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DOG-VECTOR-PARASITE INTERACTIONS IN THE CHAGAS DISEASE SYSTEM: CARDIAC CLINIC STATUS OF NATURALLY-INFECTED DOGS ACROSS THE US
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In the southern U.S., triatomine vectors maintain Trypanosoma cruzi- the protozoan parasite that causes Chagas disease in humans and animals- in sylvatic cycles. Infection with T. cruzi may be asymptomatic or lead to heart disease and death. Using dogs as a model host system, our objectives were to improve the ecological and clinical understanding of Chagas disease in the U.S. We collected 461 triatomines from Big Bend National Park from 2015- 2017 and found an overall infection prevalence of 23.1%. Blood meal analysis on 42 triatomines showed DNA evidence of humans, domestic animals, wild birds and mammalian wildlife. In 2015-17, we sampled 1,660 working dogs from 43 states using three independent serology assays to detect a seroprevalence of 7.3% (CI: 6.1-8.6%). To better characterize the cardiac outcomes in T. cruzi-infected dogs we applied a 24-hour Holter monitor to 17 T. cruzi-infected, 18 uninfected dogs and 4 dogs with discordant serology results. The presence of ECG abnormalities varied by T. cruzi infection status (p<0.001) and positive dogs had higher serum concentrations of cardiac troponin I (cTnI), a biomarker for cardiac injury, than both negative dogs (p=0.044) and discordant dogs (p=0.06). Finally, we performed a retrospective study looking at 375 dogs presented to a teaching hospital in Texas. T. cruzi-infected dogs (N=63, 16.8%) were significantly younger than negative dogs (N=312) (mean 5.9 vs. 7.4 yr old respectively; p=0.0069) with no difference in infections by sex or breed. Infected dogs were more likely to have ventricular arrhythmias (28.6%), combinations of ECG abnormalities, and cTnI greater than 0.129 ng/mL (ADVIA assay). Combining ecological and clinical approaches to enhance our understanding of Chagas disease should provide insight for vector control and measures to protect veterinary and public health.
Meyers, Alyssa Catherine (2019). DOG-VECTOR-PARASITE INTERACTIONS IN THE CHAGAS DISEASE SYSTEM: CARDIAC CLINIC STATUS OF NATURALLY-INFECTED DOGS ACROSS THE US. Doctoral dissertation, Texas A&M University. Available electronically from