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FM3_ EB > Parasitology I > Flashcards

Parasitology I Flashcards

1
Q

Endoparasites are divided into two major groups:

A
  • protozoa (unicellular)

- helminths (multicellular worms)

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2
Q

Differentiate between the definitive host and the intermediate host

A

Definitive: host in which the sexual stage of the life cycle occurs
Intermediate: host in which asexual reproduction or development can occur

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3
Q

An ______ host is not an obligate part of a parasite’s life cycle

A

incidental/ accidental

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4
Q

What is a reservoir?

A

Animal host that maintains the natural cycle of infection in the wild, often not harmed by carriage

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5
Q

List the 5 CDC neglected parasitic infections in the US

A
  1. Chagas, caused by Trypanasoma cruzi
  2. Neurocysticercosis caused by Taenia sp
  3. Toxocariasis caused by Toxocara canis/ cati
  4. Toxoplasmosis: leading cause of foodborne deaths, congenital infection
  5. Trichomoniasis
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6
Q

Most protozoan infections elicit a _____ immune response.

Worms generally elicit a ________ immune response

A

protozoa: Th1
Worms: Th2/ eosinophils

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7
Q

Differentiate between: cyst, cysticeri, hyadatid cyst

A

Cyst: Dormant stage found encysted in host tissue (intermediate or definitive) so can be passed by eating undercooked meat

Cysticerci: Encysted cestode larval forms in tissues of infected intermediate hosts. Example: Humans/pork tapeworm

Cyst, Hydatid: Specialized cysticercal form of the cestode Echinococcus granulosus found in the intermediate host

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8
Q

Metacercaria, Miracidium, Microfilariae, Cercaria,

Filariform, Rhabditiform, Schistosomula, Sporocyst are alternate names for:

A

larvae

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9
Q

Class cestoda contains the

A

tapeworms

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10
Q

Class trematoda contains the

A

flukes

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11
Q

_____ have no internal digestive system and absorb nutrients across the cuticle.
_____ have a simple digestive system

A

Tapeworms- no digestive system

Flukes/ roundworms- have a simple digestive system

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12
Q

Describe the lifecycle of Taenia solium

A

Pork tapeworm

Pigs are the intermediate hosts and get cysticeri in their meat
Humans are the definitive host and shed eggs and proglottids in feces. Pigs do not shed eggs

Pigs become infected when they eat tapeworm eggs or proglottids

Humans become infected when they eat undercooked pork with cysticeri or tapeworm eggs form other humans

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13
Q

Only ___ shed eggs of Tania solium

A

humans

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14
Q

Distinguish between taeniasis and cysticercosis

A

When humans eat undercooked pork they get taeniasis- tapeworm in the intestine
When humans eat tapeworm eggs they get cysticercosis- larva in muscle, eyes, brain

beef tapeworm eggs are NOT infectious to people, only pork tapeworm eggs cause cystircercosis

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15
Q

Describe the location of Taenia solium infection

A

location: adult worms in intestin, cysticerci in any tissue but especially brain

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16
Q

What is the definitive host of Taenia solium

A

Humans

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17
Q

What is the intermediate host of Taenia solium

A

Humans or pigs

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18
Q

Describe the pathology of Taenia solium

A
  • Taeniasis is often asymptomatic or causes abdominal discomfort, occasionally nausea, vomiting, diarrhea, weight loss & obstruction
  • Cysticercosis cysticerci located in any tissue; in the brain can cause confusion, difficulty with balance, brain swelling, hydrocephalus, seizures, headaches and mortality
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19
Q

How is diagnosis of Taenia solium made?

A

Self or clinical- proglottids in stool

X ray, CT, MRI

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20
Q

Describe any immunity to Taenia solium

A

Humoral response to adults worms, reinfection is possible

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21
Q

Describe treatment for Taenia solium

A

Praziquantel, niclosamide or albendazole, single dose effective for adult worms but prolonged treatment for cysticerci

Dexamethasone added for infection of CNS

22
Q

How can Taenia solium be avoided?

A

Fully cook pork

Public and personal hygiene

23
Q

Describe the transmission of Diphyllobothrium latum

A

Fish tapeworm

Ingestion of undercooked fish containing plerocercoid

24
Q

What is the definitive and intermediate host of Diphyllobothrium latum?

A

Definitive: Humans
Intermediate: copepod that infects fish

25
Q

Where is Diphyllobothrium latum endemic?

A

Temperate zones, brought to new world by European immigrants

26
Q

Describe the pathology of Diphyllobothrium latum

A

Like beef tapeworm; adults absorb 80-100% dietary B12 leading to deficiency, anemia, neurologic symptoms

27
Q

Describe immunity to Diphyllobothrium latum

A

No clinically relevant immunity, reinfection is possible

28
Q

How is Diphyllobothrium latum diagnosed?

A

Proglottids in stool, distinct from Taenia spp eggs

29
Q

How is Diphyllobothrium latum treated?

A

praziquantel or niclosamide, single dose

30
Q

How is Diphyllobothrium latum prevented?

A

Public hygiene, well cooked fish

31
Q

_________ causes hydatid disease

A

Echinococcus granulosus

32
Q

Ehinococcus granulosus localizes mainly to the:

A

lung, liver, spleen, kidney, heart, bone, CNS

33
Q

How is Echinococcus graulosus transmitted

A

Ingestion of eggs from dogs

34
Q

What is the definitive host of Echinococcus granulosus?

A

Wild and domestic canines

35
Q

What is the intermediate host of Echinococcus granulosus

A

Wild and domestic ungulates, humans

36
Q

Describe the life cycle of Echinococcus granulosus

A
  • Basic cestode lifecycle; humans as intermediate/ dead end host only
  • Requires intimate contact with dogs
37
Q

How are dogs infected with Echinococcosis?

A

Ingest internal organs of sheep, goats, etc. Pastoral cycle

38
Q

Describe the pathology of Echinococcosis

A

Hydatid cysts in liver (50-70%) and lungs (20-30%), but also spleen, kidney, bone and CNS
Latent periods up to 20 years
Disease onset when hydatid cysts cause pain or rupture
Cyst rupture can seed new sites by release of protoscolices
Anaphylaxis associated with rupture can be fatal but is rare

39
Q

Describe immunity to Echinococcosis

A

Circulating antibodes to hyatid cyst antigens, more pathologic than protective

40
Q

How is echinococcosis diagnosed?

A

Reside in endemic area or animal husbandry/ hunting
CT/ultrasound for cysts
Serology for confirmation

41
Q

How is echinococcosis treated

A

percutaneous drainage wiht instillation of hypertonic saline, surgical removal, albendazole if not resectable (poor cure rate)

42
Q

Describe measures to prevent echinococcosis

A

De-worm dogs, don’t feed intestines, good hygiene around dogs

43
Q

Describe transmission of schistosomiasis

A

Invasive, aquatic free living cercaria penetrate skin

44
Q

What are the definitive and intermediate hosts of schistosomiasis?

A

Definitie: humans, male-female pairings in blood
Intermediate: snails

45
Q

Pathology of schistosomiasis is proportional to ________

A

worm burden

46
Q

Schisosome _____ eggs are found in the stool and have a ____ spike
Schistosome ____ eggs are found in the urine and have a ____ spike

A

mansoni in stool, lateral spike

Haematobium in urine, terminal spike

47
Q

Describe the stages of schistosomiasis pathology:

A
  • Early: asymptomatic, rash that subsides and then fever, headache, nausea
  • Middle: immune response to eggs, blood in urine/ stool, abdominal pain
  • Chronic: eggs lodge in liver and intestine (mansoni, japonicum) or bladder (hematobium) and can lead to fibrosis and cancer
48
Q

What is Katayama syndrome?

A

Intense reaction in patients infected with schistosomiasis for the first time, fever with onset of oviposition

49
Q

Describe treatment of schistosomiasis

A

Praziquantel in single (S.m., S.h.) or multiple (S.j.) dose

Potentiates active immune system killing of adult worms

50
Q

Describe the diagnosis of schistosomiasis

A

observation of eggs in feces, urine

Serology now available

51
Q

Describe prevention measures for schistosomiasis

A

Treat infected individuals, proper waste disposal, control of intermediate hosts (snails), avoid contact with infected water

52
Q

Describe the association between hepatitis C and schistosomiasis

A

earlier mass treatment (with tartar emetic) of Schistosomiasis in Egypt used contaminated needles leading to HCV infection.
Chronic inflammation from schistosomiasis exacerbates HCV
Be suspicious in middle aged Egyptian men

FM3_ EB (25 decks)

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