Tropical Medicine: Worms

Question 1

Why do worms kill us?

Answer 1

If the human is not the natural host of the worm

Question 2

Do worms replicate inside the host?

Answer 2

No- part of their life cycle is outside the host

Question 3

What is the shape of cestodes?

Answer 3

Segmented plane

Question 4

What is the body cavity of cestodes?

Answer 4

No body cavity

Question 5

What is the digestive tube of cestodes?

Answer 5

No digestive tube

Question 6

What is the sex of cestodes?

Answer 6

Hermaphroditic

Question 7

What is the attachment organs of cestodes?

Answer 7

Suckers and Hooks

Question 8

Give an example of cestodes?

Answer 8

Tapeworm

Question 9

What is the body covering of cestodes?

Answer 9

Tegument

Question 10

What is the shape of trematodes?

Answer 10

Unsegmented plane

Question 11

What is the body cavity of trematodes?

Answer 11

None

Question 12

What is the body covering of trematodes?

Answer 12

Tegument

Question 13

What is the digestive tube of trematodes?

Answer 13

Ends in Caecum

Question 14

What is the sex of trematodes?

Answer 14

Hermaphroditic except schistosomes

Question 15

What is the attachment organs of trematodes?

Answer 15

Oral and ventral suckers

Question 16

Give an example of trematodes?

Answer 16

Schistosomiasis

Question 17

What is the shape of Nematodes?

Answer 17

Cylindrical

Question 18

What is the body cavity of Nematodes?

Answer 18

Present

Question 19

What is the body covering of Nematodes?

Answer 19

Cuticle

Question 20

What is the digestive tube of Nematodes?

Answer 20

Ends in anus

Question 21

What is the sex of Nematodes?

Answer 21

Dioecious

Question 22

What is the attachment organs of Nematodes?

Answer 22

Lips, teeth, filariform extremities and dentary plates

Question 23

Give an example of Nematodes?

Answer 23

Ascaris

Question 24

What is a cestode?

Answer 24

Tapeworms- Hydatid, pork/beef/ fish tapeworms

Question 25

What is a trematode?

Answer 25

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

Question 26

What is a Nematode?

Answer 26

Roundworms- Hookworms, Ascarids, Strongyloides

Question 27

What are the names of the pork and beef tapeworms?

Answer 27

Pork: Taenia Solium Beef: Taenia Saginata

Question 28

What causes neurocystericosis?

Answer 28

T Solium egg ingestion (faecal oral route)

Question 29

What does the dog tapeworm do?

Answer 29

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

Question 30

What is the lifecycle of the pork/ beef tapeworm?

Answer 30

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

Question 31

What is the treatment of worms?

Answer 31

Praziquantel

Question 32

What is the treatment of cysts?

Answer 32

Hydatid – drugs don’t penetrate cysts -> may require surgery, long-term albendazole, praziquantel Cysticercosis – dying worms cause trouble -> albendazole, praziquantel and steroids

Question 33

How do you prevent worms?

Answer 33

Hygiene De worm dogs Cull foxes

Question 34

How many species of schistosomiasis are there?

Answer 34

4

Question 35

What is the lifecycle of schistosomiasis?

Answer 35

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

Question 36

What is the diagnosis of schistosomiasis?

Answer 36

Sx: Bladder/ bowel damage and cancer, Cirrhosis Microscopy: Urine: S. haematobium Stool: S. mansoni, S. japonicum Serology Biopsy Response to treatment

Question 37

How do you treat and prevent schistosomiasis?

Answer 37

Praziquantel Kills snails/ worms Stop swimming in rivers

Question 38

What are the 4 important soil transmitted helminths?

Answer 38

Ascaris Lumbricoides Strongyloides Stercoralis Hookworm Lymphatic filariasis

Question 39

Why do the soil transmitted helminths cause symptoms?

Answer 39

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

Question 40

What is the life cycle of Ascaris lumbricoides?

Answer 40

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

Question 41

What is the lifecycle of Strongyloides?

Answer 41

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

Question 42

What damage does Strongyloides cause?

Answer 42

Hyperinfection Larva currens (itchy rash) Malabsorption

Question 43

How do you treat and prevent Strongyloides?

Answer 43

Ivermectin and hygiene

Question 44

What are the types of filariasis?

Answer 44

o Lymphatic filariasis Wuchereria, Brugia o Subcutaneous filariasis Onchocerciasis, Mansonella, Loa Loa o Serous cavity filariasis Mansonella, Dirofilaria

Question 45

How is filariasis spread?

Answer 45

Blackflies and Mosquitos

Question 46

How does filariasis cause damage?

Answer 46

Scrotal swelling | Onchocerciasis (river blindness. nodules, depigmentation)

Question 47

How do you diagnose filariasis?

Answer 47

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

Question 48

What is myiasis?

Answer 48

Parasitisation of human flesh by fly larvae

Question 49

What are the types of myiasis?

Answer 49

Bot Fly | Tumbu Fly

Question 50

What is the main symptoms of myiasis?

Answer 50

Local damage is caused by maggots eating necrotic flesh

Question 51

What is the treatment of myiasis?

Answer 51

Asphyxiation or surgery

Question 52

What causes eosinophilia?

Answer 52

``` 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 ```

Question 53

What is a reasonable parasite screen?

Answer 53

Serology: Strongyloides, Schistosoma, filaria (if exposure) Stool microscopy