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.
Reference
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