Chagas disease, a parasitic infection that can cause heart disease and stroke, has spread over the past decades from South and Central America to the United States, according to a statement by the American Heart Association (AHA) that this week in the journal has been published. circulation. The statement is intended to help American physicians better recognize, diagnose and treat the infection, which is transmitted by an insect called the kissing insect.
About one third of people infected with the parasite that causes Chagas disease develop chronic heart problems at some point in their lives. The infection often does not go undiagnosed until it is too late, experts say, and so early screening and prevention practices are so important.
To learn more about Chagas disease, Health spoke with Paula Stigler-Granados, PhD, assistant professor at the School of Health Administration at Texas State University. Stigler-Granados was not involved in the new AHA statement, but she has extensively investigated Chagas disease. Here is what they, and the AHA, want to let people know about this scary sounding and often silent disease.
What is Chagas' disease and how does it spread?
Chagas disease is an infection caused by Trypanosoma cruzi, a parasite that lives in the intestinal tract of the triatomine insect – also known as the kissing insect because of the tendency to sometimes (but not always) bite people by the mouth while they sleep.
The T. cruzi parasite is not spread by the bite of the humming bug in the same way as mosquito-borne viruses; it spreads through its droppings. "If the kissing bug bites you and it has a blood meal and then defecate, then scratch that area and rub it in the wound or rub your eyes, you might become infected," says Stigler-Granados. ("Yes, it's disgusting," she adds.)
In other words, says Stigler-Granados, "all stars must be aligned" so that someone becomes infected. Those who do, can have no symptoms at all or develop a mild, flu-like illness that can last for a few weeks. Then they can feel good and be completely healthy for a certain period of time. "For some people this period lasts a year, for some it is 30 years and for some it is a lifetime," says Stigler-Granados.
But eventually 30% to 40% of infected people become ill: they can develop cardiovascular disease, heart failure or life-threatening arrhythmias, and suffer from strokes or cardiac arrest. "We still do not really know what makes a person susceptible to the development of a fully developed Chagas disease instead of not getting it at all," says Stigler-Granados.
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How often does Chagas disease occur in the United States?
The Centers for Disease Control and Prevention (CDC) estimate that about 300,000 people live in the US with Chagas disease and that most of them have acquired the condition in other countries. But Stigler-Granados says that this number is a calculation based on immigrant populations moving to the United States, not on actually documented cases. Some experts believe that the actual number is closer to 1 million.
Caring beetles are common in Central and South America, but they have also been reported in 27 states in the southern United States. According to Stigler-Granados research, about 60% of the bugs tested here are infected with T. cruzi.
According to the AHA, Chagas disease has spread over the past 40 years to the United States and other new countries. But some experts think the disease has been here longer than that.
"There is some research into suspicious cases dating back to the early 1900s," says Stigler-Granados. "It's possible that it has always been here, and we just have not looked for it, we probably have a fair number of misdiagnosed cardiovascular cases over the years that were actually Chagas disease."
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Who is at risk?
Anyone who lives in Latin America, or who has spent a lot of time there, is at an increased risk of Chagas disease. But Stigler-Granados says that people who live or have lived in the south of the United States are also, especially those living in rural or poor areas.
People living in low income, substandard housing facilities, can be more exposed to insects, especially if they sleep at night. But being rich does not make you immune. "It is a complete myth that [kissing bugs] are only found in mud huts, "says Stigler-Granados." We see them everywhere, including homes of millions of dollars. "
Chagas disease can not be transmitted from person to person via touch or saliva. But it can be transmitted through blood transfusions or organ transplants or passed on from a pregnant woman to her baby. In rare cases it can also be fed by food or drink that is contaminated with kissing beetles.
How can you protect yourself?
Anyone living in a state where kissing bugs are identified should know what they look like and what to do if you find one, says Stigler-Granados. In her previous position at the University of Texas, she co-authored an image-based consumer guide – in English and Spanish – on identifying zoos and what people should know about Chagas disease.
The insects are large – usually larger than a penny – and most species have a band of orange or red stripes around the edge of their bodies. In Texas, when people find cushions at home, they can send them for testing free of charge; if the bug comes back positive T. cruzi, anyone living in that house can undergo a blood test to see if they have been infected.
Stigler-Granados notes that the kissing bug has different appearances, including the relative, the hitman. "One way to see the difference is that biting the kissing insect is painless, but bites from the assassin are hurting," she says. "If it hurts when they bite you, it's probably not a kissing bug."
Stigler-Granados is of the opinion that pregnant women who live in the south or who have lived in South or Central American countries should be screened for Chagas disease; so should someone with a parent or sibling who has been diagnosed.
Animals, including dogs, can also get Chagas disease. Anyone with a pet whose diagnosis is made should also be screened, says Stigler-Granados, because they live in the same environment and are likely also exposed to kissing.
One problem, however, is that many doctors do not know much about Chagas disease. "If you ask for a test, most doctors will tell you that you are crazy, or that you do not need it, or that they do not know it, do not even know where to start," says Stigler-Granados. "They think it's a tropical disease we do not have here in the United States."
That is why Stigler-Granados is enthusiastic about the statement of the AHA and hopes that doctors will become increasingly familiar with Chagas disease and what is needed to diagnose and treat it. "It is half the battle to inform them how to order the test and how to take it into account," she says.
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How is Chagas disease treated?
There are medicines available to treat Chagas disease if it is caught at an early stage before causing damage to the heart and the cardiovascular system. Unfortunately, this means that it must be screened and diagnosed before the symptoms appear, either because a person knows they have been bitten by or are exposed to kissing, or because a doctor acknowledges that they are at high risk.
The currently available treatment options have a success rate of 60% to 90%, according to the AHA, depending on when a patient is diagnosed and treated. The medicines can also have side effects and are not recommended for people over 50, says Stigler-Granados, but for many people they can be lifesaving.
There are currently no drugs available for dogs or other animals – which can also die of Chagas disease – but Stigler-Granados says that clinical trials are being made. "I hope we get more grip next year or two and see more progress," she says, "in both animal and human research."