Vectors, Biology And Transmission Cycles

1499 WordsMar 30, 20156 Pages
Vectors, Biology and Transmission Cycles The dengue virus is transmitted from human to human with a few members of Aedes Stegomyia subgenus serving as vectors, the most important one being the Aedes aegypti mosquito as this mosquito represents the bulk of the vector transmissions of the virus. Ae. aegypti mosquitos originate from Africa but due to human transport, they can now be found mostly in many tropical areas around the world. These mosquitos thrive in dark, damp areas in a tropical climate as their growth is slowed in cooler climates. Ae. aegypti have a lifespan of 10 days to 3 weeks. The following is a simple chart of the life cycle of Ae. aegypti: http://www.denguevirusnet.com/life-cycle-of-aedes-aegypti.html Female Ae. aegypti…show more content…
Eggs can hatch within 2 days in tropical climates or up to a week in cooler climates. Larvae are very tolerant to low nutrient sources, mainly feeding of organic particulate matter in the water. They go through 4 instars after which they turn into pupae. They do not eat during this stage and take 2 days to develop into adult mosquitos. Pathogenesis and Immunopathophysiology Once infected for the first time, the host innate defences begin to work on the dengue virus by first initiating the complement system. However, even though the complement system can inhibit the infection from many a virus, it may have either protective or pathogenic roles against the virus depending on the stage of infection and the host. Activation of the complement system initiates several antiviral mechanisms including pathogen opsonisation and/or lysis, and activation of adaptive B and T cell responses. Complement is activated through the classical, lectin and alternative pathways, depending on specific recognition molecules. The complement cascade activates mainly to prime B and T cells to get to work on damage control within the host. However, the pathological effects which come from the complement system can vary in a dengue virus infection. Later during primary infection, IgM antibodies will be produced initially in an attempt to slow down the infection and much later on IgG antibodies specific to the specific dengue virus serotype will be deployed.
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