Lectrure include: morphology, life cycle, symptoms, pathology, lab diagnosis, pervention & control methods

1. The Hook worms
Ancylostoma duodenale & Necator americanus
Lecture by: Maha Gamal Eldein

2. Introduction
• Ancylostoma duodenale & Necator americanus are nematode worms
• Commonly known as Hookworms.
• Habitat: found in human small intestine.
• They are bloodsucking nematode worms
• Causing the diseases known as hookworm infection, ground itch or tunnel
disease.
• It is soil transmitted infection;(infective stage is larva found in soil)
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3. Geographical distribution:
Hookworms are the second most common human worms after
Ascaris lumbricoides, mostly found in tropical and subtropical climate.
A.duodenale found in
• Occurs in the Middle East,
Southern Europe and North
Africa.
N.americanus found in
• Predominates in the America
(North, Central and South
America) and Australia
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4. Morphology
(worm& eggs)
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5. Morphology (the worm)
1-Shape: cylindrical
2-Color: pink- red -brown
• female pointed at posterior
ends.
• Male in both species has broad
posterior end (copulatory bursa)
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6. What is copulatory bursa?
• Is cuticle expansion at the
posterior end of the male worm.
• contain the male genital organs
(spicules)
• Helps in capturing female worm
during mating
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7. 3-Size of worms
A.duodenale
Female: 10-13 x 0.6 mm
Male: 8-11 x0.5 mm
N.americanus
Female: 9-11 x 0.4mm
Male: 7- 9 x 0.3 mm
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8. 4-Buccal capsule (mouth) help differentiation of both
species.
A.duodenale
Provided with teeth
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N.americanus
Provided with cutting plates

9. • The hook worms feed on blood, they are well adapted to suck blood
form the capillaries of intestinal mucosa.
• They use the teeth and cutting plates to attach and make wounds on
the intestinal mucosa.
• Their mouth is also provided by amphidial glands which secrete a
potent anticoagulant on the wound to ensure continuous blood
flowing.
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10. Eggs of A.duodenale & N.americanus
hookworms produce identical eggs
• Shape: oval
• Size: 60 x 40 µm
• Content: has brown colored 4-8
cells (plastomers).
• Surrounded by hyaline space
• Shell: thin
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11. Development of hookworms eggs
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After 8
hours

12. How man become infected?
• Man become infected when the infective larval stage (L3) which
found in soil penetrate through the skin.
• The larva enter the blood vessels in the epidermis, reach the heart
then lungs (heart lung migration)
• After 1 week the larva migrate from the lungs through the
bronchial tree, reach the throat then swallowed and enter the
intestine.
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13. • In the small intestine the larvae attach to intestinal mucosa, make
wound and feed on blood
• Then grow into adult (male and female) worm in about 5 weeks.
• The mature worms mate . After mating the female worms start laying
eggs.
• Necator americanus produce up to 10 000 eggs per day.
• Ancylostoma duodenale produce up to 30 000 eggs per day.
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14. Life cycle
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15. How cycle continue?
1- When infected people defecate in the soil
2- The eggs will develop under certain favorable Shade, Moisture,
Warm Temperature ,Sandy soil.
3- Two days rhabiditiform larva will hatch and develop into infective
filariform(L3) within 8-10 days. Ready to infect others.
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16. Pathology & Symptomatology
1-Cutaneous phase:
1.1 Ground itch:
• Is the first sign after exposure to soil
• Is an allergic reaction of the skin to
penetrating larva (L3)
• Characterized by itching, redness, skin rash.
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17. 1.2 Creeping Eruption:
• An allergic reaction to the motile larva under the skin.
• Characterized by, red tunnels, itching, may persist for weeks or
months.
• Usually caused by N.americanus.
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18. 2-Lung phase:
• Inflammation due to entrance of larva in lungs (pneumonitis).
• severity of lung phase depends on the number of larvae.
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19. • loss of appetite
• nausea
• stomach or abdominal pain
• vomiting
• weight loss
• Constipation
• diarrhea
• fatigue (tiredness)
• Black stool color
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3-Intestinal phase:
presence of worms in small intestine will cause the following

20. Complication of hookworm infection:
• Usually hookworms in human host live for a few years but can live up to
15 years
• The main complication of hookworm is iron deficiency anemia (microcytic
hypochromic), the Hemoglobin level may decrease to 5g/dl or less.
• this occur in chronic infection or heavy infection, due to continuous blood
loss from the wounds made by the worms on the intestine.
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21. Complicatios
1- In children
Decreased growth rate and
mental development in children
(caused by protein and iron
deficiency)
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22. 2- In Pregnant women
•The worms consumes the hemoglobin of
mother.
• result in babies with low birth weights or
even death.
• Death of mother after delivery
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23. Laboratory Diagnosis
1- what is /are suitable sample/s?
2- what is are suitable diagnostic test/s or technique/s?
3- what is/are the diagnostic stage/s?
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24. Summary:
• hookworms inhabit human small intestine
• mature worms release thousands 10,000-30,000 eggs daily, which deposit in
feces.
• If the eggs remain in the intestine for 2-3 days eg. like in constipation, the eggs
will continue development and larva may hatch in stool.
• The hookworms are not seen stool because they attach to the intestinal mucosa.
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25. 1- Stool is the best sample to diagnose hookworm infection
2- suitable diagnostic technique:
A- direct wet examination for feces eggs can be easily detected, because
they produced in large numbers
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26. 3- diagnostic stages:
A- eggs containing different stages
B- larva can be seen in stool,
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After 8
hours

27. Treatment
Several anthelmintics drugs of choice:
• Pyrantel pamoate
• Mebendozle
• Tetrachloroethylene
• Thiabendazole
• In addition to iron containing supplements
Prognosis
The prognosis is good
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28. Prevention & control
• Prevent direct contact with soil
• Prevent contamination of soil with human feces
• Construction of latrines & encouragement of their use.
• Disinfect the soil using aqueous iodine solution to kill the larva.
• Disinfect the night soil before use as fertilizer
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