Autochthonous Chagas Disease — Missouri, 2018

George Turabelidze, MD, PhD; Archana Vasudevan, MD; Christian Rojas-Moreno, MD; Susan P. Montgomery, DVM; Molly Baker, MPH; Drew Pratt, MS; Susanne Enyeart


Morbidity and Mortality Weekly Report. 2020;69(7):193-195. 

In This Article


The protozoan parasite T. cruzi can be transmitted by infected insect vectors, from mother to baby (congenital) and, much less commonly, through organ transplantation or blood transfusion from an infected donor. Transmission through the oral route has also been described.[1] Mammals, especially rodents and marsupials, are reservoirs of T. cruzi in a sylvatic cycle, but humans, dogs, and cats can also serve as reservoirs in areas where the parasite is endemic. Acute T. cruzi infection is rarely identified because it usually causes a mild nonspecific illness or is asymptomatic. Without treatment, infection persists for the lifetime of the infected person and can result in gastrointestinal disease or serious cardiac manifestations, including heart failure, stroke, or life-threatening ventricular arrhythmias in approximately 30% of those who are chronically infected.[2]

An enzootic T. cruzi transmission involving at least 11 triatomine species and 24 species of wild animals has been well documented in the southern United States going back approximately 150 years.[3] Historical records of triatomine findings show species distributed across at least 29 states in the United States.[4] There are an estimated 300,000 persons with Chagas disease in the United States, but only 28 autochthonous infections had been documented from 1955 to 2015.[5] Triatomine species in the United States are primarily sylvatic and typically not found colonizing human dwellings. Prevalence of T. cruzi infection in triatomines can vary and transmission is not efficient; the parasite is passed in the triatomine's feces and infection occurs when feces contaminate a break in the skin or conjunctiva. In Missouri, Triatoma sanguisuga vectors have been identified during 2012–2016 and as recently as July 2019 (MDHSS surveillance, unpublished data, 2019).[6] In 2018, a single finding of T. lecticularia in Missouri was confirmed by molecular typing at CDC.

Blood donor screening for T. cruzi antibodies in the U.S. blood supply was first implemented in 2007.[3] Positive results from blood donor screening for T. cruzi antibodies should be followed by diagnostic testing. Diagnosis of chronic Chagas disease is based on positive results from at least two serologic tests that use different techniques and different antigen preparations because no single test is sufficiently sensitive and specific for diagnosis.* Commonly used techniques include ELISA using recombinant antigens, TESA, and IFA. This patient's results were positive with EIA and negative with TESA. CDC's testing algorithm employs a third test when results of the first two tests are discordant. In the Missouri patient, the IFA result was positive for T. cruzi antibody. Based on the patient's testing results, history and presentation, this patient likely represents the first documented autochthonous case of Chagas disease in Missouri.

Most persons with Chagas disease acquired their infection in the parts of Latin America where Chagas disease is endemic.[5] Currently, more than a century after its discovery in Latin America, Chagas disease has a global distribution including the United States because of migration from areas with endemic disease. Few cases of locally acquired vectorborne infection have been reported in the United States. The likely autochthonous case described in this report underscores importance of health care provider awareness of possible Chagas disease even in the states considered low risk for this infection and need for the careful consideration of the patient's history to identify possible risks for T. cruzi infection.