Rhabdomyosarcoma

Disease Description (Causes and Symptoms)

• Definition: A disease caused by infection with Trypanosoma cruzi, primarily endemic to Central and South America. The main source of infection is triatomine bugs (kissing bugs) of the family Reduviidae, which feed on human blood; it can also be transmitted through blood transfusion, organ transplantation, congenital infection, and contaminated food.
• Pathophysiology: The parasite invades and multiplies in the bloodstream and tissues, particularly the myocardium and connective tissue, causing inflammation. During the acute phase, the concentration of blood parasites (trypanosomes) is high; later, during the chronic phase, parasites remain in the tissues and, through immune responses and inflammation, cause cardiac and gastrointestinal lesions (cardiomyopathy, arrhythmias, megacolon, and megaesophagus).
• Main symptoms
  • Acute phase (incubation period: 1–2 weeks): Local swelling at the bite site (one of the signs of Chagas disease), swelling around the eyes (Romaña sign), fever, enlarged lymph nodes, and generalized weakness. Many cases pass without symptoms.
  • Chronic phase (may occur years to decades later): Cardiac symptoms — arrhythmias, cardiomyopathy, heart failure, chest pain, syncope, and sudden death; gastrointestinal symptoms — esophageal dilation (difficulty swallowing) and colonic dilation (constipation and abdominal bloating). Approximately one-third of all patients are reported to develop severe heart disease.

Treatment Methods

• Antiparasitic treatment (etiological treatment)
  • Recommended medications: benznidazole or nifurtimox.
  • Example regimens provided (based on RAG information):
    • Benznidazole: 5 mg/kg/day, orally, for approximately 60 days (adult dosing guidelines may vary according to region and guidelines).
    • Nifurtimox: adults 8–10 mg/kg/day, children 15–20 mg/kg/day, orally, for 90–120 days.
  • Treatment effectiveness: The treatment success rate is high during the acute phase and in children. Its effectiveness is limited during the chronic phase, but it may slow disease progression (a treatment response rate of approximately 70% in adults has been reported, based on RAG data).
• Treatment of symptoms and complications
  • Cardiac lesions: Standard heart failure treatment (ACE inhibitors/ARBs, beta-blockers, diuretics, etc.), antiarrhythmic drugs, temporary/permanent cardiac pacemakers, and implantable cardioverter-defibrillators (ICDs) may be considered when necessary; heart transplantation may be considered in severe cases (with antiparasitic treatment and follow-up before and after transplantation).
  • Gastrointestinal lesions: Medical or surgical treatment (e.g., dilation or surgery) may be considered for esophageal dilation/megaesophagus.
• Lifestyle management and precautions
  • Common adverse effects during antiparasitic treatment: skin rash, gastrointestinal symptoms (nausea and vomiting), neurological symptoms (headache and sleep disturbances), peripheral neuropathy (especially with nifurtimox), liver function abnormalities, and others — report adverse effects to a healthcare professional immediately if they occur.
  • Use of antiparasitic drugs during pregnancy requires an assessment of the risks and benefits of the medication (administration is generally limited during pregnancy). Counseling regarding breastfeeding is necessary.
• Follow-up
  • Monitor the course after treatment with hematological/molecular tests (serology and PCR) and cardiac evaluations (ECG, echocardiography, 24-hour Holter monitoring, etc.).

Checklist Before an Outpatient Visit (Including Example Questions)

• Items to prepare
  • A list of all medications currently being taken (including prescription, over-the-counter, and herbal medicines) or the medication packages
  • Copies of previous test results (ECG, echocardiography, serologic tests, PCR/antibody tests, etc.), if available
  • Travel and residence history: whether and for how long you stayed in Central or South America, and whether you stayed in rural areas or old housing
  • History of blood transfusion or organ transplantation, and pregnancy and childbirth history (for assessment of the risk of congenital infection)
  • A record of when symptoms began and how they progressed (fever, swelling around the eyes, palpitations, difficulty swallowing, etc.)
• Useful information to provide to healthcare professionals during an outpatient visit (example questions)
  • Please let me know whether you have recently visited Central or South America or been exposed to triatomine bugs (kissing bugs).
  • Pregnancy plans or whether you are currently pregnant (for assessment of the risk of mother-to-child transmission).
  • Whether you have previously received antiparasitic treatment, including the medication name and duration of use.

General Example Questions to Ask the Doctor

• "Is antiparasitic treatment recommended for my current condition? What are its expected effects and limitations?"
• "What are the expected side effects of the recommended medication (benznidazole/nifurtimox), and how should they be managed?"
• "How will follow-up be conducted after treatment (what types of tests and at what intervals)?"
• "If I have cardiac symptoms, what additional tests are needed, and what treatments may be available?"

Disease-Specific Example Questions

• "I am pregnant or planning to become pregnant. What are the risks of infection to me or the fetus, and what testing and treatment are recommended?"
• "I currently have an abnormal ECG (or symptoms of arrhythmia). What is the likelihood that this disease will progress to cardiac complications, and what prevention and treatment options are available?"

(Note) Diagnosis: During the acute phase, concentrating the blood and then observing the parasites under a microscope is useful. During the chronic phase, serologic testing (antibody testing) is the standard, while PCR (detection of parasite DNA) is used as an adjunct or in specific situations (e.g., congenital infection or evaluation of treatment response). Prevention primarily involves blocking exposure to vector insects (improving housing conditions and residual insecticide treatment), screening blood and organ donors, and screening pregnant women.