Epidemiology of cutaneous leishmaniasis in children of Khyber Pakhtunkhwa, Pakistan

In Pakistan, cutaneous leishmaniasis is an emerging tropical disease and a very high number (>70%) of children are afflicted by this marring infection. This study aimed to scrutinise the prevalence, spatial distribution and socio‐demographic and behavioural risk factors associated with cutaneous leishmaniasis in children aged <5–15  years in Khyber Pakhtunkhwa.


INTRODUCTION
Leishmaniasis is a broad spectrum of disease that has shaped its horizons in tropical and subtropical regions of the world and is considered a neglected tropical disease [1].The disease has three main clinical manifestations (cutaneous, visceral and mucocutaneous) and is currently endemic in >100 countries [1].Approximately 80% of cutaneous leishmaniasis cases were reported in the Eastern Mediterranean region, including Afghanistan, Iran, Saudi Arabia and Pakistan [1].The disease is caused by the Leishmania species and is naturally transmitted through the bite of infected bloodfeeding female sand flies (Diptera Psychodidae).In Pakistan, cutaneous leishmaniasis is endemic and widespread throughout the country and frequent outbreaks have been reported, while visceral leishmaniasis is sporadically distributed in northern areas (Gilgit Baltistan province, Malakand, Hazara divisions, Azad Jammu and Kashmir) of the country.After the mass migration of Afghan refugees from Afghanistan, which is the endemic country of cutaneous leishmaniasis, to Pakistan, the disease has been attributed to the local residents and has now spread from endemic to non-endemic areas of the country [2,3].Leishmania tropica, L. major, and, rarely, L. infantum are responsible for causing cutaneous leishmaniasis in the country [4][5][6].
Cutaneous leishmaniasis can be observed in all age groups; however, children are a special population affected by this marring disease and are a substantial public health concern [7].The greater incidence of cutaneous leishmaniasis in young children could be due to a lack of cutaneous leishmaniasis-specific immunity, poverty, peri-domestic anthroponotic transmission, lack of awareness and access to basic health services [8,9].Disease can significantly impact child's physical, emotional, social well-being and overall health development.Cutaneous leishmaniasis-affected children are usually excluded from social life activities by the general public, particularly young girls [10].
In eco-epidemiological studies of cutaneous leishmaniasis, geographical information system and remote sensing-based analyses of cutaneous leishmaniasis in children are crucial for identifying paediatric hotspots, addressing child-specific risk factors and monitoring the disease in affected areas.Correlating the manifestations of cutaneous leishmaniasis cases with environmental settings (elevation, land use, climatic regions, etc.) provides useful insight into disease prevalence, planning for predicting future outbreaks and effective control strategies.In addition, seasonal patterns and climatic factors (temperature and rainfall) also play essential roles in understanding disease transmission dynamics and projecting vector surveillance [11][12][13][14].
Similarly, identifying risk factors associated with cutaneous leishmaniasis is crucial in designing community-level responses toward disease control.The risk of cutaneous leishmaniasis is usually associated with age, poverty, limited health facilities, socio-economic aspects, poor housing conductions, peri-domestic activities, geographical setting, occurrence of animal reservoirs in and around the house, malnutrition, migration, and lack of responsiveness.By understanding these factors, efforts to control and manage, cutaneous leishmaniasis can be more effective, ultimately reducing the disease burden on affected populations [3,[15][16][17][18].
In Pakistan, cutaneous leishmaniasis cases have surged in the country's northwestern Khyber Pakhtunkhwa and are widespread in areas adjoining with Pak-Afghan border, especially in merged tribal districts with Khyber Pakhtunkhwa.In addition, Khyber Pakhtunkhwa shares the longest northwest border with Afghanistan (endemic for cutaneous leishmaniasis), and Khyber Pass is also one of the main routes in the region through which trading and mass inflow of Afghan refugees occurred and settled in refugee camps in various parts of the Khyber Pakhtunkhwa.The disease has spread from endemic to non-endemic regions, significantly challenging national and international health authorities [6,19].Access to healthcare remains a difficulty in Pakistan, especially for people in rural communities, informal settlements and areas affected by conflict.Médecins Sans Frontières, an international health organisation, has opened a dedicated cutaneous leishmaniasis treatment centre in Peshawar, the capital of Khyber Pakhtunkhwa, and admits around 250-300 new cutaneous leishmaniasis patients each month, mostly consisting of young children.However, the number of cases is still continuing to increase.Peshawar-based clinics remain the only option for thousands of cutaneous leishmaniasis patients in Khyber Pakhtunkhwa [19].The government hospitals have inadequate drugs and usually have no welltrained staff; victimised individuals usually buy drugs at their own expense or travel to Peshawar for treatment.
Although children represent a high proportion of cutaneous leishmaniasis cases, information on the efficacy of treatment for cutaneous leishmaniasis in children is scarce in Khyber Pakhtunkhwa.They are subjected to the same cutaneous leishmaniasis treatment as advised for adults in the province [6,19].In addition, geographical information system-based spatial analysis, seasonal incidence and risk factors associated with cutaneous leishmaniasis in children in Khyber Pakhtunkhwa have not been previously well-documented.Therefore, this study was designed to determine the prevalence, spatial distribution and risk factors associated with cutaneous leishmaniasis in children in Khyber Pakhtunkhwa, Pakistan.

MATERIALS AND METHODS
The present study was conducted in Khyber Pakhtunkhwa (34 N and 72 E, area of 101,741 km 2 ), province of Pakistan.Khyber Pakhtunkhwa shared the longest northwest border with Afghanistan (endemic for cutaneous leishmaniasis), the southwest with Baluchistan (highest occurrence of cutaneous leishmaniasis), the southeast with Punjab, and the northeast with Islamabad, Azad Jammu Kashmir and Gilgit Baltistan (Figure 1).Khyber Pakhtunkhwa lies on the Iranian plateau and the Khyber Pass is the main route through which Pakistan connects with Afghanistan.The northern part of Khyber Pakhtunkhwa is dominated by the Hindu Kush mountainous series, with the highest peak of Terich Mir (7708 m), and the climate of the north is usually snowy and cold in winter, while the southern parts experience hot summers and minimum rainfall.Khyber Pakhtunkhwa is the second most deprived province after Baluchistan, and approximately 40% of the total forest area of Pakistan is located in Khyber Pakhtunkhwa.The majority of inhabitants live in mud-made houses and combined dwellings, with common rooms used for domestic animals and people (Figure 2) [17,20].Kabul, Swat, Chitral, Kunar, Siran, Panjkora, Bara, Kurram, Dor, Haroo, Gomal and Zhob are the main tributaries of the province.

Study design
This is a part of our ongoing research of cutaneous leishmaniasis in Khyber Pakhtunkhwa, Pakistan.

Archived cutaneous leishmaniasis child data
During the study, the available archived cutaneous leishmaniasis data (<5-15 years of age groups, based on the age of infected children) were acquired from the registries of all the district hospitals of Khyber Pakhtunkhwa from January to December 2020 and 2022.The registry records included clinically confirmed infected children's name, sex, age, site and size of infection, locality, status of the infection (dry or wet) and date of visit for treatment to the concerned district hospital(s).However, cutaneous leishmaniasis data from the Bajour, Chitral, Hangu, Lower Dir, Mohmand, Mardan, Nowshera, Swat and Upper Dir districts were included in the study.Other districts were excluded due to the lack of age grouping, sex and date of infection of cutaneous leishmaniasis children.

Assessment of cutaneous leishmaniasis risk factors
To assess socio-demographic and behavioural cutaneous leishmaniasis risk factors, a questionnaire (based on published risk factors of cutaneous leishmaniasis in children) was administered to the heads of 391 households of cutaneous leishmaniasis-infected children (150 in 2020 and 241 in 2022) aged <5-15 years.The households were selected in Bajour, Chitral, Hangu, Lower Dir, Mohmand, Mardan, Nowshera, Swat and Upper Dir districts hospitals in 2020 and 2022.Control in-person risk factors data were also recorded from household heads of children aged <5-15 years from 620 households (250 in 2020 and 370 in 2022) in the study districts.Informed written (signed or thumb-printed) consent was obtained from participants before administering the questionnaire to household heads/representatives.

Meteorological factors and coordinate data
In the study period, monthly rainfall and temperature (minimum and maximum) data from January to December 2020 and 2022 were obtained from the weather station Peshawar (recording and collecting meteorological data of the province), Khyber Pakhtunkhwa.The global positioning system (GPS) coordinates (latitude and longitude) of clinically confirmed cutaneous leishmaniasis children were acquired from his or her locality (village/tehsil-administrative subunit) through searches via Google Earthpro and GPS devices in the districts.

Statistical analysis
The archived clinical, in-person risk factors, climatic and coordinates data were entered into Microsoft Excel for further analysis.A total of 1, 011 (391 infected children and 620 control in-person questionnaire data) were matched by sex and age (1 ≤ 5, 2 = 5-9, 3 = 10-12 and 4 = 13-15 years) in Statistical Software: Release 13 (STATAv13, Stata Corp LP, 2013).Using general infection data, risk factors assessment was performed through univariate and multivariate logistic regression analysis in STATAv13.The coordinates data were subsequently shifted to Arc-GIS 10.5 (Environmental Systems Research Institute, USA) to prepare spatial databases for cutaneous leishmaniasis in children in Khyber Pakhtunkhwa.The coordinates were overlaid on a digital elevation model (DEM), land use, climatic and geological maps of Khyber Pakhtunkhwa for spatial distribution.DEM was extracted from an advanced spaceborne thermal emission reflection radiometer (ASTER), which is freely accessible online and launched by NASA-USA and MITI-Japan in 1999.We acquired a 12.5 m

RESULTS
A total of 682 (2020) and 877 (2022  3).During the study period, the highest number of cutaneous leishmaniasis cases were recorded in March 2020, coinciding with the maximum rainfall and minimum temperature.In 2022, a peak influx of cutaneous leishmaniasis-infected patients were observed in December with minimum temperature and rainfall (Figure 4).
In 2020 and 2022, data on cutaneous leishmaniasis cases in children were obtained from the hospitals of selected districts and digitised on DEM, land-use and geological (rocks formations) maps of Khyber Pakhtunkhwa.In GIS-based spatial analysis, maximum cases were observed at elevations ranging from 59 to 1700 m (however, few cases were also recorded above 1700 m) (Figure 5a).The highest number of cases were observed in agricultural, barren and forested areas close to human settlements in Khyber Pakhtunkhwa (Figure 5b).Moreover, the peak number of cutaneous leishmaniasis infection records were also observed in cold, sub-humid, warm, arid climatic regions and quaternary alluvium (QA) rock formations (Figure 6a,b).
During the field study, a total of 1011 risk factors data were collected from households in Khyber Pakhtunkhwa.Univariate logistic regression analysis revealed that age group, father occupation, socio-economic status, construction materials of the houses, other family members suffered from cutaneous leishmaniasis, use of insect repellents, Afghan refugee camps in the village/district, knowledge of sand flies, biting times of sand flies, frequent use of mosquito bed nets, living in crowded houses, presence of domestic animals in the house, knowledge of the transmission period of leishmaniasis and knowledge of the peak month of leishmaniasis infection were associated with an increased risk of getting cutaneous leishmaniasis in Khyber Pakhtunkhwa (p value <0.05) (Table 2).
In a multivariate logistic regression analysis, we found that being aged 13-15 years, socio-economic status, construction materials of the house, use of insect repellents in the house, presence of Afghan refugee camps in the district/village, knowledge of sand flies, biting times of sand flies, frequent use of mosquito bed nets, presence of domestic animals in the house, knowledge of the transmission period of leishmaniasis and knowledge of the peak month of leishmaniasis infection were significant risk factors for acquiring cutaneous leishmaniasis (p < value 0.05) (Table 2).

DISCUSSION
In Pakistan, cutaneous leishmaniasis is potentially disfiguring and a growing public health disease, and the country is included in the top 10 nations of the world where cutaneous leishmaniasis is endemic [1].Cutaneous leishmaniasis is prevalent in all provinces; however, enormous influxes are reported from Khyber Pakhtunkhwa and Baluchistan provinces.National and international health organisations, including the WHO and MSF, are working to control this disease in the country.However, the infection is often misdiagnosed, leading to secondary bacterial infection and additional complications are reported during treatment [19].Cutaneous leishmaniasis is usually associated with poverty, underprivileged housing conditions, malnutrition, population displacement, low socio-economic conditions, weak immune system, limited access to basic health facilities, urbanisation and deforestation [1,18,22].The infection can be observed in all age groups; however, children are more infected than adults [1,23,24].Cutaneous leishmaniasisstigmatised individuals with a disfigured body usually lose self-esteem, while young girls with facial scars face the most substantial psychosocial effect of disease [23].The victimised children, especially females, are considered objectionable for marriage and are isolated from the rest of the siblings/family to prevent the spread of the infection [10,18,20].In Pakistan, little attention has been given to cutaneous leishmaniasis in children; however, a high proportion of cutaneous leishmaniasis (>70%) is reported in young children, especially in Khyber Pakhtunkhwa [19].
In this study, we described the pattern of cutaneous leishmaniasis incidence in children in 2020 and 2022 using archived cutaneous leishmaniasis data obtained from selected districts in Khyber Pakhtunkhwa.The reported cutaneous leishmaniasis cases during 2020 and 2022 presented an increase in the incidence of cutaneous leishmaniasis in Khyber Pakhtunkhwa.However, this study was established on the basis of registered cutaneous leishmaniasis case statistics and therefore may not reveal a conclusive increase in disease burden.The actual proportion may be greater than that of the reported cases in endemic areas of the districts in Khyber Pakhtunkhwa due to the lack of a well-known leishmaniasis registry system (Table 3) and since many affected individuals usually self-medicate instead of seeking treatments from health facilities [19].Earlier reports have also revealed that cutaneous leishmaniasis infection is spreading in the form of outbreaks from endemic to non-endemic foci in Khyber Pakhtunkhwa [19].
The maximum number of cutaneous leishmaniasis cases were observed in male as compared to female children because males are usually involved in outdoor playing activities [6,20,30,32].The highest number of cases were recorded in children aged 5-9 years, as this group was most commonly affected in other studies [5,6,17,33].Children's behaviour, such as sleeping outside or on the ground in the summer season, following increased involvement in peridomestic activities may account for the greater risk of sand fly bites [14,[18][19][20].Previous studies have also suggested that in well-known endemic areas, the incidence of cutaneous leishmaniasis typically increases with age, up to approximately 15 years, after which the prevalence levels off, likely because of the acquisition of immunity [34].
We noticed that the majority of children have cutaneous leishmaniasis lesions on their exposed body parts, such as on the face, possibly because the children do not protect their faces or other extremities during active biting times of sand flies in summer [6,14].Earlier studies have shown that sand flies exhibit peak activities at warm and clear nights (in domestic and peri-domestic) with low wind speeds [20,35].We recorded the highest prevalence of cutaneous leishmaniasis in Lower Dir district compared to other districts, as various outbreaks in locals and two Afghan refugee camps were reported in the district [3,29].L. tropica and the suspected vector sand fly, P. sergenti have also been documented in Lower Dir [11,29].
We noted the highest influx of cutaneous leishmaniasis peaked in December 2022 and in March 2020, with maximum rainfall and minimum temperature.Previous reports suggested that the transmission of cutaneous leishmaniasis occurs in the summer season (July-September), and infected patients visit cutaneous leishmaniasis treatment centres and hospitals from December to March, which is consistent with the greater patient inflow in Khyber Pakhtunkhwa [32,36].It has also been reported that suspected vectors of cutaneous leishmaniasis (P.papatasi and P. sergenti) have uni-model phenology (peak abundance from  July to September) in Khyber Pakhtunkhwa and that greater chances of transmission of cutaneous leishmaniasis following the incubation period (5-6 months) correspond with the influx of cutaneous leishmaniasis cases in the health units [32].In addition, climatic conditions are largely important for vector-borne diseases, particularly leishmaniasis [37].Understanding the relationships between climatic factors, sand flies, and cutaneous leishmaniasis is crucial for predicting and preventing future outbreaks of the infection (Figure 7).The seasonal variation of sand flies can be an important factor in  the transmission of cutaneous leishmaniasis.Meteorological changes generally shape the spread of leishmaniasis through changes in temperature and rainfall, which also affect the geographic distribution of sand fly populations [6,11,20,30].
In the present study, we spatially analysed cutaneous leishmaniasis cases reported by district hospitals in Khyber Pakhtunkhwa.We observed that the infected children commonly originated from regions at elevations ranging from 59 to 1700 m; however, few cases were also noted above 1700 m in the province.Cutaneous leishmaniasis has been largely recorded at elevations ranging from 294 to 800 m in various parts of Pakistan, including the Khyber Pakhtunkhwa.Elevation has been suggested to be an important ecological factor affecting the pattern and distribution of cutaneous leishmaniasis in the region.In addition, the reported expansion of Leishmania parasites has been suggested to be linked to the range of sand fly vector populations shaped by elevation and climatic factors.The geographical distributions of cutaneous leishmaniasis-causative Leishmania species (L.tropica and L. major) closely coincide with P. sergenti and P. papatasi, inhibiting these altitudes (59-1700 m) in Khyber Pakhtunkhwa [4,16,20].We recorded cutaneous leishmaniasis cases in agricultural, barren, forest, cold, sub-humid, warm and arid areas of the province.Earlier studies reported that cutaneous leishmaniasis-suspected vector species are ecological generalists and can be observed in all ecological zones of Khyber Pakhtunkhwa [16].Proximity to forested areas, vegetation and range land is known to increase the risk of the disease.Vegetation areas (agriculture, barren areas and forests) usually provide ecological conditions for sand fly breeding and shelters for reservoir animals.The frequent vegetation (agricultural or forest) near cutaneous leishmaniasis incidence areas and domestic animals highlight the proximity of human dwellings connected with vector sand fly species breeding sites (Figure 8).Moreover, Note: Y = yes reported; -= not reported.vegetation increases the abundance of vector species around human settlements and probably boosts the infection [16,20].We witnessed the maximum number of cutaneous leishmaniasis cases in QA rock formations.This geological parameter plays an important role in the distribution and shaping of vectors (P.sergenti and P. papatasi) of cutaneous leishmaniasis in Khyber Pakhtunkhwa [16].
In our analysis, we demonstrated that the incidence of cutaneous leishmaniasis is influenced by a variety of sociodemographic and behavioural risk factors.It was evident that 13-15 years of age was significantly associated with a greater risk of acquiring cutaneous leishmaniasis.Earlier studies revealed that age and sex were risk factors for cutaneous leishmaniasis.This could also be accounted for by the greater risk of sand fly bites following the increased involvement in peri-domestic activities [6].We analysed that family socio-economic status fosters the risk of cutaneous leishmaniasis because underprivileged financial level is associated with the fundamental living principles and basic health services of families [38].In addition, locals have limited approach to basic health facilities, and most government hospitals have limited access to drugs, leaving locals to buy drugs themselves, which many cannot afford to do for infected children [19].Likewise, Afghan refugees are predominantly susceptible to the disease due to their displacement and existing conditions.Khyber Pakhtunkhwa shares its longest border with Afghanistan and serves as the main route (Khyber Pass) for frequent trading and transboundary movement with Pakistan [3,4,10,14,39,40].This makes these refugees predominantly susceptible and at greater risk of acquiring cutaneous leishmaniasis.We noticed that the use of construction materials for houses intensified the risk of infection.In Khyber Pakhtunkhwa, the majority of locals usually mix cattle dung with mud to strengthen mud walls, thus providing damp sites for sand fly development in summer [6,20].Furthermore, the cutaneous leishmaniasis risk increases with the presence of domestic animals in the house because these animals act as reservoirs of Leishmania parasites or could be a part of the disease cycle.Although domestic animals can increase the risk of cutaneous leishmaniasis, they may also decrease the risk of this disease by serving as the principal source of vector species and distracting bites to the human population.Sand flies are natural vectors for the transmission of Leishmania parasites, and approximately 70 vertebrate animal species, including humans, can be sources of L. parasites [5].Great gerbils (Rhombomys opimus) are known as the main reservoir of zoonotic cutaneous leishmaniasis in Afghanistan and Iran; however, they have not yet been confirmed as a source of zoonotic cutaneous leishmaniasis in Pakistan.Furthermore, the use of insect repellents, knowledge and biting times of sand flies, frequent use of mosquito bed nets, knowledge of the transmission period and peak month of leishmaniasis infection were associated with a greater risk of cutaneous leishmaniasis.Thus, locals can not adopt or afford protective measures despite disease-vector knowledge [6,20,32].

CONCLUSION
Cutaneous leishmaniasis is a serious public health concern, and children represent a high proportion of the disease in Khyber Pakhtunkhwa.Information on cutaneous leishmaniasis and the efficacy of cutaneous leishmaniasis treatment in children is scarce in the province.The increase in recorded cases in 2022 compared to 2020 highlights the probable extent of cutaneous leishmaniasis in non-endemic sites.Environmental (elevation and landuse, climatic and geological) factors may have contributed to the increase in cutaneous leishmaniasis incidence in the region.The present investigation also revealed certain socio-demographic and behavioural risk factors for acquiring cutaneous leishmaniasis in the area.This study emphasised the region's need for vector control and disease awareness programs.Furthermore, treatment opportunities for children are inadequate, and proper administration of the medicines may be needed.

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I G U R E 1 Study area map of Khyber Pakhtunkhwa, Pakistan.

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I G U R E 2 Mud-made houses and combined dwellings in Khyber Pakhtunkhwa.
resolution Advanced Land Observing Satellite phased array type L-band synthetic aperture radar (PALSAR) DEM for the study area.Land-use projection map of Khyber Pakhtunkhwa was obtained from the National Centre of Excellence in Geology, University of Peshawar, Khyber Pakhtunkhwa, Pakistan.Pre-described climatic, land-use and geology map (shapefile) classifications of the United States Geological Survey were used for the study area.Finally, the coordinate data were overlaid on DEM, land-use, climatic and geology maps in ArcGIS to assess the possible effects of environmental and climatic factors on the incidence of cutaneous leishmaniasis in children in Khyber Pakhtunkhwa.Furthermore, for geological mapping, natural break method was used[21].

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I G U R E 3 Cutaneous leishmaniasis infected children in Khyber Pakhtunkhwa.

F I G U R E 4
Incidence of cutaneous leishmaniasis in children (a) 2020 and (b) 2022.

F I G U R E 5
Cutaneous leishmaniasis cases projected on the digital elevation model (a) and land-use (b).

F I G U R E 6
Cases digitised on geology (a) and climatic (b) maps.
U R E 7 Flow chart of risk factors associated with cutaneous leishmaniasis.TROPICAL MEDICINE & INTERNATIONAL HEALTH and resting's sites F I G U R E 8 Sand fly breeding and feeding life cycle.
description of cutaneous leishmaniasis infected children in Khyber Pakhtunkhwa.
T A B L E 2 Univariate and multivariate logistic regression analysis of cutaneous leishmaniasis risk factors in children in Khyber Pakhtunkhwa.
Bold values are significant, p value <0.05.Abbreviations: CI, confidence interval; OR, odds ratio. Note: T A B L E 3 Previously reported cutaneous leishmaniasis vectors sand fly and Leishmania species in Khyber Pakhtunkhwa.