Exam I - Echinococcus spp. Flashcards Preview

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Flashcards in Exam I - Echinococcus spp. Deck (18)
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1
Q

What is the common name for Echinococcus granulosus?

A

Hyatid tapeworm

2
Q

What is/are the final host(s) for Echinococcus granulosus?

A

dogs (and other canids)

3
Q

What is/are the intermediate host(s) for Echinococcus granulosus?

A

herbivores (wild and domestic) and humans

4
Q

Describe the appearance of the Echinococcus granulosus adult

A

In final host, entire tapeworm is 6 mm long with 3-4 segments. Scolex with 4 suckers and 2 rows of hooks. Small and therefore difficult to see in a freshly opened small intestine

5
Q

Describe the appearance of the Echinococcus granulosus egg

A

Eggs are 25-40 um in diameter, and typically taeniid with brown color, radial striations in the shell and appearance of 6 embryonic hooks.

Morphologically, they are indistinguishable from Taenia spp.

6
Q

Is the life cycle of Echinococcus granulosus direct or indirect?

A

Indirect.

7
Q

Describe the life cycle of Echinococcus granulosus.

A
  • Indirect. The tapeworm sheds 1 gravid segment with eggs, & these are shed in feces.
  • These develop to oncospheres, which are capable of prolonged survival outside the host (viable on ground for up to 2 years)
  • After ingestion by the intermediate host, egg hatches and the hexacanth larva penetrates the intestine and migrates to the liver and lungs, as well as other organs.
  • A hyatid cyst develops, and is the infective stage to the final host.
  • It becomes larger, is slow growing, and mature in 6-12 months.
  • When final hosts such as canids ingest an infected intermediate host, the scolices envaginate and attach to the mucosa of the small intestine and mature.
  • PPP is 45-60 days
8
Q

What is the infective stage of Echinococcus granulosus

A

hyatid cyst

9
Q

What is the PPP for Echinococcus granulosus?

A

PPP is 45 - 60 days

10
Q

What is/are the site(s) of infection for Echinococcus granulosus?

A

Adult cestodes in small intestine.

In intermediate hosts and humans, unilocular hyatid cysts in liver, lungs, and other organs.

11
Q

Describe the pathogenesis associated with Echinococcus granulosus

A

Adult tapeworms are nonpathogenic and thousands may be present in a dog without clinical signs.

When humans are the intermediate hose, the hyatid develops in a pulmonary or hepatic site. This is often pathogenic.

12
Q

Which diagnostic method(s) would be appropriate for diagnosing Echinococcus granulosus?

A
  • fecal float may show eggs, but eggs are morphologically indistinguishable from *Taenia *eggs
  • Scotch tape method - apply a piece of transparent, clear tape to the perianal area, sticking the tape to a microscopic slide, and examining it for eggs.
13
Q

What is the common name for Echinococcus multilocularis?

A

Alveolar hyatid tapeworm

14
Q

What is/are the final host(s) for Echinococcus multilocularis?

A

wild canids, domestic dogs, cats, or coyotes

15
Q

What is/are the intermediate host(s) for Echinococcus multilocularis?

A

cattle, horses, swine, rodents, and humans

16
Q

Describe the appearance of Echinococcus multilocularis adult

A

In final host, entire tapeworm is 6 mm long with 4-5 segments. This is small and therefore difficult to find in a freshly opened intestine. Scolex with 4 suckers and 2 rows of hooks. Similar to entire adult cestode for Echinococcus granulosus

17
Q

What is/are the site(s) of infection for Echinococcus multilocularis?

A

Adults in small intestine. Multilocular hyatid cysts primarily in liver, with metastases to other organs

18
Q

Describe pathogenesis associated with Echinococcus multilocularis in humans

A

Invasive growth of hyatid cyst in humans can be fatal

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