Molecular characterization of Leishmania parasites in naturally infected sand flies from the endemic focus of Kerman City, Southeastern Iran

Canine leishmaniasis caused by Leishmania Tropica in southeastern Iran: a case series study

Dogs are the primary reservoirs of Leishmania infantum (L. infantum), but Leishmania tropica (L. tropica) infection is also possible in dogs and can transmitted to humans. The southeast of Iran experiences a high prevalence of canine leishmaniasis (CanL), and veterinarians frequently encounter symptomatic cases. Therefore, from December 2017 to November 2022, the present case series was designed to assess the prevalence of CanL in owned dogs with cutaneous manifestations resembling CanL. A total of 500 owned dogs with dermal lesions from two endemic cities, Zabol and Kerman, were enrolled. Impression smears from skin lesions and popliteal lymph nodes were prepared from all cases, whereas blood samples were gathered from amastigote-positive dogs for serological and molecular surveys. Commercial ELISA was done on sera samples, and two-step nested PCR was used on extracted DNA to amplify variable fragments of the Leishmania species' kinetoplast DNA (kDNA). Leishman bodies were microscopically detected in 7.2% (36/500) of dermal smears. Of the 360 owned dogs from Zabol, 2 have been diagnosed with L. tropica, and 10 have been diagnosed with L. infantum. Out of 140 owned dogs from Kerman, 8 were identified with L. tropica infection, and 16 were infected with L. infantum. Molecular results revealed the presence of 750 full dual-band bases related to the L. tropica species in 10/36 (27.7%) cases, which showed a considerable increase in canine cutaneous leishmaniosis compared with previous studies in southeastern Iran. The noticeable prevalence of L. tropica in owned dogs indicated that the dog's role in cutaneous leishmaniosis should be re-evaluated as a possible animal reservoir in endemic areas.

A long-lasting emerging epidemic of anthroponotic cutaneous leishmaniasis in southeastern Iran: population movement and peri-urban settlements as a major risk factor

Background

Epidemics of cutaneous leishmaniasis (CL) are occurring more frequently and spreading faster and farther than before in many areas of the world. The present study aimed to assess a long-lasting emerging epidemic (2005–2019) of 5532 cases with anthroponotic CL (ACL) in peri-urban areas of Kerman city in southeastern Iran.

Methods

This descriptive-analytical study was carried out for 15 years in Kerman province, southeastern Iran. The data were passively obtained through the health surveillance system and the Kerman Leishmaniasis Research Center. Every subject was diagnosed using direct smear microscopy. The representative causative agent was further examined by ITS1-PCR, PCR-RFLP, 7SL RNA gene sequencing and phylogenetic analyses. For each subject, a case report form designating demographic and clinical data was recorded.

Results

A different pattern of ACL incidence was found in peri-urban areas compared to that in the city of Kerman. The incidence rate of ACL cases has significantly increased (P < 0.001) from 2005 to 2016 in new settlements with a gradual decline after that. The overall average risk of contracting the disease was 7.6 times higher in peri-urban areas compared to Kerman city, an old endemic focus. All isolates consisting of six variants were confirmed to be Leishmania tropica. The overall pattern of the ACL infection indicates that the etiological agent of ACL is propagated and transmitted by the bite of female Phlebotomus sergenti sandflies from person to person from dissimilar clones as reflected by the complexity of the migrants’ backgrounds in the province.

Conclusions

The movement of populations and establishment of new settlements in peri-urban areas close to endemic areas are major risk factors for and are directly linked to CL. The underlying factors of this emerging ACL epidemic caused by L. tropica were disasters and droughts, among others. A robust commitment to a multilateral approach is crucial to make improvements in this area. This will require decisive coordinated actions through all governmental factions and non-governmental organizations. Furthermore, active and passive case detection strategies, early diagnosis, and effective treatment could help control the disease.

Relationship Between the Distribution and Biodiversity of Sand Flies (Diptera: Psychodidae) With the Incidence of Zoonotic Cutaneous Leishmaniasis in Endemic Foci of Golestan Province, Iran

Zoonotic cutaneous leishmaniasis (ZCL) is prevalent in Golestan Province, Iran. The current study determined the relationship between the distribution and biodiversity of sand flies with cutaneous leishmaniasis at 14 villages in plain and hillsides areas. In each village from July to September 2017, 60 sticky traps and 2 CDC light traps were laid. Spearman and Mann-Whitney tests were used to determine the relationship between the incidence of ZCL and the abundance of different species of sand flies. Simpson, Shannon-Wiener, Evenness, and Margalef indices were calculated to estimate the diversity of species. A total of 5,295 phlebotomine sand flies were collected, comprising 10 species of the genus Phlebotomus (3,947 flies) and 7 species of genus Sergentomyia (1,248 flies). The abundance of sand flies and incidence of ZCL in plain areas were greater than that of hillsides areas (P = 0.013, P = 0.002). There was a significant correlation between the incidence of ZCL and the abundance of Phlebotomus papatasi (r = 0.72, P = 0.004) and P. caucasicus groups (P = 0.006; 0.022). In the Shannon-Wiener index, the rest of the biodiversity indices were reduced in higher-altitude areas. Increasing Shannon-Wiener index showed higher diversity of sand flies in higher-altitude areas. Data of the reported cases of leishmaniasis in plain areas can reveal the relationship between less diversity index (Shannon-Wiener), higher dominant diversity index (Simpson), and incidence of leishmaniasis in these areas.

Modelling and evaluating the risk of zoonotic cutaneous leishmaniasis in selected areas of Kerman Province, south of Iran

Cutaneous leishmaniasis (CL) remains a public health problem in the world, particularly in tropical and sub-tropical countries. This study aimed to determine the hotspots of CL in Kerman Province of Iran and model their potential for the establishment of new disease foci. All documents related to studies conducted in Kerman Province on CL published between 1978 and 2017 were retrieved and categorized. Spatial distributions of the vector, reservoir and human infection of CL were mapped. MaxEnt ecological model was used to predict the environmental suitability of the vector and reservoir(s) of zoonotic cutaneous leishmaniasis (ZCL). The most hazardous sites with the potential for the establishment of new disease foci were determined for field operations. Statistics of new cases of CL was obtained from the Center for Disease Control (CDC) of the ministry of health for the period 2011-2016. A total of 6,056 cases of CL were recorded, while we found a decreasing pattern in the incidence of CL from 46.48 per 100,000 inhabitants to 22.97. The best ecological niches for Phlebotomus papatasi are located in the central, western, northwest and southwest regions of the province. Also, environmental suitability for the reservoirs was highest in the central, southern and southwestern regions. The model predicted the gerbils can be present in some foci of anthroponotic cutaneous leishmaniasis (ACL). However, this result should be confirmed through a precise field study, and if validated, plans should be made to prevent the emergence of new foci of ZCL in the risk areas.

Biodiversity, Leishmania genetic typing and host identification of phlebotomine species in endemic foci of southeastern Iran

Leishmaniasis is a growing health challenge in many parts of Iran, including Kerman Province. Investigating vector ecology and parasite-harboring capacity is prerequisite to the disease control measures. This study included six provincial sites namely Bam (Bm), Dehbakri (Di), Jiroft (Jt), Mohammad-Abad (Md), Rostam-Abad (Rd) and Darb-e-Behesht (Dt) where sand flies were trapped. The specimens were then identified before being exposed to DNA extraction. PCR-RFLP was used to detect leishmanial infection rates and feeding preference of vectors. Diversity indices indicated that the highest effective numbers of species was in plain sites, whereas, the highest expected numbers of species was in mountainous sites. P. papatasi and P. sergenti showed similar feeding preferences to both human and animal bloods. P. papatasi from indoor catches was found infected with Leishmania major at a 2% rate. The ITS1 gene sequences of isolated parasites were >99% similar to related GenBank haplotypes. Bam and Rostam-Abad remain active foci of both types of cutaneous leishmaniasis (CL). Md and Di are prone to visceral leishmaniasis (VL). Jt is not at risk of anthroponotic cutaneous leishmaniasis (ACL) due to absence of P. sergenti. Sand flies are absent in Dt, probably because of high elevation and cold climate. In conclusion, patterns of climate and ecosystem changes and vector-host-reservoirs interactions must be carefully scrutinized if leishmaniasis is to be controlled in the stricken sites.