Parasites
and viruses once thought to make their homes exclusively in exotic locales
beyond America’s borders are now gaining a foothold in the country and they are
exacting significant economic tolls and placing heavy burdens on health care
systems. Neglected tropical diseases such as cysticercosis, echinococcus,
toxocariasis, dengue, West Nile virus and Chagas have found their way into the
country due to a synergistic combination of factors, including globalization,
migration, trade and climate change.
Two
weeks ago I attended a symposium in New Orleans, LA hosted by Research!America to
discuss the issue of emerging neglected tropical diseases (NTDs) in
Louisiana and the southern United States, and to highlight the need to increase
both public awareness and research efforts. University professors,
research scientists and public health authorities from the state and beyond
urgently spoke of the dawning reality that the “neglected” status of these
debilitating diseases may not, indeed must not remain accurate
for long.
Already
these parasites and viruses affect an estimated 1.4 billion people worldwide
and are distinguished by their capacity to disfigure and disable if left
untreated (1). Some of these viruses and parasites can cause long term internal
organ damage, brain damage, blindness and seizures. Their presence in the US
bespeaks a great need to increase epidemiological surveillance of the
pathogens, their insect vectors and animal hosts, to aggressively treat cases
of disease, to develop new medical treatments, and to ensure greater public
awareness.
Certainly
America has the requisite insect vectors, the climate and the ecology to
support the presence of these diseases and, of course, a susceptible human
population to become infected. Poverty is one of the
greatest risk factors for acquiring a NTD and that too is also
present in the United States, particularly in the South and among minority
populations.
One
point repeatedly made during Research!America’s symposium was that decreased
federal surveillance and research due to widespread budget cuts stands in the
way of tackling the emergence and spread of NTDs in the US (1). In Laurie
Garrett’s book on the collapse of global public health, “Betrayal of Trust,”
she noted that “public health infrastructures [are] not terribly resilient; in
the face of societal stress and economic difficulty they quickly collapse (2).”
The
2008 recession, with the widespread crash in employment that accompanied it and
the slashing of government funding that continues today, has impaired the
capacities of public health departments around the country to adequately
provide for the prevention of and response to infectious diseases. At the
present state, NTDs will continue to percolate unnoticed through existing
insect vectors and the human population. Adequate public health infrastructure
and research is imperative to slow their emergence and spread.
Chagas
disease is an excellent example of a disease making a new home in the US.
Dubbed “the new HIV/AIDS of the
Americas,” the Chagas parasite is spread through infected triatomine
bugs, known as “kissing bugs” for their proclivity to nibble near the mouth. As
Loyola University biology professor Dr. Patricia Dorn noted during the
symposium, the bugs are “badly mannered” feeders. The bugs defecate near their
bites and the parasites are introduced when people inadvertently rub the feces
into their bite wounds. The parasite goes on to infect the heart, esophagus and
colon, and can lead to chronic heart failure and serious intestinal
complications.
Over
the past decade or so, the triatomine bugs, which are found in more than half
of the continental US, have slowly but surely become infected with the Chagas
parasite as they feed upon infected people and then go on to transmit the
infection. Up to 55% of triatomine bugs in the US may already harbor Chagas and
we are already seeing the effects of the disease in America: the CDC estimates
that 300,000 people have the disease, 315 babies are born with Chagas every
year, and hospitals in Los Angeles have found that the prevalence of the
parasite in heart failure patients rose from 4% to 17% from just 2001 to
2010 (3)(4)(5). This is, simply, an outrageous statistic.
Of
course, an unpleasantly chronic, difficult and expensive disease in the
population has onerous financial implications. Just this year, an article in
the medical journal The Lancet found that it costs $118 million
every year to treat chronic Chagas patients, while the impairment of these
workers results in economic productivity losses as high as $864 million
annually (6).
How
else are NTDs affecting the States? In Los Angeles, an estimated 10% of all
people visiting the emergency room for seizure events have been found to be
infected with neurocysticercosis, an infection of the brain with the pork
tapeworm parasite Taenia solium (7). At the southernmost tip of Texas,
over 40% of residents in Brownsville were found to show past evidence of dengue
infection (8). In the 1980s, residents in Louisiana were found to be widely
infected with toxocariasis, a disease associated with developmental delays and
asthma and spread by dogs and cats, yet comprehensive surveying has
not been performed since and the prevalence of this infection
in the population is unknown.
More
than 2000 years ago, the Roman poet Ovid wrote that in medicine and health
physicians must “act, before disease becomes persistent through long delays.”
Americans are the same crossroads, unaware that public health is hard work,
requiring much strategizing and vigilance to monitor and disrupt the presence
of disease in our environments. Public health “is a negative … at its best,
nothing happens (2).” Without sustained political will and greater
recognition by health policymakers, without investment in NTD research and
improved epidemiological surveillance, these diseases will not be able to
continue flying below our collective radars.
Resources
Opening
with the story of a woman infected with Chagas in New Orleans following the
landfall of Hurricane Katrina, ScienceLine describes the plague that is Chagas
disease in the Americas.
References
1.
Research!America (May 15, 2013) Research!American & Global Health Experts
focus on the economic and health burden of neglected tropical diseases in the
U.S [Press release]. Retrieved here on
May 16, 2013.
2.
L Garrett. (2000) Betrayal of Trust: The Collapse of Global Public Health.
New York: Hyperion Books
3.
L Stevens et al. (2012) Vector blood meals and Chagas disease transmission
potential, United States. Emerg Infect Dis. 18(4): 646-9
4.
S Montgomery. (June 5th, 2012) Protecting Americans from Chagas Disease, an
Emerging Health Threat. Our Global Voices (Web blog) Accessed May 29, 2013 here.
5.
R Nuwer (March 29, 2011) Chagas disease: the silent killer. ScienceLine
(Online). Accessed May 29, 2013 here.
6.
BY Lee et al. (2013) Global economic burden of Chagas disease: a computational
simulation model. Lancet. 13(4): 342-8
7.
S Ong et al. (2002) Neurocysticercosis in radiographically imaged seizure
patients in U.S. emergency departments. Emerg Infect Dis. 8(6):
608–13
8.
JM Brunkard et al (2007) Dengue fever seroprevalence and risk factors,
Texas-Mexico border, 2004. Emerg Infect Dis.13(10): 1477-83
The
entire article with maps can be found at:
http://blogs.discovermagazine.com/bodyhorrors/?p=1357
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