BackgroundThe aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale.Methodology and Principal FindingsLeishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate?Conclusions and SignificanceWe propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites.
Progress in the diagnosis of leishmaniases depends on the development of effective methods and the discovery of suitable biomarkers. We propose firstly an update classification of Leishmania species and their synonymies. We demonstrate a global map highlighting the geography of known endemic Leishmania species pathogenic to humans. We summarize a complete list of techniques currently in use and discuss their advantages and limitations. The available data highlights the benefits of molecular markers in terms of their sensitivity and specificity to quantify variation from the subgeneric level to species complexes, (sub) species within complexes, and individual populations and infection foci. Each DNA-based detection method is supplied with a comprehensive description of markers and primers and proposal for a classification based on the role of each target and primer in the detection, identification and quantification of leishmaniasis infection. We outline a genome-wide map of genes informative for diagnosis that have been used for Leishmania genotyping. Furthermore, we propose a classification method based on the suitability of well-studied molecular markers for typing the 21 known Leishmania species pathogenic to humans. This can be applied to newly discovered species and to hybrid strains originating from inter-species crosses. Developing more effective and sensitive diagnostic methods and biomarkers is vital for enhancing Leishmania infection control programs.
Extensive dermatophytosis caused by terbinafine-resistant Trichophyton indotineae harboring Phe397Leu and Leu393Ser substitutions in the squalene epoxidase enzyme was diagnosed in France. Analysis of internal transcribed spacer sequences revealed the wide spread of this species in Asia and Europe. Detection of T. indotineae in animals suggests their possible role as reservoirs.
BackgroundPhlebotomine sand flies are the vectors of the leishmaniases, parasitic diseases caused by Leishmania spp. Little is known about the prevalence and diversity of sand fly microflora colonizing the midgut or the cuticle. Particularly, there is little information on the fungal diversity. This information is important for development of vector control strategies.Methodology/Principal FindingsFive sand fly species: Phlebotomus papatasi, P. sergenti, P. kandelakii, P. perfiliewi and P. halepensis were caught in Bileh Savar and Kaleybar in North-Western Iran that are located in endemic foci of visceral leishmaniasis. A total of 35 specimens were processed. Bacterial and fungal strains were identified by routine microbiological methods. We characterized 39 fungal isolates from the cuticle and/or the midgut. They belong to six different genera including Penicillium (17 isolates), Aspergillus (14), Acremonium (5), Fusarium (1), Geotrichum (1) and Candida (1). We identified 33 Gram-negative bacteria: Serratia marcescens (9 isolates), Enterobacter cloacae (6), Pseudomonas fluorescens (6), Klebsiella ozaenae (4), Acinetobacter sp. (3), Escherichia coli (3), Asaia sp. (1) and Pantoea sp. (1) as well as Gram-positive bacteria Bacillus subtilis (5) and Micrococcus luteus (5) in 10 isolates.Conclusion/SignificanceOur study provides new data on the microbiotic diversity of field-collected sand flies and for the first time, evidence of the presence of Asaia sp. in sand flies. We have also found a link between physiological stages (unfed, fresh fed, semi gravid and gravid) of sand flies and number of bacteria that they carry. Interestingly Pantoea sp. and Klebsiella ozaenae have been isolated in Old World sand fly species. The presence of latter species on sand fly cuticle and in the female midgut suggests a role for this arthropod in dissemination of these pathogenic bacteria in endemic areas. Further experiments are required to clearly delineate the vectorial role (passive or active) of sand flies.
Zoonotic cutaneous leishmaniasis (ZCL) is an expanding disease and a public health issue in Iran. In the present study, rate of natural infection of rodent populations with Leishmania was investigated in six endemic foci including 28 villages in Golestan, Esfahan, Yazd, Fars, Khuzestan and Ilam provinces. A total of 593 rodents were captured and identified as Rhombomys opimus (n = 325), Meriones libycus (n = 171), Meriones persicus (n = 27), Tatera indica (n = 37), Nesokia indica (n = 12), Rattus rattus (n = 13) and Mus musculus (n = 8). Microscopic examinations of Giemsa-stained smears showed that 108 out of 593 (18.2%) rodents were infected with Leishmania spp., whereas infection of 186 out of 593 (31.4%) rodents with Leishmania was then confirmed by ITS1-PCR. The highest rate of infection was found in R. opimus (prevalence of 35%) and M. libycus (31%).
The bed bugs (Cimex lectularius and C. hemipterus) have undergone a significant resurgence worldwide since the 1990s. A compilation of findings from a database, including 2650 scientific publications from seven major medical databases, allowed us to document main evolutionary events, from fossil evidence, dating from 11,000 years ago, until the present that has led to the current worldwide expansion of Cimicid species. We present the hypotheses on the possible dispersion pathways of bed bugs in light of the major historical and evolutionary events. A detailed classification of the Cimicidae family and finally, an illustrative map displaying the current distribution of known Cimex species in each geographical ecozone of Asia, Europe, Africa, the Americas, and Australia are presented.
Summary Background Expert visualization of Sarcoptes scabiei remains essential for diagnosing human scabies, but access to said experts can be difficult. Polymerase chain reaction (PCR) is a specific tool for the detection and confirmation of S. scabiei but has poor sensitivity. Objectives To evaluate PCR as a diagnostic method for scabies using nonexpert‐dependent standardized sampling. Methods The dry swab was systematically rubbed across the front of both wrists, the eight interdigital spaces and on any suspected scabies lesions in all patients referred for scabies. A new PCR‐based diagnostic test was run on the samples. All patients underwent clinical and dermoscopic examination. Scabies diagnosis was confirmed when dermoscopic examination was positive or the patient had typical clinical signs of scabies. Results Of 183 suspected cases of scabies, 164 patients were sampled, 87 had confirmed scabies (dermoscopy positive n = 87, typical clinical signs n = 1) and 77 did not. Of the 87 patients with proved scabies, 33 patients had positive scabies PCR, resulting in a 37·9% [95% confidence interval (CI) 28·4–48·4%] sensitivity and a 61·7% (95% CI 52·4–72·7%) negative predictive value. None of the 77 patients ruled out for scabies had a positive PCR result. Conclusions This method is nontraumatic, repeatable and non‐expert‐dependent. It shows sensitivity similar to previous studies involving expert skin scraping. However, this method facilitates the multiplication of sampling, which increased the sensitivity for cluster scabies diagnosis. This method may be suitable as a first‐line diagnosis tool where a large cluster scabies outbreak is suspected. What's already known about this topic? Scabies diagnosis requires expertise. Scabies polymerase chain reaction (PCR) is specific but has poor sensitivity. Poor sensitivity is the consequence of the low efficiency of sampling methods. What does this study add? This PCR‐based diagnostic method based on nontraumatic standardized skin sampling is not expert‐dependent and is reproducible. This diagnostic method may be relevant as a non‐expert sentinel diagnosis tool in large clusters where a scabies outbreak is suspected.
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