RESUMEN
The dog's role as a definitive host for a number of zoonotic parasites has been widely studied and recognized as being a significant public health problem worldwide. This study aimed to report, for the first time, our investigation into the role of dogs as a biological transmitter for Ascaris lumbricoides, via necropsy of a sample of rural stray dogs in a developing community in Giza governorate, Egypt, where promiscuous defecation by human was common, and examination for A. lumbricoides worms as well as other ascaridiod nematodes of dogs. The recovered worms were identified in the laboratory after observing cephalic alae and egg morphology under a microscope, as well as scanning electron microscopy of their anterior ends. Of the 25 dogs examined, 14 were infected with Toxocara canis (56.0%), two with Toxascaris leonina (8.0%), and two with A. lumbricoides (8.0%). One dog was co-infected with T. canis and T. leonina. A. lumbricoides eggs were shown to be viable and 75-80% of eggs embryonated following 3 weeks of incubation at 28 degrees C. The present study suggested that dogs could act as reservoir hosts of A. lumbricoides and environmental contaminators that increase risk of infection in humans.