Ancylostoma duodenale

Human Hookworm; Old World Hookworm

Contents

Rev 06/24/2025

  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
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 Classification

Phylum:  Nematoda
Class:    Chromadorea
Order:    Rhabditida 

Superfamily:  Ancylostomatoidea

Family:  Ancylostomatidae

Ancylostoma duodenale Dubibi, 1843

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Morphology and Anatomy:

Ancylostoma duodenale

The teeth-like plates that are used to
attach the hookworm to the surface of the intestinal tract.

Adult female and male hookworms; tooth-like plates in the stoma of hookworms
Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

 

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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 fecal and other 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.

  • Eggs in soil hatch under favorable conditions
  • First juvenile stage J1 is a rhabditiform larva which grows and molts in soil to a J2. The J2 probably feed on microbes in soil and fecal material.
  • The J2 grows and molts to a J3 infective filariform stage which is able to penetrate human skin, travel through the blood vessels and heart, and reach the lungs.
  • Larvae of A. duodenale may become dormant in tiuues and then reactivate and continue migration
  • In the lungs, the filariform larva migrates through pulmonary alveoli and up through the trachea where it is swallowed and carried to the small intestine.
  • The larva attaches to the intestinal wall, matures into an adult which mates and the famles commence producing eggs.
  • Adults live in the lumen of the intestinal wall cause damage to the tissues and blood loss.
  • Eggs produced by the adults are dposited to the soil in feces. the feces; female hookworms produce up to 30,000 eggs per day (Hotez et al., 2005)
  • Although they can live for 3-5 years, most adult hookworms worms are eliminated in 1-2 years.
 
Source of life-cycle diagram: Centers for Disease Control website Note:  A. duodenale lifecycle only differs slightly from that of Necator americanus. The latter has no development arrest in immune hosts and it must continue migrating through the lungs  

For Ecophysiological Parameters for this species, click If species level data are not available, click for genus level parameters
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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.

https://www.cdc.gov/dpdx/hookworm/index.html

Hotez, P.J, Bethony, J. Bottazzi, M.E.; Brooker, S., Buss, P. 2005. Hookworm: "The Great Infection of Mankind. PLOS Medicine. 2(3) e67. doi:10.1371/journal.pmed.0020067

Roberts, L.S.; Janovy, J.; Schmidt, G.D. 2010. Foundations of Parasitology (8th ed.). McGraw-Hill. pp. 472-473. ISBN 978-0071311038

 

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