OVERVIEW

What is Chagas disease?

Chagas disease was first discovered in 1909 by the Brazilian physician Carlos Chagas, hence its alternative name, Chagas Disease.

The outbreak pattern of this disease in the Americas closely resembles the early spread of HIV/AIDS. It can be transmitted through blood or from mother to child, and both diseases have long incubation periods and are difficult to cure. For these reasons, experts have also referred to it as "the new AIDS of the Americas."

Chagas disease is a potentially life-threatening parasitic infection caused by Trypanosoma cruzi. In addition to humans, over 200 species of mammals in the Americas can also be infected with T. cruzi. The primary vector is the blood-sucking insect known as the kissing bug.

The clinical manifestations of Chagas disease vary depending on the stage of infection. Early stages may be asymptomatic or present with mild symptoms, followed by an asymptomatic latent period. In the chronic phase, the disease progressively damages the heart and digestive system. The infection can last a lifetime, and some cases may result in death.

Treatment primarily involves antiparasitic drugs such as benznidazole and nifurtimox. If diagnosed early and treated during the acute phase, outcomes can be very favorable. Treatment during the chronic phase may delay or prevent symptom progression, though some chronic cases still develop fatal heart or digestive system failure.

Currently, there is no vaccine for prevention. The most effective preventive measure is eliminating the vector insect—the kissing bug.

Is Chagas disease common? Where is it prevalent (endemic areas)?

Chagas disease is relatively common in the Americas, with an estimated 6 million people infected. The highest prevalence is found in Bolivia, Argentina, Paraguay, Ecuador, El Salvador, and Guatemala.

Originally confined to the Americas, the disease has now spread to other continents, including Europe, due to population migration, becoming a global health concern.

Are there any cases of Chagas disease in China?

There have been no reported cases of Chagas disease in China so far.

However, imported cases have been documented in neighboring countries such as Japan and South Korea, making it possible for China to see imported cases in the future. Additionally, the disease's vector insect—the kissing bug—has been recorded in China, primarily in regions like Guangdong and Hainan. Therefore, heightened vigilance is necessary.

SYMPTOMS

How long is the incubation period for Chagas disease?

If a person is infected through contact with insect feces, the incubation period is typically 5–14 days; if infected through blood transfusion, the incubation period is 20–40 days.

What symptoms does Chagas disease cause?

The symptoms of Chagas disease vary depending on the stage of infection. The stages are as follows:

• Acute phase: Parasites can be detected in the blood during this stage.
  • Most people (especially adults) may show no symptoms during the acute phase.
  • A few may experience fever, headache, loss of appetite, fatigue, muscle pain, joint pain, weakness, nausea, vomiting, diarrhea, enlarged liver or spleen, swollen lymph nodes (localized or generalized), and some may develop widespread facial or lower limb edema.
  • If the parasite invades the subcutaneous tissue, localized nodules called "chagomas" may appear.
  • If the parasite invades the conjunctiva, conjunctivitis, unilateral eyelid edema, and preauricular lymphadenitis may occur, known as the "Romafia’s sign." This typically lasts 1–2 months and is a characteristic manifestation of acute Chagas disease, aiding early diagnosis.
  • Even without treatment, acute-phase symptoms often resolve within weeks or months, with only a small number of patients dying during this stage.
• Indeterminate phase: After the acute phase, an indeterminate phase of varying duration occurs, also called the transitional or asymptomatic phase.
  • During this stage, parasites are often undetectable in the blood, and patients show no symptoms.
  • After 10–20 years, most patients progress to the chronic phase, though some may remain in the indeterminate phase for up to 40 years.
• Chronic phase: After a prolonged asymptomatic period, patients enter the chronic phase, characterized by organ failure (e.g., heart, gastrointestinal tract).
  • Cardiac abnormalities include arrhythmias (irregular heartbeat), heart failure, apical aneurysms, thromboembolic diseases (stroke, pulmonary embolism), and sudden death.
  • Gastrointestinal abnormalities include esophageal and colonic enlargement (megacolon). Esophageal enlargement can cause painful swallowing, excessive saliva, reflux, and chest pain. Colonic enlargement may lead to constipation lasting days to months.
  • Other gastrointestinal issues include asymmetrical abdominal distension, intestinal obstruction, volvulus, fecal impaction, ulcers, intestinal perforation, peritonitis, gallbladder enlargement, gallstones, and rarely, small intestine dilation.

What risks does Chagas disease pose to pregnant women?

Pregnant women with the disease can transmit Trypanosoma cruzi to the fetus, leading to premature birth, as well as hepatosplenomegaly, meningoencephalitis, retinal abnormalities, and acute myocarditis/cardiac dysfunction in the infant.

What severe complications can Chagas disease cause?

Without treatment in the acute phase, about 5%–10% of symptomatic patients may die from meningoencephalitis or severe heart failure.

As the disease progresses to the chronic phase, patients may develop cardiac, esophageal, colonic, and neurological symptoms. Some may die suddenly from arrhythmias, heart failure, thromboembolic events, or complications like intestinal perforation, necrosis, or peritonitis.

How high is the mortality risk from Chagas disease?

Current data show a mortality rate of 5%–8%. Deaths primarily occur in children with acute myocarditis or meningoencephalitis and immunocompromised patients.

CAUSES

What is the pathogen that causes Chagas disease?

The pathogen that causes Chagas disease is Trypanosoma cruzi, also known as T. cruzi.

How does T. cruzi infect and cause illness in humans?

T. cruzi has three developmental forms—trypomastigote, amastigote, and epimastigote.

• When kissing bugs suck blood from infected humans or animals, trypomastigotes enter the bug's body and transform into epimastigotes in its digestive tract.
• After 2–4 weeks of development, they move to the bug's hindgut, become infectious trypomastigotes, and are excreted in the bug's feces.
• Infectious trypomastigotes directly enter or are ingested by humans or mammals, enter the bloodstream, invade cells, and differentiate into amastigotes, which multiply and transform back into trypomastigotes.
• Trypomastigotes spread via the lymphatic and circulatory systems, invading muscle cells (cardiac, smooth, and skeletal) and ganglion cells, multiplying within cells, destroying them, and causing organ dysfunction or failure—a cycle that repeats.

What is T. cruzi vulnerable to?

T. cruzi is an intracellular parasite and can be destroyed within hours when directly exposed to sunlight or harsh environments.

Disinfectants like sodium hypochlorite, ethanol, iodine solutions, glutaraldehyde, and formaldehyde, as well as moist heat (121°C, 15 minutes) or dry heat (160–170°C, 1 hour), can inactivate T. cruzi.

How is Chagas disease transmitted? Can it spread between humans?

Chagas disease is primarily transmitted by the vector—kissing bugs.

Kissing bugs feed on the blood of infected humans or animals and excrete feces containing T. cruzi, which enters humans or mammals through mucous membranes or broken skin, causing infection.

Besides vector transmission, other routes include:

• Ingesting food contaminated with kissing bugs or their feces;
• Receiving blood, organs, or bone marrow from chronically infected individuals;
• Laboratory exposure via mucous membranes, skin wounds, accidental needle injuries, or aerosol inhalation;
• Congenital transmission—T. cruzi can cross the placental barrier and infect the fetus at any stage of pregnancy.

Which populations are most commonly affected by Chagas disease?

All populations are generally susceptible to Chagas disease.

DIAGNOSIS

How is Chagas disease diagnosed?

Individuals with a history of residence in endemic areas, use of blood products or organ transplants in endemic regions, or researchers involved in scientific experiments related to *Trypanosoma cruzi*, who exhibit symptoms of Chagas disease—particularly chagoma, hypertrophic cardiomyopathy, megaesophagus, or megacolon—should be highly suspected of having the disease.

Definitive diagnosis requires further laboratory tests, including the detection of *Trypanosoma cruzi* in the body, a positive *T. cruzi* DNA test, or a positive serum antibody test for *T. cruzi*.

Which diseases resemble Chagas disease? How to differentiate them?

When Chagas disease presents with cardiac symptoms, it must be distinguished from other cardiac conditions. If gastrointestinal symptoms occur, differentiation from certain digestive disorders—such as esophageal cancer or congenital megacolon—is necessary.

Obtaining a history of exposure to endemic areas and conducting laboratory tests can aid in differentiation.

TREATMENT

Which department should I see for Chagas disease?

Infectious diseases department.

Do Chagas disease patients need isolation?

No.

How is Chagas disease treated?

Treatment mainly involves antiparasitic drugs and symptomatic supportive therapy.

• Antiparasitic treatment:

  • Recommended for acute-phase patients, congenital infections, chronic-phase patients under 18, and children at any infection stage.
  • Primary drugs are benznidazole (BZL) and nifurtimox (NFX), with a course of 60–90 days.
  • Side effects (e.g., anorexia, weight loss, neurological symptoms, drowsiness, GI issues) are common. Combining drugs at lower doses may reduce adverse effects.

• Symptomatic supportive therapy: Chronic-phase patients require additional symptom management.

  • Antiarrhythmics (e.g., amiodarone) for irregular heartbeat;
  • Implantable cardioverter-defibrillator for unstable ventricular tachycardia or cardiac arrest;
  • Pacemaker or heart transplant for severe cardiomyopathy;
  • Balloon dilation or surgery for esophageal complications.

Can Chagas disease be completely cured?

Early treatment enables full recovery, but efficacy declines over time.

Cure rates: ~60–85% in adults within the first year of acute infection, >90% in infants. Chronic-phase adults show lower success rates.

DIET & LIFESTYLE

What are the dietary precautions for patients with Chagas disease?

Patients with Chagas disease should consume high-calorie, high-protein, and vitamin-rich foods.

Specific food choices should be based on gastrointestinal function:

• If gastrointestinal function is impaired, opt for liquid or semi-liquid diets with more broth and easy-to-digest foods.
• If gastrointestinal function is normal, patients can eat the same as healthy individuals.

What are the lifestyle precautions for patients with Chagas disease?

Attend annual follow-ups for physical examinations and electrocardiograms (ECG) to monitor for newly developed cardiomyopathy or gastrointestinal diseases.

If symptoms or signs of heart failure, thromboembolic disease, or arrhythmia occur, further cardiac evaluation, including Holter monitoring, should be performed.

If gastrointestinal symptoms such as dysphagia or constipation arise, a barium swallow study should be conducted promptly.

Echocardiography can be performed every 3–5 years, and chest X-rays should be repeated every 3–5 years.

Can patients with Chagas disease conceive or breastfeed?

Patients with Chagas disease can conceive, but it is not recommended due to the risk of mother-to-child transmission. Trypanosoma cruzi can cross the placental barrier and infect the fetus, increasing the likelihood of miscarriage and stillbirth.

Patients with Chagas disease can breastfeed, as transmission through breast milk is extremely rare.

PREVENTION

How to prevent Chagas disease? What precautions should be taken when traveling to Chagas disease-endemic areas?

• Spray insecticides in and around residential areas to eliminate the vector insect—kissing bugs.
• Install insect-proof facilities (such as window screens, mosquito nets) in living spaces and avoid staying in poorly maintained housing whenever possible.
• Avoid sharing sleeping quarters with animals (especially dogs) at night.
• Kissing bugs are often found in basements, so minimize prolonged stays in such areas.
• Wear thick clothing when outdoors to reduce exposed skin, such as long-sleeved shirts, long pants, socks, and shoes.
• Ensure food is thoroughly cooked before consumption.