It is highly contagious and transmitted by direct or indirect contact with contaminated feces. (indianstreetvet.com)
The worm is spread from dog to dog through the ingestion of contaminated feces, or from a pregnant mother through the placenta to the puppy, resulting in a case of puppy worms. (dog-health-guide.org)
It is transmitted by direct dog - to - dog contact or contact with contaminated feces, environments, or people. (anticruelty.org)