One of the key differences between roundworms and hookworms is that roundworms live freely in the intestines, while hookworms latch onto the intestinal walls. Both primarily affect pets and can be passed to humans.
Roundworm infections may be unnoticeable in adult pets, but can cause stunted growth and developmental problems in puppies and children. People and animals with roundworms often have a bloated or pot-bellied appearance. The immune systems of healthy adults attack roundworms, which causes the worms to encyst harmlessly in the muscles. Pregnancy can cause them to become active again, passing through the placenta to the developing fetus. Roundworms can cause serious complications in children because they can migrate to the eyes and cause blindness.
Hookworms can cause problems for all ages because they feed on blood, although adults may not show symptoms from smaller infections. They release an anti-coagulant while feeding, which causes internal bleeding even after the worm detaches. Serious infections can result in anemia due to blood loss, which can be life-threatening. People and animals with severe infections may exhibit weakness, pale gums or bloody diarrhea. Hookworms can be transmitted from a pregnant mother to developing fetuses or from exposure to infected feces. In heavily infested areas, they live in the soil and can also burrow through the skin. This may result in skin irritation and itchiness, typically on the bottom of the feet.