Ancylostoma duodenale Human Hookworm		Contents		Rev 09/16/2022
		Classification		Biology and Ecology
		Morphology and Anatomy		Life Cycle
Return to Ancylostoma menu				Ecosystem Functions and Services
		Distribution		Management
Return to Ancylostomatidae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

 Classification

Phylum:  Nematoda
Class:    Chromadorea
Order:    Rhabditida 

Superfamily:  Strongyloidea

Family:  Ancylostomatidae

Ancylostoma duodenale Dubibi, 1843

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Morphology and Anatomy:

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Distribution

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Economic Importance:

Contact with soil contaminated with eggs or larvae of nematode parasites is a common form of transmission that results in human infection. The nematodes can live for years as adults in the human intestinal tract. Soil becomes contaminated by fecal material of infected humans and other animal hosts.

More than a billion people are infected with at least one species.  The most important nematode infections of the human gastrointestinal tract are the intestinal roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), and hookworm (Necator americanus or Ancylostoma duodenale).

It is common for a single individual, especially a child living in a less developed country, to be chronically infected with all three of the nematode parasites, which results in malnutrition, stunted growth stunting, retarded intellectual development, and cognitive and educational deficiencies.

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Hosts:

Human

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Feeding

Rhabditiform larval stages feed on bacteria associated with organic matter.

Adult stage feeds on blood and tissue from the intestinal lining of the host.

Parasites draw mucus into their buccal cavity and suck the blood and tissue. The action of digestive juices and the shearing of teeth form a bolus of tissue that is separated from the host gut and ingested.

Host blood is drawn almost continuously into the intestine and passed out through the anus.  Blood plasma and corpuscles undergo at least partial digestion in the nematode.  Hookworms consume up to 1 ml blood per individual per day.

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Life Cycle:

When it reaches the small intestine of the host, the the infective filariform larva molts a fourth and final time and develops to maturity in about five weeks.

Adult hookworms (Ancylostoma duodenale and Necator americanus) parasitize the upper part of the human small intestine, whereas Ascaris lumbricoides parasitize the entire small intestine and adult Trichuris trichiura live in the large intestine, especially the caecum. 

The parasites can live for several years in the human gastrointestinal tract. After mating, each adult female produces thousands of eggs per day which leave the body in the feces.

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Damage:

Infection by a hookworm usually results in bloody diarrhea and anemia.

Hookworm infections undermine the health of the host, causing stunting of growth and general laziness.  Often accompanied by acute mental distress.

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Management:

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References:

Bethony, J., Brooker, S., Albonico, M., Geiger, S.M., Loukas, A., Diemert, D., Hotez, P.J.  2006. Soil-transmitted helminth infections: ascariasis, trichuriasis, and hookworm. The Lancet 9521:1521-1532.

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