The pinworms have nothing to do with dogs. They are spread commonly by school aged children who are in close contact to each other and so humans are the only hosts. You become infected with pinworms by unintentionally ingesting (or inhaling) pinworm eggs, usually deposited by an infected person onto an object. The cycle of infection begins with the ingestion of these microscopic eggs. If the infected person touches bedding, clothing, toilet seats, toys, or other household objects, the eggs transfer to these objects. Pinworm eggs can survive on these contaminated surfaces for up to three weeks.
Children transfer pinworm eggs easily because they may put infected toys or other objects directly into their mouths. The eggs can also transfer from contaminated fingers directly to food or liquids. While uncommon, it’s also possible for adults to inhale airborne eggs when shaking contaminated bedding, towels, or clothing. It is important to keep nails short and clean (we used a nail brush to get under the nails), constantly wash hands with soap and warm water, and not put anything in one's mouth. It doesn't matter if you take the medication 10 times, if the members of your household are not following proper hygiene and are exposed to others who are infected, they will become reinfected, so make sure the kids are always washing their hands at school, especially before they eat.
Use hot water to launder all bedding, towels, washcloths, and clothing in the affected house. Dry these items using high heat. Avoid shaking clothing and bedding to keep pinworm eggs from spreading into the air. Don’t allow children to bathe together, as this can cause pinworm eggs to spread in the bath water. Thoroughly clean any surfaces that may be infected, including toys, floors, countertops, and toilet seats. Carefully vacuum all carpeted areas. Keep rooms well lit during the day because the eggs are sensitive to sunlight.
We did the two rounds of treatment, but I also showed my daughter the articles that mentioned clean nails and hand washing or the possibility of swallowing eggs. Thinking of worm eggs made her grossed out enough that she made an extreme conscious effort to not put her hands in her mouth and to wash her hands before eating. Make sure to stress that enough with your daughters.