2. HOOKWORMS
• Hookworms are voracious feeders of human world.
• Two principal species that infect around 900 people are:
Necator americanus (new world hookworm)
Ancylostoma duodenale (old world hookworm)
5. MORPHOLOGY
• A. duodenale is small, cylindrical worm, greyish-white in color.
• It has two ventral plates on the anterior margin of the buccal capsule.
Each of them has two large teeth that are fused at their bases.
• A pair of small teeth can be found in the depths of the buccal
capsule.
• Males are 8–11 mm long with a copulatory bursa at the posterior end.
• Females are 10–13 mm long, with the vulva located at the posterior
end; females can lay 10,000 to 30,000 eggs per day.
6. • MALE ADULT ANCYLOSTOMA • FEMALE ADULT ANCYLOSTOMA
8. LIFESPAN
• The average lifespan of A. duodenale is one year.
• Egg to rhabditiform larva : 1 to 2 days
• Rhabditiform to flariform larva : 5 to 10 days
• Flariform larva to adult : 5 to 6 weeks after penetration.
9. EGG STAGE
• The adult hookworms release their
eggs in the faeces which come in
contact with the soil. The eggs are then
molt into larva within 1-2 days.
10. STAGE 1 LARVA
• It hatches out from the egg in 1 to 2 days.
• It actively feeds on organic debris and bacteria in the soil or the feces
for about 3 days and then molt to second stage larva.
• Have rhabditiform esophagus.
14. STAGE 3 LARVA
• Develops on the fifth day
• It is flariform larva; enclosed in sheath ; does not feed and actively motile.
• The third stage larva initiates the infection by penetrating the skin and
passing into blood circulation.
• The blood is carried to the right heart and then to pulmonary blood vessels.
• It soon breaks out of the pulmonary blood vessels into the alveoli.
16. STAGE 3 LARVA (contd.)
• These infective larva can survive 3-4 weeks in favorable environmental
conditions. They move to the surface of the soil and wave back and
forth which increases the chance to contact with the human host. After
entering into the trachea through the lung passage, they are
swallowed. The larva reach the small intestine, where they mature into
adults.
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18.
19. THE ADULT STAGE
• The teeth of the adult worm allow it to grip the villus of intestinal
mucosa. The worm secretes an anticoagulant that facilitates ingestion
of blood and juices from the host.
22. Life cycle
• After a filariform "infective" larva penetrates the intact skin – most
commonly through the feet – the larva enters the blood circulation. It is then
carried to the lungs, breaks into alveoli, ascends the bronchi and trachea,
and is coughed up and swallowed back into the small intestine, where it
matures. The larva later matures into an adult in the small intestine (jejunum
mainly), where they attach to the villi and female worms can lay 25,000 eggs
per day. The eggs are released into the feces and reside on soil; when
deposited on warm, moist soil, a larva rapidly develops in the egg and
hatches after 1 to 2 days. This rhabditiform larva moults twice in the soil and
becomes a skin-penetrating third-stage infective larva within 5–10 days.
23. Life cycle (Contd.)
• The infective rhabditiform larvae are able to sense vibrations in the
soil, heat, or carbon dioxide, and are able to use dendritic processes
similar to cilia. They use these processes as thermosensory,
chemosensory, and mechanosensory receptors to migrate towards a
host for infection. The rhabditiform larvae can then penetrate the
exposed skin of another organism and begin a new cycle of infection.
26. HABITAT
A. Duodenale is the indigenous hookworm of the north temperate zone
of the eastern hemisphere. It is confined in southern Europe , northern
Africa , India, China and southern Asia.
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28. DEFENSE FROM THE HOST
DEFENSE SYSTEM
• Ancylostoma secrete a neutrophil inhibition factor that interferes with
the activation of neutrophils.
29. PATHOGENESIS
• Hookworm larvae dermatitis:
-Penetration of the skin by the filariform larvae may be
asymptomatic in previously uninfected individuals
-Those experiencing repeated infections developed itching
known as ground itch or dew itch.
31. PATHOGENESIS (CONTD.)
• Migration of pre adult cause temporary pulmonary inflammation:
• In heavily infected individuals, there can be symptoms of pneumonia
during migratory phase in the developmental cycle of these worms.
• Abdominal pains, diarrhea, loss of appetite.
• Anaemia: it is especially in children and is hypoproteinemic because
of some loss of serum proteins.
34. SYMPTOMS
• Itching of skin as a result of penetration of the larvae.
• Congestion in lungs in heavy infections.
• Anaemia due to loss of blood, particularly due to deficiency of diet.
• Diarrohea.
• Persons with chronic hookworm disease are debilitated.
• Chronic heavy hookworm infection can damage the growth and development
of children.
• Hookworm infection has been known to be fatal, particularly in infants.
35. SYMPTOMS AND CLINICAL ASPECTS
• An ancylostoma worm results in the loss of 0.15ml of blood per day.
• Bleeding at the site of attachment.
• Hookworm infection does not mean that disease is present as blood loss
produced by light infections can be compensated by adequate food intake.
• Disease occurs when the food intake is unable to compensate the blood loss.
• Infected children are often oedematous indicating that these is a protein
losing enteropathy as well.
36. HOOKWORM DISEASE
• Hookworm disease depends on three factors :
1. Number of worms present
2. Species of hookworm.
3. Nutritional conditions of the infected person.
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38. HOOKWORM DISEASE (CONTD.)
• Ancylostoma suck more blood than N. americanus .
• Fewer worms cause greater disease.
• 100 worms cause greater symptoms.
39. Hookworm infection transmission
• The infection is contracted from contact with soil contaminated by
hookworm, by walking barefoot or accidently swallowing
contaminated soil.
• It can’t be spread from person to person.
40. DIAGNOSIS
• Diagnosis can be done by looking for hookworm eggs in the stool.
• Blood tests for anaemia and nutritional deficiencies, particularly iron
can help to confirm the diagnosis.
41. CONCLUSION
• Ancylostoma duodenale is a hookworm having human as definitive
host. It completes its life cycle in faceo-oral pathway. Male and female
worms show some structural differentiation as female is longer in size
as compared to male ones. Male worms have copulatory bursa while
females are devoid of it. These are less hazardous in little numbers but
as compared to other hookworms their less number seems to be
effective. They leads to hookworm disease, anemia, hookworm
dermatitis, etc. Diagnosis and treatments against these are available.