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Mosquitoes
Published in Gail Miriam Moraru, Jerome Goddard, The Goddard Guide to Arthropods of Medical Importance, Seventh Edition, 2019
Gail Miriam Moraru, Jerome Goddard
Japanese Encephalitis. Japanese encephalitis (JE) does not occur in the United States, but it is the principal cause of epidemic viral encephalitis in the world, with approximately 70,000 clinical cases each year and 10,000 deaths.69–71 Returning U.S. travelers from Asia are sometimes infected with the virus.72 JE epidemics have, at times, been widespread and severe. In 1924, there were 6125 cases with 3797 deaths.73 JE occurs in Asia, roughly in a triangle from Pakistan to Indonesia, north to about Siberia (Figure 25.27). The JE virus is highly virulent. Approximately 25% of the cases are rapidly fatal, 50% lead to neuropsychiatric sequelae, and only 25% fully recover. In temperate zones, JE has a summer–fall distribution, but in the tropics no seasonal peak is apparent. There are several mosquito vectors of JE, but probably the most important is Culex tritaeniorhynchus, a rice-field-breeding species. Hogs may serve as amplifying reservoirs for JE.74
Japanese Encephalitis Virus and Human CNS Infection
Published in Sunit K. Singh, Daniel Růžek, Neuroviral Infections, 2013
Kallol Dutta, Arshed Nazmi, Anirban Basu
JE is maintained in nature by extra-human hosts. Human beings are incidental hosts and are known not to play any role in perpetuating the virus. The role of mosquitoes as vectors for this disease was suggested when the virus was isolated from Culex tritaeniorhynchus in 1938. Since then, this virus has been isolated from several other culicine mosquitoes such as Culex fuscocephala, Culex vishnui, Culex sitiens, Culex annulirostris, Culex gelidus, Culex bitaeniorhynchus, Culex epidesmus, Culex pseudovishnui, and Culex whitmorei, four species of anophelines Anopheles annularis, Anopheles barbirostris, Anopheles hyrcanus, and Anopheles subpictus, and five species of other mosquito genera Armigeres subalbatus, Mansonia annulifera, Mansonia bonneael dives, Mansonia uniformis, and Aedes vigilax (Muangman et al. 1972; Reid et al. 2006; Rosen 1986; Trosper et al. 1980; Vythilingam et al. 1994). Even though JEV has been reported to effectively replicate in other arthropod hosts when infected parentally (Hurlbut and Thomas 1969), isolation of the virus from arthropods other than mosquito in nature has been reported only twice; the first case was from midges, Lasiohelea taiwana, collected while biting humans in China (Wu and Wu 1957), and the second case was from ixodid ticks, Haemaphysalis japonica, in the erstwhile USSR (Lvov 1978).
The Genus Blumea
Published in Namrita Lall, Medicinal Plants for Cosmetics, Health and Diseases, 2022
The essential oils of B. balsamifera, B. eriantha, B. mollis, B. densiflora and B. martiniana have been reported to possess potent larvicidal activity against various mosquito species. LC50 is the concentration of the chemical in the air or water that will kill 50% of the test animals with a single exposure. The B. eriantha EO showed high toxicity against larvae of six mosquito species: Anopheles stephensi (LC50 = 41.61 μg/mL), Aedes aegypti (LC50 = 44.82 μg/mL), Culex quinquefasciatus (LC50 = 48.92 μg/mL), Anopheles subpictus (LC50 = 51.21 μg/mL), Aedes albopictus (LC50 = 56.33 μg/mL) and Culex tritaeniorhynchus (LC50 = 61.33 μg/mL) (Benelli et al., 2017). The EO of B. mollis showed a significant toxic effect against early fourth-instar larvae of C. quinquefasciatus with an LC50 of 71.71 and an LC90 of 143.41 ppm (Senthilkumar et al., 2008). The B. densiflora EO has shown potent larvicidal activity against A. anthropophagus larvae with 100% mortality within six hours at 150 ppm, ten hours at 100 ppm, 30 hours at 50 ppm, and 30 hours with EO at a concentration of 25 ppm (Zhu & Tian, 2011a). Similarly, B. martiniana EO showed potent larvicidal activity against A. anthropophagus, the natural vector of malaria in a concentration-dependent manner (Zhu & Tian, 2011b). The larvicidal activity of EOs can be justified by the active components of the oil like linalool, Germacrene D, arvotanacetone, (4E,6Z)-allo-ocimene, allo-aromadendrene, borneol, β-caryophyllene, γ-terpinene, sabinene and β-bisabolene. Notice that (4E,6Z)-allo-ocimene and carvotanacetone achieved LC50 lower than 10 μg/mL on various tested mosquito species (Zhu & Tian, 2011b). The results favor the proposed Blumea EO as an alternative for developing eco-friendly mosquito control tools.
Recent developments in vaccines and biological therapies against Japanese encephalitis virus
Published in Expert Opinion on Biological Therapy, 2018
JEV is an arthropod-borne virus transmitted by mosquitoes of the genus Culex, most commonly by Culex tritaeniorhynchus [9]. In the enzootic cycle, JEV infects wading ardeid birds, especially herons, which serve as reservoirs [10]. The virus can also establish an epizootic transmission cycle involving pigs as amplifying hosts [11]. Human infection results from spill over from these cycles. Humans are dead-end hosts, because they develop low-level and transient viremia insufficient to sustain forward transmission. People working in or living near rice fields, water-logged areas, and pig farms have an increased risk to be infected and to develop the disease [12]. Based on mosquito densities and activities, different temporal transmission patterns of Japanese encephalitis occur in subtropical and tropical regions, where human infections are observed throughout the year, often with a peak during the rainy season, and in temperate regions, where epidemics are seasonal and occur during the summer and fall.
A comparative study on larvicidal potential of selected medicinal plants over green synthesized silver nano particles
Published in Egyptian Journal of Basic and Applied Sciences, 2018
Syed Zameer Ahmed Khader, Sidhra Syed Zameer Ahmed, Jagadeeswari Sathyan, Mohamed Rafi Mahboob, Kisore P. Venkatesh, Kishore Ramesh
The third instar stage larvae of Anopheles stephensi, Aedesaegypti and Culex tritaeniorhynchus were collected from Medical Entomological Centre, ICMR (field station), Virudhachalam, Cuddalore District. The larvae were maintained in aplastic tray containing water with sufficient feed. The tray was covered with muslin cloth to avoid contamination. The larvae were provided with suitable environmental condition of 25–27 °C and 75–85% humidity and the egg rafts were collected from each cage for maintaining next generation.