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Workers in the sugar cane fields of the San Antonio sugar mill in Chichigalpa, Nicaragua.
Photograph: Estban
Felix/AP
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Introduction
Chronic Kidney Disease of unknown causes has become a fatal epidemic in Mesoamerican countries over the past 15 years. This four-part series of blog posts will investigate the issue in-depth, reviewing current literature and covering the following topics:
Part 1- Introduction and Statistics
History of the Epidemic in Central America
Statistics
Chronic Kidney Disease – basics
Mesoamerican Nephropathy
Part 2 – Research and Literature Review
Introduction to the Research
Etiology
Morphology and Pathology
Possible Solutions
Areas for Additional Research
Part 3 – Social Impacts
Narrative
Financial Impacts
Part 4 - Interventions
History of the Epidemic
in Central America
Chronic Kidney Disease (CKD) is not a new
disease, however in 2002 a spike in chronic kidney disease of unknown causes (CDKu) was
noted in Central American agricultural communities. For the following ten
years, the spike persisted and what originally appeared to be endemic grew. It
became clear that this endemic was, in fact, an epidemic.
In November 2012, the Central American Program
for Work, Environment and Health (SALTRA), Central American Institute for
Studies on Toxic Substances (IRET), and the Universidad Nacional Costa
Rica (UNA) organized a workshop to officially acknowledge the epidemic of CDKu in
Central America, and to implement a plan for immediate prevention. Titled “The
International Research Workshop on Mesoamerican Nephropathy (MeN)”, the
goals of the conference were to:
- Identify variables in studying at-risk populations
- Determine a clinical definition of Mesoamerican nephropathy
- Address and define the epidemic by using current scientific evidence
- Investigate and prevent fatalities in the most effected populations through collaboration across research groups
During the decade between the spike in 2002 and
the recognition of the epidemic in 2013 by PAHO, it was estimated that over 20,000 Central Americans died of the disease.
The interactive map, below, from the PAHO and World Health Organization (WHO), demonstrates the progression of the epidemic along with the countries most affected. Use the slider on the far right to adjust the year and select a country of interest (on the map) for more information on that country. Data can also be stratified by sex and chronic kidney disease or renal failure.
http://www.paho.org/hq/index.php?option=com_content&view=article&id=9402
Statistics
As one of the most widely accepted theories is that MeN is at least partly due to repeated heat stress and dehydration, it may be helpful to examine the interaction of MeN and social determinants of health in that context (Wesseling, Crowe, Hogstedt, Jakobsson, Lucas, Wegman, Program on Work, Environment and Health in Central America, & Central American Institute for Studies on Toxic Substances, 2015). Sugar cane workers are often paid by weight of the sugar cane they cut, rather than by time spent at work. This promotes working as hard as possible in often unforgiving conditions. There is little incentive for these workers to take breaks to rest in the shade and rehydrate, as it takes time away from earning money, even though it is detrimental to their health. However, the more time the men spend in these conditions without adequate rest and hydration, the more men seem to be affected by MeN, which then leads to loss of income from work due to disease as well as money lost to medical treatment. Enacting policies to support worker’s health and safety, creating work environments where rest and hydration are encouraged, and providing people with other opportunities for economic stability are all levels where public health interventions can improve the Mesoamerican nephropathy epidemic.
This series was researched and written by (in alphabetical order): Jessica Chepp, Aleena McDaniel, Cara McShane, Christine Spees, and Kimberly Vargas
All are Master of Public Health candidates at the University of Illinois -Chicago
The interactive map, below, from the PAHO and World Health Organization (WHO), demonstrates the progression of the epidemic along with the countries most affected. Use the slider on the far right to adjust the year and select a country of interest (on the map) for more information on that country. Data can also be stratified by sex and chronic kidney disease or renal failure.
- Nicaragua and Honduras are in the top 10 for highest
mortality rates from kidney disease, with El Salvador having highest in
the world (World Health Organization, 2008)
- In 2012, Kidney disease was the sixth leading cause of
death in El Salvador and the third leading cause of death in Nicaragua
(World Health Organization, 2015)
- Chronic kidney disease was the second leading cause of
death in men of working ages in El Salvador (World Health Organization,
2008)
- Several studies have found that men are affected by MeN
at about a 3:1 ratio to women (Brooks, Ramirez-Rubio, & Amador, 2012)
Chronic Kidney Disease –
The Basics
To gain a better
understanding of the epidemic in Mesoamerica, a base line in understanding of
kidney function and chronic kidney disease is to be established.
The primary function of
the kidneys is to filter excess waste and fluid from the blood which produces
the waste product, urine. The additional functions and nuances of the process
are complex, and more information can be found on the National Kidney Foundation's webpage, titled "How Your Kidneys Work." However, it is important to
note that the kidneys also produce critical hormones for bodily function, and
they regulate salt and potassium levels within the body.
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When the kidneys stop
performing their regular functions, it is called chronic kidney disease (CKD).
This is usually brought on by other chronic disorders, such as diabetes or high
blood pressure. When the kidneys stop
functioning, waste builds up in the body, which, if left untreated, is fatal.
If the disease is caught early enough, medicinal interventions can be made to
prevent complete failure. When kidneys have completely failed, the only treatment
options to prevent death are dialysis or to perform a kidney transplant.
In the case of the
epidemic in Mesoamerica, the kidney disease is of unknown origin so it is difficult
to treat or prevent. Additionally, due to the lower socioeconomic status of the
at-risk populations, treatment options are not always economically
feasible.
Mesoamerican Nephropathy
The prevalence of this form of kidney disease
has led several researchers to question the cause of this disease. Mesoamerican
nephropathy is defined in the International
Research Workshop Report as “persons with abnormal kidney function […]
living in Mesoamerica with no other known causes for CKD.” Since the 2012
workshop which established this clinical definition, subsequent research has
shown a strong correlation between workers who cut sugar cane and develop
chronic kidney disease. With this correlation established, a cause of CKD from
working on the sugar cane plantations had to be determined. It is important to
note that these workers are typically young men, who have minimal to no other
chronic health conditions, and who are healthy when beginning work on the
plantations. However, over the course of working on a plantation, CKD often
develops and their health deteriorates.
The structure of sugar plantations is such that
the workers are exposed to several health hazards. Additionally, the low socioeconomic
status of the workers and the culture of the communities is such that the workers
have few other options for employment and have very little power to change the
conditions they work in. First, due to the nature of the sugar cane industry
and growing season, these workers are seasonal, and paid by the weight of sugar
cane that they can cut, not by the amount of time they work. Thus, the workers are
pushed, either from internal (personal) motivations or from external
motivations, to maximize their yields.
This often means that the workers have little motivation to take breaks during
the work day. The lack of breaks means a reduction of time in the shade and
fewer opportunities to rehydrate throughout the day. In the high-temperature
and high humidity regions of central America, where this is occurring, this
kind of labor intensive work without breaks and opportunities to rehydrate is
detrimental to health and believed to be a major cause of Mesoamerican
nephropathy. Additionally, if the
workers become ill, they not only have medical expenses, but have a financial
loss from the days not worked – having negative impacts for them and their families.
From a medical perspective, there are some simple preventative measures that
can be taken, however, the complexity of the social
determinants of health should not be ignored in finding a sustainable
solution.
Social Determinants of Health
Using a framework or model for health may help understand the complex disease process of Mesoamerican nephropathy. As MeN has been noted to likely have multiple causes, including social determinants of health, using a comprehensive framework, like the WHO Social Determinants of Health Framework, provides additional context.
Social Determinants of Health
Using a framework or model for health may help understand the complex disease process of Mesoamerican nephropathy. As MeN has been noted to likely have multiple causes, including social determinants of health, using a comprehensive framework, like the WHO Social Determinants of Health Framework, provides additional context.
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| WHO Social Determinants of Health Framework |
This model accounts for larger forces, called structural
determinants of health inequities, which includes policies, sociocultural
values, occupation, gender, class, and race/ethnicity, as well as more proximal
indicators of health, called intermediary determinants of health, which
includes things like behaviors and living/working conditions. The model doesn’t
just address how these social determinants can affect health, but how they can
perpetuate devastating health inequities.
When put
in the context of MeN, the involvements of various social determinants of
health are magnified. On a structural level, one must consider: work safety
policies in place (or lack thereof); how a society views work and how specific
occupations are perceived (particularly in the sugar cane industry); and how
the population affected is generally young, male sugar cane workers in lowland
areas (Correa-Rotter, Wesseling, & Johnson, 2014). On a more proximal
level, looking at material circumstances like working conditions can provide
more insight on the role of social determinants of MeN. The men who work in
sugar cane fields often work long hours under extraordinarily hot conditions,
with minimal shade and minimal rest periods, throughout the duration of the
season.
As one of the most widely accepted theories is that MeN is at least partly due to repeated heat stress and dehydration, it may be helpful to examine the interaction of MeN and social determinants of health in that context (Wesseling, Crowe, Hogstedt, Jakobsson, Lucas, Wegman, Program on Work, Environment and Health in Central America, & Central American Institute for Studies on Toxic Substances, 2015). Sugar cane workers are often paid by weight of the sugar cane they cut, rather than by time spent at work. This promotes working as hard as possible in often unforgiving conditions. There is little incentive for these workers to take breaks to rest in the shade and rehydrate, as it takes time away from earning money, even though it is detrimental to their health. However, the more time the men spend in these conditions without adequate rest and hydration, the more men seem to be affected by MeN, which then leads to loss of income from work due to disease as well as money lost to medical treatment. Enacting policies to support worker’s health and safety, creating work environments where rest and hydration are encouraged, and providing people with other opportunities for economic stability are all levels where public health interventions can improve the Mesoamerican nephropathy epidemic.
Continue to Part 2 - Research and Literature Review
All are Master of Public Health candidates at the University of Illinois -Chicago
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