1) Ascaris lumbricoides, or the roundworm, is a large nematode that lives in the small intestine of humans. 2) The female roundworm can grow up to 40 cm long and lays eggs that are passed in feces. 3) The eggs develop into infective larvae outside the body under favorable conditions and can be swallowed, entering the lungs before migrating to the intestines where they mature into adult worms.

1. Helminthic Infections
Nematoda
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2. Ascaris lumbricoides
• Common Name : Round Worm
• Morphology
– Largest nematode
– Lives in small intestine
– Use anti peristaltic movements
– Creamy white
– Do not suck blood and damage to got lumen
– Life span (Adult) – 1 Year
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3. Ascaris lumbricoides
• Male
– Small
– 15 -30 cm
– Has a curved tail with spicules
• Female
– Large
– 20-40 cm
– No curved tails
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4. Ascaris lumbricoides
• Female lays eggs, pass out in the feaces and under
favorable condition
• L2 larva develop inside the egg (10-14 days)
• Favourable conditions
– Humid climate
– Moist
– Clay soil
– Shaded area
• Eggs are destroyed by direct sunlight (45 c)
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5. Ascaris lumbricoides
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6. Ascaris lumbricoides
• Swallowed infective eggs 
• Intestine (Release L2 larva)
• Travels trough intestinal wall
• Enter to the portal circulation
• Liver,  IVC
• Lungs
• Stayed for about 2 weeks
• Undergo 2 moults (L2  L3  L4)
• Burst out through the walls of the alveolus into the
cavity of the lung
• Trachea  swallowed to oesophagus
• Then aging to intestine
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7. Ascaris lumbricoides : Transmission
• Infection can be acquired only by
swallowing infective eggs
– Directly
• From soil contaminated with human faeces
– Indirectly
• Through uncooked food items that are
contaminated with soil
• Backyard transmission
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8. Ascaris lumbricoides : Clinical features
• Most are asymptomatic
• Heavy infections :
– Lung : Pneumonitis
• Pneumonitis is partly due to damage to the
alveolar walls by the relatively large larvae, &
partly due to hypersensitivity reaction
– Cough, fever, wheeze, dyspnea ; Loeffler’s
Syndrome
– High eosinophillia
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9. Ascaris lumbricoides : Clinical features
– Chronic malnutrition
– Vit A Deficiency
– Acute obstruction of the intestinal lumen
(ileocoecal valve)
– Bile duct : biliary colic or cholangitis
– Pancreatic duct : pancreatitis
– Appendix ; acute appendicitis
– Can migrate to larynx, block it death
– Mild abdominal pain
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10. Ascaris lumbricoides : Diagnosis
• Identifying adult worms that have been
passed out in faeces or vomitus
• Finding a characteristic eggs in the faeces
• Fertilized egg : oval, transparent shell /
unsegmented embryo
• Unfertilized egg : longer and narrower
• Decorticated eggs : smooth & oval
• The intensity of an
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11. Ascaris lumbricoides : Treatment
• Albendazole
• Mebendazole
• Pyrantel pamoate
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