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The Riddle of What Is Killing Thousands of Central American Cane Workers

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Cane worker in Nicaragua

“Why the Silence Comandante Ortega?”

That paraphrasing of a headline from the great Spanish daily El Pais introduced a story in the paper on the difficulties that Nicaragua has  faced in coming to grips with the death and disability wrought by a still-unexplained kidney disease epidemic. By one estimate, at least 20,000 men throughout Central America and Mexico have met premature deaths during the last 20 years from kidney failure, many of the victims cane workers laboring in the oppressive heat of the Pacific lowlands.

The El Pais headline challenged Daniel Ortega, the Sandinista president, and purveyor of populist slogans like “arriba los pobres del mundo,” to take a more active role in addressing the crisis. Tensions over what has come to be known as Mesoamerican nephropathy came to a head on Jan. 18 when a group of former cane workers suffering from the kidney condition staged a protest at the gates of the facility owned by Nicaragua Sugar Estates Limited in the northwestern town of Chichigalpa. At some point, police opened fire, killing one man and injuring three others. one of whom was a teenage boy.

Three police who fired their weapons were criminally charged—and the government did dispatch a minister to address the group’s demands. But the epidemic that drove the men to the streets persists, not only in Nicaragua, but also for cane cutters and sometimes other manual laborers along the length of Pacific coast reaching as far as southern Mexico. Workers affected often die from end-stage kidney disease in a region ill-equipped with dialysis or transplantation programs.

One of the first entries of Mesoamerican nephropathy into the scientific literature appeared in 2002 when a paper noted that nearly 70 percent of patients at Rosales Hospital in San Salvador had advanced kidney disease without the hypertension or diabetes that usually precede the illness.

In the last 20 years, the rate of all chronic kidney disease in Nicaragua and El Salvador has been roughly 42 deaths per 100,000, three times higher for men than for women. Another statistic also points to something amiss—either in working conditions or chemical exposures. The mortality rate from chronic kidney disease in Nicaragua and El Salvador  is 17 times higher than in Cuba, another sugar-producing nation.  The impact of the disease can devastate whole communities. La Isla in Nicaragua, where many sugar workers live, is known as “La Isla de Viudas”—The Island of Widows—because funerals for the men are so common.

Dehydration from the brutal heat of the cane fields is the leading suspect—check out the photo above. Richard Johnson of the University of Colorado, Denver, and colleagues have been pursuing the hypothesis that dehydration of cane workers causes an enzyme to be activated within the kidney’s tiny tubules, converting  glucose to fructose. The fructose then gets metabolized by another enzyme, fructokinase, to produce oxidants that cause inflammation and scarring that may be the basis for the illness. Soft drinks and mango or pineapple juice with added sugar may increase fructose levels and attendant inflammation, leading to what Johnson has described as a “local holocaust.” (Johnson has received funding from Groupe Danone, the French food-products company, for a yet-to-be-published study to assess the effects of hydration on Nicaraguan cane workers.)

Other factors could also play a role, perhaps exacerbating the effects of dehydration. The list of possibilities includes heavy metals, agrochemicals, overuse of anti-inflammatory medications and contaminated alcohol. No consensus has emerged about the most likely culprit. Even the dehydration thesis is suspect, as sweat and thirst are a mainstay of field work.  “From my experience when people say it’s multifactorial, that means that people don’t really know what’s going on,” says Peter Jay Hotez, dean of the National School of Tropical Medicine at Baylor University. “Most things are not multifactorial.” Hotez suggests the possibility that the illness may result from leptospirosis (a bacterial infection), hantavirus or perhaps another communicable disease.

Preventive measures to assess workers’ kidney function is one option. “Pre-symptomatic diagnosis is actually not that difficult,” says Daniel Brooks, associate professor in the department of epidemiology at the Boston University School of Public Health, which has been contracted to study the epidemic. “A blood test for serum creatinine is a very good screening measure and a number of companies in the region employ it.” (Some of the funding for Brooks’s research has come from a fund to research chronic kidney disease, partially supported by the the Comite Nacional de Productores de Azucar.)

Desperate to earn a $5-a-day wage, workers unable to pass the test will often find ways to make it into the fields by teaming up with a subcontractor. The recognition that many workers will find any means possible to earn money by cutting cane has drawn attention to conditions in the fields. “There’s no harder job than sugar cane,” says Jason Glaser, president of La Isla Foundation, a Nicaraguan-based NGO. “The heat is intense in the lowlands and these guys are out in 95 to 105 degrees in the heat for up to 12 hours a day.” La Isla is involved in both research and advocacy for better conditions—more frequent water breaks in the shade, among other measures.

The epidemic is now drawing international attention. Three workshops have been held since 2005 and new scientific papers appear regularly. The Consortium on the Epidemic of Nephropathy in Central America and Mexico formed after the last workshop in 2012 to foster collaboration among researchers. The Centers for Disease Control and Prevention in Atlanta has set up a task force. Another NGO, Solidaridad, in a collaboration with La Isla Foundation, received a 3 million-euro grant in February to work toward eradicating the disease, funding from a Dutch lottery that raises money for charitable endeavors.

Kidney diseases of unknown origin are not a new occurrence. During the latter half of the twentieth century, Balkan endemic nephropathy perplexed epidemiologists in countries along the Danube until it was discovered that toxic aristolochic acid was contaminating wheat flour. Recent cases of unexplained chronic kidney disease have been identified in Sri Lanka, leaving a group of researchers to note recently in an editorial in The American Journal of Public Health that the disease “is probably a hitherto unrecognized global problem, although it is not clear if the … epidemics observed in other parts of the world are the same disease or are caused by the same factors as in Mesoamerica.” Epidemiologists and nephrologists are going to be spending a lot of time together for years to come.


Piet den Blanken and La Isla Foundation (photo).

Tierra Unida Films and La Isla Foundation (video)

Gary Stix About the Author: Gary Stix, a senior editor, commissions, writes, and edits features, news articles and Web blogs for SCIENTIFIC AMERICAN. His area of coverage is neuroscience. He also has frequently been the issue or section editor for special issues or reports on topics ranging from nanotechnology to obesity. He has worked for more than 20 years at SCIENTIFIC AMERICAN, following three years as a science journalist at IEEE Spectrum, the flagship publication for the Institute of Electrical and Electronics Engineers. He has an undergraduate degree in journalism from New York University. With his wife, Miriam Lacob, he wrote a general primer on technology called Who Gives a Gigabyte? Follow on Twitter @@gstix1.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. singing flea 2:50 pm 02/12/2014

    My guess is agri-chemicals. I lived near a sugar plantation on Ohau for 15 years. They finally closed the mill when it became a Superfund site as a result of all the pollution it was creating from the affluent pouring out of the mill into holding ponds. Worse than that was the potential lawsuits to the owners from the air pollution in the form of ash that resulted when the cane was burned to strip the cane of leaves before harvesting. The plantation workers breathed in this ash in huge amounts daily. The burning released tons of insecticide into the air. It was a treatment the used by the plantations to cut production costs. Plantation workers in Hawaii had a lot of health issues too that was swept under the rug by plantation owners. After all, most of those workers were Filipino and Japanese immigrants who were in no position to object. In the end, the plantation owners just dumped the whole mess on the taxpayers and got out while the going was good. They are the wealthy elites that continue to manage huge portions of Hawaiian real estate.

    Link to this
  2. 2. LaIslaFoundation 3:29 pm 02/12/2014

    La Isla Foundation (LIF) has a broad research and programmatic mission. In addition to supporting clinical and epidemiologic research we also support a human rights agenda and provide needed aid to affected communities in the form of alternate job training, potable water and access to care.

    In order to better understand the etiology of CKDu, we need to identify what toxins are present, and evaluate their impact in the presence of heat stress. LIF also seeks to examine the role of toxins on non-workers and women who inhabit the same environment. Neither LIF, nor our research partners, feel that dehydration and toxin exposure are mutually exclusive; rather, it is likely there may be a synergistic effect between the two. We will provide financial support for a series of clinical and epidemiologic studies to this end.

    In the interim, however, the evidence points towards workplace interventions that could prevent and/or slow the onset of disease. Given the high rates of mortality and morbidity among sugar cane workers and their families, we feel ethically obligated to focus on that aspect of the disease to help as many people as possible as soon as possible. One of program goals for 2014 is to adapt and apply OSHA’s Water.Rest.Shade. strategy, which has demonstrated effectiveness in similar settings.

    Science tells the story. It will take time. What the science is telling us today is that dehydration can lead to this disease: workers who are dehydrated have stressed kidney function and lose as much as 5 pounds a day. We are open to all responsible and transparent collaborations, including collaborations with responsible industry players but feel funding autonomy is a critical consideration.

    For any questions, contact LIF.

    Link to this
  3. 3. stargene 4:39 am 02/13/2014

    I’m glad NGOs are involved in the ongoing research,
    but it bothers me that some of the teams are being
    funded by big companies. It would be nice if we
    could always trust corporate mentality to opt for
    the most transparent and uncensored research for
    the total community. But experience tends to show
    otherwise. An early muckraker once wrote that it
    is difficult for someone to understand something
    when his salary depends on not understanding it.

    Link to this
  4. 4. EyesWideOpen 2:37 pm 02/18/2014

    Obviously the cane crop is sprayed by a pesticide that is killing the workers. One more reason to cease consumption of sugar in developed nations!

    Link to this
  5. 5. jgrosay 4:29 pm 02/18/2014

    There was a kidney disease having the name ‘Balkan nephropathy’, in the end it was discovered caused by a local product that contained Aristolochic acid, toxics can always be searched for such kind of diseases, as a loss of fluids from hot weather and heavy workload, leading to kidney suffering from poor blood flow would soon produce symptoms incompatible with any heavy work, much earlier than the kidney is hit.

    Drinking enough water, having an adequate diet, and decently planned work shifts, with enough and adequately distributed rest times, can overcome most of the causes proposed for this ‘Ticos’ and Nicas’ kidney disease epidemics’.

    For the ‘protectors of poor’: in the Bible the only ones called ‘rich’ are the land owners, ‘poor’ is anybody living on his work’s revenues.
    ‘Penury’ is a different thing from being poor, feeling that your kids are your only property is somehow a type of slavery, hey you, ‘proles’!, and the best way to improve the general welfare and to reduce poverty is producing enough goods and services at prices most or all would be able to afford to satify the needs of all, you can’t redistribute poverty, other approaches is ‘castles in Spain’

    Link to this
  6. 6. comefullcircle 6:06 pm 03/7/2014

    A cursory search revealed that the Gates Foundation traveled to Nicaragua and El Salvador to bestow upon the people, vaccines of a diverse variety. There is a plethora of reliable data regarding the causal relationship between vaccines and kidney disease. Here’s just one:

    - Suzanne Humphries, MD, Internist and Nephrologist speaking on Polio and other Vaccines
    at the Association of Natural Health Conference, November 2012 : – [2012 March] ‘Common vaccine ingredient implicated in NEJM article as causative in
    serious type of kidney disease.’ By Suzanne Humphries, MD: The plausible association between circulating cationic bovine (cow) serum albumin (BSA, a common vaccine ingredient) and a very difficult-to-treat form of kidney disease called Idiopathic Membranous Nephropathy(IMN)

    I argue that when a subject about “thousands of people dying mysteriously” arises, that you check to see if they were vaccinated – regardless of when – just see if that is an element of the story. I’m betting ‘yes’.

    This next section concerns information about the Polio Vaccine campaign that began in the 1950′s in America – one that I personally was a victim of. I offer an excerpt from a speech given about the “SV40 Contaminated Polio Vaccines.” ‘SV40′ being the name given to the fortieth virus detected in the vaccines; also being a cancer-causing virus. That said, I have done extensive research on the lucrative Vaccine Industry – and you couldn’t pay me enough money to submit to any vaccine today. Bottom line: they push the public worldwide,
    real hard, to get all vaccines because each one is a billion-dollar ticket for ‘them’ – and it has been discovered that physicians and governments have financial ties to the vaccine industry. So, once again, the Almighty Buck rears it’s ugly head – at our expense. We’re paying them to make us sick, folks.

    “Past is often prologue. So much can be learned from understanding the mistakes of the past so that the same mistakes are not made in the future.
    Outstanding questions about the links between vaccines, government vaccine policies and the epidemic of chronic disease in our children, including autism, learning disabilities, ADHD, asthma, diabetes and, as we have discussed today, are not going away. They will never go away when the main defense of the very lucrative Vaccine Industry with government health officials backing them, is that when anything bad happens after vaccination,
    “it is just a coincidence.” I can tell you, we are not buying it. And we shouldn’t buy it, especially when the kind of evidence that you will hear today suggests official government and Vaccine Industry denials are simply a way of avoiding accountability for failing to do
    everything they can to minimize the risks of vaccines. Legislation is urgently needed to separate government health agencies from financial ties and other ties with the Vaccine Industry so that government health officials can be free to do the job they are supposed to do:
    protect the health and well being of every American and not simply protect the vaccine supply and financial interests.” – Oral Presentation by Barbara Loe Fisher
    Co-founder & President National Vaccine Information Center
    Subcommittee on Human Rights and Wellness – U.S. House Government Reform Committee
    U.S. House of Representatives, Washington, D.C.
    September 10, 2003 Topic:
    “The SV40 Virus: Has Tainted Polio Vaccine Caused An Increase in Cancer?”

    Here are some other sources with which to educate yourself

    - Coulter, H.L., Fisher, B.L. 1985. “DPT: A Shot in the Dark.” New York: Harcourt Brace Jovanovich.;
    Allen, A. May 6, 2001. “A Shot in the Dark.” New York Times Magazine; Konrad, W. and Ginsburg, E.H. June-July 2000. “Who’s Calling the Shots?” Offspring Magazine.

    - Kyle, W.S. 1992. “Simian RetroViruses, PolioVaccine, and Origin of AIDS.” The Lancet, 339: 600-601.

    - Institute of Medicine, National Academy of Sciences, 2002. Immunization Safety Review:
    “SV40 Contamination of Polio Vaccine and Cancer.”, Washington, D.C.: National Academy Press.

    - Statement of Bonnie Brock, Lederle, at Jan. 27-28, 1997 “Workshop on SV40,” transcript pages 300-307.

    - National investigative news reports, including:
    Wechsler, P. November 11, 1996. “A Shot in the Dark.” New York Magazine.; Rock, A. December 1996: The Lethal Dangers of the Billion Dollar Vaccine Business. Money Magazine.; Bookchin, D., Schumacher, J. June 1997. “The Lonely Crusade of Walter Kyle.” Boston Magazine;
    Bookchin, D., Schumacher, J. February 2000: “The Virus and the Vaccine.” Atlantic Monthly Magazine.

    Link to this
  7. 7. doyougetmesweetheart 6:37 pm 03/7/2014

    It could be a combination of everything that everyone has mentioned here already – but I’m leaning towards the vaccinations as being the culprit. You think that the “depopulation agenda” desired by the Gates Foundation and all those linked to it, is a ‘conspiracy theory’? Think again. Before you hastily label it as that, do some checking out and don’t be surprised if you see pieces of the puzzle fall into place that you never before would have related to the big picture. Look at what’s going on in Africa and India since the Gates Foundation went there “giving” them vaccines. Over 47,500 deaths by paralysis occurred in India after the polio vaccines were administered there.

    In the Journal of Korean Medical Science is a case:
    “Vaccine-associated Paralytic Poliomyelitis : A Case Report of Flaccid Monoparesis after Oral Polio Vaccine”
    Sun Jun Kim, Sung Han Kim, [...], and Jung Soo Kim
    This vaccine was administered to an infant that was only four months old! Parents really need to do their own research before letting their children be vaccinated – especially at such a young age. As well, there are an
    extraordinary amount of vaccine-induced paralysis cases in Africa, another Gates Foundation vaccine project.

    There are so many suspicious circumstances cropping up all around vaccination projects that we would be fools to not take a closer look at what’s going on. I betca that this epidemic of sudden kidney problems is related to vaccines, just like the epidemic of soft-tissue cancers with SV40 markers in ‘em are related to the polio vaccines decades ago. That’s been proven. Even still, the government and the pharmaceutical vaccine companies refuse to admit the undeniable relationship – because to admit it, requires being responsible for the damage – and they love their money too much to do that.

    Link to this
  8. 8. Milleriv 8:49 pm 03/27/2014

    The chemicals are absorbed through the skin, yet these workers are not provided PPE (respirator, suit, boots, or gloves.)
    While there’s no current evidence to the effects of being drenched with amine, terbutryn, pendimethalin, 2,4-D, or atrazine- studies indicate trace amounts in drinking water can lead to kidney & liver disease.

    So, the riddle is why researchers insist on coming up with far-fetched theories of pathogenesis, instead of the obvious & pushing for the companies to supply proper protection for their workers who continue to die.

    Link to this
  9. 9. jjeffreymaxwell 11:37 pm 09/24/2014

    What do you think of this:

    Link to this
  10. 10. wskyle 11:43 am 09/26/2014

    Pan-microbial detection arrays developed and patented by Lawrence Livermore National Laboratories in 2010 had the capability of screening overnight for every known and sequenced virus, bacteria, fungus and pathogen – overnight – at a cost of $400.00 US per sample – not per pathogen or virus per the statement of Dr. Holly Franz, one of the developers of Lawrence Livermore`s Microbial Detection Array (LLMDA). See her statement in the VRBPAC Meeting Transcipt on May 7, 2010 and the contemporaneous article on the `inadvertent` detection of a plethora of viruses within vaccines published in Virology online April 10, 2010.
    FDA, announced at the meeting its opposition to open access to the technology, then moved to block use of of the LLMDA as a medical device.
    The lack of access to the technology explains why such anomalies remain unexplained.

    Link to this
  11. 11. tuhumom 8:16 am 10/22/2014

    Very interesting discussion. As a former kidney disease sufferer, I know how frustrating it can be to find answers. Just wanted to share a link that helped me out a lot when I was struggling to get better:

    Best of luck to everyone!

    Link to this

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