Foodborne Chagas disease causes severe symptoms and may be more common than we think

A tangerine tree with many ripe fruits in the Cauca Valley, Colombia.
Foodborne cases of Chagas disease have been associated with drinking fruit juices, such as palm wine, sugar cane or tangerine juice, that have been contaminated by the parasite T. cruzi. (Jhon Gracia – Adobe Stock)

Under the dark shroud of nighttime, they drink the blood of sleeping, unsuspecting humans. No, not vampires — kissing bugs. These insects, infamous for carrying the parasite Trypanosoma cruzi, leave bites on their victims’ faces and necks. Though painless, these bites create an opening for a nasty infection.

Close up of Triatoma sanguisuga.
Kissing bugs carry the parasite that causes Chagas disease. They can infect people by biting as well as contaminating food and drinks with infected feces. (Photo courtesy of Norman Beatty)

As the kissing bug bites its victim and creates open wounds, it also crawls around dropping infected feces. It’s the perfect setup for T. cruzi to enter the body. The resulting infection, known as Chagas disease, affects muscles in the heart and gut. Without treatment it can lead to complications in the brain and peripheral nervous system, as well as death.

But this may not always be an accurate picture of how a Chagas disease infection occurs, said Arie Havelaar, Ph.D., a member of the UF Emerging Pathogens Institute and a professor in the UF College of Agricultural and Life Sciences. While kissing bugs continue to play a major role in spreading Chagas disease, other routes like foodborne transmission receive little recognition despite having a significant impact.

“The strategies that are aimed at controlling vectors don’t really work to prevent foodborne disease,” Havelaar said. Because public health efforts remain focused on minimizing kissing bug bites, other infectious routes largely go unchecked.

How does Chagas disease spread through food and drinks?

The most common type of foodborne transmission happens when kissing bugs contaminate food and drinks. Usually this happens when they defecate in fruit juices or—in the case of nymphs, which can be just a few millimeters in size—are completely incorporated into a food product. Sugarcane juice, ice cream, soup and shrimps have also been reported as vehicles for foodborne transmission.

Another route comes from animals carrying T. cruzi, such as raccoons, armadillos and various opossum species, that can contaminate food with their feces or secretions. Some people also eat these animals or drink their blood for religious rituals and traditional medicine. If not fully cooked, the meat and bodily fluids from infected animals may cause Chagas disease.

Diagram showing different ways Chagas disease can be transmitted to humans.
People may ingest a kissing bug if it gets crushed in the beverage making process, or infected feces, if the bug poops on food or fruits. (Graphic Illustration by Jiayu Liang)

In 2015, when the World Health Organization published its first estimates of the global impact of foodborne diseases, it did not include T. cruzi due to a lack of resources. The WHO now plans to update its estimates, and scientists like Havelaar and colleagues in the WHO Foodborne Disease Burden Epidemiology Reference Group see an opportunity to alert the global community to the fact that, in some parts of the Western Hemisphere, Chagas diseases may now be transmitted more frequently in food than anything else.

This is not the case everywhere. Kissing bug bites remain a predominant source of infection to humans and other susceptible animals, and some regions of Venezuela, for example, have actually seen a rise in vector-borne transmission.

But in Argentina, Bolivia, Brazil, Chile, Paraguay and Uruguay – countries whose governments launched the Southern Cone Initiative in 1991 to eliminate kissing bugs in the region and screen blood bank donors – progress in the fight against vector-borne Chagas disease has been promising. That means foodborne Chagas may be the next frontier.

Foodborne Chagas disease is more severe

Doctors have a hard time identifying acute Chagas, a phase of the disease that happens immediately after infection, in patients bitten by a kissing bug since symptoms are either nonexistent or mild. People infected may not realize T. cruzi has entered their body, but they can still develop a chronic infection many years later.

Meanwhile, those who ingest T. cruzi experience more severe symptoms and soon end up in the hospital. Without antiparasitic medicine, patients may die from the acute phase of infection and face a higher probability of chronic disease, resulting in cardiac or gastrointestinal dysfunction.

“It’s about the inoculum—how much parasite has entered your body,” said Norman Beatty, M.D., an EPI member and professor in the UF College of Medicine. “Through vector-borne inoculum, you’re going to have far less parasite transmission than you would with oral ingestion.”

Although it’s unclear whether foodborne transmission is happening here in the United States, it seems probable. Doctors can review confirmed cases in Colombia to better understand the route of transmission.

“We see all the same elements of transmission where humans and companion animals could be infected through contaminated food or drink in the United States and even here in Florida,” Beatty said.

Oral transmission routes would look slightly different in the U.S. since kissing bugs don’t tend to occupy fruit trees in the states like they do in Central and South America. Prickly pear presents one possible exception. Its fruit juice is a popular beverage out west, and kissing bugs like to inhabit packrat nests, which are commonly found within prickly pear itself.

Another foodborne route unique to the United States could involve Virginia opossums, a reservoir for T. cruzi that researchers believe may produce infectious secretions. “If we were to consume a wildlife reservoir that was undercooked, we could potentially consume the parasite,” Beatty said. “And we do know that people consume wildlife like opossums and raccoons in the United States.”

Virginia opossum (Didelphis virginiana) climbing powerline at night, Galveston, Texas, USA
Scientists believe urban-dwelling Virginia opossums may serve as T. cruzi reservoirs. They are still researching whether the anal gland secretions from an infected opossum can contaminate food. (Ivan Kuzmin – Adobe Stock)

On top of the evolving transmission routes, Chagas disease is also moving up from Central America into the southern United States and becoming endemic in Florida. Beatty stressed the importance of recognizing changes in T. cruzi epidemiology.

This is easier said than done though, as foodborne Chagas disease is difficult to map. If an infected kissing bug defecates on fruit or in fruit juices, the disease could easily spread far and wide. An area with high incidence could be right next door to a region with low incidence.

“Chagas is not really recognized by a lot of people as a potentially foodborne disease, but there is a potential for a big outbreak,” Havelaar said.

To begin addressing foodborne Chagas disease, he said there needs to be a way to assess risk for different regions and foods or a way to identify foods that are possibly infested. Another option is to simply start pasteurizing fruit juices instead of selling them raw.

“You need to think very differently about prevention strategies,” Havelaar explained.

Doing more research to understand which fruits have a higher risk of being contaminated can go a long way towards preventing big outbreaks in the future. To stay ahead of the curve, Havelaar said, the public and research community need to be aware of the problem and willing to direct money towards addressing it.

Havelaar, a consultant to the WHO, made his case with an estimate that foodborne Chagas disease is responsible for at least 137,000 disability adjusted life years per year. But because foodborne Chagas disease is understudied and often more severe than the vector-borne version, Havelaar suspects this is an underestimation.

Written by: Jiayu Liang