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Electrocardiographic abnormalities… 2024 JAVMA article

Title: Electrocardiographic abnormalities are associated with seropositive Trypanosoma cruzi infection status using a simplified cardiac diagnostic evaluation in dogs

Authors: Kendra A. Zelachowski, Stephanie Collins, Marty Henderson, Lisa D. Auckland, Sukjung Lim, Nicholas D. Jeffery, Sarah A. Hamer, and Ashley B. Saunders

Journal/Date of Publication: Journal of the American Veterinary Medical Association, 2024

DOI: 10.2460/javma.24.05.0328

Objective: To describe associations between cardiac abnormalities and Trypanosoma cruzi serostatus by use of a simplified diagnostic evaluation in dogs at risk for T. cruzi infection.

Type of Study: Prospective, cross-sectional study

Conclusions:

  1. Seropositive dogs were more likely to show electrocardiographic conduction system abnormalities (examples: prolonged intervals, AV block, ventricular arrhythmias) than seronegative or discordant dogs.
  2. Echocardiographic findings did not clearly distinguish T. cruzi infection status in this group of dogs. Many dogs had age related myxomatous mitral valve disease.
  3. ECG abnormalities (examples: splintered QRS complexes, prolonged PR intervals) were key indicators of potential T. cruzi infection.
  4. Elevated cardiac troponin I was observed in some infected dogs, indicating myocardial damage.

Clinical Application:

  1. Electrocardiography can be used to screen for early signs of T. cruzi-related cardiac disease in high-risk dogs.
  2. Monitoring for conduction system abnormalities (prolonged intervals, AV blocks, splintered QRS complexes) can aid in identifying infected dogs.
  3. Cardiac troponin I concentrations may serve as a useful marker for myocardial damage, especially in acute or active infections.
  4. Echocardiography is useful but may not always distinguish T. cruzi-related abnormalities, especially when myxomatous mitral valve disease is present.
  5. Regular monitoring of seropositive or discordant dogs with ECG and cardiac assessments is recommended to detect and manage progression of Chagas disease.
two-panel ECG figure with notations as described in caption
Figure 2.
Lead II ECG recordings obtained in 2 dogs that were seropositive for T cruzi with splintered (asterisk) QRS complexes (panel A) and prolonged P and PR durations (panel B). Paper speed = 50 mm/s; 0.5 cm = 1 mV.

Positive clinical outcome… 2024 JVIM article

Title: Positive clinical outcome using a modified dosing regimen of benznidazole in dogs at high risk for infection or acutely infected with Trypanosoma cruzi

Authors: Sukjung Lim, Stephanie Collins, Sarah A. Hamer, Rick L. Tarleton, and Ashley B. Saunders

Journal/Date of Publication: Journal of Veterinary Internal Medicine, 2024

DOI: 10.1111/jvim.17028

Objective: The study focuses on the prevention and management of Trypanosoma cruzi (Chagas disease) infection in dogs, particularly the effects of a modified benznidazole regimen.

Type of Study: Prospective

Conclusions:

  1. Prophylactic benznidazole prevented T. cruzi infection and cardiac disease in two dogs monitored over a 2-year period.
  2. One dog without prophylaxis died from acute Chagas-related myocarditis, while another developed severe arrhythmias but showed improvement with higher-dose benznidazole treatment.
  3. Though the sample size was small, these findings suggest potential clinical benefits from prophylactic and early benznidazole use, reducing morbidity from cardiac damage.

Clinical application:

  1. Prophylactic BNZ: Modified dosing of benznidazole may prevent T. cruzi infection in some high-risk dogs.
  2. Early treatment benefit: Higher benznidazole doses (17.5 mg/kg, twice weekly) in acutely infected dogs reduced cardiac biomarker (cardiac troponin I) concentrations and arrhythmias, even without total parasitological cure.
  3. Cardiac troponin I as a marker: Monitoring levels can help track cardiac damage and recovery during treatment.
  4. Prevention in endemic areas: Some dogs in areas with high vector exposure may benefit from prophylactic treatment during peak transmission seasons.
  5. Potential for reduced mortality: Early intervention with benznidazole could reduce sudden death risk from Chagas disease in dogs.
  6. No major adverse effects: Modified benznidazole dosing was well-tolerated in these dogs, with no reported adverse effects.
scatter plot of results from study as described in caption
Figure 1.
Serum cardiac troponin I results for the 4 dogs. Dogs 1 and 2 were in the prophylaxis group, dog 3 was in the nonprophylaxis group with death after visit 2 and dog 4 was in the nonprophylaxis group and subsequently started on a modified treatment dose regimen of benznidazole. The upper limit of the reference range (0.128 ng/mL) is represented by the dotted line.

Abundant triatomines… 2024 Acta Tropica article

Title: Abundant triatomines in Texas dog kennel environments: Triatomine collections, infection with Trypanosoma cruzi, and blood feeding hosts

Authors: R.E. Busselman, R. Curtis-Robles, A.C. Meyers, I.B. Zecca, L.D. Auckland, C.L. Hodo, D. Christopher, A.B. Saunders, and S.A. Hamer

Journal/Date of Publication: Acta Tropica, 2024

DOI: 10.1016/j.actatropica.2023.107087

Objective: Triatomines were collected across central and south Texas to identify their primary bloodmeal hosts, T. cruzi status, and the T. cruzi discrete typing units (DTUs) present. 

Type of Study: Prospective

Conclusions:

  1. Triatomine insects are common in Texas dog kennels, with high infection rates of T. cruzi.
  2. Dogs are the primary blood meal host, indicating a significant risk of Chagas disease transmission in kennels.
  3. T. cruzi was found with multiple DTUs, mainly TcI and TcIV.
  4. Scent detection dogs were effective in identifying cryptic triatomine habitats.

Clinical application:

  1. Risk Assessment: Dog kennels, particularly those with outdoor exposure, are high-risk environments for Chagas disease.
  2. Detection and Surveillance: Using scent detection dogs can enhance triatomine detection in difficult-to-reach areas.
  3. Vector Control: Dogs in high-risk areas may benefit from insecticide treatments to reduce triatomine bites.
  4. Disease Prevention: Preventative measures should focus on reducing kennel exposure to triatomines, including structural modifications and pesticide application.
  5. Host Management: Since dogs are primary hosts, vector control strategies should prioritize interventions that limit dog-triatomine interactions.
three-panel graphical abstract with a map, photos and graphs depicting the written abstract from the article
Graphical Abstract.
Panel 1: 550 triatomines collected from 10 kennels throughout southern Texas
Panel 2: Triatomines tested for Trypanosoma cruzi using qPCR; Triatomines tested for bloodmeal hosts using series of cytB-targeting PCRs
Panel 3: 47.8% Trypanosoma cruzi infection prevalence (n=157); 53 bloodmeal hosts identified – dogs were the predominant host