China
Africa
Explore chapters and articles related to this topic
The Parasite's Way of Life
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
The ability of kinetoplastids to undergo sexual, genetic recombination has been debated for decades; traditionally, these parasites were believed to reproduce primarily or exclusively asexually. Yet with the development of modern techniques, numerous studies now indicate that most of these parasites also engage in genetic recombination. Evidence supporting sexual reproduction in trypanosomes was presented in Figure 2.1. Similar evidence also exists for Leishmania. These parasites are transmitted by sand flies in the genera Phlebotomus (in Africa and Asia) and Lutzomyia (in the Americas). In the vector, replication of a flagellated stage known as a promastigote occurs in the sand fly gut. Promastigotes are ultimately transferred to the vertebrate host as the sand fly feeds. Within the vertebrate, promastigotes are ingested by phagocytic cells such as macrophages, where they develop into amastigotes. Amastigotes also undergo extensive binary fission within the phagocytic cell. Following their release from phagocytic cells, newly formed amastigotes, may be taken up by a different cell, resulting in a new round of replication. Ultimately a sand fly may ingest an infected phagocytic cell as it feeds, completing the cycle.
Sand Flies
Published in Jerome Goddard, Public Health Entomology, 2022
Sand flies occur in tropical, subtropical, and temperate areas worldwide. Generally, members of the sand fly genera Phlebotomus and Sergentomyia occur in the Old World, while Lutzomyia, Brumptomyia, and Warileya occur in the tropics and subtropics of the New World. Phlebotomus papatasi is one of the most important sand fly species and is a widespread vector of zoonotic cutaneous leishmaniasis in the Old World. Lutzomyia longipalpis is a major vector of leishmaniasis in the New World.
Flies (Biting)
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
Female sand flies are blood feeders; males are not, but they will suck moisture from available sources. Despite their medical importance, much of what is known about sand flies is speculative or based on limited field observations. Sand flies are usually found in microhabitats within larger biological communities. Examples of these microhabitats are caves, cavities, tree holes, burrows, pit latrines, animal enclosures, and other buildings. Breeding is believed to take place in these areas, and feeding on hosts occurs there or in close vicinity. Sand flies in the genus Brumptomyia feed on armadillos, whereas Lutzomyia spp. feed on both mammals and reptiles. Members of the genus Sergentomyia feed on reptiles and amphibians. Phlebotomus spp. are exclusively mammal feeders. Sand flies are generally active at night when there is little or no wind, but a few species may feed during the day if disturbed or under cloudy or shaded conditions. They normally rest during the day in their microhabitats. Sand fly development is relatively slow, taking up to several months to complete the life cycle. P. papatasi, the primary vector of leishmaniasis in the Middle East region, is a nocturnal, desert species flying from sunset through dark. It enters dwellings from animal burrows up to 50 meters away. Its activity diminishes rapidly when relative humidity falls below 65%, temperature rises above 80°F, or wind velocity exceeds 5 miles per hour.
The enemy at home: leishmaniasis in the Mediterranean basin, Italy on the focus
Published in Expert Review of Anti-infective Therapy, 2020
Elena Gianchecchi, Emanuele Montomoli
More than 54 species belong to the genus Leishmania, 21 of them with critical medical importance [1]. Leishmania complex digenetic life cycle includes a susceptible vertebrate host and a permissive insect vector. Specifically, (human) pathogenic species of Leishmania are spread by the bite of different female sandflies [2], Phlebotomus (P.) spp. and Lutzomyia spp. in the Old (Southern Europe, Mediterranean basin, Middle East, Asia, and Africa) and New World (Central and South America), respectively. The parasite populates in all continents, involving also Oceania [3], a continent thought to be free of Leishmania until recent years upon the identification of cutaneous leishmaniasis (CL) in native Australian macropods [4].
From infection to vaccination: reviewing the global burden, history of vaccine development, and recurring challenges in global leishmaniasis protection
Published in Expert Review of Vaccines, 2021
Greta Volpedo, Ryan H Huston, Erin A Holcomb, Thalia Pacheco-Fernandez, Sreenivas Gannavaram, Parna Bhattacharya, Hira L Nakhasi, Abhay R Satoskar
Interestingly, investigations involving Leishmania sand fly vector saliva and promastigote secretory gel (PSG) have revealed its impact on modulating the bite site immune environment and development of disease [162–164]. Leishmania parasites have shown increased virulence when transmitted by sand fly vector, this virulence being associated with proteins in the saliva of the New World vector species Lutzomyia longipalpis [165,166]. Vector-derived factors of transmission are rarely considered in vaccine development, however, due to these observations, sand fly salivary proteins have been investigated as potential vaccine candidates either alone or combined with Leishmania proteins. It has been reported that individual saliva antigens are able to elicit paradoxical effects on disease outcome than the whole saliva. The three most promising candidates to date are LJM19 and LJL143 from the L. infantum vector Lutzomyia longipalpis, and PdSP15 from the L. major vector P. duboscqui. It is hypothesized that these proteins normally function to recruit phagocytic macrophages and neutrophils to the bite site by increasing vasodilation, in turn promoting the infection. However, studies of these candidates on mice, hamsters, dogs, and non-human primates revealed their immunogenicity and effectiveness in protecting against infection [167–172]. Furthermore, salivary proteins have been shown to induce the cell-mediated immune response without the addition of an adjuvant, unlike recombinant protein candidates [170]. Thus, investigation of sand fly salivary proteins in Leishmania vaccine development continues to be a growing area of the field.
Current and emerging medications for the treatment of leishmaniasis
Published in Expert Opinion on Pharmacotherapy, 2019
Jaya Chakravarty, Shyam Sundar
The disease is transmitted by sand fly of genus Phlebotomus in the Old World and Lutzomyia in the New World. Transmission is of two types: anthroponotic and zoonotic. There is anthroponotic transmission of VL in South Asia and the Horn of Africa, where humans with kala-azar or post-kala-azar dermal leishmaniasis (PKDL) act as the major reservoir [2,6,7]. While VL in the Mediterranean, the Middle East, and Brazil, is zoonotic, with the domestic dog as the most important reservoir [7]. CL mostly has zoonotic transmission except for disease caused by L. tropica, which is predominantly anthroponotic.