Impact of Environmental and Climate Factors on Spatial Distribution of Cutaneous Leishmaniasis in Northeastern Iran: Utilizing Remote Sensing

Abstract

Background: Cutaneous leishmaniasis (CL) is a dermal and parasitic disease.. The aim of this study was to determine the effect of environmental and climate factors on spatial distribution of CL in northeastern Iran by utilizing remote sensing from 20 March 2016 to 19 March 2017.
 Methods: In this ecological study, the data were divided into two parts: The descriptive data on human CL cases were gathered from Communicable Diseases center of Iran. The remote sensing techniques and satellite imagery data (TRMM, MODIS-Aqua, MODIS-Terra and AMSR-2 with spatial resolution 0.25°, 0.05°, 5600m and 10km) of environ­mental and climate factors were used to determine the spatial pattern changes of cutaneous leishmaniasis inci­dence.
 Results: The incidence of CL in North Khorasan, Razavi Khorasan, and South Khorasan was 35.80 per 100,000 people (309/863092), 34.14 per 100,000 people (2197/6,434,501) and 7.67 per 100,000 people (59/768,898), respectively. The incidence of CL had the highest correlation with soil moisture and evapotranspiration. Moreover, the incidence of dis­ease was significantly correlated with Normalized Difference Vegetation Index (NDVI) and air humidity while it had the lowest correlation with rainfall. Furthermore, the CL incidence had an indirect correlation relation with the air tem­perature meaning that with an increase in the temperature, the incidence of disease decreased.
 Conclusion: As such, the incidence of disease was also higher in the northern regions; most areas of North Khorasan and northern regions of Razavi Khorasan; where the rainfall, vegetation, specific humidity, evapotranspiration, and soil moisture was higher than the southern areas.

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

“…However, this was not recognized as an associated factor in a study in southern Iran [ 26 ]. Shirzadi et al [ 37 ] investigated the impact of climatic factors on CL in a large area of northeastern/eastern Iran including North Khorasan, Razavi Khorasan (northeast), and South Khorasan (east). In this region, rainfall decreases from the mountainous regions in North Khorasan to the deserts of South Khorasan, with CL rates ~ 4.5 times as high in the northeast as in the east [ 37 ].…”

“…Shirzadi et al [ 37 ] investigated the impact of climatic factors on CL in a large area of northeastern/eastern Iran including North Khorasan, Razavi Khorasan (northeast), and South Khorasan (east). In this region, rainfall decreases from the mountainous regions in North Khorasan to the deserts of South Khorasan, with CL rates ~ 4.5 times as high in the northeast as in the east [ 37 ]. This lack of rainfall dependence is probably due to the reliance on underground water to support life in this arid region, where sand flies likely exist on the limited humidity provided by water pulled from underground sources.…”

Prevalence of human leishmaniasis in Sudan: A systematic review and meta-analysis

“…In general, the high incidence and prevalence of human leishmaniasis have been highly associated with the prevalence of conditions that leads to a weak immune response, such as AIDS or tuberculosis. Studies also found a strong association between leishmaniasis prevalence and poor household status, poverty, population displacement, and recent climate change[ 4 - 7 ].…”

A Five-year retrospective hospital-based study on epidemiological data regarding human Leishmaniasis in West Kordofan state - Sudan

“…There are several different forms of human leishmaniasis, and the most common forms are cutaneous leishmaniasis (CL), which causes skin sores, and visceral leishmaniasis (VL), which affects several internal organs (usually spleen, liver, and bone marrow) (4). All forms of the disease have been strongly associated with poor socioeconomic status, population displacement, a weak immune system, and climate change (5)(6)(7)(8).…”