Tropical Medicine: Worms Flashcards

1
Q

Why do worms kill us?

A

If the human is not the natural host of the worm

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2
Q

Do worms replicate inside the host?

A

No- part of their life cycle is outside the host

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3
Q

What is the shape of cestodes?

A

Segmented plane

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4
Q

What is the body cavity of cestodes?

A

No body cavity

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5
Q

What is the digestive tube of cestodes?

A

No digestive tube

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6
Q

What is the sex of cestodes?

A

Hermaphroditic

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7
Q

What is the attachment organs of cestodes?

A

Suckers and Hooks

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8
Q

Give an example of cestodes?

A

Tapeworm

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9
Q

What is the body covering of cestodes?

A

Tegument

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10
Q

What is the shape of trematodes?

A

Unsegmented plane

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11
Q

What is the body cavity of trematodes?

A

None

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12
Q

What is the body covering of trematodes?

A

Tegument

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13
Q

What is the digestive tube of trematodes?

A

Ends in Caecum

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14
Q

What is the sex of trematodes?

A

Hermaphroditic except schistosomes

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15
Q

What is the attachment organs of trematodes?

A

Oral and ventral suckers

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16
Q

Give an example of trematodes?

A

Schistosomiasis

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17
Q

What is the shape of Nematodes?

A

Cylindrical

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18
Q

What is the body cavity of Nematodes?

A

Present

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19
Q

What is the body covering of Nematodes?

A

Cuticle

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20
Q

What is the digestive tube of Nematodes?

A

Ends in anus

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21
Q

What is the sex of Nematodes?

A

Dioecious

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22
Q

What is the attachment organs of Nematodes?

A

Lips, teeth, filariform extremities and dentary plates

23
Q

Give an example of Nematodes?

A

Ascaris

24
Q

What is a cestode?

A

Tapeworms- Hydatid, pork/beef/ fish tapeworms

25
Q

What is a trematode?

A

Flukes- Lung, Liver, Intestines, Blood (Schistosoma)

26
Q

What is a Nematode?

A

Roundworms- Hookworms, Ascarids, Strongyloides

27
Q

What are the names of the pork and beef tapeworms?

A

Pork: Taenia Solium
Beef: Taenia Saginata

28
Q

What causes neurocystericosis?

A

T Solium egg ingestion (faecal oral route)

29
Q

What does the dog tapeworm do?

A

Humans are accidental hosts- cyst phase occurs in sheep- complications from mass effect or cyst rupture

30
Q

What is the lifecycle of the pork/ beef tapeworm?

A
  1. Eggs eaten by animal,
  2. Hatch and burrow into intestines
  3. Humans eat infected meat
  4. Cysts release tapeworms into the GI tract
31
Q

What is the treatment of worms?

A

Praziquantel

32
Q

What is the treatment of cysts?

A

Hydatid – drugs don’t penetrate cysts -> may require surgery, long-term albendazole, praziquantel

Cysticercosis – dying worms cause trouble -> albendazole, praziquantel and steroids

33
Q

How do you prevent worms?

A

Hygiene
De worm dogs
Cull foxes

34
Q

How many species of schistosomiasis are there?

A

4

35
Q

What is the lifecycle of schistosomiasis?

A

o Cercariae invade human skin in contaminated water

o Worms circulate and develop in the liver

o Adult worms migrate to mesenteric venules (japonicum, mansoni) or venous plexus of bladder (haematobium)

o Eggs excreted into faeces and urine

o Hatch into miricidia, which parasitise snails

o Snails release cercariae

36
Q

What is the diagnosis of schistosomiasis?

A

Sx: Bladder/ bowel damage and cancer, Cirrhosis

Microscopy:
Urine: S. haematobium
Stool: S. mansoni, S. japonicum

Serology

Biopsy

Response to treatment

37
Q

How do you treat and prevent schistosomiasis?

A

Praziquantel
Kills snails/ worms
Stop swimming in rivers

38
Q

What are the 4 important soil transmitted helminths?

A

Ascaris Lumbricoides
Strongyloides Stercoralis
Hookworm
Lymphatic filariasis

39
Q

Why do the soil transmitted helminths cause symptoms?

A

o Migration (ascaris, hookworm, strongyloides)
o Intestinal obstruction (ascaris)
o Malabsorption and blood loss (all)
o Psychological distress

40
Q

What is the life cycle of Ascaris lumbricoides?

A

Respiratory stage
Eggs ingested, larvae hatch in GI tract, are absorbed and then migrate to lungs to grow

Gastrointestinal stage
Larvae are coughed up and re-swallowed to gastrointestinal tract to mature

41
Q

What is the lifecycle of Strongyloides?

A

INVADE skin
MATURE into pinworms in small bowel
EGGS HATCH rhabditiform larvae
AUTOINFECT (only worm to do so) via perianal skin

42
Q

What damage does Strongyloides cause?

A

Hyperinfection
Larva currens (itchy rash)
Malabsorption

43
Q

How do you treat and prevent Strongyloides?

A

Ivermectin and hygiene

44
Q

What are the types of filariasis?

A

o Lymphatic filariasis Wuchereria, Brugia

o Subcutaneous filariasis Onchocerciasis, Mansonella, Loa Loa

o Serous cavity filariasis Mansonella, Dirofilaria

45
Q

How is filariasis spread?

A

Blackflies and Mosquitos

46
Q

How does filariasis cause damage?

A

Scrotal swelling

Onchocerciasis (river blindness. nodules, depigmentation)

47
Q

How do you diagnose filariasis?

A

o Find microfilariae (blood film, skin snips)
o Find antibodies (ELISA)
o Find adults (dance sign on USS, Loa Loa migration across the eye)

48
Q

What is myiasis?

A

Parasitisation of human flesh by fly larvae

49
Q

What are the types of myiasis?

A

Bot Fly

Tumbu Fly

50
Q

What is the main symptoms of myiasis?

A

Local damage is caused by maggots eating necrotic flesh

51
Q

What is the treatment of myiasis?

A

Asphyxiation or surgery

52
Q

What causes eosinophilia?

A
o	Atopy 
o	Drug allergy 
o	Malignancy:
	Hodgkin's lymphoma 
	Some forms of Non-Hodgkin Lymphoma 
o	Systemic autoimmune disease (e.g. SLE) 
o	Some forms of vasculitis (e.g. Churg-Strauss syndrome) 
o	Cholesterol embolism (transient)
o	PARASITES
	Soil transmitted helminths (especially Strongyloides)
	Schistosomiasis
	Filariasis 
	Leaking hydatid cysts
53
Q

What is a reasonable parasite screen?

A

Serology: Strongyloides, Schistosoma, filaria (if exposure)

Stool microscopy