L9- Parasitology

Question 1

What is the life cycle of the tsetse fly?

Answer 1

1. Parasite injected into blood stream when infected fly bites human
2. Injected metacyclic trypomastigotes transform into bloodstream trypomastigotes and are carried to other sites
3. Trypomastigotes multiply in various body fluids

Question 2

What is the treatment for trypanosomiasis?

Answer 2

• Pentamidine- T. gamb.
• Melarsoprol- both, toxic
• Elflornithine- T.b. gamb.
• Suramin- T. b. rhod.

Question 3

What is the host immune response?

Answer 3

• Not killed by immune system
• Variable surface glycoprotein coating is present and it makes the cell membrane thick and hard to recognise
• Antigenic variation is frequent and no vaccines

Question 4

What are schistomes?

Answer 4

• Heminth worms causing schistomiasis (snail fever)
• Carried by fresh water snails (intermediate host)
• Infection occurs when larval forms of the parante penetrate skin during contact with infested water

Question 5

What is the life cycle of schistomes?

Answer 5

• Larvae develop into adult schistomes in body and live in blood vessels where females release eggs
• Eggs passed out of body in faeces or urine to continue parasites life cycle
• Others become trapped in the body tissues causing immune reactions and progressive damage

Question 6

What are symptoms of schistomiasis?

Answer 6

• No initial symptoms
• Rash or itchy skin within days
• 1-2 months fever, chills, cough, muscle aches

Question 7

What are the different types of schistomiasis?

Answer 7

• Urinary- haematouria (blood in urine), bladder cancer
• Intestinal- GI bleeding, abdominal pain and enlarged liver
• Rarely eggs found in brain or spinal cord and cause paralysis, seizures and inflammation

Question 8

What is acaris?

Answer 8

• Cream coloured round worm
• Parasitic in intestines of humans
• Most common helminthic nematode human infection

Question 9

What are the modes of transmission of acaris?

Answer 9

Definitive host: humans or pigs, no intermediate host
• Occurs mainly via ingestion of water or food contaminated with A. lumbricoides eggs
• Contaminated soil or dust

Question 10

What are the symptoms of round worm infection?

Answer 10

• Haemorrhagic/eosinophilic pneumonia
• Cough, breathing difficulties
• Fever
• Abdominal discomfort
• Malnutrition

Question 11

What is the host immune response?

Answer 11

• Innate- worms coated with IgG and IgE which increase release of eosinophil granules on worms surface
• Adaptive- Th2 immune response with IL-4 production, high IgE, eosinophilia and mastocytosis