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A New Weapon In the Zika Virus Fight

Posted February 18, 2016 7:00 AM by cheme_wordsmithy

You may have heard about the Zika virus in the news. It's the latest in a long line of mosquito-born illnesses that seems to be spreading in epidemic proportions across many countries in the Americas. While there are few immediate complications, health experts believe that Zika is responsible for microcephaly in babies of infected mothers. Microcephaly (abnormal smallness of the head) is a serious birth defect, and pregnant women are being urged not to travel to countries with known outbreaks.

The culprit is the Aedes aegypti mosquito, which has made its home in parts of Africa, Asia, the South Pacific, Australia, and the Americas. This mosquito has been responsible for the spread of yellow fever, dengue fever, and other dangerous viruses that have infected and killed thousands of people. And while efforts to reduce mosquito populations have been ongoing for many years, the emergence of the Zika virus has brought a renewed urgency to the fight.

Perhaps the most promising weapon against mosquitoes is the recent development of "gene drive" technology. A gene drive differs from an ordinary gene in an organism's DNA because its trait is passed to all of its offspring (rather than just 50%). A gene drive could thus be used to pass destructive genes to the Aedes aegypti mosquito, such as those that destroy female mosquito chromosomes, prevent female mosquitoes from flying, or cause a mosquito to be born male. By releasing genetically altered mosquitoes into the wild, female populations of the target species would be reduced with each generation, until the population is eradicated. Gene technology has already been used to help control the spread of malaria, however the approach is complicated by the fact that there are a number of diverse species that carry this disease. With dengue and Zika, the Aedes aegypti species is primary carrier.

One of the biggest advantages of the gene-drive-based approach is that it is species-specific. Traditional methods of control (insecticides and removing breeding sites) attack all mosquitoes, meaning the entire ecosystem is effected. Gene-drive technology would attack the Aedes aegypti while not affecting other (less harmful) mosquito species, potentially causing less damage to the environment and the surrounding ecosystem.

There are still concerns to this new approach, however. Most notably is whether the eradication of the Aedes aegypti could have any unintended consequences, like for example leaving room for some new or potentially more harmful species to emerge. And there have been looming fears about the broader impact of gene-editing technology and the possibility of its accidental or intentional misuse. But whether these fears will delay or prevent its use against the Zike mosquito remains to be seen.

Meanwhile, we will likely continue to see the spread and impact of Zika, and a vaccine against the virus looks to be at least a year away.

Source: MIT Technology Review

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#1

Re: A New Weapon In the Zika Virus Fight

02/18/2016 8:46 AM

DDT works pretty well. That ought to get things going.

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#6
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 9:34 AM

DDT also does not break down fast enough in the environment, so it bio-accumulates. Spray the insects, and the insect eating birds get a larger dose from eating so many poisoned bugs, then the predators that eat those birds capitalize on the 'sick, weak' (poisoned) birds and get an even larger dose, etc. etc. until we end up with Bald Eagles back on the Endangered Species list due to DDT poisoning weakening the eggshells and causing the unborn chicks to be crushed by the nesting parents.

In case you haven't noticed, I kind of like having Bald Eagles around, and they were pushed dangerously close to extinction by DDT.

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#7
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 10:14 AM

"Background

DDT (dichlorodiphenyltrichloroethane) was first synthesized in 1877,1 but it was not until 1940 that a Swiss chemist discovered that it could be sprayed on walls and would cause any insect to die within the next six months, without any apparent toxicity to humans.2 DDT's effectiveness, persistence, and low cost (only 17 cents per pound) resulted in its being used in antimalarial efforts worldwide. It was introduced into widespread use during World War II and became the single most important pesticide responsible for maintaining human health through the next two decades. The scientist who discovered the insecticidal properties of DDT, Dr. Paul Müller, was awarded the 1948 Nobel Prize in Physiology and Medicine.3

The Scare

In 1962 Rachel Carson's lyrical yet scientifically flawed book Silent Spring was released. The book argued eloquently but erroneously that pesticides, and especially DDT, were poisoning both wildlife and the environment and also endangering human health. The emotional public reaction to Silent Spring launched the modern environmental movement.4 DDT became the prime target of the growing anti-chemical and anti-pesticide movements during the 1960s. Reasoned scientific discussion and sound data on the favorable human health effects of DDT were brushed aside by environmental alarmists who discounted DDT's enormous benefits to world health with two allegations: (1) DDT was a carcinogen, and (2) it endangered the environment, particularly for certain birds.

In 1969 a study found a higher incidence of leukemia and liver tumors in mice fed DDT than in unexposed mice.5 Soon, too, environmentalists were blaming the decline in populations of such wild bird species as the osprey and peregrine falcon on the contamination by DDT of their environment. A number of states moved to ban DDT, and in 1970 the U.S. Department of Agriculture announced a plan to phase out all but essential uses.6

The Reaction

Numerous scientists protested that the laboratory-animal studies flew in the face of epidemiology, given that DDT had been used widely during the preceding 25 years with no increase in liver cancer in any of the populations among whom it had been sprayed. And when the World Health Organization (WHO) investigated the 1969 mice study, scientists discovered that both cases and controls had developed a surprising number of tumors. Further investigation revealed that the foods fed to both mice groups were moldy and contained aflatoxin, a carcinogen.7 When the tests were repeated using noncontaminated foods, neither group developed tumors. In 1970 the National Academy of Sciences declared, "In little more than two decades, DDT has prevented 500 million human deaths due to malaria, that would otherwise have been inevitable."8"...

Read all...

http://dwb.unl.edu/Teacher/NSF/C06/C06Links/www.altgreen.com.au/Chemicals/ddt.html

"The ban on DDT was considered the first major victory for the environmentalist movement in the U.S. The effect of the ban in other nations was less salutary, however. In Ceylon (now Sri Lanka) DDT spraying had reduced malaria cases from 2.8 million in 1948 to 17 in 1963. After spraying was stopped in 1964, malaria cases began to rise again and reached 2.5 million in 1969.33 The same pattern was repeated in many other tropical- and usually impoverished-regions of the world. In Zanzibar the prevalence of malaria among the populace dropped from 70 percent in 1958 to 5 percent in 1964. By 1984 it was back up to between 50 and 60 percent. The chief malaria expert for the U.S. Agency for International Development said that malaria would have been 98 percent eradicated had DDT continued to be used.34"

The banning of DDT was based on bad science and alarmism....God save us from the do-gooders...

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#8
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 10:55 AM

Bald Eagles are just fine. Where is the actual proof (studies) that demonstrated 100% link between DDT residual and thinness of eggshells? I don't recall where it went, but I thought I remembered some papers on it.

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#9
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 1:11 PM

"In addition, later research refuted the original studies that had pointed to DDT as a cause for eggshell thinning. After reassessing their findings using more modern methodology, Drs. Hickey and Anderson admitted that the egg extracts they had studied contained little or no DDT and said they were now pursuing PCBs, chemicals used as capacitor insulators, as the culprit.20

When carefully reviewed, Dr. Bitman's study revealed that the quail in the study were fed a diet with a calcium content of only 0.56 percent (a normal quail diet consists of 2.7 percent calcium). Calcium deficiency is a known cause of thin eggshells.21-23 After much criticism, Bitman repeated the test, this time with sufficient calcium levels. The birds produced eggs without thinned shells.24

After many years of carefully controlled feeding experiments, Dr. M. L. Scott and associates of the Department of Poultry Science at Cornell University "found no tremors, no mortality, no thinning of eggshells and no interference with reproduction caused by levels of DDT which were as high as those reported to be present in most of the wild birds where 'catastrophic' decreases in shell quality and reproduction have been claimed."23 In fact, thinning eggshells can have many causes, including season of the year, nutrition (in particular insufficient calcium, phosphorus, vitamin D, and manganese), temperature rise, type of soil, and breeding conditions (e.g., sunlight and crowding).25"

http://dwb.unl.edu/Teacher/NSF/C06/C06Links/www.altgreen.com.au/Chemicals/ddt.html

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#10
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 1:49 PM

Good job sir! I must say it makes a great deal more sense that birds could be affected by leaks around transformers that contained PCB's than DDT moving through the food chain. PCB's are among the most insidious known compounds, primarly through their property of being endrocrine mimics. For such compounds, health effects in humans noted include reproductive effects, changes in secondary sexual characteristics, etc.

Agreed that many "scientific" studies have been conducted in our past with exceptionally shading selection of experimental conditions that are the equivalent to the butcher with their thumb on the scales. Apparently, one does not get continued funding for research that does not produce the sought after result "of the community".

That in itself is a broken paradigm. Perhaps, if not for this, our country could have had more money for research into other more important, relevant topics to help solve issues that are more pressing, such as "how do I make a totally unsinkable war ship", or something to that effect.

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#2

Re: A New Weapon In the Zika Virus Fight

02/18/2016 12:38 PM

Very interesting article. Personally I think there will be unintended consequences, whether the gene therapy affects other animals when the mosquito bites them and transfers the gene or be it by altering an eco-system. There are always unintended consequences. Call it cause and effect.

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#4
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 9:21 AM

Absolute drivel! Mosquitoes do not pass their genes to their victims. You watch too much porn!!!

I say kill all the mosquitoes, but then the mosquito darters would not be happy.

I say give Zika virus to a few Washington politicians, then (1) this will reduce the appearance of megacephaly (the big head), and (2) the problem will then get solved within months after the first one shows up with his little head sticking out above his neck tie. Most politicians usually keep the big head above the neck tie, but are still led around by the small head.

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#11
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 4:57 PM

I like your last paragraph, but I think initially the virus should be given only to those politicians who have made a career out of Washington, in the event that unforeseen circumstances are noted.

Same goes for advisers, consultants and lobbyists.

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#3

Re: A New Weapon In the Zika Virus Fight

02/19/2016 5:00 AM

Interestingly some medical people in the field are now questioning if it is Zika at all, with a suspicion that treated drinking water, treated because roof tanks are a breeding ground for mosquito's, may be involved. Those counties where Zika is now endemic, but they are not adding those chemicals to the drinking water report very few or no microcephaly cases.

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#5
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Re: A New Weapon In the Zika Virus Fight

02/19/2016 9:22 AM

Is that because the nasty, septic pigeon poo infested water is killing the mothers before they give birth? What a pile of applesauce!

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#12

Re: A New Weapon In the Zika Virus Fight

02/20/2016 10:58 AM

Adding controversy to the fire: http://gmwatch.org/news/latest-news/16706

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#13
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Re: A New Weapon In the Zika Virus Fight

02/20/2016 4:45 PM

Bogus news article....

"On February 3, the rumor that pyriproxyfen, not the Zika virus, is the cause of the 2015-2016 microcephaly outbreak in Brazil was raised in a report of the Argentinean organization Physicians in the Crop-Sprayed Villages (PCST).[13] It attracted wide media coverage.[14][15] The statement from Abrasco was cited in the PCST report; subsequently, Abrasco clarified that position as an misinterpretation of their statement, saying "at no time did we state that pesticides, insecticides, or other chemicals are responsible for the increasing number of microcephaly cases in Brazil". They also condemned the behavior of the websites that spread the misinformation, adding that such "untruths...violates the anguish and suffering of the people in vulnerable positions".[16] In addition, the coordinator for the PCST statement, Medardo Ávila Vazquez, acknowledged in an interview that "the group hasn't done any lab studies or epidemiological research to support its assertions, but it argues that using larvicides may cause human deformities."[17]"

https://en.wikipedia.org/wiki/Pyriproxyfen

http://npic.orst.edu/factsheets/pyriprogen.html

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