By David DiSalvo
Chagas, a
disease caused by a parasite transmitted via the Triatoma
bug (aka, the kissing bug), is claiming thousands of lives in Central and
South America. Some experts are even calling it the “new
HIV/AIDS of the Americas”. But is this comparison accurate, and how big a threat is the
disease to the US?
Chagas is not a new disease. It’s named
after Carlos Chagas (circa 1909), a Brazilian doctor
who discovered that Triatoma carry a potentially lethal parasite called Trypanosoma cruzi. After several of his patients developed a
strange infection that he couldn’t identify, Chagas set out to investigate how
humans come in contact with the pathogen and its effects on the body of its
host. He probably didn’t realize at the time that his work was
groundbreaking in the history of epidemiology (Chagas later went on
to identify the parasitic fungal genus Pneumocystis, another
major discovery).
Kissing bugs, named because they bite the
face and lips of humans (they’re also called assassin bugs), live in tropical
climates near warm-blooded vertebrates to gain easy access to their blood.
They stay hidden for much of the day, living
in concealed places such as the cracks in a piece of wood and
thatched roofs, and usually strike their victims as they sleep.
The bugs defecate as they feed, allowing the parasite they carry
to infect a new host.
According to the Centers for Disease Control and Prevention (CDC), the early stage of Chagas occurs immediately after infection and may have mild or no symptoms at all. Symptoms generally include fever, malaise, and a swelling of one eye. If left untreated, the infection can continue for years, often with no further symptoms, and over time it damages the heart, intestines and esophagus. There are two known treatments for the disease but they only work when administered in the early stages of infection. Once organ tissue has been damaged, it’s usually too late.
According to an editorial in the online
journal PLoS, about 10 million people are currently
living with Chagas, making it one of the most common neglected tropical diseases
in Latin America and the Caribbean. It kills roughly 20,000 people worldwide
every year. Lead author Dr. Peter Hotez, dean of the National School of
Tropical Medicine at Baylor College of Medicine in Houston, warns that the disease is spreading
globally and there may be between 300,000 and 1 million cases in the US.
While the infection is triggered by
contact with a kissing bug, the disease appears to spread most rapidly via
blood transfusions, organ transplants, and from mother to child during
pregnancy — hence the comparison with HIV/AIDS.
There are, however, major differences
between Chagas and HIV/AIDS, including that the parasite is not transmitted via
sexual contact. And unlike HIV, which evaded detection in the blood supply for
years, Chagas can be identified through blood screening and eliminated before
it spreads. The problem is that screening requirements differ from
country to country, and too often screening procedures are poorly administered
or simply ignored.
Also unlike HIV/AIDS–at least in the early
days of the disease–we know proven ways to prevent Chagas infection.
Insect nets that prevent kissing bugs from biting humans are
effective. Proper screening of the blood supply and reporting the disease are
critical steps, as well as screening for the disease during pregnancy.
Is the disease a threat to the US? That
depends on where you live. Texans, in particular, may have cause for
concern because blood-donation screening is not mandatory in the state and
physicians are not required to report the disease’s occurrence to health
authorities, according to Wired.
What we do know is that Chagas is a major
problem throughout Central and South America, and will continue to be
until measures are taken to prevent its transmission.
Unfortunately, those
measures require adequate funding, and the countries most
afflicted by the disease are also among the poorest. And since people can
remain infected for up to 30 years before succumbing, we may have only started
to see the true extent of the damage.
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