The Mosquito – World’s Deadliest Creature

The Mosquito –  World’s Deadliest Creature

Re-written and updated to address the extreme importance to be vigilant against the present outbreak of Dengue in the country. This article includes news about the deadly Zia virus, which threatens many parts of the world.

 

Dengue  mosquito (Aedes) after feeding. (Internet)

Dr Abe V Rotor

Living with Nature School on Blog [avrotor.blogspot.com]

Virtually no one escapes this cosmopolitan uncanny vampire, that hardly a day passes without sustaining a surreptitious bite from it.

The mosquito follows wherever man goes, and oftentimes is even ahead in the frontiers. Its is there in the polar regions of Siberia, marshes of tropical America and Asia, at the Dead Sea basin, 1,300 feet below sea level, and on the Andes and Himalayas.

They come in armies or swarms but are not true colonies like those of the bees and ants. Swarming is just an accident of enormous population buildup concentrated in a local breeding area.

The mosquito changed the course of history. When irrigation canals built by the Babylonians joined the Tigris and Euphrates rivers, a vast swamp developed and became infested with malaria. It was here Alexander the Great and his powerful army lost - to malaria.

The mosquito has successfully defended the wildlife bastions such as the Amazon, the jungles of India and Africa, and the forest islands of the Pacific. The development of the tropics - the mosquito belt - was retarded for centuries, and mosquitoes almost prevented the building of the Panama and Suez Canals.

The mosquito occupies a vital link in the food chain, being a major food source for fish and amphibians. Fishes feed upon its larvae, the wrigglers, while the adults are frog's favorite. Man's dependence on fish, - which are dependent on mosquitoes in turn - places him at the apex of the food pyramid. There is only one guarantee that man continues to occupy this position - if he is willing to shed blood for it. Without blood, mosquito eggs fail to hatch and without a sip once in every 25 generations, its particular generation dies out, thus breaking the food chain and toppling the food pyramid.

In today's modern living, with technological breakthroughs in pests and disease control, human encounters with the once dreaded mosquito have been reduced mainly to physical annoyance and "pesky" problems. This is not however, entirely true as we shall see later.

Here are some questions commonly raised about the mosquito, and their scientific answers to update our acquaintance with our old enemy and friend.

Q. Do mosquitoes bite only warm-blooded animals?

A. In general yes, but there are also species of mosquitoes that bite turtles and snakes.

Q. Do all mosquitoes bite?

A. Only the female mosquito does. The regular food of adult, male mosquitoes is plant sap and nectar.

Q. How are mosquitoes able to locate their suitable hosts?

A. They have chemoreceptors - a combination of smell and touch - located at the plumose antennae and hairy legs. These are sensitive to heat waves and odor emitted by the hosts.

Q. Do mosquitoes invade places far from their breeding grounds?

A. Yes, although they seldom travel farther than 1000 feet from their birthplace. Mass raids have been monitored to as far as 50 to 75 miles away, the swarm usually riding on air currents.

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The British named their bombers and reconnaissance planes in World War II, Mosquito, so with the Italians for their anti-tank rockets – a tribute to the superb agility of this pesky minutia.

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Q. What is the needle of the mosquito made of?

A. Actually it is a sheath bundle of modified mouthparts, the equivalent of teeth, lips and whiskers elongated to form a drill, siphon, probe and guide and rolled into a needle or proboscis.

Q. How can this tiny needle penetrate tough skin and clothing?

A. It works on the principle of jackhammer with high frequency.

Q. What prevents blood from clotting in the body of the mosquito?

A. The blood, before it is sucked, is first thinned by the mosquito's saliva, which contains an anti-coagulant substance. It has also an anesthesia effect on the host.

Q. Is this the reason why we do not feel a mosquito bite at once?

A. Yes, and probably the location of the bite is away from a nerve.

Q. Why do mosquitoes make their presence known by buzzing near the ear?

A. This is not true. They simply whine and emit short wave buzzing which is picked up when passing near the ear. (Wing beat is 600 per second, and the cymbal sound-producing membrane vibrates nearly 7000 cycles per second.).

Q. How do you recognize disease-carrying species from one another?

A. Anopheles, the malaria carrier has its head, body, and proboscis in straight line to each other but at an angle to the resting surface. It has spotted colorings on the wings. Its wrigglers lie parallel to the water surface.

Culex, the carrier of viral encephalitis and filariasis holds its body parallel to the resting surface. Its scaly proboscis is bent and uniform in color. Its wrigglers are slender and long with breathing tubes covered with hair tufts.

Aedes, the carrier of yellow fever, dengue and encephalitis, holds body parallel to the resting surface with proboscis bent down, thorax silvery with white markings. Its wrigglers are short and stout with breathing tubes containing a pair of tufts. They hang from the water surface at 45 degrees angle.

When you see a mosquito resting, or wrigglers hanging down from the surface of a pond, use the above reference.

Q. How serious is Dengue fever? How can it be controlled?

A. The disease threatens two billion people in 100 countries. In 1998 alone, 514 died of Dengue in the Philippines with one death for every 100 patients who were mostly children. Metro Manila had the highest incidence with more than six thousand cases. Since the disease is specifically transmitted by Aedes egpypti, the key to the control of the disease is the extermination of the breeding places of the mosquito vector.

Q. Do mosquitoes follow certain feeding hours?

A. Yes. For example, the Anopholes or malarial mosquito bites chiefly in the evening and early morning, while the Aedes bites during the day.

Q. How fast do mosquitoes multiply?

A. In a year's time there may be from 15 to 20 generations produced. At the normal rate of 100 eggs laid per generation, a common mosquito could spawn 31 billion descendants in six generations.

Q. What attracts mosquitoes?

A. They are attracted by the regular breathing, color and texture of clothing, and odor. Dr. A. Brown of the University of Ontario reported that the rate of breathing is the principal factor in attracting mosquitoes. He also found that only one-tenth landed on white clothing than on dark or black material. The texture most avoided is luminescent satin. A person who has not taken a bath gets more mosquito bites. Try it.

Q. What is the best insecticide to make our homes "mosquito- proof?"

A. When DDT was not yet banned, 200 milligrams of the powder could give effective proofing from 6 to 12 months. Dieldrin at 50 milligrams gives a three-month proofing. Carbamates, like Sevin, are preferred. Even if they have shorter residual effect, they are safer to health and the environment. Eucalyptus trees in the surroundings repel mosquitoes. Now and then smudge the area by burning dried leaves of Eucalyptus specially in the afternoon.

Q. Do mosquitoes develop resistance to chemicals?

A. Yes, through biological specialization, survivors from previous sprayings tend to carry on a certain degree of resistance, which could be passed on to the next generation. Chemical control should be judiciously practiced to cushion this phenomenon. Return to plant derivative insecticide like pyrethrum, rotenone, nicotine and derris is highly recommended.

Q. How does a film of oil on water kill mosquito wrigglers?

A. When they stick their tails out of the water to breath, the oil slick clogs the breathing tube, thus resulting to asphyxiation.

Q. If it is impractical to drain the breeding ground of mosquitoes, how do we get rid of wrigglers and pupae?

A. Keep the water free from organic matter and scum which are food of wrigglers. Better still, put some fish, like kataba (Poecilia) and Gambusia, to feed on them.

Q. Do mosquitoes fight each other?

A. They seldom engage in combat, but there are species, which have preying habits. These are Toxorphynchites nornatus, T. splendens, and T. brevipalpis which were introduced into Hawaii, Fiji, Australia and Southeast Asia to control pest mosquitoes. Their wrigglers are larger and larvivorous, feeding on the smaller wrigglers of other mosquito species.

Next time a mosquito comes buzzing around your ears, take the message seriously because it is the world’s deadliest creature. More people have died because of its bite than all who perished in all wars combined.

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What is the Zika virus? Everything you need to know about the outbreak
ZIKA virus could spread to Europe this summer, world health leaders have warned. But what is it and what threats does it pose?
By Becky Fletcher and Alice Foster

GETTY Zika virus: 1.5 million people xxx infectedThe risk in Europe is highest on the island of Madeira and the north-eastern coast of the Black Sea, according to the World Health Organisation.
In its first assessment of the threat Zika poses to Europe, the WHO’s European office classified the overall risk as small to moderate.
In February the WHO declared a global health emergency over the Zika virus. The outbreak has now spread to more than 50 countries.
Here is everything you need to know about the disease, symptoms and ways to prevent its spread.

What is the Zika virus? The virus - a once rare disease confined to the depths of subtropical Africa - was first identified in Uganda in 1947.
It is an “arbovirus” - spread by mosquitoes and belongs to the same family as dengue fever and the chikungunya virus.
Because the virus has been so rare prior to 2015, there has been little research in to the virus, meaning it is difficult to clinically diagnose someone.
GETTY The virus is transmitted by mosquitoes

How is Zika virus spread? The virus is spread by a certain type of mosquito that transmits the disease when it bites someone infected with Zika, and then goes on to bite another person.
In some cases, Zika virus is transmitted through sex.

Where has Zika virus been reported? Previous outbreaks were confined to small regions in Africa, South East Asia and the Pacific Islands.
In May 2015 Zika virus was first reported in Brazil. The disease has since struck other parts of South America as well as Central America, the Caribbean and Pacific Islands

What are the symptoms of Zika virus? Only one in five of the infected is thought to develop symptoms including, mild fever, sore eyes, headache, joint pain and a red, bumpy rash.
The illness is mild with symptoms lasting several days to a week. Those who have it are advised to rest, drink plenty of fluids and take medicines to reduce pain and fever.
Because four out of five don’t develop symptoms, virologists are concerned that it could be easily spread by people who don’t know they have the Zika virus.

Zika virus may reach Europe this summer Wed, May 18, 2016The Zika virus, an infectious disease linked to severe birth defects in babies, may spread into Europe as the weather gets warmer

Which birth defects can Zika virus cause? The biggest concern - and why so many pregnant women are being urged to avoid pregnancy - is microcephaly.

Microcephaly is a birth defect being associated to women who have been infected by the virus. It is caused by below normal brain development in utero.

Babies born with the birth defect have a below-average head size often caused by failure of brain to grow at a healthy and normal rate. There is a link between birth defects and the Zika virus The severity can vary, but some babies are left with brains so underdeveloped they might experience walking, sight, hearing and learning difficulties.

Children who survive face severe disabilities and possible seizures.The rates of microcephaly in Brazil shot up by 1,792 per cent between 2013 and 2015.

How is Zika virus treated?

There is currently no vaccine for Zika virus.
People should avoid getting bitten by using insect repellents, covering up with long-sleeved clothes and keep doors and windows closed.Pregnant women should not travel to affected areas.
Male travellers should wear condoms to prevent the transmission of Zika virus through sex.

ZIKA SEX WARNING: Mosquito virus linked to baby brain damage may spread via intercourse
THE Zika virus, which is causing panic across the Americas, could be passed on through sex, findings suggest.Two cases have been unearthered whereby Zika could have been spread sexually

The condition, which has been linked to birth defects and is rapidly spreading through Brazil, has been linked to intercourse twice in medical literature.
It has led to calls for urgent research into the virus.The first known case occurred when scientists found high levels of the virus in the semen of a 44-year-old man from French Polynesia.

The WHO says more evidence needs to be proven before a link between sex and Zika can be made

Neither passed the disease to their kids or close family, so the couple believe it could have been sexually transmitted.

Health experts have said while the cases do not warrant a health warning, it should be investigated further. The World Health Organisation says more evidence is needed to prove that sexual contact is a means of transmitting the virus.

The US Centers for Disease Control and Prevention say the cases are a “theoretical risk” but there is insufficient evidence to issue public health warnings.

The virus has been linked to a birth defect called microcephaly

Only 20 per cent of those infected show symptoms of the short-lived virus.
Typically symptoms include low-grade fever, joint pain, a rash, conjunctivitis, headache, muscle and eye pain.

The virus itself is not thought to be dangerous to most people but it has been linked to pregnant women and the birth defect microcephaly.

Countries in the affected regions are warning women to postpone 
pregnancy until more is known about the previously rare virus.

Zika outbreak: What you need to know
By James Gallagher Health editor, BBC News website

The World Health Organization has declared the Zika virus a global public health emergency.
The infection is suspected of leading to thousands of babies being born with underdeveloped brains.
Some areas have declared a state of emergency, doctors have described it as "a pandemic in progress" and some are even advising women in affected countries to delay getting pregnant.
But there is much we do not know in this emerging infection.

What are the symptoms?
Deaths are rare and only one-in-five people infected is thought to develop symptoms.

These include:
mild fever
conjunctivitis (red, sore eyes)
headache
joint pain
a rash

A rare nervous system disorder, Guillain-Barre syndrome, that can cause temporary paralysis has been linked to the infection.There is no vaccine or drug treatment so patients are advised to rest and drink plenty of fluids.
But the biggest concern is the impact it could have on babies developing in the womb and the surge in microcephaly.

What is microcephaly?

It is when a baby is born with an abnormally small head, as their brain has not developed properly.
The severity varies, but it can be deadly if the brain is so underdeveloped that it cannot regulate the functions vital to life. Children that do survive face intellectual disability and development delays.It can be caused by infections such as rubella, substance abuse during pregnancy or genetic abnormalities.
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Articles about the Zika Virus from Internet