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Classification of
Metazoa/helminthes/worms
Metazoa/helminths
Nemathelminthes
Platyhelminthes
(roundworms/ nematodes)
(flatworms)
Trematoda Cestoda
(flukes) (tapeworms)
General characters of
Nematodes
Nematode
The intestinal nematodes
– Ascaris lumbricoides
– Enterobius vermicularis
– Ancylostoma duodenale
– Trichuris trichiura
 Elongate
cylinder worms with body
cavity & digestive tract.
 Sexes
are separate.
separate.
 Male smaller
 Free
than female.
living in soil & water
water..
 The
body nonsegmented, transluscent,
flesh color, tapering at both end.
 The
alimentary canal consist of oral
cavity, esophagus, midgut, hindgut or
rectum ending with anus.
1. Ascaris lumbricoides
(Round worm)
 The
body is covered with cuticle to
resist digestive juices & enzymes of
the host.
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lumbricoides is the largest
nematode (roundworm) parasitizing the
human intestine
intestine..
 Ascaris lumbricoides is an intestinal worm
found in the small intestine of man.
man.
 They are more common in children then in
adult..
adult
 Ascaris
Adult
Male shorter with coiled posterior
end with 2 minute spicules
spicules..
Female longer
posterior end
end..
with
straight
3 lips which carry minute teeth
A pair of female and male worms of A.
lumbricoides. Notice the the coiled end of the male
lumbricoides.
worm..
worm
A scanning electron micrograph of
Ascaris showing the three prominent
“lips”
INFECTION TO MAN
Host
It
occurs when the man
swallows the infective eggs of
Ascaris with contaminated
food or water
water..
 Definitive
host : Humans
 Intermediate
Host : -none
none--
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Egg
 Round
 The
or oval
oval,, brownish in color
color..
Egg shell
egg shell is colorless
colorless,, aluminous
Ovum
covering, when lost named decoricated
Albuminous layer
egg..
egg
A. lumbricoides,
lumbricoides, fertilized egg
(unsegmented
unsegmented)
)
 Fertilized egg
 Unfertilized
egg
soil
A. lumbricoides unfertilized egg
The life cycle of A. lumbricoides
 Adult
Living site
Adults in small
intestine
Migration
Larvae migrate
though the lungs
HOST
MAN
Diagnostic stage
Unfertilized
eggs in feces
Method of infection
Infective stage
Infective eggs are
ingested
Eggs embryonate in
soil by 2-3 wks
worms live in the lumen of the small
intestine.
intestine.
 A female produce 200
200,,000 eggs per day,
passed with faeces .
 Un
Unfertilized
fertilized eggs may be ingested but are
not infective
infective..
 Fertile eggs embryonate and become
infective after 18 days to several weeks
weeks..
 After infective eggs are swallowed
swallowed..,
 The
larvae
(Rhabditiform
Rhabditiform))
hatch , invade the intestinal
mucosa,, carried via the portal,
mucosa
 then systemic circulation to the lungs
lungs..
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 larvae
mature further in the lungs (10 to
14 days), penetrate the alveolar walls,
ascend the bronchial tree to the throat,
and are swallowed
swallowed..
 Upon
reaching the small intestine, they
develop into adult worms
worms..

Between 2 and 3 months are required
from ingestion of the infective eggs to
oviposition by the adult female
female..

 Adult
worms can live 1 to 2 years
years..
with underweight, pale, pot
pot-bellied due to abdominal distention
Symptoms of Ascariasis
 Fever
and breathing difficulty
and pneumonia (Ascaris
pneumonities;; dyspnoea,
pneumonities
dyspnoea, asthma
asthma))
 Abdominal cramps (umbilicus), loss of
appetite, diarrhea, bulky foul smelling
stool..
stool
 Intestinal obstruction due to aggregates
masses of warm
warm..
 Peritonitis
Peritonitis..
 Malnutrition
Malnutrition..
 Worm in stool
 Worm in vomit
 Coughing
 Children
 appendicitis
 Liver
or pancreatitis
Diagnosis
 Eosinophilia
Eosinophilia..
 Egg
in feces (which?
(which?))
abscess formation
 Malnutrition,
vitamin A & C deficiency
deficiency..
Treatment
 Mebendazole
Mebendazole..
 Pyrantel
pamoate or
Piperazine citrate.
The drug may cause Anaphylactic shock .
Supportive therapy
Cortisone.
Prevention
 Avoid
contacting
soil
that
may
be
contaminated with human feces
 Do
not defecate outdoors
 Wash
hands with soap and water before
handling food
Bronchodilator.
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2. Enterobius vermicularis
(pin worm)
Enterobius vermicularis egg. Flat
at one side, convex at the other
Host
 Humans
are the only host in nature
Infection
Stage Infective eggs, larvated ,
immediately infective
 No
intermediate host (direct life cycle)
 No
larval migration between organs
pinworm
infection
or
enterobiasis is a human parasitic
disease and one of the most
common childhood parasitic
worm infections in the developed
world t is caused by infestation
with the parasitic roundworm
Enterobius
vermicularis,,
vermicularis
commonly called the human
pinworm
 Infection
usually occurs through the
ingestion of pinworm eggs, either
through contaminated hands, food,
or less commonly, water.
water.
 The
incubation time from ingestion
of eggs to the first appearance of new
eggs around the anus is 4 to 6 weeks
weeks..
Pinworms are usually considered a
nuisance rather than a serious
disease
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Auto
infection
Life cycle
Perianal
Infective
 Ingestion
of infective embryonated egg
egg..
 Larve hatch in the small intestine
intestine..
 Migrate into large intestine, mature into
adult..
adult
 After copulation
copulation,, male die
die,, gravid female
migrate to anus during night to deposit
eggs..
eggs
 Migrate to vagina of female
female..
Mode of transmission
 Person
to person through contaminated
clothes.
clothes.
 Small no
no.. are airborne or inhalated
inhalated..
 Retroinfection ; hatched larvae from anal
skin back to rectum.
rectum.
 autoinfection (either through the anus
anus--to
to-mouth route)
Signs and symptoms
 The
main symptoms are perineal
pruritus, i.e., itching in and around the
pruritus,
anus..
anus
 The itching occurs mainly during the
night,, and is caused by the female
night
pinworms migrating to lay eggs around
the anus
anus..


The itching leads to continuously
scratching the area around the anus,
which further results in tearing of the
skin and complications such as
secondary bacterial infections
infections,, including
bacterial dermatitis and boil
boil..
 Vulvovaginitis
Diagnosis
 Ova
(which?)) in perianal region or
(which?
vagina.
 Adult
worm in feces
in females.
females.
 Eosinphilia
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Treatment
 Pyrantel
pamoate
pamoate..
 Mebendazole
Mebendazole..
 1%
white ppt ointment at bed time
to relief itching
itching..
Majority of hookworm infections in
humans caused by
1) Ancylostoma duodenale
2) Necator americanus
N. americanus & A. duodenale
New
old
capsule set with Buccal capsule set with
two
crescent--shaped symmetric pair of
crescent
cutting plates on ventral sharp teeth on ventral
side (shearing chitinous side
side.., smaller dorsal
plates)
pair
3. Ancylostoma duodenale
(Hookworm)
Morphology
anterior end of the body has slight
bend giving hook like appearance
appearance..
 The male’s posterior end is expanded to
form a copulatory bursa (2 spicules
spicules,,
cloaca in which rectum & genital canal
open)..
open)
 Buccal capsule with 2 ventral curved
teeth, small dorsal pair (Sucking blood)
 Eggs
Eggs:: oval in shape, shell is thin and
colorless..
colorless
 The
Ancylostoma
 Buccal
dumb
soil
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Life cycle
 Eggs
are passed with feces
feces..
 Eggs hatch (rabditiform larva) in about 1-2
days under favorable conditions such as
(damp soil),which feed upon bacteria in the
feces..
feces
 After 5-10 days they become filariform
(infective stage)
 When they contact with the human host, the
larva penetrate the skin and are carried
through the veins to the heart and then to
the lungs
lungs,, and are swallowed
swallowed..
 The larva reach the small intestine, where
they reside and mature in to adults.
adults.
Symptoms
1. Skin (Cutaneous or invasion phase)
– itching
itching,, pruritus
pruritus,, swelling (ground itch)
itch)..
2. Lung Infection (Pulmnonary phase)
– pneumonia, cough, sputum (larva)
larva).
3. GIT Infection (Intestinal phase)
 Attach
to mucosa by teeth causing tissue
deterioration& intestinal bleeding
bleeding,, bloody stool,
reddish brown)
brown)..
 Microcytic hypochromic anemia
anemia..
 Hypoproteinemia
Hypoproteinemia..
 Nausea, vomiting, diarrhea, polyphagia
polyphagia..
Diagnosis
1. anemia.
anemia.
2. Esoinophilia
3. Egg in stool (which?
which?)).
4. Larva in sputum
sputum..
Treatment
1.mebendazole.
mebendazole.
2. pyrantel pamoate
pamoate..
therapy..
3. iron therapy
Trichuris trichiura
4. Trichuris trichiura
(whip worm)

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Morphology
 Its
commonly called whip worm because
of the shape of this worm (anterior thin
and posterior thick
thick)).
 Posterior
end contain spear like
projection enveloped with sheath
sheath;;
(penetrate intestinal mucosa
mucosa))
Life Cycle
Eggs::
Eggs
Shape: barrel
Shape:
barrel––shaped
μm
Size:: 50
Size
50--55 x 25
25--30
30μm
Shell:: thick egg shell with 2 polar plugs
Shell
Color:: Yellow
Color
Yellow--brown
Content:: immature egg cells
Content
Caecum,
Caecum,
appendix
soil
Life cycle
• Eggs pass out unembryonated (soil)
• Embryo develops inside the egg
egg..
• embroynated eggs swallowed  1st stage
larvae hatch in small intestine and
penetrate villi
• Then migrate to large intestine and attach
to mucosa with the thin anterior end
(caecum , appendix
appendix)).
• After 2-4 month females mature and lay
eggs..
eggs
Symptoms
 Abdominal
distention over the caecum
resemble appendicitis
appendicitis..
 Bloody diarrhea
Rectal prolapse
prolapse..
 Children’s infection can cause rectal
prolapse,, The reason is the rectum is
prolapse
damaged by the worm, the rectum can be
pushed out from the anus
anus..
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Laboratory diagnosis
1- Eggs (Which?
Which?)or
)or worm in feces
feces.. Eggs are
oval, barrel shaped
shaped..
2- Eosinophilia may occur
occur..
3- In heavy infection proctoscopy or can
show the worms attached to the mucosa
mucosa..
Treatment
 Mebendazole
is the drug of choice,
with albendazole as an alternative
alternative..
 Personal hygiene
4- Visual detection of adult worms on
prolapsed rectum
rectum..
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