Original Project Description:
Chagas disease is a deadly parasitic heart disease of dogs, humans, and other mammals. Chagas disease is a risk where ‘kissing bug’ insect vectors are located, including South America, Central America, Mexico, and the southern United States. The risk of Chagas disease in dogs also extends to regions where dogs from the south may travel or be re-located, so dogs across the US may be at risk. However, tools to prevent and manage canine Chagas cases are lacking as there is no vaccine and no widely-validated antiparasitic treatments. The investigators have spent the past 8 years characterizing how natural infections impact the health of dogs, and how disease progresses in the absence of treatment. Given this baseline information, the team will develop and refine a canine Chagas disease scoring system to categorize the severity of the disease (measured by a panel of sensitive diagnostic tests and clinical assessments). This scoring system is a critical prerequisite for deploying new treatments.
The investigators will then treat 100 dogs with a modified dosing regimen of benznidazole. In preliminary studies, this dosing protocol achieved a high success in curing dogs of the parasitic infection while also improving their clinical status. The team will specifically enroll dogs in different stages of disease (asymptomatic dogs; dogs with mild disease; dogs with severe disease) to draw conclusions on which dogs will benefit most from treatment. Given the team’s expertise in epidemiology, cardiology, and parasitology, and their foundation of work with Chagas -infected dogs, they are uniquely qualified to carry out this study to provide tools to help dogs while also advancing the One Health initiative.
Presentations:
Kissing bugs and Chagas disease: What about the dogs? Greater Houston Golden Retriever Club Meeting. Outreach talk. April 2025. Sarah Hamer and Rachel Busselman. Lexington, TX.
American Association of Veterinary Parasitology, St. Louis, MO, June 20-23, 2025. Invited by Elanco for sponsored evening keynote. Chagas disease- a neglected yet increasingly recognized veterinary threat. Sarah Hamer.
Report to Grant Sponsor from Investigator:
Canine Chagas disease is prevalent throughout the southern United States and impacts dogs in a variety of ways. While some infected dogs live without symptoms for years, others develop acute life-limiting disease or go on to develop late-stage heart problems and heart failure due to the damage the parasite inflicts on heart tissue. Based on data we have collected from hundreds of dogs over many years, we are beginning to develop a disease staging system for Chagas disease that can help us understand disease progression and identify the best testing and treatment options for dogs at each stage of the disease.
From clinical experience and initial impressions of the data, we have proposed preliminary disease ‘stages’ of Chagas disease that describe the infection status and clinical impact on the dogs, including dogs that are infected with no symptoms (stage A), dogs that experience some ECG abnormalities (stage B1), dogs that experience Echo abnormalities indicating structural changes to the heart (stage B2), and dogs experiencing congestive heart failure (stage C). We will continue to refine and validate these stages as we collect historic data from our research and integrate the results of diagnostic tests often used in the staging decisions.
Additionally, we will soon begin to enroll dogs infected with the Chagas disease parasite across the different stages of Chagas disease. These dogs will receive advanced diagnostic tests to understand their infection and a complete cardiac work-up by board-certified cardiologists to understand the scope of disease. Dogs will then be treated with benznidazole, and their disease progression and infection status will be monitored for one year. We look forward to working with the Texas A&M Small Animal Hospital to enroll client-owned dogs and learn more about how treatment affects clinical disease.