Hookworm

An intestinal helminthic disease caused by nematode parasites that attach to the small intestinal mucosa and feed on host blood

Aetiology

Causative Organisms

Species
Key Characteristics
Ancylostoma duodenale
Larger worm, greater blood loss
Necator americanus
Most common worldwide
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Morphology

Feature
Description
Adult worm
Small cylindrical nematode
Length
8–13 mm
Anterior end
Hook-shaped
Mouth
Cutting plates or teeth
Eggs
Oval, thin-shelled
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Pathophysiology

The infection occurs via the fecal–oral route.

Life Cycle Stages

  1. Eggs are passed in human feces
  1. Eggs hatch in soil
  1. Larvae develop into filariform larvae (infective stage)
  1. Larvae penetrate human skin
  1. Enter bloodstream
  1. Travel to lungs
  1. Ascend bronchial tree
  1. Swallowed into gastrointestinal tract
  1. Mature into adult worms in the small intestine
Adult worms attach to the intestinal mucosa and consume blood.
Species
Blood loss per worm/day
Ancylostoma duodenale
~0.2 mL
Necator americanus
~0.03 mL
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Clinical Presentation

Cutaneous Phase

Skin penetration causes:
Manifestation
Description
Ground itch
Pruritic erythematous rash
Papular lesions
At entry site
Localized inflammation
Feet or legs
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Intestinal Phase

Adult worms cause:
Symptom
Mechanism
Abdominal pain
Intestinal irritation
Diarrhea
Mucosal inflammation
Fatigue
Anemia
Pallor
Chronic blood loss
Growth retardation
Nutritional deficiency

Pulmonary Phase

During larval lung migration:
  • Dry cough
  • Wheezing
  • Mild fever
  • Eosinophilia
Similar to Löffler syndrome.

Severe Disease

In heavy infections:
  • Severe iron deficiency anemia
  • Hypoproteinemia
  • Cardiac failure (rare)
  • Developmental delay in children

Investigations

Stool Examination (Diagnostic Test)

Test
Finding
Stool microscopy
Hookworm eggs
Concentration techniques
Increased detection
 
Egg characteristics:
Feature
Description
Shape
Oval
Shell
Thin
Contents
Segmented embryo

Blood Tests

Test
Finding
Hemoglobin
Low
MCV
Microcytic anemia
Ferritin
Low
Eosinophil count
Elevated

Management

First-Line Anthelmintic Drugs

Drug
Dose
Albendazole
400 mg SD
Mebendazole
100 mg 2x1 for 3 days
Pyrantel pamoate
10 mg/kg SD
Preferred treatment:
Albendazole 400 mg single dose