Mosquito Repellent
CHAPTER 1
THE PROBLEM AND ITS SCOPE
Rationale of the study
There are more than 3 000 known mosquito species. However, of the 150 species that are potential vectors, only 30 are considered dangerous. The three genera Anopheles, Aedes and Culex, from three sub-families, are disease relevant. The epidemiology and the life cycle stages demonstrate the importance of climatic factors and that water is the essential environmental component for mosquitoes. The immature stages such as eggs, larvae and pupae require an aquatic environment, whereas adult mosquitoes live in terrestrial ecosystems. The quality and quantity of water, whether it is running or standing, shallow or deep, clean or polluted, sweet or brackish, shaded or sunlit, permanent or seasonal, and finally the climate will determine which particular species can breed. (WHO, 1982). As a group, mosquitoes breed in an almost infinite variety of sizes, types and qualities of water bodies and each species requires specific environmental breeding and living conditions. However, most of the mosquito vectors breed in a rather restricted and narrow range of habitats. It is the number of potential transmitting species and their population dynamics which makes control efforts difficult. A comprehensive classification by species, country and habitat, including potential environmental management measures, is presented in the Manual on Environmental Management for Mosquito Control (WHO, 1982). Insect vectors represent the largest group of disease transmitting agents. In most cases and for the most widespread diseases, mosquitoes are the main vectors. As a matter of fact, many people are suffering from mosquito-borne diseases in which dengue fever is worldwide phenomenon. In fact, there are up to 100 million cases of dengue fever worldwide every year. These existing problems are due to people’s negligence and unsanitary environment.
More than half of
THE PROBLEM AND ITS SCOPE
Rationale of the study
There are more than 3 000 known mosquito species. However, of the 150 species that are potential vectors, only 30 are considered dangerous. The three genera Anopheles, Aedes and Culex, from three sub-families, are disease relevant. The epidemiology and the life cycle stages demonstrate the importance of climatic factors and that water is the essential environmental component for mosquitoes. The immature stages such as eggs, larvae and pupae require an aquatic environment, whereas adult mosquitoes live in terrestrial ecosystems. The quality and quantity of water, whether it is running or standing, shallow or deep, clean or polluted, sweet or brackish, shaded or sunlit, permanent or seasonal, and finally the climate will determine which particular species can breed. (WHO, 1982). As a group, mosquitoes breed in an almost infinite variety of sizes, types and qualities of water bodies and each species requires specific environmental breeding and living conditions. However, most of the mosquito vectors breed in a rather restricted and narrow range of habitats. It is the number of potential transmitting species and their population dynamics which makes control efforts difficult. A comprehensive classification by species, country and habitat, including potential environmental management measures, is presented in the Manual on Environmental Management for Mosquito Control (WHO, 1982). Insect vectors represent the largest group of disease transmitting agents. In most cases and for the most widespread diseases, mosquitoes are the main vectors. As a matter of fact, many people are suffering from mosquito-borne diseases in which dengue fever is worldwide phenomenon. In fact, there are up to 100 million cases of dengue fever worldwide every year. These existing problems are due to people’s negligence and unsanitary environment.
More than half of