Ancylostoma duodenale

Ancylostoma duodenale is one of a few nematodes that cause the infection called hookworm. Ancylostoma duodenale is described as the Old World hookworm.

Disease / Pathology

Ancylostoma duodenale initially produce an intense itch or papule at the site of skin penetration. Though bronchial pneumonitis can occur in the lung stage of the parasite, this is uncommon and only seen in very heavy infections. The penetration of the worm into the intestinal wall will cause host blood loss by two causes. The first is by the ingestion of blood by the worm(s) and the other is by blood loss due to hemorrhaging at the site of attachment. This will manifest itself as a microcytic / hypochromic anemia in the host when infections are heavy and will lead to a chronic infection that produces symptoms such as pallor, listlessness, facial and pedal edema. In children infections can result in mental and physical development to be impaired.

Intestinal symptoms include flatulence and diarrhea. This may lead to weight loss, dizziness, loss in strength. The loss of blood chronically may also lead to iron deficiency. Nutritional supplementation may be needed to counteract the effects of the infection as the patients may also suffer from hypoproteinemia. In heavy infections not even nutritional supplementation can negate the losses.

In areas where infections are high there is a significant loss in human productivity due to hookworm infections.

Location in the Host

Ancylostoma duodenale is located in the small intestine of the host.

Geographic Distribution

Ancylostoma duodenale has a worldwide distribution. It is especially prevalent in areas where herbivorous animals are raised.

Life Cyce

Morphology and Diagnosis

Ancylostoma duodenale eggs are found in the feces and are diagnostic. The eggs are indistinguishable from those of Necator americanus.


Ancylostoma duodenale egg in fecal concentrate stained with Lugol’s iodine. Note the thin shell and clear interior around the developing ova – photo by W. Vientos