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What are Hookworms?

Nicole Madison
Nicole Madison
Nicole Madison
Nicole Madison

Hookworms are small, thread-like worms that burrow into the intestinal wall and consume blood. They are most commonly found in warm climates. There are numerous species of hookworms capable of infecting mammals, including humans.

Of the many types of hookworm, the Ancylostoma duodenale and Necator americanus hookworms most commonly infect humans. In fact, they currently infect about 800,000,000 people worldwide. The A. caninum and A. braziliense hookworms, which most commonly affect dogs and cats, respectively, are next in line in terms of their frequency of infecting humans.

Cats can be infected with hookworms.
Cats can be infected with hookworms.

Hookworms are an average of .39 inches (10 mm) in length. When they mate, the female lays eggs in the host. Though the number of eggs produced depends on the species, females can lay as many as 10,000 to 25,000 eggs in one day. These eggs are then passed in the feces of the host.

Juvenile hookworm eggs hatch about two days after they are passed in fecal matter. Juvenile hookworms, called larvae, reach the infective stage in just five days. The larvae are able to infect a new host by penetrating the host's skin. Once inside, they travel through the host's body to take up residence in the small intestine. They remain there as they grow to sexual maturity.

Dogs can be infected by the A. caninum hookworm.
Dogs can be infected by the A. caninum hookworm.

After entering the body of a new host, hookworms travel through the blood of their host to the lungs. They then penetrate the pulmonary capillaries and enter the alveoli. The alveoli are thin sacs in the lungs in which carbon dioxide and oxygen are exchanged. After they penetrate the alveoli, hookworms are coughed up and swallowed, traveling on to the small intestine.

After entering a new host body, hookworms travel through the blood to the lungs.
After entering a new host body, hookworms travel through the blood to the lungs.

Hookworms have mouthparts equipped with cutting plates. They attach to the small intestine using their mouthparts, penetrate blood vessels, and consume the host's blood. When they infect humans, the result can be excessive loss of blood. Infection is particularly devastating to children.

Hookworm infection may cause not only the depletion of blood, but also the permanent loss of iron and blood proteins. This creates an iron deficiency anemia and protein malnutrition that can, in severe cases, be fatal. In children, it most often leads to severe growth and developmental retardation. It can also lead to a physical weakness and listlessness that is often incorrectly identified as laziness.

Hookworms do not grow to maturity in cats and dogs.
Hookworms do not grow to maturity in cats and dogs.

Though some species of hookworm grow to maturity in humans, the cat and dog species do not. Instead, they remain in the skin, continuing to migrate for weeks and even months at a time. Cat and dog hookworms eventually die in human hosts, but their migration and eventual death causes an inflammatory disease called cutaneous or dermal larval migrans. To treat this disease, the migrating larvae must be surgically removed.

Intestinal parasites commonly cause abdominal pain, nausea, vomiting, diarrhea and cramping.
Intestinal parasites commonly cause abdominal pain, nausea, vomiting, diarrhea and cramping.

To determine if a mammal is infected with hookworms, the presence of eggs must be detected. The feces of the suspected host must be examined to look for eggs. However, the particular species of hookworm eggs cannot be determined using this type of examination.

Nicole Madison
Nicole Madison

Nicole’s thirst for knowledge inspired her to become a WiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

Learn more...
Nicole Madison
Nicole Madison

Nicole’s thirst for knowledge inspired her to become a WiseGEEK writer, and she focuses primarily on topics such as homeschooling, parenting, health, science, and business. When not writing or spending time with her four children, Nicole enjoys reading, camping, and going to the beach.

Learn more...

Discussion Comments

phoenix04

I found out I have hookworms, however the news was not surprising because I have not dewormed in over two decades. I took combiworm and metroph as directed by the pharmacist, but I need to know if this is enough of a cure for it having read about the danger it poses.

anon251006

how do dogs get hookworm and why

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    • Cats can be infected with hookworms.
      Cats can be infected with hookworms.
    • Dogs can be infected by the A. caninum hookworm.
      By: Gelpi
      Dogs can be infected by the A. caninum hookworm.
    • After entering a new host body, hookworms travel through the blood to the lungs.
      By: boscorelli
      After entering a new host body, hookworms travel through the blood to the lungs.
    • Hookworms do not grow to maturity in cats and dogs.
      By: Ilike
      Hookworms do not grow to maturity in cats and dogs.
    • Intestinal parasites commonly cause abdominal pain, nausea, vomiting, diarrhea and cramping.
      By: graphicgeoff
      Intestinal parasites commonly cause abdominal pain, nausea, vomiting, diarrhea and cramping.