After reading this article you will learn about the prevention of disease caused by mosquito.
But of all insects that transmit diseases, the mosquito represents by far the greatest menace. It remains mankind’s most indomitable foe, resisting costly efforts to eradicate or even control it. The mosquito is the vector for different diseases such as malaria, dengue fever and yellow fever, which together cause several million deaths and hundreds of millions of cases every year.
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Mosquitoes also spread lymphatic filarisis (elephantiasis), which infects about 120 million people up to 1990, and Japanese encephalitis, which takes its biggest toll among children.
Different species of mosquito are involved in the transmission of different diseases, each with its own particular habits: some feed by day and others by night; some prefer to feed indoors and others prefer to do so outside; some rest after feeding and others depart; some prefer to feed on humans and others on animals; and various species choose different places for laying their eggs.
Mosquito control requires a knowledge of these habits.
Today, the mosquito is literally spreading its wings as a carrier of diseases and settling in new areas far from its original geographical boundaries. Some of the reasons—international travel, trade and migration—have already been outlined.
In addition, expanding agriculture, the clearing of forests or the building of dams and irrigation schemes and unplanned urban development provide mosquitos with new breeding grounds, while at the same time bringing more people into contact with them.
Changes in climatic conditions are enabling mosquitoes and other disease carrying insects to survive and breed at more northern latitudes and higher altitudes. One example illustrates the role of international travel and trade.
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The Asian tiger mosquito, which can transmit deadly strains of encephalitis virus as well as dengue and yellow fever, has been introduced into the United States, Brazil and parts of Africa in cargoes of rubber vehicle tyres shipped from Asia. In the United States alone, this mosquito is established in at least 23 states and can survive winters as far north as Chicago (even at -2°C).
Malaria is endemic in 91 countries, with about 40 per cent of the world’s population at risk. Each year there are 300-500 million clinical cases of malaria, 90 per cent of them in Africa and between 1.5 million and 2.7 million deaths. Among all infectious diseases, malaria continues to be one of the biggest contributors to disease burdens in terms of deaths and suffering.
By undermining the health and capacity to work of hundreds of millions of people, it is closely linked to poverty and contributes significantly to stunting social and economic development.
In many parts of the world, malaria is becoming an even greater problem than before. Epidemics are recurring in areas where transmission had been interrupted and are generally associated with deteriorating social and economic conditions.
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Malaria is a febrile disease caused by the four species of human malaria parasites belonging to the genus Plasmodium and naturally transmitted to people by the bite of an infected female mosquito of the genus Anopheles.
Early symptoms include fever, shivering, aches and pains in the joints and headache. In Falciparum malaria, infected red cells can obstruct the blood vessels of the brain, causing cerebral malaria, which is often lethal. Other vital organs can also be damaged, with fatal consequences.
In the 1950s, there were hopes that malaria would be eradicated in a fairly short time, mainly through the intensive use of insecticides. However, malaria still remains a serious threat in endemic countries today.
According to National Vector Borne Disease Control Programme (NVBDCP) report estimates 25 million recorded cases of malaria with 30,000 deaths in 2009 against WHO’s estimated 1.53 million cases and 15,000 deaths in global scale.
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Those at greatest risk of dying from the disease are children under age 5 in malaria-endemic areas; pregnant women; people moving from non-malarious to malarious zones for reasons of work, migration, refuge, war or tourism; and travellers who visit endemic countries and return home with the disease.
WHO’s global malaria strategy (which is intended to prevent mortality, reduce morbidity and lead to a decrease in social and economic loss) consists of providing early diagnosis and prompt treatment; planning and implementing selective and sustainable preventive measures, including vector control; detecting early, containing or preventing epidemics; and strengthening local capacities in basic and applied research to permit and promote the regular assessment of a country’s malaria situation, in particular the ecological, social and economic determinants of the disease.
The main problems in malaria control are shortages of resources and resistance to pesticides and drugs. Dengue fever, a severe influenza-like illness and dengue hemorrhagic fever are closely-related conditions caused by four distinct viruses transmitted by Aedes aegypti mosquitos.
Dengue is the world’s most important mosquito-borne virus disease. A total of 2,500 million people worldwide are at risk of infection. An estimated 20 million cases occur each year, of whom 500,000 need to be hospitalized up to 1990. There is no cross-immunity, which means that an individual who has recovered from one remains susceptible to the other three.