Chagas Disease

There are two phases of Chagas disease: acute and chronic. Both phases can be symptom-free or life-threatening.

The acute phase of the disease occurs during approximately the first 8 weeks of infection. Symptoms, if present, may include:

• Fever

• Malaise

• Body aches

• Rash

• Headache

• Loss of appetite

• Vomiting

• Diarrhea

• Localized swelling (“chagoma”) where the parasite entered the body

People with acute illness may also have mild enlargement of the liver or spleen. They may also have swollen lymph nodes and other less common findings. The most recognized sign of acute Chagas disease is called Romaña's sign. This is swelling of the eyelids on the side of the face near the bite wound or where bug feces entered the eye. Symptoms of acute illness can last weeks to months and then disappear, even without treatment. The acute phase of the disease may go unnoticed because it often causes no symptoms or only mild symptoms.

The chronic phase of the disease follows the acute phase and includes a form without symptoms (“indeterminate” or “latent” infection) and another form with symptoms. The majority of people in the chronic phase will remain symptom-free for life, but 20-30% will develop symptomatic illness. This may include:

• An enlarged heart (cardiomyopathy), heart failure, altered heart rate or rhythm, or sudden death

• Or, less commonly, an enlarged esophagus (megaesophagus) or enlarged colon (megacolon), which can cause difficulties eating or having bowel movements

The T. cruzi parasite is transmitted in the feces of blood-feeding triatomine bugs (also called reduviid bugs, kissing bugs, or cone-nosed bugs). The triatomine bug vectors usually become infected after feeding on an infected animal or, more rarely, a person. After the organism reproduces in the bug, it can spread to people if the infected bug defecates while feeding on them. This usually happens while the person is sleeping at night, and the person rubs the feces into the bite wound, an open cut, or a mucous membrane.

People also can become infected through:

• Congenital transmission (from a pregnant woman to her baby)

• Blood transfusion

• Organ transplantation

• Consumption of beverages or uncooked food contaminated with feces from infected bugs

• Accidental laboratory exposure

Chagas disease is not transmitted from person to person like a cold or the flu, or through casual contact with infected people or animals. Contact your medical provider if you think you have Chagas disease, have been exposed to a triatomine bug, or share risk factors with a family member who has Chagas disease.

Laboratory Diagnosis

Laboratory diagnosis of acute Chagas disease can be made via microscopic identification of T. cruzi in blood smears or detection of T. cruzi DNA by polymerase chain reaction (PCR).  Prior to collecting diagnostic specimens for the diagnosis of acute Chagas disease (i.e. in neonates born to a Chagas-positive mother; in recipients of organs or blood from a Chagas-positive donor; in lab/occupational exposures; and in persons with confirmed exposure to a T. cruzi-infected triatomine bug), clinicians should consult with DSHS Regional Zoonosis Control (ZC) program staff to discuss testing options. Providers wishing to submit samples to CDC for molecular testing (PCR) must consult with the DSHS Regional Zoonosis Control (ZC) program before sample submission. 

Laboratory diagnosis of chronic Chagas disease is based upon serologic testing. Because no currently-available serologic test is sensitive or specific enough to confirm a diagnosis, two or more serologic tests which use different parasite antigen preparations to detect T. cruzi-specific antibody are used to determine infection status. If you wish to test a patient for Chagas disease, please note the following:

• CDC will not accept serologic specimens for initial screening for chronic Chagas disease. Serologic screening should first be performed at the DSHS laboratory or one of the commercial laboratories which offer testing.
• Patients testing positive at a commercial lab should have additional testing at the DSHS laboratory; all samples testing inconclusive at DSHS will be forwarded to CDC for confirmatory testing provided there is sufficient sample volume available.

Laboratory testing recommendations for Chagas disease can be complex. The DSHS Chagas Disease Exposure Assessment and Testing Guide and list of Major Laboratories that Currently Perform Trypanosoma cruzi Testing may be helpful.

Blood Donor Testing

Blood banks screen first-time blood donors for evidence of T. cruzi infection. Donors testing positive are notified by the blood bank and are advised to consult their medical provider for additional laboratory testing and clinical evaluation. Blood donor screening tests are not suitable for confirmation of clinical diagnosis. Blood donors who receive a letter stating that they tested positive for Chagas disease should have serum tested at the DSHS laboratory or a commercial laboratory.

Clinical Evaluation of Laboratory-Diagnosed Patients

For patients with confirmatory laboratory testing for Chagas disease, medical providers should obtain a thorough history to evaluate potential routes of exposure, travel to or residence in areas endemic for human disease, previous history of blood transfusions or organ/tissue transplants, and the possibility of maternal transmission. Baseline clinical workup should include a complete physical exam and a 12-lead ECG with a 30-second lead II rhythm strip. Additional cardiac and gastrointestinal studies may be performed if indicated by the patient’s symptoms or clinical signs. Evaluation and testing of household contacts may be indicated for those sharing similar risk profiles and is strongly recommended if maternal transmission is a possibility, either from the index case or to the index case. Patients should be counseled not to donate blood or tissues for the remainder of their lifetime.

Treatment

Antiparasitic treatment is indicated for all acute infections, for chronic infections in children up to 18 years of age, for chronic infection in adults up to age 50 who have no indication of advanced cardiomyopathy, and for reactivated infections in immunocompromised patients. The decision to treat patients over age 50 years who do not have advanced cardiomyopathy should be made weighing the potential benefits and risks for the individual patient. CDC consultation is available to assist with management of patients with Chagas disease [parasites@cdc.gov, (404) 718-4745]. 

Two drugs—benznidazole and nifurtimox—are available for treatment of U.S. patients. Benznidazole has been approved by the U.S. Food and Drug Administration (FDA) for use in children 2-12 years of age, although it may be used “off-label” for other age groups. Nifurtimox (Lampit®) has been FDA approved for use in children from birth to 17 years of age. Both drugs may cause significant side effects that some patients may not tolerate.

Continuing Medical Education

Chagas disease CME is available via an online course offered on the CDC Chagas disease website.

Blood banks screen first-time blood donors for evidence of T. cruzi infection. Donors who test positive are notified by the blood bank and should consult their medical provider for evaluation and more laboratory testing. Potential blood donors infected with T. cruzi should not donate blood or tissues for the rest of their lifetime.

T. cruzi infection has been reported in dogs in Texas and several other states, including Louisiana and Oklahoma. Infections in domestic cats have been reported but are much less common. Outdoor dogs are at much higher risk due to their outdoor exposure, the likelihood of infestation of outdoor kennel areas, and the tendency for some dogs to eat triatomine bugs. Studies conducted in South Texas in 1999 found that 7.5% of the stray dogs tested were positive for the parasite. Infection in coyotes has also been reported. If you think your dog may have been infected, contact your veterinarian. Your veterinarian will be able to examine your dog and collect blood samples for laboratory testing. Currently, there are no drugs available in the U.S. to treat dogs infected with T. cruzi.

When traveling to areas with a high risk of infection, it's important to take preventive measures. This can help reduce the likelihood of getting bitten by disease-carrying insects and lower the risk of getting infected.

Some measures include:

• Using bed nets that are treated with long-lasting insecticides

• Wearing protective clothing that covers your skin

• Applying insect repellent to the exposed areas of your body.

To reduce the risk of transmission to animals and humans in the U.S.:

• Keep yard and kennel areas clean to get rid of habitat for the bugs; remove brush piles, rock piles, excessive buildup of leaf litter, etc.

• Control rodents to remove a potential food source that may sustain populations of bugs in the yard

• Turn off outdoor lights at night so that bugs aren’t attracted to the house and yard

• Identify and seal entry points for the bugs into the home and consider the appropriate use of a long-lasting insecticide

• Keep pet food and water bowls inside to prevent contamination with feces from the infected bugs

• Keep dog houses and poultry coops clean, fill in crevices where the bugs might hide, and consider the appropriate use of long-lasting pesticides in and around these structures

For additional information about Chagas disease in Texas, please contact the appropriate Regional Zoonosis Control Program or DSHS Zoonosis Control Branch at the.vet@dshs.texas.gov.

Find more detailed information about Chagas disease on the following websites:

• U.S. Centers for Disease Control and Prevention (CDC)
• Pan American Health Organization
• World Health Organization
• TAMU Kissing Bugs & Chagas Disease in the United States

• Downloadable Information Guide – “Kissing Bugs and Chagas Disease: What You Need to Know”

  • English (PDF, 2.3 MB)
  • Spanish (PDF, 1.7 MB)