Natural infection of Trypanosoma cruzi in a dog with heart lesions: a case report from Malinalco, State of Mexico, Mexico

A Barbabosa-Pliego¹, V Velázquez-Ordóñez¹, MC López-Rosas¹, MU Alonso-Fresán¹, E Burgos-Aparicio¹, L Ochoa-García², V Camacho-Sierra¹, C Guzmán-Bracho³, S Martínez-Castañeda¹, RC Fajardo-Muñoz¹, JG Estrada-Franco^4,6, NJ Garg^4,5, JC Vázquez-Chagoyán^1
1Centro de Investigación y Estudios Avanzados en Salud Animal, Facultad de Medicina Veterinaria y Zootecnia Universidad Autónoma del Estado de México, Toluca, México; ²Laboratorio Estatal de Salud Pública del Instituto Salud del Estado de México; ³Instituto de Diagnóstico y Referencia Epidemiológicos, SSA, Mexico; ⁴Departments of Pathology, ⁵Microbiology and Immunology, University of Texas Medical Branch, USA; ⁶Universidad Autónoma de Chiapas, Tapachula, Chiapas, México

Background: Chagas disease is widely distributed in tropical and subtropical regions of the Americas, including more than 50% of the Mexican territory. The southern region of the State of Mexico (the Tejupilco Sanitary Jurisdiction) was recently reported as endemic; however the pathogenicity of the circulating strains has not been studied in depth. Recent studies have reported Trypanosoma cruzi seropositive dogs in the villages of Malinalco and Zumpahuacan in the central south of the State of Mexico. Dogs are epidemiologically important, because the evolution of symptoms and pathology of Chagas disease in this vertebrate mimics the human disease, and because dogs maintain the domestic cycle of parasite transmission.
Objectives: To study the clinical and pathological findings of a dog showing serological evidence of T. cruzi infection. The study of the canine, identified in the Malinalco locality, is expected to contribute to the general characterization and behavior of the pathogen in the region.
Methods: Clinical (electrocardiogram, echocardiogram and clinical exam), pathological (necropsy and histopathology) and serologic (indirect hemagglutination test and enzyme-linked immunoassay) analyses were conducted in a 4-year-old dog naturally infected with T. cruzi.
Results: The canine was diagnosed with dilated cardiomyopathy and hepatomegaly associated with congestive cardiac insufficiency, presumably provoked by chronic myocarditis and derived from natural infection with T. cruzi.
Conclusion: T. cruzi strains circulating in the village of Malinalco, State of Mexico are pathogenic for dogs, and could be affecting other domestic animals, and even infecting humans in the region.

Keywords: Trypanosoma cruzi, Chagas disease, cardiomyopathy, dog, natural infection, Malinalco, State of México