the Eastern Mediterranean, with foci in Africa and some regions of southern and central Asia [1]

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