Parasitology

Question 1

What type of parasite is schistosomiasis?

Answer 1

→helminths

→flukes

Question 2

What are the three main species of schistosomiasis?

Answer 2

→• Schistosoma mansoni
→S. haematobium
→ S. japonicum

Question 3

Describe the life cycle of schistomiasis

Answer 3

→Eggs shed from infected human
→eggs hatch and release miracidia
→miracidia penetrate snail tissue
→sporocysts develop in snail
→free swimming cercariae released from snail into water
→cercariae penetrate skin
→cercariae lose tails during penetration and become schistosomulae
→circulation
→migration to portal blood in liver and maturation into adults
→paired adult worms migrate to bowel, liver, bladder
→eggs shed in urine

Question 4

What is the presentation of schistosomiasis cercarial dermatitis?

Answer 4

→Allergic-type reaction

Question 5

What is a key feature of immune response in schistosomiasis?

Answer 5

granuloma formation

eggs become organised in granulomas

Question 6

What damage can granulomas do in schistosomiasis?

Answer 6

tissue repair leads to fibrosis and

organ damage

Question 7

Which schistosomiasis strains result in hepato-intestinal symptoms?

Answer 7

S.mansoni

S.
japonicum

Question 8

What type of parasite if onchocerciasis?

Answer 8

helminths

Question 9

What is a major disease in onchocerciasis?

Answer 9

blinding disease

Question 10

What is onchocerciasis caused by?

Answer 10

filarial parasite

onchocerca volvulus

Question 11

What is onchocerciasis transmitted by?

Answer 11

blackfires

Question 12

Describe the geographical distribution of onchocerciasis

Answer 12

Africa

South America

Question 13

Describe the life cycle of onchocerciasis

Answer 13

→blackfly takes a blood meal
→subcutaneous tissues
→adults produce unsheathed microfilariae found in skin and lymphatics, urine
→blackfly takes blood meal
→microfilarie penetrate blackfly’s midgut and migrate to thoracic muscle
→migrate to head

Question 14

Why is there damage and scarring in the skin and eyes in onchocerciasis?

Answer 14

→ repeated episodes of inflammation to microfilariae

Question 15

Describe the clinical presentations of skin disease in onchocerciasis

Answer 15

→Acute papular onchodermatitis
→Chronic onchodermatitis
→ sowda

Question 16

What are the clinical eye presentations in onchocerciasis?

Answer 16

→• Punctate keratitis
• Acute iridocyclitis
• Sclerosing keratitis
→Optic neuritis/atrophy
• Chorioretinopathy

Question 17

What are the different molecules involved in acute or chronic onchocerciasis?

Answer 17

Acute
→dendritic cell
→natural or adaptive TReg
→eosinophil

Question 18

What are the different molecules in chronic immune response of onchocerciasis?

Answer 18

→activated macrophages
→IgG
→B2 cells

Question 19

What causes progressive tick paralysis?

Answer 19

→failure of acetylcholine release in neuromuscular junction

→toxin blocks motor nerve fibres

Question 20

What is the difference in disease between hard bodied ticks and soft-bodied ticks?

Answer 20

→hard bodied= rickettsal, bacterial, protozoan diseases

→soft bodied= fever, Q-fever

Question 21

Where do body lice lay their eggs?

Answer 21

→on clothing

Question 22

What are the two types of sucking lice?

Answer 22

→crab lice

→public lice

Question 23

How does suckling lice spread?

Answer 23

→close contact

Question 24

Describe the life cycle of botfly

Answer 24

→fly bites cow

→produces larvas

Question 25

Where is botfly disease endemic to?

Answer 25

→South America

Question 26

What are some treatments for protozoa?

Answer 26

→Tinidazole
→metronidazole
→nitazoxanide

Question 27

What are some treatments for helminths?

Answer 27

→albendazole
→praziquantel
→Ivermectin

Question 28

What are some treatments for ectoparasites?

Answer 28

→ivermectin

→benzyl

Question 29

What are the three ways of controlling parasites?

Answer 29

→behaviour
→environmental interventions
→poverty reduction

Question 30

What are some environmental interventions?

Answer 30

Spraying of residual insecticides for household vectors
• Mosquito nets for malaria
• Improved housing
• Sewage disposal and potable water
• Drainage of swamps

Question 31

Why must treatment be given periodically over long periods?

Answer 31

→re-infections are rapid or

→treatment kills larval rather than adult stages