They have been described from very ancient times, when it was sometimes confused with earthworm. The specific name lumbricoids is derived from its resemblance with earthworm . It is most common human helminths and is distributed worldwide. The incidence may be high as 80-100% in rural areas with poor sanitation. They have been described from very ancient times, when it was sometimes confused with earthworm. The specific name lumbricoids is derived from its resemblance with earthworm . It is most common human helminths and is distributed worldwide. The incidence may be high as 80-100% in rural areas with poor sanitation.They are also known as Round worm. Adult worm lives in the small intestine (85% in jejunum and 15% in ileum). The roundworm, is the largest nematode parasite in the human intestine.Adult worm:- They are large cylindrical worms, with tapering ends, the anterior end being more pointed than the posterior. They are pale pink or flesh colored when freshly passed in stools, but become white outside the body. The mouth at the anterior end has three finely toothed lips, one dorsal and two ventrolateral.

1. B Y: - S WA S T I K A S I N G H C H A N D E L
Ascaris lumbricoids

2. History
 They have been described from very ancient times, when it was
sometimes confused with earthworm.
 The specific name lumbricoids is derived from its resemblance
with earthworm .
 It is most common human helminths and is distributed
worldwide.
 The incidence may be high as 80-100% in rural areas with poor
sanitation.

3. Habitat
 They are also known as Round worm.
 Adult worm lives in the small intestine (85% in jejunum and 15%
in ileum).
 The roundworm, is the largest nematode parasite in the human
intestine.

4. Morphology
Adult worm:-
 They are large cylindrical worms, with tapering ends, the anterior
end being more pointed than the posterior.
 They are pale pink or flesh colored when freshly passed in stools,
but become white outside the body.
 The mouth at the anterior end has three finely toothed lips, one
dorsal and two ventrolateral.

5. Male and female A. lumbricoids

6. Male worm:-
 The adult male worm is little smaller than female.
 Its measures about 15-30 cm and 2-34 mm in thickness.
 The posterior end is curved ventrally to form a hook and carries
two copulatory spicules.

7. Female worm:-
 The female is larger than male,.
 Measuring 20-40cm in length and 3-6mm in thickness.
 The posterior extremity is straight and conical.
 The vulva is situated mid- ventrally, near the junction of the
anterior and middle thirds of the body.
 A single worm lays up to 200,000 eggs per day. The eggs are
passed inn feces.

8. Egg :-
 Two types of eggs are passed by the worms:-
1. Fertilized eggs
2. Unfertilized eggs
 The fertilized eggs, laid by females, inseminated by mating with a
male, are embryonated and develop into the infective eggs.
 The unfertilized eggs are laid by uninsemiated female. These are
non-embryonated and cannot become infective .

11. Lifecycle
 Life cycle of Ascaris involves only one host.
 Natural host :- man is the only natural host .
 There is no intermediate host.
 Infective form :- embryonated eggs.
 Infection occurs when the egg containing the infective
rhabditiform larva is swallowed.
 Infection may also be transmitted through contaminated drinking
water.

12. Life cycle of A. lumbricoides

13. Pathogenesis
 Disease is called as Ascariasis.
 Clinical manifestation in Ascariasis can be caused either by the
migrating larvae or by the adult worms.
 Symptoms is seen due to migrating larvae.
 It can also causes Ascaris pneumonia .
 It can also causes Acute biliary obstruction or pancreatitis.

14. Laboratory diagnosis
 Detection of Parasite:-
 Adult worm:-
1. The adult worm can occasionally be detected in stool or sputum
of patients by naked eye.
2. Barium meal may reveal the presence of adult worm in the
small intestine.
3. A plain abdominal film may reveal masses of worm in gas-
filled loops of bowel in patients with intestinal obstruction.

15.  Larvae:-
1. In the early stages of infection , when migrating larvae cause
Loffler's syndrome , the diagnosis may be made by
demonstrating the larvae in sputum, or more often in gastric
washing.
 Eggs :-
Definitive diagnosis of Ascariasis is made by demonstration of eggs
in feces.
Eggs may be demonstrating in the bile obtained by duodenal
aspirates.

16.  Serological examination :-
Ascaris antibody can be detected by:-
 Indirect hem agglutination
 Indirect fluorescence antibody
 ELISA
 Blood examination :-
 Complete blood count may show eosinophilia in early stage of
invasion.