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Malaria, malaria control, and DDT
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mac



Joined: 07 Mar 1999
Posts: 5558

PostPosted: Mon Aug 12, 2013 4:20 pm    Post subject: Malaria, malaria control, and DDT Reply with quote

There is a right wing meme about DDT that has been posted here by mrgybe and repeated by Bard, that runs along the lines that the banning of DDT was done for political reasons, without scientific backing or integrity, and led to the death of millions in Africa. (50 million was the last number used by mrgybe.) This meme shows up on multiple right wing sources, and appears to have originated, or been spread, by Steven J. Milloy, a columnist for Fox News and a paid advocate for Phillip Morris, ExxonMobil and others. Mrgybe’s original posting was not original, and paraphrased the essence of Milloy’s argument. When I see such highly suspicious and unreliable postings I wonder two things. First, what are the facts? Second, why do people leap to believe such sources? Contrary to the idea that posting on this web is a waste of time, or doesn’t change anybody’s mind, it stimulates me to do some thinking and research.

There is a fundamental problem with the “environmentalists don’t care meme” that makes this argument suspect. Malaria control is a highly important activity that needs to be supported by “do gooders”; as the narrative below will make clear, funding is absolutely critical to progress on malaria control. People who want to change policy, including those who might seek public and private support for malaria control, rarely start by attacking their potential allies. That is more a tactic of political ops, schooled in the Karl Rove school of animating the base. People involved in trying to change policy are extraordinarily careful to maintain their credibility and don’t start with attacks that are replete with easily-rebuttable factual errors.

The narrative in this meme ignores both the history of malaria control before the banning of DDT, malaria control efforts between 1972 and the Stockholm Convention, and more recent efforts at malaria control. When I started digging I asked if malaria deaths had really increased after DDT was banned, what other measures had been used, and if reintroduction of DDT had caused a dramatic decrease in malaria deaths. The facts are interesting, and surprising.

It is necessary to give DDT its due; widespread use of DDT was successful in eliminating malaria in a number of countries. To simplify and give the impatient the punch line, success in eliminating the malaria organism required eliminating enough mosquitoes to prevent sufficient of the malaria organism before the mosquitoes developed resistance to DDT. While that worked in some areas, it did not work in Africa. Here from “Successful malaria elimination strategies require interventions that target changing vector behaviours” by Tanya L Russell1 et al


Quote:
In 1955, the World Health Organization (WHO) launched the Global Malaria Eradication Programme (GMEP) based primarily on DDT-IRS supplemented with mass drug administration in malaria-endemic countries outside of sub-Saharan Africa [5]. The GMEP was moderately successful, eliminating malaria from 37 countries; however it was unable to eradicate malaria. There were a number of technical, administrative, financial, and logistical challenges that contributed to this disappointing outcome.
One of the technical reasons for the failure to eliminate malaria was over reliance on a single intervention and the subsequent development of behavioural resistance by the mosquito vectors [6-8]. DDT was shown in some areas to irritate mosquitoes and reduce both the rate of house entering and successful blood feeding by those mosquitoes that did enter the house [9,10]. Those mosquito populations that responded by changing their behaviour to avoid DDT by feeding outdoors and not resting indoors had a selective advantage. This was observed after DDT use in various species including Anopheles farauti[9,10], Anopheles sundaicus[11], Anopheles pseudopunctipennis[12,13] and Anopheles albimanus[12-14]. Towards the end of the GMEP, transmission was being maintained in many “problem areas” by physiologically susceptible vectors that avoided or minimized their exposure to DDT [6-8].

With the collapse of the GMEP, malaria cases steadily increased. Faced with pandemic transmission levels, the global interest in alternative vector control tools was renewed leading to the development of insecticide-treated nets (ITNs) and then wash-resistant, long-lasting insecticide-treated nets (LLINs). LLINs, like IRS, kill vectors inside houses but also provide a physical barrier against mosquitoes attempting to feed on sleeping humans. During the past decade, LLIN use increased across the malaria-endemic world alongside improved treatment of infected individuals with artemisinin combination therapy (ACT). These measures significantly reduced the global malaria incidence and led the Bill & Melinda Gates Foundation (BMGF) and the WHO to announce that global malaria eradication was again a public health priority. This goal was subsequently endorsed by the Roll Back Malaria programme in 2007. Similar to the first GMEP, the present-day strategies include vector control inside houses (LLINs and IRS) as a critical element.

The problems faced during the original GMEP highlight that programme success will require vector control interventions to target species-specific vector behaviour. Notably, under insecticide pressure vector populations can change over time in several ways: 1) physiological resistance to insecticides can develop in which mosquitoes exposed to insecticides are not killed, and/or, 2) the relative composition or abundance of multiple vectors in an area can change, and/or, 3) the behaviour(s) of individual mosquito species can change. Of these phenomena, physiological resistance is the most straightforward and easy population change to detect and has been widely documented [15], and its monitoring has been implemented into control strategies.


I certainly appreciate the irony of conservative support for the United Nations in this task; one of the main missions of the John Birch Society was to get the US out of the UN. But the World Health Organization and UNICEF, both part of the UN, pioneered this effort and hold the collective history of success and failure. An interesting account was put together by Jeremy Shiffman et al in “The Emergence of Global Disease Control Priorities”, in Health Policy and Planning, 2002. The US was the primary funder of this effort, providing $407 million in grants and loans between 1957 and 1969. Dramatic increases in malaria incidence and mortality were achieved. While initial efforts in Sri Lanka resulted in a dramatic reduction in malaria cases—down to 17 in 1963, the number of cases had rebounded to 500,000 by 1969. The WHO moved from eradication to control in 1969—before, of course, DDT was banned in the US. From Shiffman:

Quote:
…success was far from uniform. Resurgence of malaria endemicity occurred frequently, particularly in Central Africa and Southeast Asia. Reasons for failure of eradication included resistance to DDT, inadequate epidemiological knowledge, insufficient administrative capacity and weak health care systems in poor countries. At the same time, another potentially eradicable disease, smallpox, was competing for the attention of the global health community…

Efforts turned to research and development of new anti-malarial drugs, the search for a vaccine, and nets.

After 1993, and in response to criticism of their social policies, the World Bank began providing money for malaria control. In response, the WHO began an effort to roll-back malaria in 1998, and secured an exception for DDT use in the general ban on persistent organic pollutants under the Stockholm Convention. Not exactly the right wing/Steven Milloy narrative.

Recent malaria control efforts have been successful in reducing malaria by about 25% in Africa. It is not clear that the availability of DDT for indoor spraying has much to do with this reduction. Most studies, for example http://www.malariajournal.com/content/4/1/35, point to higher use of insecticide treated netting (ITS) by the exposed population for reductions.

The final irony in all of this, which cuts against the use of meme’s and talking points, is that expanded effective control of malaria requires funding from the first world. As noted, malaria control competes with smallpox control and polio control for funding, and most of the sources indicate greater funding is essential to reach more people. DDT may, or may not, be part of an overall malaria control strategy. But the rapid bounce back in Sri Lanka and other locations show that it is not a magic bullet. Some argue that the results in Mexico, where DDT is not used, shows that cost-effective malaria control can be done without DDT. Regardless, my point is not to argue against use of DDT for public health, provided that there are no better alternatives. Rather, it is a complicated world, and attack pieces and memes, while they may play into biases and reassure people’s hatreds, provide little benefit in understanding complicated problems, or devised effective solutions.
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mac



Joined: 07 Mar 1999
Posts: 5558

PostPosted: Sat Aug 17, 2013 6:42 pm    Post subject: Reply with quote

While this continues to get views, there have been no responses. Kind of in the return to meme vein. So I will add a bit more, and how science might be used if there was a willingness to actually embrace science.

The right-wing accusation that the banning of DDT has led to 50 million deaths from malaria can be found on junkscience, but a more complete discussion, that uses the number 50 million, can be found here: http://www.discoverthenetworks.org/viewSubCategory.asp?id=1259

When I first started digging into this question, I posed for myself the possibility that banning DDT had, albeit indirectly, resulted in resurgence of the disease and increased deaths. In 2006, malaria caused 800,000 deaths. I guess someone could get to 50 million malaria deaths by multiplying a million deaths a year times the 34 years between 1972 and 2006 and then rounding way up. But it would only be accurate to blame the banning of DDT for all deaths if banning DDT were the only cause. Further, it would be possible to see a pretty clear signal in the time series of deaths. If you examined the number of deaths from malaria each year, and adjusted for overall population growth, you would have a time series over the duration. If there was a statistically significant increase after 1972, and a statistically significant decrease after 2006, it would support the hypothesis that DDT was a significant, or first order factor, in DDT deaths.

I tried to find annual statistics for malaria deaths, without much success. Indeed, even if the WHO kept and published such statistics, it is highly likely that many deaths are simply not recorded, or misattributed in a continent as large and poor as Africa. But I did find a statistically significant decrease in malaria related deaths following 2006. Renewed use of DDT may have been a factor in this decrease because mosquito resistance to DDT had declined in the 40 years. But all of the sources working on malaria control attributed success to subsidized nets treated with pyrethroids and other pesticides, not to wall spraying of DDT.

One factor comes up again and again in the literature about the failure to eradicate malaria in Africa; the fractured and incomplete public health infrastructure that would allow eradication efforts to target high malaria areas effectively before the mosquito population became resistant to DDT.

There is one huge error in some articles which attribute rebound of malaria in Sri Lanka to banning DDT. If you actually look at the history, malaria had rebounded in Sri Lanka by 1969 due to resistance to DDT; the same thing occurred in Africa. Indeed, the WHO abandoned the idea of eradicating malaria in, I believe, 1976.

Only someone completely uneducated in statistical methods, or with a burning and irrational hatred for environmentalists, would blame all malaria deaths on the banning of DDT. Particularly when the literature shows that mosquito populations were becoming resistant to DDT and their populations were rebounding well before that banning. But a contempt for science, and a willingness to spin the results, is unfortunately common in our society.
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reinerehlers



Joined: 25 Jul 2001
Posts: 1100

PostPosted: Tue Aug 20, 2013 6:39 pm    Post subject: Reply with quote

http://www.youtube.com/watch?v=zzSFCABlsi8
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keycocker



Joined: 10 Jul 2005
Posts: 3538

PostPosted: Tue Aug 20, 2013 8:34 pm    Post subject: Reply with quote

The guy who discovered aspirin extracted it from willow trees that flourish in swamps, in the belief that damp swampy places cause the flu and colds.
Good answer wrong science.
The guy who proposed the fan to keep mosquitoes away didn't stop to think that a fan sucks in mosquitoes and blows them toward you as well as away.
They keep Mosquitos off all right,because they can't home in on you with their brand of radar if the air mass is moving or otherwise disturbed.
You will find that standing even in light winds in an open area works too.
Tip from the jungles of Belize.
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reinerehlers



Joined: 25 Jul 2001
Posts: 1100

PostPosted: Fri Aug 23, 2013 7:08 pm    Post subject: Reply with quote

https://www.youtube.com/watch?v=pNjyLRQutXs
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reinerehlers



Joined: 25 Jul 2001
Posts: 1100

PostPosted: Mon Aug 26, 2013 11:40 am    Post subject: Reply with quote

^
^
^
^

https://www.youtube.com/watch?v=f4-6Sy9vGDg
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mac



Joined: 07 Mar 1999
Posts: 5558

PostPosted: Mon Aug 26, 2013 1:03 pm    Post subject: Reply with quote

A sad but not surprising lack of substance. For the artistic approach, try:

http://www.youtube.com/watch?v=O42zwjj-9yI
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mac



Joined: 07 Mar 1999
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PostPosted: Thu Sep 19, 2013 10:02 am    Post subject: Reply with quote

Among the myths of the right wing meme on DDT and malaria is the canard that DDT was safe. Of course, there is a reality based world, that uses research and peer review, which shows that decades after banning DDT is still creating problems:

Quote:
In the coastal redwood forests of Central California, scientists trying to unravel the mystery surrounding the reproductive problems of dozens of endangered condors think they have uncovered the culprit: the long-banned pesticide DDT.

The soaring scavengers with wingspans wider than NBA players are tall were reintroduced to the rugged coast of Big Sur in 1997 after a century-long absence. Upon arrival, the birds found plenty to eat, with dead California sea lions and other marine mammals littering the craggy shoreline.

While a good food source, sea lion blubber often has high levels of DDT, a pesticide banned in 1972 that has proven to be a persistent pollutant because it accumulates in bodies of creatures throughout the food chain when animals eat one another.

Once used widely in agriculture, DDT was banned because it is a human toxin considered a possible carcinogen by the U.S. Centers for Disease Control and Prevention.

Kelly Sorenson, executive director of Ventana Wildlife Society and a co-author of a new study on condors, said researchers who spent six years studying their reproductive problems have "established a strong link" to DDT in the birds' food source.

The peer-reviewed paper written by 10 condor experts, including biologists from the Los Angeles and Santa Barbara zoos and the U.S. Fish and Wildlife Service, is being published this month in the University of California journal the Condor.

"In science, rarely is anything definitive but we've established a strong link between ... DDT and eggshell thinning in California condors," Sorenson told the Associated Press.

The eggshell mystery began in 2006, when a biologist inspecting a condor nest in the cavity of a redwood tree on the Central California coast found the first thin shell.

Over the next six years, the scientists observed condors feeding on dozens of sea lions, and found that the Big Sur condor population had a low hatching success - just 20 to 40 percent - for 16 nesting pairs. In contrast, 70 to 80 percent of Southern California condors in the Tejon area had hatched successfully over the same time. The Southern California condors are inland, and sea lions are not a food source.
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nw30



Joined: 21 Dec 2008
Posts: 1908
Location: The eye of the universe, Cen. Cal. coast

PostPosted: Fri Sep 27, 2013 1:48 pm    Post subject: Reply with quote

If you are really concerned about the plight of eagles, condors, and the like, maybe you should expand your concern about the wind farms vs. those magnificent birds.
~~~~~~~~~~~~~~~
California wind farm seeks permit to kill eagles

UPI 9/27/2013 5:37:15 PM

SAN FRANCISCO, Sept. 27 (UPI) --
A Solano County, Calif., wind farm would be the first renewable energy project in the nation allowed to kill eagles under a federal plan, a U.S. agency said.

Under the U.S. Fish and Wildlife Service proposal, outlined in a draft environmental report released Thursday, the Shiloh IV Wind Project would be issued a golden eagle take permit for its 3,500-acre plant in the Montezuma Hills, the San Francisco Chronicle reported.

The plan would allow the company's 50 wind turbines to kill as many as five golden eagles in a five-year period in exchange for measures to protect the birds, including retrofitting 133 power poles to prevent electrocutions, the Chronicle said.

"The bottom line is a permit will help preserve eagles," said Scott Flaherty, the deputy assistant regional director of external affairs for the Fish and Wildlife Service. "I think it really does set a precedent. It shows the service can work with wind energy companies ... and ensure that we conserve eagles and other wildlife."

The report, currently in a 45-day public comment period, analyzed four alternatives, including the possibility of denying the permit application, the Chronicle said.

The Chronicle said about eight eagles a year are killed at the four Shiloh plants.

Eric Davis, FWS assistant regional director for migratory birds and state programs, said investigations of bird deaths have begun and have been turned over to the Department of Justice, but there haven't been any prosecutions under the federal Bald and Golden Eagle Protection Act.

"There is no law out there that says this project requires a take permit, [but] eagles are protected," Davis said. "If they did not receive a permit, they could build the project and they would be in compliance with the Bald and Golden Eagle Protection Act until the first eagle was taken. Then they would be subject to enforcement action."

_________________
I don't drink the 'cool' aid, I drink tequila, it's more honest.
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pueno



Joined: 03 Mar 2007
Posts: 2763

PostPosted: Fri Sep 27, 2013 2:52 pm    Post subject: Reply with quote

nw30 wrote:
If you are really concerned about the plight of eagles, condors, and the like, maybe you should expand your concern about the wind farms vs. those magnificent birds.

Golly. Those poor, unappreciated, right-wing, constitution-loving, NRA eagles. They're such majestic, beautiful, poised birds.

Or maybe not.

Read here.

Look, Mr. Turdy, I realize that this came from a science publication... but give it a chance. It might be factual. I know, I know, that's a foreign concept to you -- facts, I mean.
.
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