Chagas Disease: Why a Neglected Tropical Disease Matters for US Clinicians (Heindel, 3/5/25)

 A recording of this presentation is available HERE. 

Dr. Leah Heindel gave a wonderful Grand Rounds presentation this week on Chagas Disease. Perhaps the most important moment of the presentation was this slide:

"Look," Dr. Heindel, urged, "look at how this little "kissing bug" (aka triatomine) creates a cascade that has impact on immigrant health justice, reproductive health, whole-family care, global health, and how we think of screening and prevention in the US in 2025. This is family medicine."

Family medicine, indeed, is all of these.

Epidemiology and Disease Burden

Chagas Disease, which infects 7-8 million people worldwide, mostly in Latin America, presents a health burden seven times higher than malaria in the Western Hemisphere. There are an estimated 300,000 people living in the US with Chagas disease, many of whom are immigrants from Mexico, El Salvador, Guatemala, and Honduras. Unfortunately, only about 1% of those have been identified. Both vector and vertical transmission occurs in the US (22-100 cases congenital chagas in the annually).

Chagas disease has both an acute and indolent phase. The overwhelming majority of people infected with Chagas disease (90%) will be asymptomatic in the acute phase, but chronic impacts (especially GI, cardiac) typically appear 20-30 years after initial infection. 

Seroprevalence in immigrants from endemic countries is believed to be about 1% in the general population, though it varies widely depending on how these estimates are made. For example, you can see in the table below from the IDSA that there is a MUCH higher seroprevalence in immigrant patients from endemic areas with otherwise unexplained non-ischemic cardiomyopathy (13-19%). 

Vertical transmission occurs in 2-13% of cases, most congenital infection is asymptomatic, but Chagas has been associated with preterm delivery, low birthweight and low APGAR scores. 

Clinical manifestations

Chagas disease is generally spread via the bite of the "kissing bug", usually on the neck and face at night while people are sleeping; the same bug defecates close to that area, then the disease is transferred to the bloodstream via scratching at the site and introduction of bug feces to the broken skin. The acute phase of Chagas (only in about 10% of people infected) presents as a non-specific viral syndrome, including fever malaise, and anorexia. One pathognomonic sign of acute Chagas is Romaña's sign, pronounced swelling of the eyelid (as seen in image below). Domesticated and farm animals serve as reservoirs of the disease, and thatched roofs are a known risk factor in endemic areas.

After decades long latency, most common manifestations include cardiac (sudden cardiac death as #1 cause of death from Chagas, 55-60% of people, also HFrEF (25-30%) and embolic disease (10-15%). It seems that the parasite has a particular predilection for the electrical and conducting system. 

GI effects are also well-documented and occur in 10-21% of people with chronic Chagas, including both esophageal and colonic manifestations. In the esophagus, dysphagia and regurgitation are common; in the colon sigmoid rectal dilatation and progressive constipation. 

Neurologic effects including peripheral neuropathy and even dementia have been suggested. In addition there is a reactivation syndrome that can affect people with transplant or other immunosuppression.

Screening and Diagnosis 

The earlier Chagas is detected, the better the outcomes. Once someone has chronic cardiac or GI effects, treatment has shown to be unhelpful.

Diagnosis is done via is a serum IgG test with reflex to confirmation (goes to CDC), which is available through most laboratories. 

Both the CDC and IDSA recommend targeting screening based on risk factors, in particular being born in or lived in endemic areas, having a family member with Chagas Disease. 

Screening during pregnancy has been shown to be cost effective and may be something we should be integrating locally in our at-risk population-- more on this to come. Options for pregnancy-screening include pre-pregnancy screening (this MOST preferred because cannot treat during pregnancy) vs. routine OB screening vs. L&D serum IgG vs. newborn cord blood or PCR and even the possibility of universal newborn screening.

Diagnostic testing is warranted in patients who come from endemic areas AND present with electrocardiogram abnormalities (wide range, including 1st degree AV block, afib, PVCs, RBB, low voltage), thromboembolic phenomenon, HFrEF otherwise unexplained, and megacolon or megaesophagus.

Treatment

There are two approved treatments for Chagas Disease, both for extended duration (see image below for dosing)

1) Benznidazole x 60 days

2) Nifurtimox 90 days

Both treatments have high side effect profiles (GI, CNS, marrow suppression). They are contraindicated in pregnancy, though safe in lactation, and contraindicated in severe hepatic and renal dysfunction. These medications also may be hard to come by locally.

The IDSA offers guidelines for who should and should NOT be treated. On the list for who should be treated includes: anyone with acute Chagas, all children with acute/chronic infection, reproductive age women, and people with impending immunosuppression. On the list of people NOT to treat, includes adults with advance cardiac and/or GI manifestations (treatment doesn't reverse these), unless people have impending immunosuppression. Also, not during pregnancy and not in severe hepatic or renal dysfunction. 

Finally, Dr. Heindel recommends this book, The Kissing Bug, written by a first generation immigrant journalist and author, whose family was directly impacted by this disease and who follows the socio and geopolitical forces that influence the management of Chagas in the US immigrant population today.