Hookworm

• Objectives


  • Classification
  • Morphology
  • Transmission
  • Clinical Presentation
  • Diagnosis
  • Treatment
• Hookworms


  • Necator americanus
  • Ancylostoma duodenale
• Metazoa


  A major group of multicellular organisms
• Nematoda


  A phylum of roundworms
• Three forms of hookworms

  • Ova
  • Adults
  • Larva
• Adults (Male & Female)

  • Cylindrical, white, grey or reddish brown
  • Females are about 11 mm x 50 um with uterus
  • Males are smaller and have a copulatory bursa at the rear end
  • N. americanus shorter and slender than A. duodenale
• Morphology of Ancylostoma duodenale

  • Buccal capsule contains 2 pairs of large teeth
  • Copulatory bursa is at posterior end and contains 2 thin spicules that separate distally
• Morphology of Necator americanus

  • Buccal capsule contains a pair of cutting plates
  • Copulatory bursa contains spicules that are fused distally
• Eggs / Ova


  • Eggs are elliptical
  • About 60um x 35um
  • A transparent shell
  • Contains 2 or 4 segments or blastomeres (when freshly laid)
  • Eggs of N. americanus are slightly larger than that of A. duodenale
• Differences between A. duodenale and N. americanus

  • A. duodenale female can lay 25,000 – 35,000 eggs daily and live for 6 years or more
  • N. americanus female lays 6,000 – 20,000 eggs daily and lives for an average of 5 years
• Ancylostomiasis


  The most prevalent worm infection, second to ascariasis
• Transmission methods


  • Contact with soiled clothes
  • Through human milk
  • Infants put on contaminated soil
  • Transplacental infection (rare)
  • Skin penetration (filariform larvae)
  • Ingestion of larvae (in contaminated food or water)
• Life cycle of hookworms

  1. Skin penetration

  2. Larvae undergo migration

  3. Enter circulatory system

  4. Penetrate alveoli

  5. Ascend bronchi and trachea

  6. Swallowed into intestine

  7. Attach to walls of small intestines
• Pathology / Symptoms


  • Entry point (ground itch)
  • Migration in lungs (pulmonary)
  • Established intestinal infections
• Symptoms of hookworm infection

  • Ground itch
  • Bronchitis
  • Pneumonitis
  • Dry cough
  • Asthmatic wheezing
  • Necrosis of intestinal tissues
  • Blood loss - anaemia
  • Fatigues
  • Nausea
  • Digestive disturbances
  • Vomiting
  • Abdominal pain
  • Diarrhoea with black or red stools
• Diagnosis of hookworm infection

  1. Identification of eggs in fresh or preserved faeces

  2. Species cannot be distinguished by egg morphology

  3. Rhabditiform larvae may be found in stale stools in Stercoralis strongyloides
• Treatment options


  • Administer iron orally
  • Albendazole
  • Mebendazole
  • Levamisole
  • Combantrin (pyrantel pamoate)
  • Akopar (Bephenium hydroxynaphthoate)
• Prevention and control measures

  • Sanitary disposal of faeces
  • Put on footwear / Avoid soil contact
  • Avoid use of untreated faecal matter and soil
  • Avoid defaecation into the soil
  • Good health education programme
• Summary of topics


  • Classification
  • Morphology
  • Transmission
  • Clinical Presentation
  • Diagnosis
  • Treatment & Control