Lecture 5 - Parasitic diseases

Question 1

Name the most common species of malaria

Answer 1

plasmodium falciparum (75% of UK cases)

Question 2

Briefly describe the life cycle of malaria

Answer 2

mosquito injects sporozoites into human blood stream. after 15 mins sporozoites enter liver and replicate (into schizont) - no symptoms in hepatic phase.
Some may become latent at liver stage (hypozoites). some emerge and enter back into blood (trophozoites) these go on to infec RBCs and replicate - rupture causing symptoms.
merozoites > gametocytes ( male and female) ingested by mosquito, join together in gut and life cycle continues

Question 3

Who has the highest burden of mortality associated with malaria

Answer 3

children in africa

Question 4

Which type of worms are :
Nematodes
Cestodes
Trematodes

Answer 4

roundworms
tapeworms
flukes

Question 5

What are p. vivax
and p. ovale
examples of ?

Answer 5

parasites that cause malaria

Question 6

How do female mosquitoes transfer malaria?

Answer 6

plasmodium in salivary gland - spat out into human blood

Question 7

Name the main active malaria treatment

Answer 7

quinine + either (doxycycline or clindamycin)

Question 8

name the treatment for benign species of malaria

Answer 8

• chloroquine for RBCs

- primaquine (hypnozoites)

Question 9

Describe the mechanism of choroquine + quinine

Answer 9

when malaria invades red blood cells it forms a parasitophorous vacuole. it then reverses the polarity of RBCs membrane transporters and allows Hb to be pumpes into the vacuole. This is split by malaria into haem (toxic) and globin. The haem is usually polymerised into haemozoin by haem polymerase BUT chloroquine inhibits this therefore the toxic free haem kills plasmodium

Question 10

How does chloroquine get into the RBCs

Answer 10

binds to plasmodium transporters

Question 11

How common is chloroqine resistance in malaria? How does it occur?

Answer 11

20-50% resistance in parts of Africa (and thai boarders) - mutation causes increased chloroquine removal from parasitophorous vacuole

Question 12

What is african trypanosomiasis? transmitted by? reservoir?

Answer 12

protozoan transmitted by tesetse flies

cattle is reservoir

Question 13

What does african trypanosomiasis cause in humans

Answer 13

‘sleeping sickness’ = CNS invasion

Question 14

American trypanosomias is transmitted by? effect in humans?

Answer 14

reduviid bug rubbing faeces into the skin. 
causes swelling (romanes sign) and if enters smooth muscle e.g. GI and heart (causes aneurysm)

Question 15

Where is leishmaniasis from? effect in humans?

Answer 15

sand flys. multiplys in tissue and can be cutaneous and mucocutaneous and visceral.

Question 16

Effect of toxoplasmosis in the immunocompromised and the immunocompetant

Answer 16

Immunocompetant - lymphadenopathy - like galndular fever

immunocompromised - brain absess

Question 17

What is strongyloides?

Answer 17

worm capable of long term infection - hyper infection in immunocompromised - can cause death by gram negative sepsis

Question 18

What is onchocerciasis?

Answer 18

river blindness from blackfly. adults cluster forming a nodule then the lava migrate into tissues. can cause blindness if gets in the eye - need a nodulectomy!

Question 19

Side effects of ivermectin in treating river blindness?

Answer 19

fever, oedema, itch, arthritis and lymphadenopathy

Question 20

How common is p. falciparum resistance to quinine?

Answer 20

still generally sensitive but 50% on some places in Thai boarders

Question 21

What does mabendazole treat?

Answer 21

enterobius (pinworm), ascaris, trichuris, hookworm

Question 22

What is schistosomiasis?

Answer 22

worm that lives in fresh water, snails act as a vector. adults get into the bladder and bowel

Question 23

How is schistosomiasis treated

Answer 23

praziquantel - mass chemotherapy programme,

Question 24

What does praziquantel treat?

Answer 24

Schistosomiasis, cestode - tape worm from taenia (beef or pork)