Chagas Information for Healthcare Professionals

Page originally published 04/05/2024. Last updated 07/17/2024.

Diagnosing Chagas Disease

Acute Chagas Disease Diagnostic Testing:

• Acute Chagas disease can be diagnosed through various methods, including:
  • Visualization of T. cruzi by microscopic examination (e.g. thick and thin Giemsa-stained blood smears, wet mount examination; histologic examination of biopsy specimens), or 
  • by detection of T. cruzi DNA by polymerase chain reaction (PCR). 
• Testing can be performed on any tissue or body fluid.
• Because of periodicity, parasite numbers in the blood may vary; therefore, multiple specimens should be collected, and a number of techniques should be used to detect acute Chagas disease in blood or body fluids.
• Following identification of T. cruzi parasites via microscopic examination, health care providers should consult with the Epidemiology Unit, to determine if submission to Centers for Disease Control and Prevention (CDC) for confirmatory testing is indicated. 
  • Positive microscopic results from specimen types other than blood or tissue may not be sufficient in diagnosing acute Chagas disease.

Chronic Chagas Disease Diagnostic Testing:

• Chronic Chagas Disease can be diagnosed based on serologic testing (e.g., Enzyme Immunoassay (EIA) – detecting IgG antibodies to T. cruzi).
• Testing can be requested and performed using a commercial diagnostic lab, including ARUP, Quest Diagnostics, and Mayo Labs. 
• Following identification of T. cruzi antibodies, health care providers should consult with the Epidemiology Unit to determine if submission to CDC for confirmatory testing is indicated as one test is not sensitive or specific enough for diagnosing chronic Chagas disease. 
• CDC may perform antibody detection by EIA to detect IgG antibodies to T. cruzi or use the Indirect Fluorescent Antibody Assay (IFA) to detect antigens of T. cruzi.

Note: Healthcare personnel working with specimens from patients suspected of having Chagas disease must use Standard Precautions. Trypomastigotes are highly infectious, and certain strains of the parasite are more virulent than others.

Screening for Chagas Disease

The U.S. Food and Drug Administration (FDA) recommends that all blood donors should be tested at least once for detection of T. cruzi antibodies.

• Blood banks screen all first-time blood donors for evidence of T. cruzi infection.
• Donors who test positive are notified of their test results and recommended to follow up with their medical provider to further discuss the findings, potential implications, and more laboratory testing.
• Potential blood donors infected with T. cruzi should not donate blood or tissues.
• Donors who test negative are qualified to return to donate.

Treating Chagas Disease

Benznidazole and nifurtimox are the two FDA-approved antiparasitic medications recommended for children with nifurtimox indicated for children starting at birth.

• Benznidazole: Benznidazole is FDA-approved for Chagas disease in pediatric patients 2–12 years of age. Use of benznidazole for patients outside this age range is based on clinical diagnosis and decision by the patient’s treating physician.
• LAMPIT (Nifurtimox): Lampit® (nifurtimox) is FDA-approved for Chagas disease treatment in pediatric patients from birth to younger than 18 years (weighing at least 2.5 kg). Use of nifurtimox to treat a patient outside this age range is based on clinical diagnosis and decision by the patient’s treating physician.

The American Academy of Pediatrics (AAP) supports treatment of Chagas Disease in pediatric patients.

• Children younger than 18 years: Indicated for all patients in the acute phase or reactivated Chagas disease and for patients in the chronic phase. Congenital infections are considered acute disease.
• Adults 50 years and younger: Treatment is strongly recommended for patients with chronic infection, who do not already have advanced cardiomyopathy.
• Adults over 50 years: The decision to treat patients with chronic infection using antiparasitic drugs should be individualized, weighing the potential benefits and risks.

Resources for Healthcare Professionals

• Order of the Health Officer (Locally Reportable Disease and Conditions for Providers and Laboratories) - April 10, 2024

California Health Alert Network Communications

• Health Advisory: Disease Reporting Requirement: Chagas Disease Now Locally Reportable in San Diego County (April 10, 2024)

Centers for Disease Control and Prevention (CDC)

• Chagas Disease - Resources for Health Professionals
  • Antiparasitic Treatment
• Chagas Disease: What U.S. Clinicians Need to Know

Screening for Pregnant Women and Evaluation for Congenital Chagas Disease

• Algorithm for Evaluation of Chagas Disease in Pregnant Women (CDC)
• Algorithm for Evaluation of Chagas Disease in Infants Less than 3 Months of Age (CDC)
• Algorithm for Evaluation of Chagas Disease in Infants Older than 3 Months of Age (CDC)

Other

• Chagas Disease as an Emerging Infectious Disease in the USA: A CTSA-PBRN Pilot Project | Clinical Directors Network, Inc. (cdnetwork.org)

For more information, contact the One Health Epidemiology Program via email at phs.ohep.hhsa@sdcounty.ca.gov, or call the Epidemiology Unit at (619) 692-8499.