Ebola: Symptoms, treatment, and causes

A Little-known Parasite Infects 300,000 People In The U.S.

This story appears in the June 2019 issue of National Geographic magazine.

I grew up believing that my auntie had almost died because she ate an apple in South America.

According to the family stories, the fruit had been contaminated, or maybe an insect had been crawling on it and had bitten Tía Dora. However it had happened, my family understood this: A New York doctor had diagnosed my auntie with Chagas disease. It meant my auntie could die. We didn't ask questions. English wasn't our first language. My parents worked in factories. We took care of my auntie as she went in and out of hospitals for decades. When I reached my late 30s, Tía Dora was rushed to the hospital one night. A week later, she died. She was 59 years old, and I thought Chagas was a rare disease. I was wrong.

Named after the Brazilian doctor who discovered the disease in 1909, Chagas is more prevalent today in the United States than the Zika virus. And in the Western Hemisphere, the disease burden of Chagas is almost eight times that of malaria.

Some 10,000 people die each year from Chagas disease. The Centers for Disease Control and Prevention (CDC) estimates that about 300,000 people living in the United States have the disease. Many, like my auntie, grew up in poor communities in South America, Central America, or Mexico. Few know they have Chagas disease because the parasite that causes it, Trypanosoma cruzi, is a cunning microorganism.

The parasite can live in the body throughout a person's life without causing symptoms, but 20 to 30 percent of infected people will suffer cardiac damage.

It's transmitted to people by way of a triatomine insect called a kissing bug. In the acute stage, people usually can be cured; unfortunately, less than one percent of infected people are diagnosed or treated. The parasite can live in the body throughout a person's life without causing symptoms, but 20 to 30 percent of infected people will suffer cardiac damage. Chagas-related heart problems include irregular heartbeats, left ventricular aneurysms, and even heart failure.

Just as frightening is this: T. Cruzi can cross the placenta. It's estimated that as many as 315 babies a year are born with Chagas in the United States. I think of them as the "no-name babies" because health officials don't know who these children are. Pregnant women are not routinely screened for Chagas in the United States.

Another target of the bug's bite

In the United States, transmission of the deadly Trypanosoma cruzi parasite to humans is rare, but dogs appear to be more vulnerable. A recent study tested for Chagas disease among dogs that U.S. Agencies use in tasks such as sniffing for explosives or helping with search-and-rescue operations. Though the dogs showed no signs of being sick, more than 7 percent of those tested were infected. "When we take a look at their hearts, then we see signs of heart disease," says study director Sarah Hamer, an associate professor at Texas A&M University's College of Veterinary Medicine and Biomedical Science. Similar rates of infection have been found among dogs in Texas animal shelters. Scientists say dogs might be more at risk for the disease than people because dogs may eat bugs that carry the parasite. However, they say, the risk of infection passing from dogs to humans is extremely low. —DH

In 2014, a few years after my auntie's death, I traveled to Colombia. At the University of the Andes in Bogotá, biologist Felipe Guhl has been studying the kissing bug disease for more than four decades. There I learned that these insects are homebodies, often living where they don't have to crawl far to reach prey. That might be a human, a dog, a marsupial, a raccoon—the bugs aren't picky about which animals they bite. In rural areas of Latin America, they live in the cracks of mud houses during the day and come out at night to feed. The bite, though painless, leaves a small wound. The T. Cruzi parasite is in the bugs' feces and is transmitted when fecal material enters the bite wound.

Guhl says that to eradicate Chagas, you'd have to do away with wildlife—obviously not possible. Also, given the beetle-like bug's many species, "It's like a baseball game," he says. If you get rid of one, "there are other players on the bench." And the parasite itself is ancient. Guhl and an international team of researchers found T. Cruzi in 9,000-year-old mummies from the deserts of Peru and Chile.

Having grown up hearing about Chagas disease and knowing that a dreaded bug could kill me, the last thing I wanted was to see one. And yet I did. Maybe I wanted to face my fears. Maybe I wanted to see the truth of what I only knew as family folklore.

Off I went with Guhl's research assistant to see their insect colony. The day was chilly, but when the graduate student opened the door to a room the size of a walk-in closet, I stepped into a world both balmy and dimly lit. Think of a mild summer night out in the woods of North Carolina.

The room had shelves filled with glass jars of kissing bugs crawling on filter paper folded accordion style. Several were dark with pretty patterns of amber and black at the edges of their abdomens. Some, like the Rhodnius prolixus, were less than an inch long; others, like the Panstrongylus geniculatus, were longer. Kissing bugs tend to fly when they're starving. Now they began scrambling up the filter paper toward the cheesecloth covering on the jars. The graduate student smiled at me weakly. "They think we're going to feed them," he said. Their dinner? Chicken blood.

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Kissing bugs are native to the United States, too. At Texas A&M in College Station, the entomology department has about a hundred specimens, collected years ago. In fact, Texas has the greatest diversity of kissing bug species in the country, and the CDC funded the start of the Texas Chagas Taskforce to raise awareness there.

The CDC, however, estimates 75 or fewer cases of what could be called "homegrown Chagas"—cases where people have been infected by kissing bugs native to the United States.

Disease Cases Down

The World Health Organization lists Chagas, sleeping sickness, and Guinea worm disease among "neglected tropical diseases." But there's progress reining them in thanks to successful interventions: controlling for disease vectors, ensuring that people can filter their water, and getting infected people access to health care. Chagas disease1990: 30 million infected2010: 6 to 8 million infected The blood-sucking triatomine bug transmits the parasite that causes Chagas disease. The insect is active at night, searching for a meal—and earned its English-language name "kissing bug" because it generally bites an exposed part of the body such as the face. The feces left by the bug near its bite carry the Trypanosoma cruzi parasite, which can be spread to the wound when the bite is rubbed or scratched.

Gabriel Hamer/TAMU

If we have kissing bugs aplenty in Texas and some 300,000 people in the U.S. Infected, why do so few of us know about Chagas? "It's a disease of poverty," says Sheba Meymandi, a cardiologist whose team in California's San Fernando Valley has screened about 9,000 people who were born in Latin America for the disease. Many of the people infected have other issues to worry about: their immigration status, diabetes, and jobs that vanish overnight. Patients come to her when their hearts are failing. Because Chagas isn't easily transmitted between people, the disease stays largely confined to the Latino community—and that contributes to the lack of knowledge about it.

Through word of mouth in the Washington, D.C., area, I met Janet, a law school graduate from South America who's married to a U.S. Citizen and who asked that we not use her last name to preserve her privacy. Janet had never been screened for Chagas, but her dad was infected and so was her sister. In 2015, pregnant with her second son, she found herself in an emergency room. Her baby, born at 30 weeks, was infected with T. Cruzi. While babies infected with this parasite often don't show any signs of distress, Janet's premature son weighed less than four pounds and already had scar tissue on his heart. "It was shocking to learn that I could transmit this to my baby," she told me.

Doctors were able to treat Janet's son. But the recommended guidelines for newborn screening from the Department of Health and Human Services don't include congenital Chagas disease, even though there are more estimated cases of the disease than at least 15 other diseases currently listed.

This is particularly devastating because the drug benznidazole can often eliminate the parasite in infected children. In 2017 the Food and Drug Administration approved the drug for use among children. It sounds like good news, and it is, except benznidazole, which was developed in the 1960s and '70s, can have negative side effects for people with chronic Chagas. The other drug available for Chagas, nifurtimox, also has these limitations. Research funds continue to be scarce for this disease.

I've come a long way from thinking that my auntie ate a poisoned apple and contracted an infectious disease. However, the real story—spanning borders and sitting at the intersection of science and social issues like poverty and immigration—has also become more complicated than anything I could have imagined when I was a child.

Daisy Hernández is the author of A Cup of Water Under My Bed: A Memoir and co-editor of Colonize This! Young Women of Color on Today's Feminism. She is an assistant professor in the creative writing program at Miami University in Ohio, and her book, In Search of the Kissing Bug, is forthcoming from Tin House Books.

Correction: A previous version of this article included an incorrect picture of the triatomine bug. It has been updated with a correct picture.

Kissing Bug Project

Content

Pictured in the poster above are the three Triatoma species common in Texas (photos courtesy of Dr. Edward Wozniak). Kissing bug specimens (dead or alive) can be placed in a Ziploc bag or a pill vial and mailed in a padded envelope to the address indicated on the submission form. Please fill out the collection information on the submission form include it the in envelope with the specimen. If you have more than one insect, each should be in their own bag and have their own submission form (please make copies if needed, or just write the information on a separate sheet of paper).

The feces of kissing bugs may contain the parasite, so please use caution when handling the insects. If you encounter a kissing bug or its nymph, do not use bare hands trying to catch it, but rather use gloves or an inverted plastic bag or Ziploc bag over your hand. For the same reason the surfaces the bug crawled on should be decontaminated with bleach or similar disinfectants.

A Kissing Bug Humans Do Not Want To Canoodle

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Kissing bugs are vectors of a parasite that causes Chagas disease, which can lead to serious heart problems. Jennifer K. Peterson, University of Delaware assistant professor and medical entomologist, is studying kissing bugs in Delaware after two were discovered in homes in the northern part of the state.

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Credit: Kathy F. Atkinson/ University of Delaware

In July 2023, a New Castle County resident was getting ready for bed when they pulled back their comforter and saw a large black and orange insect sitting on their pillow.

Three months later, the same resident found another specimen of the same insect on a cookie sheet in their kitchen. It was similar to the first one in size, shape and color.

University of Delaware entomologists confirmed the two insects to be the kissing bug species Triatoma sanguisuga. What's more, the insect found on the homeowner's pillow was confirmed to be infected with Trypanosoma cruzi, the parasite that causes Chagas disease, a parasitic infection characterized by flu-like symptoms shortly after infection followed by a years-long phase where the parasite quietly reproduces in its hosts' tissues. If left untreated, the infection can ultimately lead to serious heart problems or even death. Studies have found infection prevalences between 30-60% in kissing bugs in other parts of the U.S.  

UD researchers detail the discovery of the two kissing bugs in a new paper published in the American Journal of Tropical Medicine and Hygiene. The authors say the presence of a kissing bug infected with the parasite Trympanosoma cruzi in a Delaware homeowner's bed is concerning, though not unexpected, given the high percentage of these bugs in the Mid-Atlantic region.

"It's not surprising that it was infected," said Jennifer K. Peterson, a UD assistant professor and medical entomologist and the faculty member who identified the two specimens as kissing bugs. "It's more of a wake-up call that this bug needs to be studied."

A wild goose chase 

Kissing bugs infected with T. Cruzi transmit the parasite through their excrement. The likelihood of a kissing bug biting a person then defecating on the wound and transmitting the parasite is low, "but like any sort of thing, the more times you roll the dice, the more likely you are to get the most unlikely combination," Peterson said.

This is not the first time a kissing bug has been confirmed in Delaware. It is, however, the first time a kissing bug in Delaware has been confirmed to have the Chagas disease-causing parasite T. Cruzi. Chagas disease is estimated to affect 6-7 million people around the world.

Peterson said kissing bugs are likely native to the Northeast and Mid-Atlantic and have been here for thousands of years. But they're understudied in our region. 

The fact that two were found in the same home months apart isn't surprising to Peterson. She said the home was in an area of farmland and forest fragments. Kissing bugs tend to live in natural areas, but they're driven by food.

"If there is not enough food in the forest and a kissing bug sees some twinkling lights coming from someone's house, it's going to fly in and see if there is a meal," Peterson said.

In the new paper, the researchers detail the long and frustrating course the homeowner took to get answers after they found the first insect on their pillow. The resident went on a wild goose chase to confirm if the bug was a kissing bug, and if so, get testing for Chagas disease.

When the homeowner found the first insect in July, they immediately began to seek answers. After contacting the Centers for Disease Control and Prevention, the CDC recommended the homeowner call their county health department. Since Delaware does not have county health departments, the homeowner called the Delaware Department of Health and Social Services. The homeowner then called back the CDC, which gave them the phone number for a pest company that could identify the insect. When the pest company couldn't ID it, the company referred the homeowner to UD Cooperative Extension.

Cooperative Extension identified the insect down to the order Hemiptera. A couple months later, when Peterson joined the UD Department of Entomology and Wildlife Ecology as a faculty member, she identified it down to species. By early October, Extension got back in touch with the homeowner and referred them to Peterson. Upon getting in touch, the homeowner told Peterson that they had found a second specimen in their kitchen the night prior.

It also took months for the homeowner to get tested for T. Cruzi antibodies, which indicate infection. The homeowner reached out to their primary care physician, who did not know what to do, so the physician reached out to two infectious disease doctors. 

Eventually, the homeowner was tested for T. Cruzi antibodies and the test results came back negative, meaning the homeowner probably did not have Chagas disease.

Although the homeowner eventually got answers and relief provided by the negative test, the case represents a systemic gap that needs to be addressed, Peterson said.

"The bugs are here," Peterson said. "They're making contact with people. This paper was written to illustrate that there is a hole in the system."  

Closing the gap 

Peterson doesn't blame anyone or anything in particular for the knowledge gap on the kissing bug T. Sanguisuga, the parasite T. Cruzi, and their prevalence in Delaware. She is simply setting out to close that gap and help others avoid instances like the New Castle County homeowner's lengthy pursuit and the anxiety they faced trying to get answers.

Peterson is studying the kissing bug in Delaware over the summer. She is working with graduate students Alex Kelley and Hanna Cortes and Summer Scholars Alex Hemelt and Jillian Tunstall to catch kissing bugs at various sites across the top two-thirds of Delaware and test them for the T. Cruzi parasite.

"You can get so much information just from testing them," Peterson said. "You can put a little of the stomach contents of each bug on a forensics rapid test and it can tell you in an hour or two if there was human blood in the bug. Then you know if it came into contact with people."

The goal is to find out where the kissing bug is, what it is eating, where it is breeding and the infection prevalence of the T. Cruzi parasite.

"I hesitate to say that people need to be concerned or worried," Peterson said. "Rather, I am a proponent of arming oneself with knowledge." 

Once the research team has collected enough data to form a more specific picture of the kissing bug and its parasite's prevalence in the region, Peterson hopes to create a readily available resource for members of the public to consult should they find a kissing bug.

"It could be something like an app or public awareness campaign that can ensure that people can quickly get the information or help they need if they come into contact with one of these insects," Peterson said.

Journal

American Journal of Tropical Medicine and Hygiene

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