Nematodes- Trichinellosis Flashcards Preview

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Flashcards in Nematodes- Trichinellosis Deck (25):

Which species causes trichinellosis?

species from the Trichinella genus


What makes Trichinella parasites unique?

largest INTRA-cellular parasites, smallest nematodes, great cause of disease worldwide, same host is both definitive AND intermediate host


What is the distribution of Trichinella?

worldwide EXCEPT Puerto Rico and Australia


Which sex is larger?

the female


How are Trichinella transmitted?

form cysts in muscle tissue, therefore passed by ingesting infected, improperly cooked meat. bears are heavily infected


Is trichinellosis a zoonose?

yes. humans are accidental hosts


How is Trichinella an intra-cellular parasite?

multi-intracellular parasite, has parts of body in different cells at one time. characteristic of L1-L5 phase larvae


Which muscles are more heavily invaded?

eye, tongue, masticator muscles, diaphragm, intercostals, arms, legs


Which muscles do not get infected by Trichinella nurse cells (cysts)?

heart muscle, smooth muscle, or nervous tissue


What are the steps of trichinellosis pathogenesis?

1. larvae enter muscle fibre cell
2. fibre loses its myofilaments
3. fibre nuclei enlarge
4. fibre smooth ER increases
5. fibre mitochondria degenerate
6. encapsulation of the unit by collagen secretion by adjacent fibroblasts


How are Trichinella juveniles like viruses?

they invade the hepatoportal system and pass through all types of tissues before reaching skeletal muscle.
they invade host cells, redirect the host cell metabolism for their own survival, and alter host cell gene expression


What do Trichinella larvae do to the muscle fibre?

they transform them into nurse cells by inducing angiogenesis around the cell


What are the five Trichinella species that affect humans?

T. spiralis, T. nativa, T. britovi, T. pseudospiralis, T. nelsoni


What is the stichosome?

the mature muscle larval stage that forms a single row of ~50 cells called stichocytes.
antigens released by stichocytes cross-react with antigen of living muscle larvae. may be immunogenic and responsible for host cell gene expression alteration


What does the stichocyte cytoplasm contain?

mitochondria, golgi-like structure, RER, 2 types of secretory granules


Which 3 stages of development cause disease?

intestinal stage, migrating larvae, muscle stage


What is the pathology of the intestinal stage?

causes traumatic damage to the tissues. causes nausea, vomiting, sweating and diarrhea


What is the pathology of the migrating larvae?

juveniles damage blood vessels, causing localized edema. can cause pneumonia, encephaitis, eye damage, etc


What symptoms do muscle cysts cause?

muscle pain, difficulty breathing and swallowing. causes intense inflammatory reaction in muscle tissue that is alleviated after the secretion of antigen from the stichocytes


Which species are not affected by trichinellosis?

fish, reptiles, amphibians are innately protected


What are the three types of immune response?

innate response, non-specific acquired immunity, specific acquired immunity


What is an example of non-specific acquired immunity with trichinellosis?

previous infection with Mycobacterium tuberculosis protects against trichinellosis because both cause similar Th1 type response
similarly, mice infected with Toxoplasma are protected against trichinellosis


Which cells are present after a specific acquired immune response to trichinellosis?

IgM, IgG and IgE in the serum, IgA in the gut, cell mediated Th1 response (particularly eosinophils)


How can trichinellosis be diagnosed?

adults and migrating juveniles cannot be detected, muscle nurse cells are detected by biopsy, serology is not very sensitive, PCR is useful


How can trichinellosis be treated?

Analgesics and immunosuppressive drugs like
prednisone and corticosteroids are given to relieve
the symptoms due to the intense inflammatory
mebendazole and albendazole are used to eliminate worms from the intestine, but not recommended to remove nurse cells
with small pathogens such as these, most of the pathology is due to the immune system reaction