Hookworms

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Hookworms
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Hookworms

• The hookworms cause hookworm disease,
  which is one of the five major parasitic disease
  in China(malaria, shistosomiasis, filariasis,
  kala- azar and hookworm disease). At least two
  species of hookworms infect man, Necator
  americanus and Ancylostoma duodenale. They live
  in small intestine.

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Ancylostoma duodenale
Egg
Rhabditiform larva
Adult
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Hookworms

• Ancylostoma is found in Europe around the
  Mediterranean, on the West coast of South America
  and in parts of China and India
• Necator is found over much of the western
  hemisphere, Africa and South East Asia
• More than a billion people infected

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Hookworms

• Acylostoma was found coal and other mines
  throughout Europe
• At the turn of the last century, severe hookworm
  disease was an officially recognized occupational
  hazard in German coal mines and an eligible
  disease for workmans compensation

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Hookworms

• Hookworms were wide spread in the Southern USA .
• Hookworm control programs were a big part of the
  public health campaign in the South during and
  right after World War II
• 1972 12 of school children from rural costal
  Georgia tested positive for hookworm infection

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   Morphology

• 1. Adults They look like an odd piece thread and
  are about 1cm. They are white or light pinkish
  when living. ?is slightly larger than?.The males
  posterior end is expanded to form a copulatory
  bursa.

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• 2. Eggs 6040 µm in size, oval in shape, shell
  is thin and colorless. Content is 2-8cells.

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Differences between two hookworms
Adults of A. duodenale
Adults of N. americanus
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Acylostoma duodenale Necator americanus --
human hookworms

• Small nematodes (1-1.5 cm)
• Head is slightly bend (hook) and the mouth
  carries characteristic teeth (Ancylostoma) or
  plates (Necator, note that these are not real
  teeth but cuticular formations of the buccal
  capsule)
• The posterior end of the male worm is elaborated
  into a copulatory bursa

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• Scanning electron micrograph of the mouth capsule
  of Ancylostoma duodenale, note the presence of
  four "teeth," two on each side.

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• Scanning electron micrograph of the mouth capsule
  of Necator americanus, another species of human
  hookworm.  Note the presence of two cutting
  "teeth.

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• Ancylostoma duodenale - copulatory bursa and
  spines of male(a side view)

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• Copulatory bursa of N. americanus(a side view)

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• Left picture Copulatory bursa and spines of N.
  americanus(a side view)
• Right picture copulatory bursa of A. duodenale(a
  top view)

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• Morphologically it is not possible to
  differentiate between A. duodenale and N.
  americanus. Interference contrast. 400.
  Enlarged by 5.4.

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The Morphological Differences between Two species
of Hookworms

• _____
• A. duodenale
  N. americanus
• Size larger
  smaller
• ________________________________________________
• Shape single curve, looks like C
  double curves, looks like S
• _____________________________________________
• Mouth 2 pairs of ventral teeth
  1peir of ventral cutting plates
• _______________________________________________
• Copulatory circle in shape
  oval in shape
• Bursa (a top view)
  (a top view)
• ________________________________________________
• Copulatory 1pair with separate
  1pair of which unite to form
• spicule endings
  a terminal hooklet
• ________________________________________________
• caudal spine present
  no
• ________________________________________________
• vulva position post-equatorial
  pre-equatorial

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Life Cycle

• 1.  Final host man
• 2.  Inf. Stage Larva 3 or filariform larva
• 3.  Inf. Route by skin
• 4.  Food blood and tissue fluid
• 5.  Site of inhabitation small intestine
• 6.  Life span Ad 15years, Na 3-7years
• 7. Blood-lung migration
• skin, cavum, right heart, lungs

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Life cycle of hookworm
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• Adult worms live in the small intestine and
  female lay 5-10000 eggs a day over 5 years
• Eggs are passed with the feces
• Larvae develop outside the body and molt twice
• The filariform or L3 larvae move to the surface
  in search for a host
• If they come into contact with the host they
  penetrate the skin, enter blood vessels and leave
  the circulatory system into the alveoli
• The larvae move up the trachea into the
  esophagus, are swallowed and finally reach the
  intestine, where they molt twice more before they
  reach maturity

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Pathogenesis and Clinical Manifestations

• 1. Larval migration
• (1) Dermatitis, known as "ground itch" or
  "stool poison".The larvae penetrating the skin
  cause allergic reaction, petechiae 0r papule
  with itching and burning sensation. Scratching
  leads to secondary infection.

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• (2) pneumonitis (allergic reaction), Loeffier's
  syndrome cough, asthma, low fever, blood-tinged
  sputum or hemoptysis, chest-pain, inflammation
  shadows in lungs under X-ray. These
  manifestations go on about 2 weeks.

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• 2. Adults in small intestine
• (1) Epigastric pain as that of a duodenal
  ulcer.
• (2) A large worm burden results in
  microcytic hypochromatic anemia (character
  manifestation). The symptoms are lassitude,
  edema, palpitation of the heart. In severe case,
  death may result from cardiac failure or physical
  exhaustion.

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• (3) Allotriophagy (orpica) is due to the
  lack of trace element iron .
• (4) Amenorrhea, sterility, abortion may take
  place in women.
• (5) Gastrointestinal bleeding
• (6) Infantile hookworm disease

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Adults in intestinal mucosa
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Diagnosis

• Criterion
• 1. hemoglobin is lower than 120g/L in man, 110g/L
  in woman.
• 2. find hookworm egg
• Method
• 1. saturated brine flotation technique
• 2. direct fecal smear
• 3. culture of larvae

         
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Treatment

• Albendazole
• Mebedazole

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Prevention

• Unified measures
• 1. sanitary disposal of night soil
• 2. individual protection
• 3. health education
• 4. cultivate hygienic habits
• 5. treat the patients and carriers.

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