Oral Transmission of Chagas Disease Has Severe Effects

 Thanks to decades of successful vector control strategies, vector-borne transmission of Chagas disease has significantly decreased in many regions. Oral ingestion of Trypanosoma cruzi through contaminated food and beverages, however, is increasing. Unlike vector transmission, oral transmission of Chagas disease entails high lethality in pediatric and adult populations.

"The oral transmission of Chagas disease is becoming a much more recognized route, and it is crucial to understand that people can die from this type of transmission," Norman L. Beatty, MD, assistant professor of infectious diseases and global medicine at the University of Florida College of Medicine in Gainesville, Florida, told the Medscape Spanish edition. Beatty is the lead author of a recent article on the subject.

In regions where the parasite circulates in the environment, people are consuming foods, fruit juices, and possibly wild animal meat that may be contaminated. "As we experience changes in our environment and in the way we consume food, it is crucial to consider how food preparation is carried out in areas where T cruzi transmission occurs in the environment," said Beatty. "And as organic farming methods without insecticides become increasingly common, more research is needed in these areas, both in Latin America and in the United States, to understand if oral transmission of T cruzi is occurring."

In the Amazon basin, foodborne transmission is already the leading cause of acute Chagas disease. It has been described in Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, and Venezuela.

Beatty's colleagues recently treated a Brazilian patient at the hospital in Florida. "He came to our hospital very ill, with acute myocarditis after consuming contaminated açaí." Clarifying that there is widespread awareness about oral transmission in Brazil, he stated, "We are concerned that it may not be recognized in other areas of Latin America."

Mexico and regions of Central America have little to no information on oral transmission, but it is likely occurring, and cases may be going undetected in the region, said Beatty.

He investigated the issue in Colombia as part of an international collaboration involving the University of Antioquia, aiming to find ways to mitigate oral transmission and create a model that can be used throughout Latin America and the United States. For the Colombia study, they reviewed all cases reported to the Ministry of Health and Social Protection, and oral transmission turned out to be more common than the research group expected. "Still, I imagine that in certain areas with limited resources…there are many more cases that are not being reported.

"A myth I would like to dispel is that Chagas disease is not being transmitted in the United States," Beatty added. He mentioned that at least 30 American states have vectors, and in Florida, it was documented that triatomines invaded homes and bit residents. In addition, 30% of these insects are infected with T cruzi. Research is underway to determine whether Floridians are becoming infected and if they are also at risk of contracting Chagas disease orally, said Beatty. "In the United States, we know very little about how many people are infected and what the infection routes are. Much more research is needed."

Roberto Chuit, MD, PhD, a doctor in public health and an external consultant for the Pan American Health Organization (PAHO), agreed that this route of food contamination, which occurs because of vector-borne parasites, was until recently masked or hidden by the predominance of vector presence. Just as it began to gain importance as other transmission routes were controlled, "it now has extremely high importance in the Americas, as does vertical transmission," he said.

In 2023, more than 50 years after the first description of oral transmission, the PAHO expert meeting proposed to alert health services and the broader community about the severity and potential lethality of oral Chagas disease outbreaks to elicit immediate responses and mitigation measures. The body also proposed conducting studies to provide detailed information on the contamination source and the wild vectors present in oral transmission foci.

Unique Clinical Manifestations

The exacerbated signs and symptoms of oral infection (see sidebar) are attributed to the high parasite loads in contaminated food and beverages. A single crushed triatomine along with a food or beverage harboring T cruzi can contain an estimated 600,000 metacyclic trypomastigotes, compared with 3000-4000 per µL when infection occurs by triatomine fecal matter. The robust systemic immune response observed in patients with acute oral Chagas disease is thought to result from more efficient transmission after penetration through the oral, pharyngeal, and gastric mucosae.

Seven Things to Know About Orally Transmitted Chagas Disease

1. It presents with exacerbated symptoms and rapid disease progression in immunocompetent individuals. This presentation is not common in vector-borne, congenital, or transfusion-related transmission. It can cause fulminant myocarditis and heart failure, meningoencephalitis, or potentially fatal shock due to parasitemia.
2. Most patients (71%-100%) with acute oral Chagas present with fever.
3. Electrocardiographic abnormalities, specifically ventricular depolarization alterations and pericardial involvement, are observed in most patients.
4. Facial edema, which typically affects the entire face and parts of the lips, is present in 57%-100% of patients with acute oral Chagas disease. In those with acute symptoms from vector transmission, unilateral periorbital swelling (Romaña's sign) is more common.
5. Other notable systemic symptoms include edema of the lower extremities, myalgia, generalized lymphadenopathy, abdominal discomfort, dyspnea, vomiting, diarrhea, hepatomegaly, splenomegaly, headache, chest pain, cutaneous erythematous rash, jaundice, arthralgia, epistaxis, hematemesis, melena, and palpitations.
6. The incubation period after oral ingestion of products contaminated with Trypanosoma cruzi is approximately 3-22 days, in contrast to 4-15 days for vector-borne transmission and 8-160 days for transfusion and transplant-related transmission.
7. Patients need antiparasitic drugs immediately.

Thinking Epidemiologically

Chuit recalled that suspicion of food contamination should be based on epidemiology, especially in outbreaks affecting several people and in regions where Chagas vectors have been described. Sometimes, however, a single careless tourist consumes contaminated products.

"The difficulty is that many times it is not considered, and if it is not considered, the search for the parasite is not requested," said Chuit. He added that it is common for the professional to consider Chagas disease only if viral and bacterial isolation tests are negative. Clinicians sometimes consider Chagas disease because the patient has not responded to regular treatments for other causes, such as antibiotics and hydration.

Epidemiology is important, especially when Chagas disease is diagnosed in groups or a family, because they are usually not isolated cases but outbreaks of 3-40 cases, according to Chuit. "Under these conditions, it must be quickly considered…that this parasite may be involved."

One of the difficulties is that the source of these oral transmissions is not recognized most of the time. In general, the sources are usually foods that are more likely to be contaminated by insects or insect feces, such as orange juice or sugarcane. But in fact, any food or beverage left unattended could be contaminated by vectors or possible secretions from infected marsupial odoriferous glands.

An analysis of 32 outbreaks from 1965 to 2022 showed that the main foods involved in oral transmission were homemade fruit juices. But different vector species were identified, and the reservoirs were mainly dogs, rodents, and large American opossums (Didelphis).

The largest oral Chagas outbreak was linked to the consumption of contaminated guava juice in a primary school in Caracas, Venezuela. Nonindustrially produced açaí is a common source of orally acquired Chagas disease in Brazil. In Colombia, Chagas disease has been associated with the consumption of palm wine, sugar cane, and tangerine juice. Other oral transmission routes include consuming meat from wild animals and ingesting blood from infected armadillos, which is related to a traditional medicine practice.

Deadly Yet Easily Treatable

In the outbreak of 119 confirmed and suspected cases in Venezuela, 20.3% required hospitalization, and a 5-year-old child died of acute myocarditis. These percentages differ from those reported in vector transmission, which is asymptomatic in the acute phase for 95%-99% of cases or will only develop a mild febrile illness that resolves on its own.

"Not all cases will present as severe, because depending on the inoculum, there may be individuals with subclinical situations. But any food poisoning that occurs in endemic areas, where food is not properly controlled, and these street foods are associated with processes in jungle areas, raises the possibility that T cruzi is involved and should be considered as a differential diagnosis," noted Chuit. "The treatment is highly effective, and people recover quickly."

"The most important thing about oral transmission of Chagas is that someone infected in this way needs antiparasitic drugs nifurtimox and benznidazole immediately. We can cure them if we treat them immediately," said Beatty, adding that treatment is sometimes delayed due to lack of access to appropriate antiparasitic drugs. "Here in the United States and in Latin America, it is quite common for healthcare professionals not to understand the differences between vector, vertical, and oral transmission. By not treating these patients, they become ill quickly."

Beatty and Chuit declared no relevant financial conflicts of interest.

https://www.medscape.com/viewarticle/oral-transmission-chagas-disease-has-severe-effects-2024a100042f