Lecture 05 – Trichinella and Trichuris

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Transcript Lecture 05 – Trichinella and Trichuris

Trichinella spiralis
Trichinella spiralis
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Common name: Trichina worm- The Pork worm
Trichinella spiralis means spira, how this coils up in its host.
diseases: Trichinosis, Trichiniasis,
is a zoonotic disease. it is passed between humans and animals.
Habitat: females in mucosa of small intestinal
The same animal acts as final and intermediated host
is most common in Europe, North America, and Asia,
Infective stage: contaminated meat (muscle) containing encyst larvae (pig)
Diagnostic stage: larvae encysted in muscle (human)
Can be fatal if large numbers of cysts form in the heart muscle.
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The sperm fertilizes the egg, but the female doesn’t release the
eggs until they have hatched within her uterus, which is usually
within the fifth or sixth day of infection.
Female worms can produce approximately 1500 newborn
larvae (immature L1) during a life span (4-16 weeks), before
expulsion by the host immune system.
Viviparous:
Expel active larvae
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Oviparous: Eggs laid in 1-cell stage
or early cleavage stage.
Ovoviviparous: Eggs laid containing embryo or
larva (L1). Some hatch out prior to passage
in feces.
Viviparous: Expel active larvae
Morphology:
Anterior end: slender with small non papilated mouth.
Male:1.5mm
posterior end ventrally curved
with 2 copulatory appendages
Female: 3.5mm single ovary
Posterior end bluntly rounded
LARVAE
Measures 80-120 um by 5.6 u at birth
And grows but little until it has entered
A muscle fiber, size 900 um
developed.
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Female worms deposit larvae into:
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The mucosa of small intestine
Directly into the lymphatics
Blood stream.
The larvae carried to all parts of body,
but the larvae developing only in striated muscle.
Epidemiology
 The disease among humans, rats, and pigs
 Rats and pigs feeding on garbage that includes infected pork
waste, become infected in turn
 Dead or dying infected rats are themselves eaten by pigs
 Raw or poorly cooked pork (sausage) harboring infective larvae
then becomes the vehicle for human infections
 Trichinellosis is a cosmopolitan disease that occurs most
commonly in Europe and the US
Pathogenesis:
1--Penetration of the adult females into mucosa
The first symptoms appear between 1- 2 days after ingestion.
The worms migrating in the intestinal epithelium
Inflammation of duodenal and jejunal mucosa:
This causes:
 inflammation,
 nausea,
 vomiting,
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sweating, and diarrhea.
2- The migrating larvae
Ten days after infection the larvae will penetrated the
muscle fibers, carried to all parts of body, This causes
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muscular pain,
difficulty breathing
Per orbital edema and conjunctivitis
heart (myocarditis),
lungs (pneumonitis),
brain (encephalitis).
Can be fatal if large numbers of cysts form in the heart
muscle. heart failure or respiratory or kidney malfunction
Diagnosis :
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Muscle biopsy at the encystment stage
blood test for eosinophilia
increased levels of creatine phosphokinase CPK,
Serology test Immunoassays, such as ELISA
At the diarrheal stage, adult and larvae may be found
in feces
Treatment
Anti-inflammatory drugs. When infected, it is
also suggested that you get a lot of rest to help
give your body time to recover.
 Mebendazole is the drug of choice.
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Trichuris trichiura
Whip worm
Trichuris trichiura
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Common name: whip worm
Disease: trichuriasis, whip worm infection
Final host: human, dogs, pig, monkey
Habitat: large intestinal ( cecum, appendix, rectum)
Geographical distribution: Cosmopolitan with poor sanitation.
Children are more likely to be infected than adults because they are more
likely to have have close physical contact with contaminated soil
Infective stage: infective larva in egg
Transmission occurs through ingestion of eggs, usually on contaminated
vegetables or soil.
Diagnostic stage: Egg barrel shape with polar plugs
Morphology:
Adult female worm:
The anterior two-thirds of the body being very thin
(looks like a whip)
and the remaining posterior end is thick and linear.
Size: 3.5-5cm in length
Adult Male worm:
smaller than the female, 3.0-3.5cm.
The posterior end is curved and has a single spicule
enveloped with sheath.
The anterior end two-thirds of the body being very thin
(looks like a whip).
 Adult worm penetrates into and embed its whip-like anterior
portion in the intestinal mucosa, By small spear
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Adult female
-Longer than the male.
- posterior end is thick
and linear.
Adult male
-Shorter than the female.
posterior end curved and
-has a single spicule
enveloped with sheath.
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posterior end curved and
has a single spicule
enveloped with sheath
Eggs:
Shape: barrel–shaped
Size: 50-55 x 25-30μm
Shell: thick egg shell with 2 polar plugs
Color: Yellow-brown
Content: immature egg cells
3000-10000 eggs daily daily output
Life cycle:
• Eggs pass out immature
• Embryo develops inside the egg (that takes about 3weeks
at 25C)
• Mature 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
• After 2-4 month females mature and lay eggs.
Pathology:
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Light infection with Trichiuris are asymptomatic
Heavier infections are characterized by
1- diarrhea,
2- anorexia,
3- nausea
4- abdominal pain
mucosal 5- anemia may be the result of hemorrhaging when the worms
penetrate the intestinal wall)damage)
 Rectal
prolapse.
Children’s infection can cause rectal prolapse, The
reason is the cecum is damaged by the worm, the
cecum can be pushed out from the anus.
PROLAPSED RECTUM
Laboratory diagnosis
1- Eggs or worm in feces. Eggs are oval, barrel shaped,
2- Eosinophilia may occur.
3- In heavy infection proctoscopy or sigmoidoscopy, can
show the worms attached to the mucosa.
4- Visual detection of adult worms on prolapsed rectum.