Transcript NEMATODA - Kardz Med

NEMATODA
NEMATODES
NEMA: thread
EIDOS: form
Nematohelminthes are either :
round, cylindrical, spindle shaped.
Examples:
ENTEROBIASIS = OXYURIASIS ( pin worm)
ASCARASIS = round worm
ANCYLOSTOMIASIS = hook worm
TRICHINOSIS
TRICHURIASIS = whip worm
Intestinal Nematodes
Ascaris lumbricoides
• Giant intestinal
roundworm
• Whitish or pinkish
worm
• More than 1 billion
individuals are affected
• 70% from Asia
• Soil transmitted
helminth
• Polymyarian
• Somatic muscles are
numerous and project
well into the body
cavity
•
Epidemiology
World
wide
distribution,
very
common in China, especially in the
countryside.
Factors favoring the spread of the
transmission:
1. Simple life cycle.
2. Enormous egg production ( 240,000
eggs/ day/ female ).
3. These eggs are highly resistant to
ordinary
disinfectants( due to the
ascroside). The eggs may remain
viable for several years.
4. Social customs and living habits.
5. Disposal of feces is unsuitable.
Ascaris lumbricoides
• Males = 10-31
cm
• Ventrally curved
posterior end
with 2 spicules
• Females = 22–
35cm
• Straight, conical
posterior end
Ascaris lumbricoides
• Trilobate lips
The lips of Ascaris
lumbricoides
The three lips
are seen at the
anterior end. The
margin of each lip
is lined with minute
teeth which are not
visible
at
this
magnification.
Ascaris lumbricoides
• Unfertilized eggs
•
•
•
•
Narrower
Longer
Thin shell
Refractile granules
are not organized
• Found in the
absence of males
Ascaris lumbricoides
• Fertilized eggs
• Thick
transparent
hyaline shell
• Ovoid mass of
protoplasm
which develops
into larvae at
about 14 days
Ascaris lumbricoides
• Embryonated
eggs
• Infective stage
• Embryonation
occurs in the soil
Life Cycle
•
1. Site of inhabitation: small intestine
2. Infective stage: embryonated eggs
3. Route of infection: by mouth
4. No intermediate and reservoir hosts
5. Life span of the adult: about 1 year
This worm lives in the lumen of small
intestine,
feeding
on
the
intestinal
contents, where the fertilized female lays
eggs. An adult female can produce
approximately 240,000 eggs per day, which
are passed in faeces. When passed, the
eggs are unsegmented and require outside
development of about three weeks until a
motile embryo is formed within the egg.
Ascaris lumbricoides
Retrieved fromhttp://parasitol.wkhc.ac.kr/image/nema/lifeal.JPG Feb. 2008
Pathogenesis
There are two phase in ascariasis:
1. The blood-lung migration phase
of the larvae: During the migration
through the lungs, the larvae may
cause a pneumonia. The symptoms
of the pneumonia are low fever,
cough, blood-tinged sputum, asthma.
Large numbers of worms may give
rise
to
allergic
symptoms.
Eosionophilia is generally present.
These clinical manifestation is also
called Loeffler’s syndrome.
•
2. The intestinal phase of the
adults. The presence of a few
adult worms in the lumen of the
small intestine usually produces
no symptoms, but may give rise to
vague
abdominal
pains
or
intermittent colic, especially in
children. A heavy worm burden
can result in malnutrition. More
serious manifestations have been
observed.
Complication
• Wandering adults may block the
appendical lumen or the common bile
duct and even perforate the intestinal
wall. Thus complications of
ascariasis, such as intestinal
obstruction, appendicitis, biliary
ascariasis, perforation of the
intestine, cholecystitis, pancreatitis
and peritonitis, etc., may occur, in
which biliary ascariasis is the most
common complication.
Diagnosis
• The symptoms and signs are for reference
only. The confirmative diagnosis depends on
the recovery and identification of the worm or
its egg.
A. Ascaris pneumonitis: examination of
sputum for Ascaris larvae is sometimes
successful.
B. Intestinal ascariasis: feces are examined
for the ascaris eggs.
(1) direct fecal film: it is simple and
effective. The eggs are easily found using this
way due to a large number of the female
oviposition, approximately 240,000 eggs per
worm per day. So this method is the first
choice.
(2) brine-floatation method:
(3) recovery of adult worms: when adults or
adolescents are found in feces or vomit and
tissues and organs from the human infected
with ascarids , the diagnosis may be defined.
Ascaris lumbricoides
• Treatment
• Albendazole
• Drug of choice
• 400 mg single dose
• 200 mg for children under 2 year old
• Mebendazole
• 500 mg single dose
• Pyrantel Pamoate
• 10 mg/kg body weight (max. of 1 g)
Prevention
• 1.Sanitary disposal of faeces.
• 2.Hygienic habits such as
cleaning
of
hands
before
meals.
• 3.Health education.
•Ancylostoma
duodenale
Ancylostoma duodenale
• Slightly larger
than Necator
americanus
• Head curves in
the same
direction as the
curvature of the
body
Morphology
1. Adults:
They look like an
odd piece thread and are
about 1cm. They are white or
light pinkish when living. ♀is
slightly
larger
than♂.The
male’s
posterior
end
is
expanded to form a copulatory
bursa.
2. Eggs: 60×40 µm in size, oval
in shape, shell is thin and
colorless. Content is 2-8cells.
• Scanning electron micrograph of the
mouth
capsule
of
Ancylostoma
duodenale, note the presence of four
"teeth," two on each side.
Ancylostoma duodenale
• Buccal capsule
• 2 pairs of curved
ventral teeth
Ancylostoma duodenale
• Copulatory
bursa of male
• Ancylostoma duodenale copulatory bursa and
spines of male(a side view)
The Morphological Differences between
Two species of Hookworms
_____________________________________________________
A. duodenale
N. americanus
______________________________________________________
Size
larger
smaller
______________________________________________________
Shape
single curve, looks like C
double curves,
looks like S
______________________________________________________
Mouth
2 pairs of ventral teeth
1peir of ventral
cutting plates
____________________________________________________________
Copulatory
circle in shape
oval in shape
Bursa
(a top view)
(a top view)
____________________________________________________________
Copulatory 1pair with separate
1pair of which unite
to form
spicule
endings
a terminal hooklet
_______________________________________________________
caudal spine
present
no
_______________________________________________________
vulva position
post-equatorial
pre-equatorial
Ancylostoma duodenale
• Filariform larva
• infective stage
to humans
Ancylostoma duodenale
• OVA
• Bluntly rounded
ends
• Single, thin
transparent
hyaline shell
• Unsegmented
during
oviposition
• 2-8 cell stages in
fresh feces
Life Cycle
1. Final host: man
2. Inf. Stage: Larva 3 or filariform
larva
3. Inf. Route: by skin
4. Food: blood and tissue fluid
5.
Site of inhabitation: small
intestine
6. Life span: Ad 15years, Na 37years
7. Blood-lung migration:
skin, cavum, right heart, lungs
Life cycle of hookworm
Ancylostoma duodenale
Pathogenesis and Clinical
Manifestations
• Pathology of hookworm infection
involves
• The skin, at the site of entry of
filariform larva
− Maculopapular lesions “ground
itch” or “dew itch”(The larvae
penetrating the skin cause allergic
reaction, petechiae or papule with
itching and burning sensation)
− Itching, edema, erythema leading
to papulovesicular eruption lasting
for 2 weeks
• The lung, during larval migration
−Bronchitis
−Pneumonitis
Loeffier's syndrome: cough,
asthma, low fever, bioodtinged sputum or hemoptysis,
chest-pain, inflammation
shadows in lungs under X-ray.
These manifestations go on
about 2 weeks.
• The small intestine, the habitat
of the adult worm
−Abdominal pain
−Steatorrhea
−Diarrhea with blood and
mucus
−Eosinophilia ( 30% to 60%)
Adults in intestinal mucosa
Necator americanus
Ancylostoma duodenale
• Epidemiology
• Over 900 million people infected
• Associated anemia causes 50,000
deaths annually
Ancylostoma duodenale
Necator americanus
Ancylostoma duodenale
• Prevention and Control
•
•
•
•
•
Sanitary disposal of human faeces
Wearing of footwear
Health education
Treatment of infected individuals
Mass chemotherapy when prevalence is
greater than 50%
• Protection of susceptible individuals
through
• Improved diet to prevent malnutrition
Ancylostoma duodenale
• Diagnosis
• Direct fecal smear
• only for heavy infections
• Kato Technique
• Increases detection rate
• Kato Katz Method
• Quantitative diagnosis
• Zinc Sulfate Centrifugation
• Formalin Ether Concentration
• Harada-Mori
• Allow hatching of larvae from eggs on strips
of filter paper with one end immersed in
water
Ancylostoma caninum
Ancylostoma braziliense
• Ancylostoma
caninum
• Dog hookworm
• Ancylostoma
braziliense
• Cat hookworm
Both cause
creeping
eruptions
Ancylostoma duodenale
• Treatment
• Albendazole
• Drug of choice
• Ovicidal and larvicidal
• 400 mg single dose in adults and children
over 2 years old
• Available in chewable tablets or suspension
• Not recommended for pregnant women
• Mebendazole
• 500 mg single dose in adults and children
• Not recommended for children below 2 years
old
Trichuris
trichiura
Trichuris trichiura
• Whipworm
• Soil transmitted helminth
• Often observed occuring
together with Ascaris
lumbricoides due to similarities
in transmission and mode of
distribution
Adultos machos Trichuris trichiura
Trichuris trichiura
• Anterior threefifths long and
whip-like
• Posterior two-fifths
is thick and fleshy
• Inhabit the large
intestine
• Insert into the
intestinal wall of
the caecum in a
pin-fashion
• Male
• 30-45 mm
• Coiled posterior end
• Single spicule
• Retractile sheath
• Female
• 35-50 mm
• Bluntly rounded posterior end
• Can produce over 60 million ggs in an
average life span of 2 years
macho
Trichuris trichiura
hembra
Trichuris trichiura
• Ova
• Passed out
together with
faeces
• Embryonation in
the soil (2-3
weeks)
• Protuberant
bipolar mucus
plugs
• Football in shape
Trichuris trichiura
• Pathogenesis & Clinical
Manifestations
• Trichuriasis
• Petechial hemorrhages
predisposing to amoebic dysentery
• Over 5,000 eggs /g of stool:
symptomatic
• Over 20,000 eggs/g : severe
diarrhoea or dysenteric syndrome
Clinical Course
• Light infection: Asymptomatic.
• Middle infection: Clinical
manifestations are usually
abdominal pain, anorexia,
diarrhoea and constipation.
• Heavy infection: Bloody
diarrhoea, emaciation and rectal
prolapse may occur (in
malnourished children)
Adultos Trichuris trichiuria en mucosa intestinal
Adultos Trichuris trichiuria en mucosa intestinal
Adultos Trichuris trichiuria en mucosa intestinal
Trichuris trichiura
• Rectal
prolapse
during heavy
infection
Trichuris trichiura
Trichuris trichiura
• Diagnosis
• Direct fecal
smear
• Kato Thick
smear
• Kato Katz
• Concentration
Techniques
− ZnSO4
− Formalin
Ether
Trichuris trichiura
• Epidemiology
• Distributed in warm. Moist areas of
the world
• 20% – 30% prevalence in
temperate countries
• 60% - 85% in tropical countries
• Children 5 to 15 years of age are
frequently infected
Trichuris trichiura
• Treatment
• Mebendazole
• Drug of choice
• 500 mg single dose in light infections
• 2 – 3 days of consecutive treatment for
moderate and heavy infections
• Contraindicated during early pregnancy and in
hypersensitivity
• Albendazole
• 400 mg single dose
• Contraindicated during pregnancy
• Oxantel plus pyrantel pamoate:
dosage is 10 to 12mg/kg body weight as a
single dose. Heavy infections, treatment
may be repeated for 2-3 times.
• Iron:
addition in blood stream helps to solve iron
deficiency and rectal prolapse.
Prevention and control
• Training adults and children in
proper sanitary disposal of faeces
and washing of hands is
necessary.
• Treating water sources before
use.
• Avoid living in overcrowded
places and using human faeces as
fertilizer on farms.
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