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Caitlin Brennan

Caitlin Brennan

The University of Georgia
College of Veterinary Medicine
Class of 2020

Research Interests

The Diroscope: calibration of a smartphone microscope for quantitative diagnosis of canine heartworm infection

Caitlin R. Brennan, Michael V. D’Ambrosio, Daniel A. Fletcher, Ray M. Kaplan, Guilherme G. Verocai

Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia (Brennan, Kaplan, Verocai); Department of Bioengineering, University of California, Berkeley, Berkeley, California (D’Ambrosio, Fletcher)

Canine heartworm disease is caused by the mosquito-borne nematode Dirofilaria immitis, the most important canine parasite in the United States. The American Heartworm Society recommends annual testing for microfilariae (mf) in tandem with antigen testing. Mf may be detected qualitatively via direct microscopy, or quantitatively via thick smears or Knott’s test; however, these quantitative tests are time-consuming and subject to technical variability. A software-controlled smartphone microscope was recently developed to quantify Loa loa, a human filarial parasite, in fresh blood. This device counts mf in less than two minutes by analyzing short videos of blood within a glass capillary. We hypothesize that this device, after software modification, will rapidly count D. immitis mf and prove more accurate than traditional measurement methods. Our project aims to (1) complete the software recalibration and (2) test the accuracy of the Diroscope for quantitative diagnosis of heartworm infection. The algorithm was calibrated for D. immitis by an iterative process where we manually tagged mf in videos of dog blood with low and high mf concentrations (n=10/concentration) and scanned mf-free blood, then adjusted the software to optimize mf motility recognition. Next, we will spike blood with known numbers of mf (0, 50, 100, 250, 500, 1000, 10000 mf/mL) to measure the Diroscope’s accuracy using the formula: (mf observed / mf expected). Across all mf counting methods, accuracy and mf means will be compared using ANOVA and Tukey’s test, respectively. We expect that the Diroscope will provide a quantitative, point-of-care diagnostic test for clinicians, and also facilitate mf reduction tests in suspect anthelmintic resistant cases.

Research Grant: University of Georgia College of Veterinary Medicine

Student Support: Boehringer Ingelheim, Veterinary Medical Experiment Station, UGA College of Vet Medicine

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