"In the San Gabriel Valley, our foothill communities tend to be perfect habitats for this particular mosquito," said Kelly Middleton, Mosquito and Vector Control District.
This mosquito is about half the size of a typical mosquito. In the past 17 years, only 60 of these mosquitoes have been captured. But this season, over 300 of these mosquitoes have already been captured.
"We got a lot of rain this year so this mosquito lays its eggs in tree holes and these tree holes have filled up with rain water which is allowing more of these to hatch and survive," said Middleton.
The disease is curable if diagnosed in the early stages but once infected, a dog may not show symptoms of sickness or weakening for over a year.
Pet owners are discouraged from rushing out and purchasing heartworm medicine but rather having their pet tested. Pet owners are urged to visit the veterinarian first to see if they're positive and then seek guidance from there.
Prevention is difficult because these mosquito eggs can remain dormant for years and are found in small places. Homeowners can help prevention by filling small tree holes with sand.