MicroB

• Hookworm


  Intestinal nematode, found in small intestines
• Hookworm


  • Caused by Ancylostoma duodenalis & Necator americanus
  • Worldwide distribution, more in tropics
  • In Africa, Necator americanus predominates
  • Common in areas with poor sanitation
  • Disease called ancylostomiasis or necatoriasis
  • 2nd most common intestinal parasite, Ascaris lumbricoides (1st)
• Hookworm forms


  • Adults
  • Larvae
  • Eggs

  
• Adult hookworms


  • 1-1.5 cm in length
  • Females > males
  • A. duodenale has 2 pairs of teeth
  • N. americanus has cutting plates

  
• Hookworm eggs


  • Have a visible segmented ovum
• Hookworm larvae


  • Rhabditiform larvae - short and stout
  • Filariform larvae - infective form, long and slender

  
• Hookworm life cycle


  1. Adults in small intestine, mate, female lays eggs, eggs passed in stool

  2. Develop to release rhabditiform larvae (7 days), then to filariform stage (7 days)

  3. Penetrate skin of man (usually feet), get into blood circulation, go to heart, lungs, out of blood, bronchi, coughed out, ascend trachea to epiglottis, swallowed

  4. Stomach > small intestine attach to mucosa, develop to adult

  5. From skin penetration to adult: 6-8 weeks

  6. A. duodenale also infect via mucous membrane in mouth
• Hookworm infection


  • Early infection - dermatitis (ground itch), dry cough, dyspnoea, abdominal pain & discomfort
  • Light infection often asymptomatic
  • Heavy infection - anaemia: pallor, leg swelling, dyspnoea, palpitation, PBF- hypochromic microcytic; anaemia = sucking of blood (A.duodenale > N.americanus), bleeding sites, anticoagulants from worms
  • Black stool (melena). digested blood from upper GIT bleed
• Hookworm diagnosis


  1. Stool microscopy - characteristic eggs

  2. Stool (non-fresh) - rhabditiform larvae

  3. Kato-Katz technique - Parasite quantification

  
• Hookworm treatments


  • Albendazole
  • Mebendazole
  • Levamisole
  • Bephenium hydroxynaphthoate
  • Pyrantel pamoate
• Supportive hookworm treatment


  • Iron supplements
  • Transfusion of blood if anaemia is severe
• Hookworm prevention and control

  • Proper faecal disposal - pit latrines etc
  • Don't use untreated human waste as manure
  • Wearing of protective shoes
  • Health education on how infection is transmitted and how it can be prevented
  • Treatment of infected persons
  • Treatment of soil
• Cutaneous larval migrans


  Zoonotic infection with hookworm species that do not use humans as a definitive host
• Cutaneous larval migrans


  • Most commonly A. braziliense & A. caninum
  • Normal definitive hosts for these species are dogs & cats, respectively
• Cutaneous larval migrans treatment and prevention

  1. Systemic - Albendazole, Ivermectin

  2. Topical - Thiabendazole

  3. Avoiding exposure of skin to contaminated soil or sand - wearing shoes in areas where these parasites are known to be endemic offers protection from infection

  4. Ban dogs from loitering e.g beaches in an attempt to control human infection