Co-detection and isolation of Leishmania and Crithidia among naturally infected Tatera indica (Rodentia: Muridae) in Fars province, southern Iran

Parasite Detection in Visceral Leishmaniasis Samples by Dye-Based qPCR Using New Gene Targets of Leishmania infantum and Crithidia

Visceral leishmaniasis (VL) is a neglected disease considered a serious public health problem, especially in endemic countries. Several studies have discovered monoxenous trypanosomatids (Leptomonas and Crithidia) in patients with VL. In different situations of leishmaniasis, investigations have examined cases of co-infection between Leishmania spp. and Crithidia spp. These coinfections have been observed in a wide range of vertebrate hosts, indicating that they are not rare. Diagnostic techniques require improvements and more robust tools to accurately detect the causative agent of VL. This study aimed to develop a real-time quantitative dye-based PCR (qPCR) assay capable of distinguishing Leishmania infantum from Crithidia-related species and to estimate the parasite load in samples of VL from humans and animals. The primer LinJ31_2420 targets an exclusive phosphatase of L. infantum; the primer Catalase_LVH60-12060_1F targets the catalase gene of Crithidia. Therefore, primers were designed to detect L. infantum and Crithidia sp. LVH60A (a novel trypanosomatid isolated from VL patients in Brazil), in samples related to VL. These primers were considered species-specific, based on sequence analysis using genome data retrieved from the TriTryp database and the genome assembling of Crithidia sp. LVH60A strain, in addition to experimental and clinical data presented herein. This novel qPCR assay was highly accurate in identifying and quantifying L. infantum and Crithidia sp. LVH60A in samples obtained experimentally (in vitro and in vivo) or collected from hosts (humans, dogs, cats, and vectors). Importantly, the screening of 62 cultured isolates from VL patients using these primers surprisingly revealed that 51 parasite cultures were PCR+ for Crithidia sp. In addition, qPCR assays identified the co-infection of L. infantum with Crithidia sp. LVH60A in two new VL cases in Brazil, confirming the suspicion of co-infection in a previously reported case of fatal VL. We believe that the species-specific genes targeted in this study can be helpful for the molecular diagnosis of VL, as well as for elucidating suspected co-infections with monoxenous-like trypanosomatids, which is a neglected fact of a neglected disease.

Calomyscid Rodents (Rodentia: Calomyscidae) as a Potential Reservoir of Zoonotic Cutaneous Leishmaniasis in a Mountainous Residential Area in the Plateau of Iran: Inferring from Molecular Data of kDNA and ITS2 Genes of Leishmania Major

Cutaneous leishmaniasis (CL), a neglected tropical disease, is an important health problem in Fars Province, southern Iran. Fars, the fourth most populous Province in Iran, is the center of both anthroponotic and zoonotic cutaneous leishmaniasis (ZCL). Rodents, the reservoir of Leishmania major, play an important role in transmitting ZCL. In the present study, we report Leishmania infection in calomyscid rodents for the first time in mountainous residential areas of Shiraz, the capital of Fars Province, in southern Iran. Rodents were trapped in urban mountainous areas. The skin, liver, and spleen of rodents were examined microscopically for Leishmania infection. In addition, DNA was extracted from the tissues and they were evaluated for Leishmania infection by targeting the kDNA and subsequent sequencing of the nuclear rDNA internal transcribed spacer two (ITS2) region. DNA of L. major was detected in the spleen and liver of calomyscid rodents. Molecular evolution based on DNA-sequencing of the ITS2 gene confirmed the taxonomic situation of the parasite as L. major. Our findings suggest the eco-epidemiological importance of calomyscid rodents in the foci of leishmaniasis in the mountainous residential area on the plateau of Iran. These rodents may play a role in the transmission of leishmaniasis in a residential area and could be considered a potential reservoir for CL.

Cutaneous leishmaniasis in Iran: A review of epidemiological aspects, with emphasis on molecular findings

Leishmania parasites can cause zoonotic cutaneous leishmaniasis (CL) by circulating between humans, rodents, and sandflies in Iran. In this study, published data were collected from scientific sources such as Web of Science, Scopus, PubMed, Springer, ResearchGate, Wiley Online, Ovid, Ebsco, Cochrane Library, Google scholar, and SID. Keywords searched in the articles, theses, and abstracts from 1983 to 2021 were cutaneous leishmaniasis, epidemiology, reservoir, vector, climatic factors, identification, and Iran. This review revealed that CL was prevalent in the west of Iran, while the center and south of Iran were also involved in recent years. The lack of facilities in suburban regions was an aggravating factor in the human community. Some parts of southern Iran were prominent foci of CL due the presence of potential rodent hosts in these regions. Rhombomys opimus, Meriones lybicus, and Tatera indica were well-documented species for hosting the Leishmania species in Iran. Moreover, R. opimus has been found with a coinfection of Leishmania major and L. turanica from the northeast and center of Iran. Mashhad, Kerman, Yazd, and sometimes Shiraz and Tehran foci were distinct areas for L. tropica. Molecular identifications using genomic diagnosis of kDNA and ITS1 fragments of the parasite indicated that there is heterogeneity in leishmaniasis in different parts of the country. Although cutaneous leishmaniasis has been a predicament for the health system, it is relatively under control in Iran.

Epidemiological and clinical features of cutaneous leishmaniasis and its time trend model in a high-endemic focus of disease in the southwest of Iran from 2014 to 2019

BACKGROUND

Cutaneous leishmaniasis (CL) is a tropical infection with a relatively high incidence rate in Iran. The present study aimed to explore the time trend and associated factors of CL in Dezful, in southwest Iran.

METHODS

This case series study was conducted on all CL patients registered from 2014 to 2019. The descriptive analysis of the data was done using SPSS 20 software and the time series model on the number of cases was run through Interactive Time Series Modeling software.

RESULTS

A total of 5349 leishmaniasis cases were identified in the study area during 2014-2019. The highest incidence rate was 35 840 per 100 000 in 2014. The fitted time series model revealed a decreasing trend with an annual periodic pattern. The mean age of infection was 19.82 y (standard deviation 21.87). The infection was most frequent in the 1-10 y age group (41.7%). Also, females were more prone to leishmaniasis (54.7%). Most lesions were located on the hand (23.1%), face (19.7%), and forearm (17.75%) and 48.5% of patients had only one lesion.

CONCLUSIONS

The results revealed a decreasing trend of leishmaniasis in Dezful. It has been predicted that this infection will reach a minimum rate (300 per 100 000) in the winter of 2021.

Bionomics of phlebotomine sand flies species (Diptera: Psychodidae) and their natural infection with Leishmania and Crithidia in Fars province, southern Iran

Phlebotominae sand flies are involved in human diseases, such as leishmaniasis, and cause a considerable number of deaths every year. Besides, some of them have been identified as allergen sources or the potential mechanical vectors related to nosocomial infections. The present study aimed to assess the monthly activity, fauna, and detection of protozoan agents in phlebotomine sand flies using polymerase chain reaction (PCR) in re-emerging zoonotic cutaneous leishmaniasis foci of Shiraz and Kharameh in Fars province, southern Iran during 2016-2017. To determine the monthly activity, sand flies were caught from indoors and outdoors of both studied areas. Afterward, all female phlebotomine sand flies were processed for DNA extraction and PCR assays for Leishmania and Crithidia detections. During the study, 6975 sand flies of 16 species (eight Phlebotomus and eight Sergentomyia species) were caught in both foci. Sand flies' monthly activities started in early April and terminated in late November and October. Additionally, two active peaks of sand flies were observed in both foci; first in June and second in August to September. Phlebotomus papatasi (47.1%) was the most dominant species in out/indoors of both Shiraz (31.1%) and Kharameh (16.0%). It was also the only species which was found infected with Leishmania major, indeed, 2.68% and 2.53% of P. papatasi were infected to L. major in Kharameh and Shiraz, respectively. However, none of the female sand flies was positive for Crithidia spp. Despite various control strategies, especially against Leishmania, considerable cases of leishmaniasis are recorded from Iran every year. Phlebotomine plays the main role in transmission of Leishmania in these foci. Therefore, further studies are needed to determine the role of different phlebotomine species in epidemiological aspects of leishmaniasis.