Variability of Cutaneous Leishmaniasis Lesions Is Not Associated with Genetic Diversity of Leishmania tropica in Khyber Pakhtunkhwa Province of Pakistan

Epidemiology of cutaneous leishmaniasis in children of Khyber Pakhtunkhwa, Pakistan

OBJECTIVES

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.

METHODS

A total of 1, 559 clinically confirmed records of children diagnosed with cutaneous leishmaniasis (January-December) from 2020 and 2022 were obtained from selected district hospitals. In addition, a risk factors-related questionnaire was administered to 1, 011 households (400 in 2020 and 611 in 2022) in nine districts during a household survey.

RESULTS

The maximum number of cutaneous leishmaniasis cases was recorded in 2022 (n = 877, 56.25%) as compared to 2020 (n = 682, 43.75%). The hospital records showed a greater number of male patients in the 2022 cohort (n = 603, 68.76%). The highest number of cases were observed in children aged 5-9 years in 2022 (n = 282, 32.16%) and 2020 (n = 255, 37.39%). In 2020 and 2022, cutaneous leishmaniasis cases showed peak aggregation in March (n = 118, 17.3%) and January (n = 322, 36.72%). From a spatial analysis, the maximum number of cutaneous leishmaniasis cases was recorded at 59-1700 m elevation in various land-use/land-cover and climatic regions with quaternary alluvium rock formations. A multivariate logistic regression model analysis of risk factors from the households survey suggested that age group, socio-economic status, construction materials of the house, use of insect repellents, Afghan refugee camps in the village/district, knowledge and biting times of sand flies, frequent use of mosquito bed nets, presence of domestic animals in the house, knowledge of the transmission period and peak month of leishmaniasis infection increased the risk of acquiring cutaneous leishmaniasis (p  value < 0.05).

CONCLUSION

Our analysis demonstrated that cutaneous leishmaniasis in children is influenced by a variety of environmental, socio-demographic and behavioural risk factors in Khyber Pakhtunkhwa. The increase in recorded cases of cutaneous leishmaniasis in children in 2022 compared to 2020 suggests that the infection likely extended to new foci in the province.

Environmental and socio-demographic factors associated with cutaneous leishmaniasis in district Khyber, Pakistan; alarming spread of the disease to new foci

Cutaneous leishmaniasis (CL) is a sand fly-borne infection of significant public health concern in Pakistan (endemic for CL). This study aimed to scrutinize the environmental and socio-economic risk factors for CL in district Khyber (located on Pak-Afghan border), Pakistan. Clinically confirmed 2881 CL case records for (January-December) 2017 and 2020 were obtained from district hospital. In addition, a questionnaire for CL risk factors assessment was administered to 525 households (175 in 2017 and 350 in 2020) in 40 villages throughout the district in a household survey. Higher number of CL cases were recorded in 2020 (N = 1824 belonging to 90 villages) compared to 2017 (N = 1057 from 42 villages). Highest number of CL patient cases were recorded in tehsil Jamrud (N = 2248, 39.01 %), followed by Landi Kotal (N = 398, 6.91 %) and Bara (N = 235, 4.08 %). Records showed higher number of CL cases in males (N = 1,659, 57.58 %) compared to females (N = 1,222, 42.41 %). In 2017 and 2020 the disease burden peaked in January. GIS-based spatial analyses of hospital records revealed that CL cases were abundant at 294-1,916 m elevation, in agriculture and range lands. Univariate logistic regression model analysis of risk factors suggested that higher education, family size >15, knowledge of CL, having family member/s that suffered from CL in the past, knowledge about biting time of sand flies, use of mosquito spray, presence of Afghan refugees in the village/s and living in mud-made houses increased the risk of acquiring CL. The multivariable logistic regression model showed none of the risk factors to be statistically significant. Findings of the study are crucial towards effective and targeted control of CL in district Khyber.

Taxonomy, Population Structure and Genetic Diversity of Iranian Leishmania Strains of Cutaneous and Visceral Leishmaniasis

BACKGROUND

Despite the broad distribution of leishmaniasis in Iran, there is a little genetic information about the causative agents and epidemiological status of the disease. Genetic diversity of the parasite is suggested to be one of the factors, which influences the clinical manifestations of the disease. In this study, we investigated the genetic variations, population structure, and evolutionary history of Leishmania species from endemic foci of Iran.

METHODS

Fifty-two isolates from humans, canines, and rodents from different endemic foci of Iran were used to sequence the N-acetyl glucosamine-1-phosphate transferase (Nagt) gene. Phylogenetic and structure analyses were performed to investigate inter- and intra-species diversity of the Leishmania isolates.

RESULTS

In total, 10 haplotypes including L. major (n = 6), L. tropica (n = 2), L. infantum (n = 1) and L. turanica (n = 1) were identified across 52 isolates. Haplotype diversity (Hd) ranged from zero for L. infantum and L. turanica to 0.78 ± 0.136 for L. major. This study identified population structure of Leishmania isolates from different geographical regions of Iran. The results of the phylogenetic tree showed 4 distinct clades for each species of Leishmania. In addition, the highest intraspecies diversity was observed among L. major isolates. No correlation was observed between species and geographic distribution of haplotypes.

CONCLUSIONS

Leishmania isolates were identified at the species level using the Nagt gene, low variation within species indicates conservation of this gene in Leishmania. The results provide knowledge into the evolutionary history of Iranian Leishmania isolates.

Characterization of sand fly breeding sites in district Malakand, Khyber Pakhtunkhwa, Pakistan, and evaluation of risk factors for cutaneous leishmaniasis in the region

Present study was carried to determine the sand fly species composition, breeding sites ecology, seasonal abundance, and spatial distribution in district Malakand, Khyber Pakhtunkhwa, Pakistan. In addition, risk factors associated with cutaneous leishmaniasis (CL) were also evaluated. Survey of indoor and outdoor habitats was carried out using sticky traps in 31 villages of Dargai and Batkhela tehsils of Malakand. Soil from habitats of adult and immature sand flies was analysed. Questionnaire-based household survey was also performed in these villages to assess risk factors associated with CL. Soil samples from selected CL positive households were analysed for its contents. Additionally, clinicoepidemiological data from local health centres was examined for the year 2019. Total of 3,140 sand flies belonging to 18 species were collected. Phlebotomus sergenti was the most abundant species (38.16%). Its abundance had a strong positive correlation with mean monthly relative humidity and negative correlation with average temperature. Phlebotomus sergenti and Phlebotomus papatasi were abundant at an elevation ranging from 320 to 1,120 m above sea level and in agricultural lands near human settlements. Flight height preference apparatus collected maximum sand flies at 30 cm (1ft) above the ground and all species associated negatively with height. Soil analysis from habitats of adult and immature flies showed that highest mean number of adults and immatures were recorded from silt loam which carried highest concentrations of K₂ O, Mg, Ca, and Zn. Number of immature sand flies correlated moderately (r = .7, p < .05) with K₂ O soil concentrations. There was significant similarity between organic matter contents in soil samples from positive breeding sites and CL households (Wilcoxon rank-sum test, p = .1976). In multivariate analysis model for CL risk factors, age (26-35 and >35 years), knowledge of leishmaniasis, living in a middle and upper class, preachers visit to villages, and assumption that Afghan refugees are more prone to CL were significant. CL patient's archived data from health centres showed that majority of patients had lesions on face and hands. Patient's influx was highest in February and March.

The impact of refugees on leishmaniasis in Turkey: a new Syrian/Turkish Leishmania tropica population structure described by multilocus microsatellite typing (MLMT)

Turkey is one of the leishmaniasis endemic countries, and according to the recent reports, more than 45% of the cases were reported from the Southeastern part of Turkey. The disease is endemic in Syria with annually 25,000 cases, and it is emphasized by WHO that the actual number was estimated to be 2-5-fold higher than the reported numbers. Due to the civil war in Syria, more than seven million people were displaced and migrate to neighboring countries. The population structure of Leishmania tropica was investigated in the present study using clinical samples, which were obtained from Syrian patients residing in Turkey. Previously reported database was used to compare the results obtained in the present study. According to the multilocus microsatellite typing profiles, three populations (Şanlıurfa, Mediterranean, and Syrian/Turkish) were identified. Syrian/Turkish population, which is a new structure and identified for the first time in the present study, was comprised of clinical samples obtained from Syrian patients. The newly described population structure was homogeneous and solid comparing to previously identified population structures in Turkey. Further analyses revealed two sub-populations under the main Syrian/Turkish population structure. The findings of the present study revealed that the epidemiological status of leishmaniasis is more complicated than it is estimated. We believe that the data presented here will provide valuable information on the leishmaniasis epidemiology.