Leishmania (World Class Parasites)

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To confirm the etiology of injuries, authors have used molecular methods that have identified Leishmania DNA in three of the individuals analyzed. Zink et al. The analysis of parasite DNA found in 13 of these mummies was consistent with the DNA of Leishmania Leishmania donovani , suggesting the visceral form of infection. Nerlich et al. The positive identification of Leishmania infection in bone samples was obtained using two independent approaches. The first one was the molecular analysis of ancient DNA aDNA by the amplification of a specific fragment of bp base pairs from a conserved region of the mini-circle molecule of the Leishmania kinetoplastid mitochondrial DNA kDNA 67 , 68 and the results were compatible with L.

This result is achieved through the technique of Polymerase Chain Reaction PCR that was replicated in two independent laboratories. The second approach was a protein assay that showed a positive reaction, i.

As noted, the different methodologies used have been productive, providing considerable information that helps us in paleoparasitological studies of this protozoan. Small aDNA fragments detected in tissues and bones of mummies, as well as immunodiagnostic techniques used to assist molecular methods have shown that infection by this parasite were present in mummies from different regions and different periods, clarifying questions about the host-parasite relationship and providing evidence for the studies of evolution and phylogeny of these parasites.

Parasitic infections and parasitic diseases are two distinct situations originated from a single process. The parasite is a necessary condition but not sufficient to start a parasitic disease The parasitic disease results from the presence of a certain parasite in a certain host, in a given population, in a given environment, and over a period of particular life coevolution of both protagonists The first attempts to classify clinical forms of leishmaniasis date from the early twentieth century.

The different clinical forms in patients affected by cutaneous leishmaniasis induce many specialists to an erroneous diagnosis One of the forms resembles very much the manifestations of hanseniasis; at that time called leprosy. The first atypical and rare cases, one in Brazil, one in Bolivia and two in Venezuela presented maculo-papular and nodular lesions and the spread of the disease, its chronicity and resistance to treatment, the wealth of parasites in the lesions and the great similarity with leprosy led this clinical manifestation of leishmaniasis to be called "lepromatoid form" 71 , Destombs 73 , in , comparing leishmaniasis with the polar forms of leprosy, considered the primary diffuse cutaneous and the cutaneous forms of leishmaniasis as the benign and malignant poles of the disease.

The historic and classical classification of leishmaniasis is: visceral Kalazar produced by the L. However, this classification was made exclusively by observing the clinical and evolutionary behavior of the disease However, according to Azulay 76 who had already found clinical and immune-pathological differences among leishmaniasis infections, he related the differences to defensive reactions of the human organism.

Most of the times, the clinical descriptions of American cutaneous leishmaniasis ACL were attributed to infections by L. In addition, there is a close relationship among the occurrence of different clinical forms of the disease and factors related to species and parasite strains, vector habits, factors related to the host immune response and to the host-parasite interaction. Regional differences have also been observed in the occurrence of geographical areas of disease 6 , 38 , Considering the original description of species and proposed classifications based on extrinsic criteria and on results obtained by biochemical and molecular methods, it is currently accepted that there are several Leishmania species, of which more than 20 are associated with human disease in the Old and the New World 7.

Regardless of the limitations of molecular paleoparasitology studies in which only small fragments can be analyzed, molecular techniques have recently provided the first evidence of aDNA sequences of L. Although, more studies are needed in an attempt to recover L. This finding reopens the debate about the potential existence of a L. Nevertheless, as has been discussed in the case of sauroleishmanias, until the moment, no pathogenic effect caused by L. The finding of this Leishmania species in the Brazilian mummy raises an important question that could be related to epidemiological investigations performed in endemic areas in which positive serological results were found, but there was no evidence of injury.

A similar situation was demonstrated by Marzochi et al. The study found positive antibody titers in Would those be cases of Leishmania infection without illness? However, the detection of a DNA fragment compatible with L. Unfortunately, questions related to parasites of the genus Leishmania still remain, especially regarding the origin of these parasites. The paleoparasitology can clarify events that took place in ancient times among the species of Leishmania and their hosts, contributing to the understanding of the origin and evolution of the parasite Although the immunodiagnostic techniques continue to be applied in paleoparasitologic studies for the diagnosis of Leishmania spp.

The technical adaptation of PCR to detect aDNA made the diagnosis of various infections in prehistoric populations possible. However, there is always the need to develop new methods and procedures adjustments according to the process and the status of preservation of the archaeological material 85 , 86 , The paleoparasitological steps are promising to clarify the gaps that still exist in relation to leishmanias.

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The most encouraging is that there are many possibilities for the paleoparasitology research that could bring new data on the antiquity and developmental stages of the host-parasite relationship, and also epidemiological data which could suggest strategies applicable today. National Center for Biotechnology Information , U. Published online May Author information Article notes Copyright and License information Disclaimer. Received May 15; Accepted Nov Copyright notice.

This is an open-access article distributed under the terms of the Creative Commons Attribution License. Abstract Species of the genus Leishmania Kinetoplastida, Trypanosomatidae are causative agents of leishmaniasis, a complex disease with variable clinical spectrum and epidemiological diversity, constituting, in some countries, a serious public health problem.

Leishmaniasis in the Americas For a long time, the history of leishmaniasis has been studied, requiring further clarifications regarding the origin and the behavior of parasites responsible for this infection, as well as host-parasite relationships along time. Hypotheses for the origin of the genus Leishmania and subgenera Leishmania and Viannia Several possible origins of the genus Leishmania and subgenera Leishmania and Viannia are proposed.

Speculations about the origin of some Leishmania species and infection by Leishmania spp. Direct evidence of DNA fragments of Leishmania spp. Leishmania - infection and disease Parasitic infections and parasitic diseases are two distinct situations originated from a single process. Rey L. Rio de Janeiro: Guanabara Koogan; Coura JR. A review of the geographic distribution and epidemiology of leishmaniasis in the New World. Am J Trop Med Hyg. Lainson R. The American leishmaniasis: some observations on their ecology and epidemiology.

Lainson R, Shaw JJ. Evolution, classification and geographical distribution. The leishmaniases in biology and medicine. London: Academic Press; World Health Organization. Leishmaniasis: 09 December Geneva: WHO; Laveran A, Franchini G. Des hematozoaires du gecko et specialement de Herpetomonas tarentolae.

Bull Soc Pathol Exot. Leishmania: origin, evolution and future since the Precambrian. Leishmania tarentolae taxonomic relatedness inferred from phylogenetic analysis of the small subunit ribosomal RNA gene. Mol Biochem Parasitol. Fu G, Kolesnikov AA. Leishmania gymnodactyli and Leishmania infantum minicircles contain the same guide RNA genes as do minicircles of Leishmania tarentolae.

Wenyon DM. Observations on the intestinal protozoa of three Egyptian lizards, with a note on a cell-invading fungus. Chatton E, Blanc G. C R Soc Biol. Adler S, Theodor O. Investigation of Mediterranean Kala Azar: X. A note on Trypanosoma platydactyli and Leishmania tarentolae. Parrot L, Foley H. Arch Inst Pasteur Alger. Acta Trop. Presence en France de Leishmania tarentolae Wenyon, parasite du gecko Tarentola mauritanica. Ann Parasitol Hum Comp. Elwasila M. Leishmania tarentolae Wenyon, from the gecko Tarentola annularis in the Sudan. Parasitol Res. Searching for virulence factors in the non-pathogenic parasite to humans Leishmania tarentolae.

Description and ultrastructure of Leishmania zuckermani n. Genome sequencing of the lizard parasite Leishmania tarentolae reveals loss of genes associated to the intracellular stage of human pathogenic species. Nucleic Acids Res. Live nonpathogenic parasitic vector as a candidate vaccine against visceral leishmaniasis.

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Visceral Leishmaniasis: An Update and Literature Review

Infect Immun. Krjukova AP. Problemy kozhnogo leishmanioza. Ashkhabad: Turkmengosizdat; Experimental cutaneous leishmaniasis of wild rodents of Turkmenia; pp. Apud Wilson V, Southgate B. Lizard Leishmania. The genus Leishmania belongs to a family Trypanosomatidae order Kinetoplastida [ 10 , 11 ]. The parasite is categorized in two main groups; the old world species occurring in Europe, Africa and Asia, and the new world species occurring in America [ 11 , 12 ].

About 53 species of the parasite have been described from different regions of the world; of these, 31 species are known to be parasites of mammals and 20 species are pathogenic for human beings [ 9 , 13 ]. Many of the leishmania species infecting human are zoonotic, having a complex variation in domestic and wild mammal reservoir hosts; while, other species of the parasite are anthroponotic, having human-to-human transmission in the presence of the vector [ 9 ].

Leishmania donovani is usually considered to be an anthroponotic parasite though studies reported the presence of parasite or circulating antibodies against the parasite antigens in domestic and wild animals of India and East [ 8 , 14 ]. The global distribution of each of Leishmania species determines the type of disease that occurs in an area. Leishmania major causes cutaneous leishmaniasis in Africa, the Middle East and parts of Asia; while L.

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In south America, again several species of Leishmania cause cutaneous form of the disease [ 11 , 15 ] Table 1. Leishmania species have a heteroxenous life cycle. The parasite exhibits two morphological forms in its life cycle; amastigote in macrophages of the mammalian host and promastigote in the gut of the sand fly vectors [ 11 ]. Human stage of the life-cycle starts when a parasitized female sand fly injects metacyclic promastigotes into human body.

The multiplication of the parasites occurs inside the macrophages. Leishmaniasis is transmitted by the bite of infected female sand flies. There are over species of sand flies divided into five genera: Phlebotomus and Sergentomyia in the Old World and Lutzomyia, Brumptomyia, and Warileya in the New World [ 4 , 16 , 17 ].


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Although human-biting sandflies occur in various genera, the only proven vectors of human leishmaniasis are species and subspecies of the genus Phlebotomus and Lutzomyia Table 2. Various species in the genus Phlebotomus are responsible for transmission of leishmaniasis in the Old World and Lutzomyia species in the New World.

Each sand fly species typically transmits only one species of parasite and each parasite leads to a particular type of disease [ 8 , 18 , 19 ]. The development of leishmania parasite within the vector sand flies is an inevitable stage for the transmission of leishmaniasis among various hosts.

Pathology Outlines - Leishmania

Female sand flies acquire leishmania parasites when they feed on an infected mammalian host in search of a blood-meal. The amastigote forms of the parasites taken up by sand flies are not usually found in the peripheral circulation; rather they are present in the skin itself. Parasites present in organs such as liver and spleen are not accessible to sand flies.

Amastigotes are intracellular parasites found in phagolysosomes of macrophages and other phagocytes [ 20 ], and their uptake by the blood-feeding sand fly is assisted by the cutting action of the mouthparts. Thus sand flies are pool feeders, meaning they insert their saw-like mouthparts into the skin and agitate them to produce a small wound into which the blood flows from superficial capillaries [ 21 ]. Then the parasite multiplies and further differentiates into other stages, metacyclic promastigote being the final mammalian-infective stage which movies to the foregut of the vector sand fly [ 22 ].

The metacyclic promastigotes are deposited in the skin of a new mammalian host when the fly takes another blood meal, leading to the transmission of disease. There are two main sources of human leishmaniases, zoonotic leishmaniases, in which the reservoir hosts are wild animals, commensals or domestic animals, and anthroponotic leishmaniases, in which the reservoir host is human.

Although each Leishmania species generally falls into one or the other of these categories, there are exceptions where the anthroponotic species cause zoonotic transmissions [ 8 ]. Rock hyraxes, rodents , mongoose, dogs, cats, foxes, jackals, wolves, bats, primates, armadillos and other domestic animals are among the multihost reservoirs to maintain transmission of leishmaniasis in different localities [ 23 - 25 ]. However, leishmania reservoirs are so complex that they show regional and temporal variations [ 26 ], and only a local studies involving ecological and parasitological analysis can determine whether these animals are playing a role as reservoir in a given environment [ 24 ].

The sylvatic transmission of leishmaniasis is effected as a result of established wildlife populations in and around human settlements in the presence of appropriate vector. Dogs and cats may be involved in the transmission cycles of these parasites in urban areas, and the presence and frequency of these animals may have a significant effect on disease pressure to humans.

In urban and peri-urban areas, the frequency of contact between wildlife and humans changes from sporadic encounters to permanently sharing the environment, thus greatly increasing the chance of transmission of leishmania parasite to humans [ 27 ]. They always require treatment. Liposomal amphotericin B and paromomycin can treat mucocutaneous leishmaniasis. Visceral disease always requires treatment. Several medications are available. Commonly used medicines include sodium stibogluconate Pentostam , amphotericin B, paromomycin, and miltefosine Impavido.

Visceral leishmaniasis is often fatal due to the effects it has on both internal organs and your immune system. The only way to prevent leishmaniasis is to avoid getting bitten by a sand fly. Medication can cure the disease. However, treatment is most effective when started before extensive damage to your immune system occurs. Identifying your triggers can take some time and self-reflection. In the meantime, there are things you can try to help calm or quiet your anxiety…. If your take on meditation is that it's boring or too "new age," then read this.

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Leishmania

What are the types of leishmaniasis? What causes leishmaniasis? Who is at risk for leishmaniasis? What are the symptoms of leishmaniasis?

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