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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I.   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.
• 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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• 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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• The bursa of the male canine hookworm (A.
  caninum) can be seen wrapped around the female
  hookworm during the act of copulation

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Hookworm egg
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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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3.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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Hookworm egg
Decorticated ascaris egg
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Differences between Decorticated Ascaris and
Hookworm eggs

• _______________________________________
• Decorticated ascaris egg
  hookworm egg
• __________________________________________________
  __________________
• Shell thick
  thin
• __________________________________________________
  __________________
• Egg cell unsegmented
  4-8cells
• __________________________________________________
  __________________
• Space between new moon shaped space
  empty space surrounding
• Shell and cell between cell and ends of
  shell the segmented cells
• __________________________________________________
  __________________

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II. 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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• 8. The differences between the life cycle of
  Ascaris and Hookworm.
• __________________________________________________
  __________
• A.
  lumbricoides Hookworm
• __________________________________________________
  __________
• Infective stage embryonated egg
  filariform larvae
• __________________________________________________
  ___________________
• route of infection by mouth
  by skin
• __________________________________________________
  ___________________
• mode of infection passively
  actively
• __________________________________________________
  ___________________
• blood-lung pass through the
  liver dont pass through the liver
  
• migration in lungs of
  host, larvae the larvae dont molt
  and
• molt
  twice and stay stay in
  the lungs
• for10
  days
• __________________________________________________
  ___________________
• food of the adults intestinal content
  blood
• __________________________________________________
  ___________________
• life span 1 year
  several years
• __________________________________________________
  ___________________

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Life cycle of hookworm
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• Penetrate skin
• Filariform larvae
  cavum right heart
• vesseles, lymphatics
• lungs(alveolus, bronchiole,
  bronchus) trachea, pharynx
• molt3,4
  deposit
• duodenum
  adults eggs
• Passed
  25-30?,moisture
• outside of the body
  rhabditiform larvea1
• In feces
  O2, 24hours
• molt1
  molt2
• rhabditiform larvae2
  (L2)
• 48hrs
  6days

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III. 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.
• (2) pneumonitis (allergic reaction),
  Loeffier's syndrome cough, asthma, low fever,
  biood-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.
• (3) Allotriophagy (or pica ???) 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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Bleeding of intestinal wall
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IV. 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
• V. Treatment
• 1. Albendazole 2. Mebedazole
• VI. Epidemiology
• worldwide distribution. 22-26? is the
  optimal temperature for Ancylostoma duodenale
  development, Ancylostoma duodenale mainly
  prevalent in north of China. 31-35? is suitable
  for Necator americanus, it is mainly prevalent in
  south of China
• VII. 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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Enterobius vermicularis

• The pinworms are one of the most common
  intestinal nematodes. The adult worms inhabit the
  cecum and colon. Right after mating, the male
  dies. Therefore, the male worms are rarely seen.
  The female worms migrate out the anus depositing
  eggs on the perianal skin. Humans get this
  infection by mouth and by autoinfection.

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I.     Morphology

• 1. Adults The adults look like a pin
  and are white in color. The female worm measures
  about 8 to 13 mm in size and is fusiform in
  shape. The male adult is only 2-5mm. The tail of
  a male is curved. They die right after mating,
  thus males are rarely seen. The anterior end
  tapers and is flanked on each side by cuticular
  extensions called cephalic alae. The esophagus
  is slender, terminating in a prominent posterior
  bulb , which is called esophageal bulb. The
  cephalic alae and esophageal bulb are important
  in identification of the species. .
• 2. Egg 50 to 60m by 25 µm, persimmon
  seed-like, colorless and transparent, thick and
  asymmetric shell, content is a larva.

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Adult worm of E. vermiculais
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Anterior part of E. vermicularis. Note cephalic
alae and esophageal bulb .
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• The cephalic alae are clearly seen at the
  anterior end. The cuticle and the alae are
  transversely striated. The oesophageal bulb are
  also visible.

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• Egg 50 to 60m by 25 µm, persimmon seed-like,
  colorless and transparent, thick and asymmetric
  shell, content is a larva.

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Eggs of Human Pinworm
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• Anal smear showing large numbers of Enterobius
  eggs under the lower power. In the background are
  also two Ascaris eggs.

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II. Life cycle

• 1. site of inhabitation cecum and colon
  
•   2. infective stage embryonated egg
•   3.  infective route by mouth
• .  4. without intermediate host and reservoir
  host
• 5. life span of female adults 1-2 months
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• migrate out anus
  6hours
• Adults eggs on perianal
  skin embryonated eggs
• lay
• swallowed by host larvae
  hatch out molt
• intestinal lumen
  adults in cecum
• 
  2-4 wks migrate down

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III. Symptomatology

• About one-third of pinworm-infected
  persons are asymptomatic, The adult worms may
  cause slight irritation of the intestinal mucosa.
  
• Major symptom is anal pruritus, which
  associates with the nocturnal migration of the
  gravid females from the anus and deposition of
  eggs in the perianal folds of the skin.
  Restlessness, nervousness, and irritability,
  probably resulting from poor sleep associated
  with anal pruritus,. In young girls, migration of
  the worms may produce vaginitis and salpingitis
  or granuloma of the peritoneal cavity.

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Adult Pinworms on the perianal skin
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IV. Diagnosis

• Diagnosis depends on recovery of the
  characteristic eggs. The eggs and the female
  adults can be removed from the folds of the skin
  in the perianal regions by the use of the
  cellophane tape method. The examination should be
  made in the morning, before the patient has
  washed or defecated

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V.Treatment and prevention

• Since the life span of the pinworm is
  less than two months, the major problem is
  reinfection. Albendazole is the drug of choice.
  Repeated retreatment may be necessary for a
  radical cure.
• Prevention 1. treat the patients and
  carriers 2. individual health 3. public health
  4. health education and hygienic habits
• VI. Epidemiology
• Geographical distributioncosmopolitan in
  temperate zones with about 30 to 50 of the
  population infected. It is more common in white
  than colored people and more prevalent in
  children than adults. Enterobiasis is most common
  where people live under crowded conditions such
  as orphanages, kindergartens, and large families.