Common round worm; Intestinal Nematode

1. Intestinal nematodes
ASCARIS LUMBRICOIDES
Common round worm
Umar Farooq, Ph.D
Module 2.2

2. Objective
• The students will be learn about Intestinal
Nematodes which causes morbidity and
mortality to human biengs

3. •Ascaris lumbricoides has world wide distribution. It is
common in both temperate and tropical countries like
China, India and other South-east Asian countries
•1400 million infected persons in the world (23% of the
world population), with about 60,000–100,000 deaths
annually.
Geographical Distribution

4. • Habitat
• Adults are normally found in the lumen of the
small intestine but do not attach to the
mucosa
• Morphology
• Large, stout nematodes, tapering at both ends
• Females (25 to 40 cm in length and 5 mm in
diameter)
• Males (15–30 cm in length and 2–4 mm in
diameter) but may show great variation in
size, depending on age and worm load

5. Morphology cont..
• Mouth: Three lips, each of which has a pair of
sensory papillae on its lateral margin, and rows of
small denticles or teeth.
• Principal structural protein:Collagen, tabilized by
disulphide bonds.
• Female
• Female: the paired, tortuous, tubular ovaries,
oviducts, seminal receptacles and uteri lead into
a vagina, which opens by a small vulva on the
ventral surface .
• Eggs: 200,000 per female and each may lay a
total of 25 million during her lifetime

6. • Male
• The posterior end of the male is curved ventrally
and there are two almost equal copulatory
spicules (measuring 2.0–3.5 mm) and numerous
preanal and postanal papillae.
Curtsy: Atlas Medical Helminthology and Protozoology

7. Eggs
• Fertilized egg
• Ovoid and measure 45–70 μm X 35–50 μm.
• Shell is thick and transparent
• outer albuminous coat
• Stained light brown with bile pigments.
• Ova are un-segmented when passed in the faeces.
• Unfertilized egg
• Longer and narrower 90 μm X 40 μm,
• uncoated with a thin shell, more irregular outer
covering .
• Rapid production of eggs allows some to pass through
unfertilized or because only female worms are present

8. Curtsy: Atlas Medical Helminthology and Protozoology

9. Clinical Manifestations
• Incubation period: 60-75 days
• Migrating larvae
• Pneumonitis with cough, dyspnoea, substernal
pain, fever and sometimes a blood stained
sputum (which may contain larvae).
• These symptoms begin 5 to 6 days after
infection and usually last 10–12 days.
• This is known as Loeffler’s syndrome and the X-
ray findings often show dense pulmonary
infiltrations, resembling acute tuberculosis.
There is moderate eosinophilia.

10. Clinical Manifestations cont..
• Adult worm
• Light worm load asymptomatic. Its cause
malabsorption of protein, carbohaydrate and
vitamins, in malnourished children, adult
worm cause growth retardation.
• Heavy worm load causes: vomiting, intestinal
obstruction, fever, appendicitis, obstructive
jaundice and acute hemorrhagic pancreatitis.

11. Laboratory diagnosis
• Direct evidence
• Finding of adult worm in stool or vomit.
• X-Ray diagnosis: The presence of A. lumbricoides has been
demonstrated by Radiography with barium emulsion, which
being ingested by the worm within 4-6 hours, casts an
opaque shadow.
• By direct microscopy: Finding of eggs in stool
• In Bile Juice: Bile aspiration examined by microscope.
• Demonstration of larvae in sputum and bronchial aspirates.
• Indirect evidence
• Ascaris antibody can be detected by IHA and immuno-
fluorescence antibody test.
• Dermal reaction: “Scratch test” with powdered Ascaris
antigens has often been found to be positive but the results
are variable.

12. • Treatment
• Pyrantal pamoate in a single dose of 11 mg/kg.
• Mebendazole in a dose of 100 mg twice daily for
3 days
• Piperazine citrate in a dose of 75 mg/kg daily 2
days.
• Prophylaxis
• Proper disposal of human faeces.
• Avoidance of eating raw vegetable and salads.
• Periodic treatment with an effective
antihelminthic, in communities that lack sanitary
facilities