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Trichinella spiralis is most commonly known as
trichina worm
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T. spiralis is highly complex because
of its very low host specificity resulting in many zoonotic infections
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It is regarded as an accidental host for the parasite t. spiralis. Why?
Under normal condition the parasite reaches a dead end in man, because it cannot complete its life cycle.
This is because flesh of the host containing the infective larvae must be ingested by another host. Human flesh is not to be ingested.
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Distinction of trichinella spiralis body.
Their anterior end is
- provided with a spear-like burrowing tip at its tapering anterior end.
- it is slender with small non-papilated mouth
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Distinction of trichinella spiralis body.
To identify male t. spiralis worm you can observe _______.
its posterior end is ventrally curved with 2 copulatory appendages.
- *this is already mentioned in the previous flashcards.*
- Males have 2 copulatory appendages ( reproductive organ)
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Distinction of trichinella spiralis body.
To identify male t. spiralis worm you can observe _______.
- Female posterior end is bluntly rounded they have a single ovary.
- *this is already mentioned in the previous flashcards.*
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Due to female t. spiralis worm being _____ it is difficult to estimate the rates of infection within population.
viviparous -bringing forth live young that have developed inside the body of the parent.
Viviparous females are found within the intestinal mucosa and the larvae produced are immediately carried via the circulatory and lymphatic systems to the muscle fibers within which they quickly encyst.
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Enumerate the life cycle of trichinella spiralis spp.
Note: Remember there are several species of trichinella due to its complexity.
1.After exposure to gastric acid and pepsin, the larvae are released from the cysts. Ingestion.
2. They invade the small bowel mucosa (small intestine) where they develop into adult worms.
- 3.The life span in the small bowel is about four weeks. After 1 week, the females release larvae
- 4.that migrate to striated muscles where they encyst.* Take note of this*
5. Diagnosis is usually made based on clinical symptoms, and is confirmed by serology or identification of encysted or non-encysted larvae in biopsy or autopsy specimens.
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Other host of t. spiralis spp aside from humans.
The domestic cycle most often involved pigs and anthropophilic rodents, but other domestic animals such as horses can be involved.
In the sylvatic cycle, the range of infected animals is great
Animals most often associated as sources of human infection are bear, moose and wild boar.
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Infection of trichinellosis is caused by _______.
ingestion of undercooked meat containing encysted larvae
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Adult worms live around the _________ of the small intestine and the larvae live in _________ of the same mammal.
- Adults:columnar epithelial cells of the small intestine
- Larvae:live in striated muscle cells
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In t. spiralis what are the stages of pathology?
1.
2.
3.
- 1.During the stage of invasion of the small intestinal wall by burrowing females.
- 2.During the stage of larviposition
- 3.During the period of larvae encystment
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This stage of t. spiralis pathology exhibits:
Irritation & inflammation of the mucosa takes place resulting in GIT symptoms of nausea, vomiting, colic, diarrhea & even hemorrhage.
(this stage may start few hours after eating infected pork)
Stage 1: Invasion of the females, burrowing into the intestinal mucosa.
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This stage of t. spiralis pathology exhibits:
Rheumatic muscular pains due to inflammation of the muscles
(myalgia) causing difficulty in breathing,swallowing, talking & mastication.
Stage 2: Larviposition
(laying of larvae by female insects of a relatively small number of species in which eggs hatch inside the female)
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This stage of t. spiralis pathology exhibits:
the critical part of the cerebral disease
Death or recovery may take place.There may be cerebral, cardiac, pleural or renal involvement.
Stage 3:larvae encystment (to enclose in a cyst)
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Trichinosis symptomatology.
Within 24- 72 hours host will experience ______ as symptoms as the larvae release by female t. spiralis invade the small intestinal mucosa.
Nausea,vomiting,diarrhea,abdominal,pain,headache.
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Infective stage of trichinella spiralis
ingestion of uncooked meat
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Diagnostic stage of trichinella spiralis
when encysted larvae penetrates the striated muscles, this may cause muscular pain
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Trichinosis symptomatology.
Within 10-21 days host will experience ______ as symptoms when the circulation and muscles are affected.
Edema, periorbital conjunctivitis,photophobia,fever, chill, sweating, muscle pain, spasm,eosinophilia.
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Trichinosis symptomatology.
Within 10-21 days host will experience ______ as symptoms it affects the myocardium.
Chest pain,tachycardia,EKG changes,edema of extremities, vascular thrombosis.
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Trichinosis symptomatology.
Within 10-21 days host will experience ______ as symptoms affects the myocardium.
Chest pain,tachycardia,EKG changes,edema of extremities, vascular thrombosis.
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Trichinosis symptomatology.
Within 14-28 days host will experience ______ as symptoms affect the brain and meninges.
Headache (supraorbital),vertigo, tinnitus,deafness,mental apathy,delirium, coma,loss of reflexes
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Trichinella spiralis can be diagnosed through:
Direct procedure such as
1.
2.
3.
- Muscle biopsy
- Stool examination
- Xenodiagnosis (a diagnostic procedure in which the insect vector is used as a culture medium for the detection of infection in a mammalian host )
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Trichinella spiralis can be diagnosed through:
Indirect procedure such as
1.
2.
3.
4.
5.
6.
- History
- Blood examination
- Serology
- Radiological examination
- PCR
- Bachman intradermal test.
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To prevent infection of trichinella spiralis you must
1.freeze pork.
- -in less than 6 inches thick for 20 days at -15 degree celsius to kill any worms
- - freezing wild game meats,may not be effective in killing all worms.
- 2.Proper cooking
- 3. Most effective methods is to stop the practice of feeding pigs with raw garbage.
- 4.Extermination of rats from pic farms, they can spread infection.
- 5. Smoking, salting or drying the meat does not destroy the infective stage. However it is more effective to freeze the meat.
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Treatment
For mild cases
supportive treatment like bedrest, analgesics and antipyretics
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Treatment
Moderate cases
Albendazole and Mebendazole
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Treatment
Severe cases
add glucocorticoids like prednisolone to albendazole or mebendazole
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