Helminths of Medical & Veterinary Importance

Question 1

Zoonosis

Answer 1

Refers to a disease / infection / infestation which is naturally transmitted between vertebrate animals and humans

Question 2

Anthropozoonosis

Answer 2

Infections acquired by humans from other vertebrates

Question 3

Zooanthroponosis

Answer 3

Infections primarily of human origin that are acquired by other vertebrates

Question 4

Trematoda (flukes) (class)
Egg

Answer 4

• Shed in faeces or urine

Question 5

Fasciola (Genus)
Liver Fluke
Give the Species and their definitive hosts

Answer 5

Fasciola hepatica
Fasciola gigantica

Small stock / cattle + Pig/Horse (rare) + Humans

Question 6

Fasciola (Genus)
Liver Fluke
Give the Genus of the infective host

Answer 6

Lymnaea
( aquatic or freshwater snails)

Question 7

Fasciola (Genus)
Liver Fluke
Give the Predilection site

Answer 7

Bile ducts

Question 8

Fasciola (Genus)
Liver Fluke
Explain the Parasitic development (DH)

Answer 8

• Excystment of metacercariae and penetration of intestinal
  wall
• Migration of juvenile flukes in peritoneal cavity
• Migration in liver parenchyma
• Growth to maturity in bile ducts

Question 9

Fasciola (Genus)
Liver Fluke
Give the Characters of adult worms

Answer 9

 2-7.5 cm long + 3-15 mm wide
 Dorsoventrally flattened
 Leaf-shaped
 Brown greyish
 Conical anterior end

Question 10

Fasciola (Genus)
Liver Fluke
Give the Characters of the eggs

Answer 10

 Oval
 Large-sized
 Contain fine granular material
 Yellowish-brown
 Thin-shelled
 Indistinct operculum

Question 11

Fasciola (Genus)
Liver Fluke
Importance

Answer 11

-One of the economically most important helminth
infections of ruminants in SA
-Anthropozoonosis (vegetables grown in snail-infested
habitats grazed by ruminants)
-no treatment available for human infections

Question 12

Schistosoma (Genus)
Blood fluke
Give the Species and their definitive hosts

Answer 12

• Schistosoma haematobium
• Schistosoma mansoni
  HUMANS

Question 13

Schistosoma (Genus)
Blood fluke
Give the Genus of the infective host

Answer 13

Bulinus
Aquatic freshwater snails

Question 14

Schistosoma (Genus)
Blood fluke
Give the infective stage

Answer 14

Cercaria

Question 15

Schistosoma (Genus)
Blood fluke
Infection

Answer 15

Percutaneous + Ingestion of cercariae
Cercaria penetrates skin

Question 16

Schistosoma (Genus)
Blood fluke
Characters (adult worms)

Answer 16

 Elongate
 Unisexual and dimorphic
♀ Cylindrical
♂ Longitudinally curved (‘gutter’)
 Always encountered in pairs

Question 17

Schistosoma (Genus)
Blood fluke
Characters (eggs)

Answer 17

 Spindle-shaped
 Large-sized

Question 18

Schistosoma (Genus)
Blood fluke
Clinical Signs of Schistosoma haematobium

Answer 18

• Haematuria (blood in urine)
• Tissue reactions to retained eggs (granuloma formation in bladder - malignant
  neoplasia)

Question 19

Schistosoma (Genus)
Blood fluke
Clinical Signs of Schistosoma mansoni

Answer 19

• Blood in stool
• Tissue reactions to retained eggs (granuloma formation in liver - occlusion of
  intrahepatic portal veins)

Question 20

Cestoda (tape-worms) (class)
Describe the head Strobilar stage - Scolex

Answer 20

 Spherical
 Four suckers (acetabula)
 With or w/o protrusible rostellum armed with hooks

Question 21

Cestoda (tape-worms) (class)
Describe the Strobila

Answer 21

 Chain of proglottids
 Each proglottid with 1 or 2 sets of ♂ and ♀ sexual organs
 Gravid proglottids
- Contain embryonated (infective) eggs

Question 22

Cestoda (tape-worms) (class)
What are the metacestode types?

Answer 22

 Cysticercoid
 Cysticercus (measle)
 Hydatid, hydatid cyst

Question 23

Dipylidium caninum
Infective host?

Answer 23

Fleas + Lice
Ctenocephalides felis

Question 24

Taeniidae (Genus)
Definitive host?

Answer 24

Humans: Taenia solium + Taenia saginata

carnivores: Echinococcus granulosus

Question 25

Taeniidae (Genus)
Intermediate host?

Answer 25

Small stock / Cattle / Pig: Taenia spp. + Echinococcus granulosus

Question 26

Taeniid eggs
Characteristics

Answer 26

Cannot be differentiated
morphologically or morphometrically
to genus or species level
Spherical
Small-sized

Question 27

Pork tapeworm

Answer 27

Taenia solium

Question 28

Beef tapeworm

Answer 28

Taenia saginata

Question 29

Cysticercus cellulosae

Answer 29

Pork measles

Question 30

Does Taenia solium or Taenia saginata have an armed rostellum on the scolex?

Answer 30

Taenia solium

Question 31

Cysticercus bovis

Answer 31

Beef measles

Question 32

Are humans an accidental host for Taenia solium or Taenia saginata?

Answer 32

Taenia solium

Question 33

Hydatid disease in humans caused by?

Answer 33

Echinococcus granulosus

Question 34

Nematoda (Roundworms)
which larval stage is infectious for DH

Answer 34

3rd larval stage

Question 35

Nematoda (Roundworms)
which larval stage is infectious for IH

Answer 35

1st larval stage

Question 36

Strongyloides stercoralis (Threadworm) definitive host

Answer 36

Humans

Question 37

Strongyloides stercoralis (Threadworm) predilection site

Answer 37

Upper small intestine

Question 38

Ancylostoma (hookworm)
predilection site

Answer 38

small intestine

Question 39

Ascarsis (Genus)
give the species and definitive hosts

Answer 39

Ascarsis suum - pig
Ascarsis lumbricoides - man

Question 40

Toxocara (Genus)
what do these eggs look like

Answer 40

Golf balls

Question 41

Loa loa vector?

Answer 41

Chrysops

Question 42

Can Loa loa be found in the eye
Yes
No

Answer 42

Yes

Question 43

What causes elephantiasis?

Answer 43

Wuchereria bancrofti

Question 44

What causes river blindness?

Answer 44

Onchocerca volvulus

Question 45

Vector of river blindness?

Answer 45

Simulium (Black fly)

Question 46

What is whipworm?

Answer 46

Trichurus trichiura

Question 47

What do the whipworm eggs look like?

Answer 47

Lemons