Locally Transmitted Trypanosoma cruzi in a Domestic Llama (Lama glama) in a Rural Area of Greater New Orleans, Louisiana, USA

Abstract

Trypanosoma cruzi-associated megaesophagus was diagnosed in a domestic Louisiana-born llama with no significant travel history. The llama resided in the same rural area of greater New Orleans, Louisiana, where the first human autochthonous case of Chagas disease was identified in the state. Venous blood from the llama tested positive for T. cruzi kinetoplastid DNA by conventional PCR. The cardiac evaluation was unremarkable, while thoracic radiographs revealed generalized megaesophagus. The llama received supportive care, but was ultimately humanely euthanized. The esophagus was severely distended throughout its length on necropsy, and histologic evaluation showed no microscopic changes in esophageal tissue and minimal to mild lymphoplasmacytic inflammation in cardiac tissue. T. cruzi DNA was detected by conventional PCR in the esophagus, small intestine, and blood despite no protozoan organisms being observed in multiple tissue sections examined. This report contributes to the growing body of evidence of local transmission of T. cruzi in the southern United States, and Chagas disease should be considered a differential diagnosis when evaluating llamas and other large animal species for esophageal dysfunction. There is little research describing megaesophagus or Chagas disease in llamas, and this report aims to increase awareness about this zoonotic disease that is becoming more frequently reported in the southern United States.

Keywords: Chagas disease; Trypanosoma cruzi; autochthonous Chagas case; esophageal dilatation; llama; megaesophagus.

FIG. 1.

Megaesophagus. (a) Left lateral thoracic radiograph showing diffuse distention of the thoracic esophagus. The esophagus contains fluid and gas that creates a gas–liquid interface (white arrows) as well as gravity-dependent mineral debris (black arrow). (b) Gross necropsy image of the esophagus, located between the vertebral column dorsally (top of photo) and the trachea ventrally (asterisk), enlarged, and focally narrowed by the overlying azygos vein (arrow) where it courses over the esophagus.

FIG. 2.

Photomicrograph of the heart with a small area of lymphocytic to plasmacytic inflammation (asterisk) in the interstitium, H&E stain (scale bar = 100 μm).

FIG. 3.

DNA gel electrophoresis of PCR amplicons from llama blood and tissue samples from different collection years. (a) Blood samples collected in the year 2017: Lane 1: 1-kb ladder; Lane 2: blood sample No. 1 (9/11/17); Lane 3: blood sample No. 2 (9/27/2017); Lane 4: blood sample No. 3 (10/2/2017); Lane 5: Trypanosoma cruzi positive control (strain WB1); and Lane 6: negative control. (b) Blood and tissue samples collected in the year 2019: Lane 1: 1-kb ladder; Lane 2: blood sample No. 1 (9/13/2019); Lane 3: blood sample No. 2 (10/28/2019); Lane 4: esophagus tissue; Lane 5: small intestine tissue; Lane 6: T. cruzi positive control (strain WB1); and Lane 7: negative control.