Diagnostic Findings [Last Modified: ]
Hookworm
[Ancylostoma duodenale]
[Necator americanus]
Causal Agent Life Cycle Geographic Distribution Clinical Features Laboratory Diagnosis Treatment

Microscopy

Hookworm egg Hookworm egg
A B

A, B: Hookworm eggs examined on wet mount (eggs of Ancylostoma duodenale and Necator americanus cannot be distinguished morphologically).  Diagnostic characteristics:

  • Size 57 to 76 µm by 35 to 47 µm
  • Oval or ellipsoidal shape
  • Thin shell

The embryo in B has begun cellular division and is at an early (gastrula) developmental stage.

Hookworm egg, advanced cleavage Embryonated hookworm egg
C D

C: Hookworm egg, advanced cleavage (iodine).
D: Embryonated hookworm egg.

Hookworm rhabditiform larva Hookworm rhabditiform larva
E F

E, F: Hookworm rhabditiform larva (wet preparation).

Hookworm filariform larva Hookworm filariform larva
G H

G, H: Hookworm filariform larva (wet preparation).

Hookworm filariform larva Hookworm filariform larva tail Hookworm filariform larva tail
I J K

I, J, K: Hookworm filariform larva (I and J, wet preparations; K, iodine).  Larva tail is depicted in Figures J and K.

A. duodenale adult, anterior end N. americanus adule, anterior end
L M

L: Adult worm of Ancylostoma duodenale.  Anterior end is depicted showing cutting teeth.
M: Adult worm of Necator americanus.  Anterior end showing mouth parts with cutting plates.
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