Zoonotic hookworms are hookworms that live in animals but can be transmitted to humans. Dogs and cats can become infected with several hookworm species, including Ancylostoma brazilense, A. caninum, A. ceylanicum, and Uncinaria stenocephala. The eggs of these parasites are shed in the feces of infected animals and can end up in the environment, contaminating the ground where the animal defecated. People become infected when the zoonotic hookworm larvae penetrate unprotected skin, especially when walking barefoot or sitting on contaminated soil or sand.
Each day in the intestine, a mature female A duodenale worm produces about 10,000-30,000 eggs, and a mature female N americanus worm produces 5000-10,000 eggs (see the image below). After deposition onto soil and under appropriate conditions, each egg develops into an infective larva. These larvae are developmentally arrested and nonfeeding. If they are unable to infect a new host, they die when their metabolic reserves are exhausted, usually in about 6 weeks.
Human infection with A duodenale or N americanus is estimated to affect approximately 600 million people worldwide. These parasites drain the equivalent of all the blood from approximately 1.5 million people every day.