GARDEN GROVE, Calif.—Active cases of dog heartworm, a parasite only transmitted from animal to animal through mosquito bites, have been detected in at least three cities in Orange County, the county’s vector control district confirmed in a Jan. 19 statement. “Heartworms are a preventable but serious and potentially fatal parasite,” Monica Schmidt, OC Animal Care assistant director, said in the statement. The Orange County Mosquito and Vector Control District confirmed that, of the 260 mosquito samples tested last year, four tested positive in two different mosquito species—the Aedes and Culiseta—in Fullerton, Huntington Beach, and Seal Beach. “It is a really low risk right now, but we want to be transparent, especially if we are conducting tests,” Heather Hyland, spokeswoman for the vector control district, told The Epoch Times. Hyland said the district developed the ability to test for the parasite after the Aedes species populated every city in Orange County …