Ancylostoma duodenale and Necator americanus are bloodsucking hookworms found in the human small intestine, causing infections characterized by various symptoms including anemia and skin reactions. The hookworms' life cycle includes the production of thousands of eggs daily, which develop into infective larvae in soil, leading to human infection through skin penetration. Diagnosis is primarily through stool examination, and treatments involve anthelmintic drugs along with iron supplements.

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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