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FM3_ EB > Parasitology 2 > Flashcards

Parasitology 2 Flashcards

1
Q

What is the causative agent of pinworm?

A

Enterobius vermicularis

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2
Q

Describe the transmission of Enterobius vermicularis

A

ingestion of eggs, direct person to person

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3
Q

What is the definitive host of Enterobius vermuclaris

A

Humans- no intermediate host needed

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4
Q

Describe the epidemiology of pinworm

A

More common in children, daycare

very common worldwide and in the US

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5
Q

Describe the lifecycle of Enterobius vermicularis

A

Gravid female emerges from anus to lay eggs, perianal scratching facilitates transmission and auto-infection
Eggs in clothes, sheets can be transmitted to others
Eggs are swallowed, hatch in intestine, adults mate and migrate to colon

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6
Q

Describe immunity to pinworm

A

None- re-infection is common

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7
Q

How is pinworm diagnosed?

A

Perianal itch, restlessness, insomnia

observation of eggs, scotch tape test

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8
Q

What treatments can be used for pinworm?

A

Pyrantel pamoate, mebendazole, albendazole
Multiple treatment for severe infection, stop reinfection
Thorough housecleaning

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9
Q

Trichuris trichiura, or _____, infects humans worldwide and is most common in tropical countries and the poorer communities of the southern US

A

whipworm

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10
Q

What is the definitive host of whipworm?

A

Humans only, no intermediate

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11
Q

How is whipworm transmitted?

A

Ingestion of embryonated eggs only, no direct person to person

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12
Q

Describe the lifecycle of the whipworm (Trichuris trichuria)

A

Eggs swallowed, hatch in intestine, adults mate and migrate to colon
Adults attach in colon
Eggs passed in feces
Eggs mature 10 days in soil before infectious

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13
Q

Pathology of whipworm infection depends on _______

A

worm burden

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14
Q

Describe the pathology of whipworm infection

A

Low to moderate: usually none; bleeding; bacteremia
High: disrupted colonic mucosa, bloody stool, prolapse, anemia

Heavy burden in children leads to impaired growth cognitive ability

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15
Q

Is there any immunity to whipworm infection?

A

Possibly some- acquired immunity in natural infections

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16
Q

How is whipworm diagnosed?

A

Only by eggs in stool

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17
Q

What is the treatment for whipworm?

A

3 days of ivermectin, mebendazole or albendazole

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18
Q

Describe transmission of Ascaris lumbricoides

A

Ingestion of eggs from soil, no direct person to person

Adult worms localize to upper intestine

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19
Q

______ is considered a US neglected disease of poverty and is common in Appalachia and the southern US

A

Ascariasis
Hookworm- Necator americanus
Strongyloides

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20
Q

Describe the lifecycle of ascaris lumbricoides

A

Females lay eggs that are passed in feces
Eggs mature in soil then are swallowed
Larvae hatch and invade the intestinal mucosa, enter venous circulation to the lungs and are coughed up and swallowed
Mature and mate in small intestine

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21
Q

The life cycle of _____ is very unique in that the eggs enter through the GI tract but must travel to the lungs, be coughed up and swallowed in order to return to the intestine

A

Ascariasis

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22
Q

Describe the pathology of Ascariasis

A

usually none with low to moderate worm burden
Heavy worm loads can lead to intestinal obstruction
Stressed worms migration to nose, ear, peritoneal, thru body wall
Chronic malnutrition leads to poor mental & physical development

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23
Q

Describe immunity to ascariasis

A

Allergic inflammation from larval migration through the lungs

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24
Q

How is Ascariasis diagnosed?

A

Eggs in stool

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25
Q

How is Ascariasis treated?

A

Mebendazole, albendazole or ivermectin

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26
Q

Necator americanus and Ancylostoma duodenale are also known as:

A

hookworms

27
Q

Describe the transmission of hookworms

A

Invasion of skin in contact with soil

NO direct person to person

28
Q

What is the definitive host of hookworm?

A

Humans

no animal reservoir

29
Q

Describe the life cycle of hookworm

A

Filariform larvae invade skin and go into circulation, lodge in lungs
Larvae are coughed up and swallowed and mature into adults in intestine
Eggs in feces mature in the soil to infectious filariformlarvae form

30
Q

List two worm infections that involve invasion of the lungs and coughing to introduce the organism into the GI tract

A
  • Hookworm (Necator americanus, enters bloodstream through invasion of skin–> lung–> GI)
  • Ascariasis (enters GI–> lung–> back to GI)
31
Q

Describe the pathology of hookworm

A

Initial pruritis at penetration sites
Heavy infection, larval migration through lungs can cause bronchitis
Prolonged infection leads to pulmonary symptoms like Ascaris
Exsanguination (0.03 - 0.3 ml blood/worm/day)
Anemia, reduced mental & physical development in children

32
Q

Describe any immunity to hookworm

A

Asthmatic pathology with repeated infection

33
Q

How is hookworm diagnosed?

A

Anemia + eggs in stool

34
Q

How is hookworm treated?

A

Pyrantel pamoate, albendazole & mebendazole

35
Q

Describe transmission of Strongyloies stercoralis

A

Filariform larvae penetrate

localize to small intestine

36
Q

_______ with strongyloides can result in long term infection

A

Autoinfection

37
Q

What is the definitive host of strongyloides?

A

Humans

38
Q

Describe the life cycle of strongyloides

A

Adult female lays eggs in intestinal mucosa, hatch

  1. Direct: larvae are excreted in feces
  2. Indirect: sexual reproduction occurs in soil under some conditions (environmental amplification)
  3. Autoinfection: larvae mature in the host, enter through colonic mucosa or perianal skin (host amplification)
39
Q

How is strongyloides diagnosed?

A
  • wet mount of stool stained with iodine
  • human fecal smear with immunostaining
  • agar plate culture for motile larvae
  • gram staining of sputum can detect filariform larvae for diagnosing pulmonary strongyloidiasis
40
Q

Gram staining of sputum can detect filariform larvae for diagnosis of _______

A

pulmonary strongyloidiasis

41
Q

Describe the pathology of strongyloides

A

Pulmonary manifestations
High burden leads to chronic intestinal malabsorption, dysentery
Rash on buttocks, legs and lower back due to autoinfection
Autoinfection and immunosuppression leads to hyperinfection that can be fatal

42
Q

_______ infection in immune suppressed people can lead to hyperinfection that can be fatal

A

Stronyloides autoinfection

43
Q

How is strongyloides diagnosed?

A

Larvae in stool, sputum
eggs NOT seen in fecal specimens
serology

44
Q

How is strongyloides treated?

A

ivermectin 1st choice, thiabenazole 2nd choice

45
Q

_______ is transmitted by eating raw or undercooked pork containing encysted larvae

A

Trichinella spiralis (trichinosis)

46
Q

What are the definitive and intermediate hosts of Trichiniella spiralis?

A

Definitive: bears, swine
Incidental: humans- dead end hosts

47
Q

Describe risk factors for Trichinosis

A

Home made sausage, hunting, undercooked pork and bear meat

48
Q

Describe the life cycle of Trichinella

A

Transmitted to humans by eating undercooked meat containing encysted larvae
Larvae are released into GI tract
Adults develop, mate in small intestine, female embeds in mucosa
Live larvae are birthed (no eggs)
Larvae enter lymphatics, blood and encyst in muscle
Larvae develop into an encapsualted spiral which is viable for up to 10 years

49
Q

In ____, the female embeds in the intestinal wall after mating and births live larvae rather than laying eggs

A

Trichinella spiralis

50
Q

Describe the pathology of Trichinosis

A

Mild pathology from adult worms= nausea, cramps
Localized inflammation around individual cyst;
degeneration of muscle cell architecture
Severity related to the number of cysts. Severe symptoms: fever, muscle pain, weakness, cardiac and neural dysfunction, conjunctivitis

51
Q

List unique clinical sigs of Trichinosis

A

eosinophilia, periorbital edema, myositis, fever

52
Q

How is Trichinosis diagnosed

A

clinical presentation

serologic tests

53
Q

How is Trichinosis treated

A

Mebendazole or albendazole

corticosteroids for symptoms

54
Q

_______ is transmitted by cats and dogs

A

Toxocariasis canis/ cati

55
Q

What are the definitive and intermediate hosts of Toxocariasis

A

Definitive: dogs
Incidental: humans

56
Q

How is toxocariasis transmitted

A

ingestion of embryonated eggs from soil, no direct person to person

57
Q

Describe the life cycle of Toxocara canis

A

Sexual cycle in dogs produces eggs in the feces, larvae encyst in tissue and infect puppies in utero
Humans are infected by ingestion of eggs from dogs
In humans larvae burrow through the intestine and migrate for months in any tissue

58
Q

What is visceral larva migrans

A

Toxocara canis larval migration in a dead end host

in humans- larvae burrow through the intestine and migrate through different tissues

59
Q

Describe the pathology of Toxocariasis

A

Light infection: self-limiting with little pathology
Heavy worm loads can lead to severe necrosis in any location
Enlarged liver, pulmonary complications, ocular lesion, neurological symptoms all grouped as visceral larva migrans

60
Q

Describe any immunity to toxocariasis

A

Asthmatic and immune hypersensitivity are common

61
Q

How is toxocariasis diagnosed?

A

NO eggs in stool because infection does not progress to adults
History of geophagia (eating dirt) and/or exposure to dogs
ELISA for larval antigens, but can cross with Ascaris

62
Q

How is toxocariasis treated?

A

Albendazole or mebendazole in all cases

Corticosteroids in severe cases

63
Q

How can toxocariasis be prevented?

A

Properly dispose of dog waste

De-worm dogs

FM3_ EB (25 decks)

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