Fig. 1

Dirofilaria immitis prevalence in canines by state and geographical region. a Among 39 states with specimens available for this study, D. immitis DNA was identified in canine blood samples from 17 states; b D. immitis prevalence in dogs from the South region was 7.5% (68/803), being significantly higher than in the West (1.7%, 1/58), Midwest (3.3%, 4/120), and Northeast (3.1%, 3/98) (P < 0.5; Chi-square test). Different letters (a, b) denote significant difference. Only one canine sample was submitted from the Pacific region, which was not included in the comparison. The definition of different regions can be found at www. chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://www2.census.gov/geo/pdfs/maps-data/maps/reference/us_regdiv.pdf