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Trevor A. Crowell, M.D.
Hookworm is a topic covered in the Johns Hopkins ABX Guide.

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  • Members of the family Ancylostomatoidea (nematodes):
    • 18 total genera
    • Two species account for most human infections:
      • Ancylostoma duodenale (AD)
      • Necatur americanus (NA)
    • Estimated prevalence of 16.5% among school-aged children globally
  • Adult hookworms are 5-11mm (males) or 9-13mm (females). Identification based on size, number and arrangement of teeth, length of esophagus, size of eggs, morphology of bursa (males), or position of ova (females). Eggs are morphologically indistinguishable.
    • AD [Fig 1]: head in same direction as body, 2 pairs of ventral teeth, larger than NA, caudal spine present.
    • NA [Fig 2]: head curved opposite body, dorsal and ventral semi-lunar cutting plates, caudal spine in female absent. Found in New World, including U.S.
  • Life cycle: [Fig 3]
    • Eggs [Fig 4] are passed in the stool and hatch into rhabditiform larvae after 1-2 days.
    • Rhabditiform larvae grow in the soil, molt and become infective filariform larvae after 5-10 days.
    • Filariform larvae penetrate human skin, mostly feet, (AD can also enter via ingestion of contaminated food) and travel through venous circulation to lungs, through alveoli, to pharynx and are swallowed into the GI tract where they mature and attach to the walls of the small intestine.

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Last updated: November 29, 2015


Crowell, Trevor A. "Hookworm." Johns Hopkins ABX Guide, The Johns Hopkins University, 2015. Johns Hopkins Guide, www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540275/all/Hookworm.
Crowell TA. Hookworm. Johns Hopkins ABX Guide. The Johns Hopkins University; 2015. https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540275/all/Hookworm. Accessed July 17, 2019.
Crowell, T. A. (2015). Hookworm. In Johns Hopkins ABX Guide. Available from https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540275/all/Hookworm
Crowell TA. Hookworm [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2015. [cited 2019 July 17]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540275/all/Hookworm.
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TY - ELEC T1 - Hookworm ID - 540275 A1 - Crowell,Trevor,M.D. Y1 - 2015/11/29/ BT - Johns Hopkins ABX Guide UR - https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540275/all/Hookworm PB - The Johns Hopkins University DB - Johns Hopkins Guide DP - Unbound Medicine ER -