The Perfect Storm: Factors that lead to increased transmission and resistance emergence of heartworm in the United States

2013 student Paige Miller worked with Dr. Andrew Park to investigate dynamics of canine heartworm in the United States.

  Abstract  Heartworm disease has been observed all over the world but is distributed heterogeneously and hotspots are thought to be promoted by factors such as climate, pet and owner demographics, and percent of canid population given medication. Recent concerning evidence has suggested the establishment of drug resistant worm in some areas of the United States. Because only one class of drugs exists to treat heartworm, resistance presents a large problem. Two of the first models for heartworm disease dynamics and drug resistance emergence, one deterministic and one stochastic, were developed in order to identify factors that could lead to higher rates of transmission or faster rates of resistant allele increases. Factors analyzed included vector abundance, treatment coverage, and fitness benefit of mutation. It was found that areas with high mosquito abundance and low treatment coverage are more likely to suffer from higher worm burdens in general. Speed of resistance emergence and probability of resistant worm invasion depend on the fitness cost of mutation in heartworms and founding size of resistant worm population. Collectively, these models help to identify key factors and regions that are associated with successful and rapid establishment of drug resistant heartworm populations.

Download (PDF, 3.87MB)