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Source:  Assignment    Tag:  western equine encephalitis symptoms
Introduction
Mosquito-borne diseases  or  mosquito-borne illness  are disease caused by   bacterial, viruses or parasites  transmitted by   mosquitoes. They can transmited disease without being affected themselves.Some important disease transmitted by mosquitoes include:   malaria,   dengue  and   West Nile virus. Nearly 700 million people get a mosquito borne illness each year resulting in greater than one million deaths. Mosquito borne illnesses include: malaria, dengue, West Nile virus,   chikungunya ,  yellow fever ,  Japanese encephalitis ,  St Louis encephalitis ,  Western equine encephalitis ,  Venezuelan equine encephalitis ,  Eastern equine encephalitis  and  La Crosse virus . The female mosquito of the genus   Anopheles  carries the  malaria   parasite  (see  Plasmodium ). Worldwide,  malaria  is a leading cause of premature mortality, particularly in children under the age of five, with an estimated 207 million cases and more than half a million deaths in 2012, according to the World Malaria Report 2013 published by  WHO . The   human botfly  (Deramatobia hominis) uses a mosquito to deliver its eggs and transfer it to a person, the eggs are in the underside of the mosquito vector. When the mosquito takes a blood meal to their human host,the eggs landed on the skin and started to hatched into Larvae and start to feed on Human flesh and blood. Some species of mosquito can carry the   filariasis  worm, a parasite that causes a disfiguring condition (often referred to as  elephantiasis ) characterized by a great swelling of several parts of the body; worldwide, around 40 million people are living with a  filariasis  disability.



Types of Mosquitos

 

Anopheles (uh-noph-o-lease)

Adults of this genus are found primarily in temporary rain pools, swamps, and ponds. They feed readily on humans. Certain species of this genus serve as the primary vector of malaria.


Coquillettidia (co-quill-ah-tid-ee-ah)

This genus has but one species, Cq. perturbans. This species is extremely aggressive and feeds primarily on large mammals. It is very common throughout all of Florida and is found in very large numbers, with emergences occurring in early spring and late fall. This species also is suspected of being a bridge vector for Eastern Equine Encephalitis (transmitting the virus from the bird to a human or horse).
The larvae of Cq. perturbans are closely associated with aquatic plants such as cattails, water lettuce, and water hyacinth.  The larvae pierce the roots of these plants to obtain oxygen.  This species will often fly great distances in search of blood meals.

Culex (cue-lex)

Species of this genus are found breeding in freshwater habitats such as pools, ditches, ponds, and even in effluents of sewage treatment plants.  Species in this genus are considered to be of medical importance in that they have been proven to be the primary vector of St. Louis Encephalitis and also play an active role in the transmission of West Nile Virus. They are most active at dusk, but are known to be active daytime biters.



Diseases
     

Malaria

Malaria is the most well-known mosquito-transmitted illness. Malaria is spread by a particular type of mosquito (the infected Anopheles mosquito) found only in certain parts of the world. People living in, or visiting, those places can reduce the risk of malaria by taking antimalarial tablets, and taking measures to avoid being bitten. For more info see Malaria

Dengue fever

The mosquitoes that transmit dengue fever breed in containers that hold water, and bite during the day, not mainly at dusk or evening like other types of mosquito. People infected with the virus may have no symptoms, but others may experience high fever, severe headache, muscle and joint pain, rash and extreme fatigue. In rare cases, dengue fever can be severe and even fatal (dengue haemorrhagic fever). It is important to seek immediate medical advice if you suspect you have dengue fever.
There is no vaccine against dengue fever, so mosquito prevention measures are essential. The mosquito responsible (the infected Aedes mosquito) is found in many tropical and subtropical areas. The World Health Organization reports (2009) that dengue is found in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia and the Western Pacific. Close to home, affected areas include northern Australia and many Pacific nations. 

Japanese encephalitis

Japanese encephalitis is an infection of the brain caused by a virus that is spread by infected mosquitoes. The mosquitoes become infected after biting pigs infected with the virus. Japanese encephalitis occurs in parts of Asia and Papua New Guinea. There have also been cases in north Queensland in Australia. Most infected people have no symptoms, but a small proportion may have severe symptoms, including headaches, high fever, convulsions and coma. There is no treatment, but a vaccine is available to protect against the infection in people travelling to, or resident in, areas where the virus is found.

Ross River virus infection

Occurring widely in Australia, the Ross River virus is spread from animals to humans by several different types of mosquitoes. Although many people infected with this virus have no symptoms or only slight symptoms, other people may have a fever, joint pain and swelling and a rash. There is no specific treatment but medicines may be taken to help relieve the symptoms.

Barmah Forest virus infection

The Barmah Forest virus is also widespread in Australia and causes a similar illness to Ross River virus infection but the symptoms usually last for a shorter length of time. The virus is spread from animals to humans by mosquitoes. Again, there is no specific treatment for this infection, but medicines may be taken to help manage the symptoms.

Murray Valley encephalitis

Murray Valley encephalitis is a very rare disease involving swelling of the brain tissue. The disease is caused by infection with a virus that is spread by the bite of infected mosquitoes. The mosquito responsible is found throughout Australia and breeds in surface pools of water. Water birds, such as herons, are a natural reservoir of the virus. Most people infected with the Murray Valley encephalitis virus do not develop symptoms, but others may have high fever, severe headache, neck stiffness, irritability, seizures (or fits), and drowsiness. Immediate medical advice should be sought for these symptoms.

Yellow fever

Yellow fever occurs in areas such as Africa and South America, and is spread by infectedAedes and Haemogogus mosquitoes. It can be spread by mosquitoes in jungle/rural areas as well as urban areas. Yellow fever causes a flu-like illness, but some people develop a more severe form which can be life threatening. The ‘yellow’ relates to jaundice which occurs as part of the severe illness. No specific treatment is available other than supportive measures.

Controlling Measures

·         trying to stay indoors at dusk (when most mosquitoes do their biting)
·         wearing light-coloured, long-sleeved shirts, long trousers and covered shoes at this time of the day (but note, dengue-carrying mosquitoes also bite during the day)
·         using effective insect repellents (eg, DEET) when outdoors
·         choosing accommodation that has air-conditioning or insect screens on rooms (otherwise, sleeping under a mosquito bed net, preferably pre-soaked in permethrin)
·         using insect sprays inside
·         if applicable, removing outside containers that hold water where mosquitoes might breed


Conclusion
Mosquito species found in many parts of the world can transmit a number of diseases, such as malaria, dengue fever and yellow fever. People going on overseas travel (including to some parts of Australia and the Pacific, as well as further afield), should be aware of potential disease threats from mosquitoes, and try to avoid mosquito bites.





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