Entries in Mosquitoes (10)


Mosquitoes May Be Developing Tolerance to DEET, Research Shows

iStockphoto/Thinkstock(NEW YORK) -- Mosquitoes may be developing a tolerance to DEET, according to new research at the London School of Hygiene and Tropical Medicine.

Researchers at the school have found that mosquitoes are repelled when they are first exposed to the bug spray, created in 1946 by the U.S. military. But according to researcher Nina Stanczyk, mosquitoes get used to the smell and begin to ignore it, just like humans.

Researchers say, however, not to give up on DEET, as it is still the best defense against the disease-carrying insects.

Copyright 2013 ABC News Radio


Malaria Deaths Twice as High as Previously Reported

Stockbyte/Thinkstock(SEATTLE) -- Malaria kills 1.2 million people each year, more than twice as many deaths as previously thought, according to new research published in The Lancet.

However, according to the Institute of Health Metrics and Evaluation, which conducted the new research, efforts to combat the disease, both through drug treatments and prevention, have resulted in a decline in malaria-related deaths.

"This runs counter to most assumptions about the disease," said Dr. Stephen Lim, associate professor of global health at the Institute.  "The good news, though, is that even though the overall number of deaths is higher, the trend is sharply downward."

Researchers also found that while many believe most malaria deaths occur in children under age 5, in fact, 42 percent of all malaria deaths occur in older children and adults.

Authors from the Institute collected data on malaria deaths over two decades, from 1980 to 2010.  They found that 1.2 million people died of the disease in 2010: twice as many deaths as reported by the World Malaria Report released last year.  The World Health Organization estimated that about 650,000 people worldwide died of the disease in 2010.

Researchers said the higher death tally is likely due to the fact that more reliable data became available.

Based on the new numbers, malaria deaths have fallen by 32 percent since 2004, dropping from 1.8 million deaths worldwide to 1.2 million in 2010.

"That's a massive decrease, and it appears to be the result of the huge scale-up in spending to fight malaria, especially by the Global Fund to Fight AIDS, Tuberculosis and Malaria," Lim said.

Malaria is caused by a parasite passed to humans through mosquito bites.  The parasites then travel through the bloodstream to the liver and infect red blood cells, according to the National Institutes of Health.

The parasites multiply within the body, and then symptoms, including chills, fever, vomiting and coma, occur 10 days to four weeks after the mosquito bite occurs.  If left untreated, complications can include kidney failure, liver failure, meningitis and, ultimately, death.´╗┐

Copyright 2012 ABC News Radio


Researchers Trace Origins of Malaria

MALARIA MOSQUITO HEAD, Getty Images(IRVINE, Calif.) -- Researchers at the University of California, Irvine think they know how malaria jumped continents may years ago.

The study, which will be published in the Proceedings of the National Academy of Sciences, traced the origins of the mosquito-borne disease back to the 16th century.

Researchers in Irvine say they relied on DNA as a molecular clock appearing to answer how malaria got from Africa to South America and then the rest of the Americas. The team of researchers say the disease, which kills over a million people a year, came aboard Spanish and Portuguese slave ships in the 16th century.

Copyright 2011 ABC News Radio


Asian Tiger Mosquito Spotted in Southern California

Aedes albopictus mosquito, also known as the Asian tiger mosquito, feeding on human blood. This mosquito is known to transmit West Nile virus. Kallista Images/GettyImages(EL MONTE, Calif.) -- The Asian tiger mosquito, a rare and dangerous insect native to Southeast Asia, made an appearance in Southern California last week, prompting action from local pest controllers and health officials.

The mosquito, known for its black body and white stripes, is capable of carrying several viruses, including dengue fever, West Nile virus and yellow fever. It is smaller than most mosquitoes and bites during the day, not just at night, and already has a foothold in the U.S. Southeast.

While it is unclear how the Asian tiger mosquitoes arrived in Southern California, no one has become sick since spotting the bug in El Monte, Calif. The San Gabriel Valley Mosquito & Vector Control District plans to fog the area where the mosquito was found as early as Friday.

District officials are going door-to-door in El Monte to educate the public on how to they can assist in fixing the problem.

“We’ll be making the best effort to eliminate the mosquito,” said Kenn Fujioka, assistant manager of the San Gabriel Valley Mosquito & Vector Control District. “It’s the risk to our public and the uncertainty how it will behave that concerns us.”

The Asian tiger mosquito made its first U.S. appearance when it surfaced in Houston in 1985 after being transported from Asia in old tires meant for recycling. The mosquitoes soon migrated to Florida, and now, more than two decades later, they can be found throughout much of the Southeast.

“People in other parts of the country aren’t able to eradicate the problem because the humid conditions are too favorable for the mosquito,” said Fujioka. “Southern California is too dry for them to take advantage of the environment so easily, so we have a better chance at fixing the problem.”

“The best way to control an area is to eliminate sources where larvae can develop,” said Fujioka.

Health officials urged residents to dump out any containers holding standing water, even very small amounts. The mosquito is known to lay eggs in small, water-filled holes like those in trees, asphalt and concrete. Dispose of any unused containers and tires stored outdoors and drill drain holes in the bottom of playground equipment. If residents in the area spot one of the bugs, officials recommend they call the agency.

“The bite will appear like any other bug bite,” said Fujioka. “If people are bitten by any type of mosquito and they develop headache, fever or rash five to seven days later, they should get in and see a doctor to rule out diseases transmitted through insects. It’s the risk we’re concerned about.”

Copyright 2011 ABC News Radio


NC Girl Dead From Suspected Mosquito-Related Virus

Stockbyte/Thinkstock(ASHEVILLE, N.C.) -- An 8-year-old North Carolina girl died this week from encephalitis, after she was bitten by a mosquito likely carrying LaCrosse virus. Her death and the hospitalization of her younger brother are the latest evidence that a wet spring and a hot, wet summer have boosted the insects' population and power to imperil public health.

Health officials on Friday awaited results of lab tests to confirm the underlying cause of the brain inflammation that proved fatal to the Henderson County, N.C., child. The youngster, whose name was being withheld, died Wednesday at Mission Hospital in Asheville, in the mountains of western North Carolina. The LaCrosse virus, which travels from the bloodstream into the brain, can cause headaches, fever, nausea, vomiting and weakness. It can only be spread to people through the bite of an infected mosquito. It cannot be spread from person to person.

"North Carolina is one of the areas where LaCrosse virus is endemic, so having them report cases is not uncommon," J. Erin Staples, a medical epidemiologist at a branch of the Centers for Disease Control and Prevention in Fort Collins, Colo., said Friday. "LaCrosse disease is described more often in children, likely due to the interaction between children and the tree-hole breeding mosquitoes that carry the virus."

As of Aug. 30, there were 22 confirmed and probable LaCrosse illnesses reported to the CDC. The CDC tally consisted of four cases from North Carolina, along with others from Georgia, Indiana, Ohio, South Carolina, Tennessee, West Virginia and Wisconsin.

Mosquito surveillance that began in late spring in such states as Connecticut has shown an explosion in the numbers of mosquitoes caught in traps. As a result of this banner year for the buzzing biters, entomologists and health agencies have repeatedly reminded Americans to use insect repellants and avoid being outside at dawn and dusk, when mosquitoes are likeliest to turn to people for their blood meals. They also advise emptying standing water that mosquitoes use as breeding grounds, a particular risk in many states following the flooding from Hurricane Irene. Screened windows and doors can put more distance between mosquitoes and vulnerable skin.

Melting of the heavy winter snowfall, Mississippi River flooding and high waters from Hurricane Irene can be blamed for some of this year's profusion of "nuisance mosquitoes," although they're not the culprits in potentially fatal mosquito-linked diseases, Staples said. She and her colleagues worry more about the high heat of summer, which boosts the population of mosquitoes carrying West Nile virus. Cases peak in late August and early September, Staples said. The virus first appeared in this country in 1999.

The most devastating of the mosquito-linked illnesses is Eastern equine encephalitis, which is rare, but fatal in about a third of cases. There is no treatment. Survivors often have brain damage. EEE is carried by Culiseta melanura mosquitoes, which live in marshes, swamps and other bodies of still water. So far, New York has reported the only human case for 2011. Seven other states have detected the disease in mosquitoes, birds and other animals.

As of Aug. 30, Arkansas reported a probable human case of St. Louis encephalitis, typically found in Eastern and Central states, and most dangerous to older patients. Florida and Nevada have detected it in insects and animals, the CDC's latest tally showed.

Copyright 2011 ABC News Radio


Mosquito Numbers Decline in Certain African Areas

Stockbyte/Thinkstock(TANZANIA) -- Malaria-affected mosquito populations are declining in certain areas across Africa, according to recent figures, though researchers are unsure as to why.

The Malaria Journal reports that researchers are unsure if the decline means the pesky insects have been eradicated for good, or if they will come back in a stronger force.

The BBC reports that malaria cases dropping in Tanzania, Eritrea, Rwanda, Kenya and Zambia, according to data.

Anti-mosquito bed nets are lessening the spread of the disease in some sub-Saharan countries.

Researchers also cite that mosquito traps installed over the course of 10 years have caught insects by the thousands in Tanzania, and the numbers have drastically been reduced over the years.

Scientists captured over 5,000 mosquitoes in 2004, and could only trap 14 in 2009.

Copyright 2011 ABC News Radio´╗┐


Houston Drought, Heat Wave Brings Plague of Bugs, Broken Pipes

Stockbyte/Thinkstock(HOUSTON) -- Houston is suffering through its worst drought in decades, and the misery is being compounded by a plague of mosquitoes carrying West Nile virus, infestations of fleas, and a cascade of bursting water pipes that are spilling the city's precious water supply.

Most worrisome for the city is the sudden surge in the number of mosquitoes carrying West Nile.

"This summer we had an incredibly dry, very hot summer and so that will do nothing but increase the positive number of mosquitoes," said Kristy Murray, an assistant professor at the University of Texas Health Science Center, who has studied the West Nile virus for nine years.

More than three times the number of mosquitoes as last year have tested positive for West Nile virus, she said.

With so little water and such high temperatures, mosquitoes and birds are coming into more frequent contact as they seek out the same limited water sources.  The birds, which carry West Nile, transmit the virus to the mosquitoes when the birds are bitten, Murray said.

So far only four cases of West Nile have been reported in humans this year, but Murray said she expects even more cases in her state.

"Usually 80 percent of cases occur in August and September in humans," she said, adding that people sometimes don't show symptoms right away.

West Nile Virus causes inflammation of the brain and meningitis, and can be fatal.

For some reason the drought and heat wave has also increased the activity of fleas in Houston.

Murray said her dogs have fleas, something that can be attributed to the climate.

"I have been using every flea product on my dogs, from oral to topical, and they still have them," she said. "Fleas have never been a problem for my dogs before."

Murray said she had heard similar stories from neighbors, who have had to treat their pets for infestations for the first time.

Just as Houston is trying to preserve its dwindling supply of water, its system of water pipes are bursting at a rate of 700 a day, up from the usual rate of 200 a day at this time of year.

The heat wave has dried out the ground so much that the soil is shrinking, leaving gaps around the pipes.  At times, the pipes sag and crack.  At other times, the increased use of water bursts through older, worn out pipes at a spot where the soil has fallen away the from pipes.

With so much water spilling into streets, the city is having trouble maintaining water pressure and instituted water rationing this week.

Copyright 2011 ABC News Radio


Genetically-Engineered Spermless Mosquitoes Offer Malaria Hope

Stockbyte/Thinkstock(LONDON) -- Where mosquito netting and bug spray fail, European scientists are turning to a unique solution to stem the tide of malaria infection worldwide: they're breeding boy bugs that shoot blanks.

In a study released Monday in the Proceedings of the National Academy of Sciences, researchers in Italy and the U.K. showed they were able to genetically modify male Anopheles mosquitoes so that they wouldn't produce sperm. The bugs would still produce seminal fluid, so mating rituals would go on per usual, but the fruit of coupling would be sterile eggs that don't hatch.

"If mosquitoes [don't] produce any progeny...the number of mosquitoes in the wild will be reduced, eventually reducing the chances of malaria transmission," says study co-author Dr. Flaminia Catteruccia of the Imperial College in London.

Though there are thousands of mosquito species, only a handful of them can transmit malaria, Catteruccia says, so targeting these species has the potential to reduce the spread of disease and is less likely to negatively impact the local ecosystem.

The fact that the Anopheles species of mosquito tends to be monogamous only enhances the effect, as those females who mate with sterile males tended to not seek out other, potentially virile mates.

Sterility may even prove a reproductive boon for spermless males, authors note, because making sperm is energy-consuming, thus the modified males may appear to be stronger mates.

More than 225 million people worldwide suffer from malaria. Each year, nearly 800,000 people will die from the disease -- many of whom are children living in Africa.

"Given the constant spread of the disease, alternative approaches to the use of insecticides are urgently needed," the study's authors wrote.

Monday's research is just the most recent example of a number of mosquito-modifying techniques tested in the past few years in hopes of limiting the mosquito population or the bugs' disease-transmission capabilities.

Other mosquito-limiting tactics have included modifying males to be unable to fly (and who have offspring who also cannot fly) and injecting mosquitos with a special fungus that is thought to reduce the bug's ability to pass malaria to humans, even when the bugs themselves become infected.

The hope with these various methods is that disease rates can be lowered without negatively impacting the surrounding ecosystems, which often include several species of insects and animals that rely on mosquitoes for food.

Copyright 2011 ABC News Radio


Stinky Feet, Scented Deodorants Attract Mosquitoes

Jupiterimages/Thinkstock(MOUNT LAUREL, N.J.) -- From perfume, to the color of your shirt, right down to the smelliness of your feet, mosquitoes seem to find any reason to sink themselves into human skin.

Scientists say that stinky feet and socks can be added to the list of factors that attract mosquitoes to feed off human blood. One African scientist is now using that bit of research to help fight malaria in Tanzania by creating traps that give off chemically replicated smelly foot odors, hoping to lure the bloodsuckers that carry the disease to their hosts.

"Scientists have known for a long time that mosquitoes smell people; that they do not see us, but instead they smell us," wrote Dr. Fredros Okumu in an email from Tanzania where he heads the research project at the Ifakara Health Institute. "It is the things that we produce in our breath, sweat of skin that [mosquitoes] use as a signal to find us. So if you are wearing socks, these skin-derived chemicals remain on the sock fabric and can still be detected by mosquitoes even after you have removed your socks."

Okumu's project received a $775,000 grant Wednesday from the Bill and Melinda Gates Foundation and Grand Challenges Canada to fund the traps and help further development.

But unclean feet and dirty socks aren't the only things that entice a mosquito to go in for the kill. Experts say that Limburger cheese has also been found to be attractive to certain mosquito populations. Ned Walker, a professor in the Department of Microbiology and Molecular Genetics at Michigan State University, studies mosquitoes extensively. Walker said that everything from body build to the type of perfume you wear can be the difference between deterring and attracting the pests.

However, determining why some people leave a picnic covered in bites while others escape without a battle wound is still up for debate.

Joe Conlon, technical adviser at the American Mosquito Control Association, said genetics as well as fair skin may also play a role in appealing to mosquitoes, although scientists remain unsure whether the bites are simply more noticeable on people with fair skin.

And while fair skin might be more attractive to the insects, lighter colors of clothing turn them off.

Conlon said that the only surefire way of preventing mosquitoes from biting is to wear a repellant, to watch what clothes you wear and to get rid of standing water that collects in places like at the bases of flower pots and in the bottom of air conditioning drip pans.

He also cautioned against using any substitutes to DEET repellants like vitamin B, saying that double blind tests have proven these remedies not to work effectively.

Copyright 2011 ABC News Radio


Bug Buster? New Chemical Compound Could Ward Off Deadly Mosquitoes

Stockbyte/Thinkstock(NASHVILLE, Tenn.) -- Somewhere in the world, every 45 seconds, malaria claims the life of one child. The large majority of those are deaths are in Africa. And they are preventable.

"The most dangerous animal on the planet is the Anopheles gambiae,'' the mosquito that carries malaria, said Dr. Lawrence Zwiebel, a researcher at Vanderbilt University who has been working for the past six years to find a way to repel the deadly insects.

Zwiebel's team has taken a novel approach. Rather than looking for ways to eradicate the insects or disrupt the ecosystem, they sought to change the habits of the ancient pests, their feasting habits, to be precise, by making humans less appetizing to the nasty predators.

Last month, Zwiebel's team announced that they may have hit the jackpot. They identified what's called a behaviorally disruptive olfactory compound that they believe could be thousands of times more effective than the most commonly used insect repellent on the market, DEET.

The compound, which the Vanderbilt scientists have named VUAA1, works by activating all 76 of the insect's odor receptors at once, over-stimulating and confusing the bugs, said Patrick L. Jones, a postdoctoral research fellow working on Zwiebel's team.

If not humans, they would target birds and other mammals not treated with the repellent as their prey. "Mosquitoes are fairly promiscuous," he said.

What's more, Jones said, the compound seems to work on other bugs. "This a potential new repellent that could repel virtually every insect," disease-carrying as well as merely nuisance species.

"No one has ever seen a molecule like this with this type of activity," said Zwiebel. "We're trying to understand why it is able to do what it does."

Researchers hope their findings will lead to repellents that will deter crop-eating pests, which feast on and destroy the world's food sources, as well as flies attracted to human sweat.

The researchers, whose work, in partnership with John Carlson at Yale University, as well as laboratories in Gambia, Kenya and the Netherlands, is funded by the Bill & Melinda Gates Foundation and the National Institutes of Health, caution that while they are optimistic about their findings, there is a long road ahead before their work begins to save lives -- or make your backyard barbecue more comfortable.

It will take at least five years and millions of research and development dollars before a product based on the new compound is approved for sale and becomes available commercially. But when it does, they say, some of the profits from the product will be channeled to offset the costs of supplying the repellent to countries that cannot afford it.

Copyright 2011 ABC News Radio

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