Should people in Dallas-Fort Worth fear Chagas disease?


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Chagas disease is an epidemic in Central America and South America, and it is spread by bites from “kissing bugs."

Article updated November 30, 2015.

A chilling story in the Dallas Morning News described Chagas disease, a nasty parasite that can cause serious heart, esophagus, and colon problems in patients. Chagas disease is an epidemic in Central America and South America, and it is spread by bites from “kissing bugs” – small insects that bite around the mouth and eyes.

The story left out one very important fact: Chagas infections that are acquired within the state of Texas, or within the United States as a whole, are extremely low. That means your chance of getting Chagas disease is slim to none.

That said, we do have a lot of people in the Dallas-Fort Worth area who have Chagas disease. These folks have moved here from Central and South America, where the disease is more common.

The good news is Chagas disease doesn’t spread from person to person like a cold or flu virus. You can’t catch Chagas disease from being around people who are infected. In fact, most people who have it don’t even realize they’re infected.

How do people get Chagas disease?

The most common route of infection is a bite from a reduviid bug – a blood-eating insect more commonly known as the kissing bug. The kissing bug hosts a parasite called Trypanosoma cruzi, which lives in its digestive tract. The kissing bug tends to leave fecal droppings where it bites, and when a person rubs or scratches the bite, the parasite in the feces is rubbed into the wound and the parasite gets into your bloodstream.

A second, less common way to become infected is if you receive a blood transfusion or a transplanted organ from a donor who has been infected. Chagas disease screening is a standard test before you can be approved as a blood donor. The blood donation center screens your blood for antibodies from the parasite, and if you test positive, you are banned for life from donating blood. Chagas disease screening for blood donors is only required on the first donation.

A study published in the American Journal of Cardiology reported that 154 blood donors tested positive for Trypanosoma cruzi enzymes through the Gulf Coast Regional Blood Center between 2007 and 2012. Of those 154 blood donors, 30 volunteered for a Chagas disease study through Baylor College of Medicine and the blood center. Of the 30 volunteers, just 17 were confirmed positive upon further testing. Only six of these 17 volunteers were suspected of locally acquired infection.

Organs that are presented for donation also are screened for Chagas disease antibodies and are not used if they test positive. Let me be clear: The chance of a blood or organ recipient becoming infected within Texas or even the United States is extremely low. Additionally, infected mothers also can transfer the disease to their unborn babies.

Will I get Chagas disease if I travel outside the United States?

The chance you’ll get infected during work or leisure travel to Central or South America is not impossible, but it’s unlikely. That’s because, more often than not, you’ll be staying in accommodations that are similar to what we’re accustomed to in the United States. People who get infected in Central and South America typically live in substandard housing compared to what most tourists seek. In other words, your risk of infection while traveling abroad is slim.

For about 10 years, I‘ve been working on a project in the Toledo District of Belize, which is in the southernmost part of the country. My project is focused on looking for the prevalence of Chagas disease. I go to the Toledo District in 1- to 2-week stretches once or twice each year. I’m in the thick of a very rustic part of the country. Even after all that travel for the past decade, I’ve never been bitten, and I’m not even worried about it!

Chagas disease symptoms

On the extraordinarily rare chance that you are infected, there’s only a 20 to 30 percent chance that you’d later develop symptoms or complications. The majority of patients have no symptoms. Frankly, the only way most people know if they’re infected is to be tested for the antibodies.

For those who do have symptoms, there are three long-term side effects that could occur:
  1. Heart failure: The heart muscle deteriorates to the point where it doesn’t work well, and the heart dilates and fails. If someone presents with these symptoms, unfortunately, anti-parasitic agents won’t help. These individuals will be treated for heart failure, and some may require heart transplants.
  2. Mega-esophagus: Some patients will lose function of their esophagus. The esophagus dilates, gets large and flabby, and stops working properly. These patients become malnourished because they can’t eat well.
  3. Mega-colon: In this symptom, the colon becomes huge and ceases to function properly. The individual will no longer be able to have proper bowel movements, which can cause a whole host of painful problems.
I’ve never known of any cases with these long-term effects when the disease was acquired in the United States. Incidents of these symptoms are typically found in Central and South America, where Chagas disease is most common.

The only time treatment is effective is if a patient does not have symptoms but does have the antibodies. If the patient is 50 or younger and is positive for antibodies, we can offer one of two anti-parasitic drugs: nifurtimox and benzmidazole (which is the more effective of the two). These drugs will rid the body of the parasite.

Both drugs have numerous side effects, and we have to treat patients for several weeks. But once long-term symptoms develop, these drugs won’t have any effect on the parasite and won’t reverse the symptoms. These drugs are only available in the United States by petition to the Centers for Disease Control and require confirmation by two or more types of antibody tests.

Local Chagas disease research

I have done two Chagas disease survey studies at Parkland Memorial Hospital. One study focused on individuals with Hispanic surnames who sought general care at Parkland. Among this group, about 2 percent have the Trypanosoma cruzi antibody. None of them were sick with Chagas disease symptoms – they just had the antibodies.

The other study was of women with Hispanic surnames who delivered babies at Parkland. This group also had about a 2 percent infection rate. All of the individuals in both surveys were immigrants – they were not originally from America, and their infections did not occur in Texas.

There are people who are infected with Chagas disease living among us. But these folks who are infected are not a threat to your health. Living in Dallas-Fort Worth, in Texas, or in America, there is no reason to be afraid of developing Chagas disease, even if you occasionally travel outside the country.