PH1123 - protozoa & helminths

Question 1

What are the properties of protozoa?

Answer 1

Eukaryotic, unicellular, heterotrophic, lives in or on other organisms often in aqueous environments

Question 2

What are the 2 stages of the malaria life cycle?

Answer 2

Erythrocytic cycle and the Exoerythrocytic cycle.

Question 3

How can malaria be prevented?

Answer 3

Mosquito control- nets, insecticides.

Prophylaxis- chosen on many factors e.g risk of exposure.

Question 4

What is the exoerythrocytic cycle

Answer 4

Stage that involves the liver, this is where the parasite multiplies in the liver cell. It then bursts releasing merozoites.

Question 5

What is the erythrocytic stage?

Answer 5

Merozoites infect erythrocytes to form an immature then a mature trophozoite, the immature trophozoite can either form a gametocyte which will be ingested by a mosquito or can mature and causes lysis of the cell so more merozoite is released.

Question 6

Why does prophylaxis have to be taken up to 4 weeks after leaving an endemic area?

Answer 6

Malaria prevention drugs only work in the erythrocytic cycle so if a patient stops taking treatment and a merozoite releases then symptoms will start to appear.

Question 7

What are the 4 malaria prevention drugs?

Answer 7

Chloroquine, Mefloquine, Doxycycline, Malarone.

Question 8

What are the 3 malaria treatments?

Answer 8

Quinine, Malarone, Riamet.

Question 9

How does riamet work?

Answer 9

Stops the malaria parasites being able to convert haem into haemozoin this is toxic if haem gets to high so parasites in the blood stage are killed.

Question 10

How does malaone work?

Answer 10

Interferes with pathways that make pyrimidines required for nucleic acid replication.

Question 11

What does the protozoa Cryptosporidium parvum cause?

Answer 11

Cryptosporidiosis. If ingested causes diarrhoea, abdominal pain and nausea. its spread by the faecal oral route or by water contamination.

Question 12

What is the treatment for cryptosporidiosis?

Answer 12

Fluid and electrolyte replacement ( no licensed drugs in the uk)

Question 13

What cause amoebic-dysentery?

Answer 13

Entamoeba histolytica spread through contaminated water and the oral faecal route.

Question 14

What are the symptoms of amoebic dysentery?

Answer 14

It may or may not b symptomatic and can remain latent. Ranges from mild diarrhoea to blood and mucus in the stool.

Question 15

What are the two major forms of severe amoebiasis infection?

Answer 15

Invasion of intestinal lining causes amoebic dysentery or amoebic colitis.
If parasite reaches the blood stream then it can spread to the liver where it causes amoebic liver abscesses.

Question 16

What is the life cycle of Entamoeba histolytica?

Answer 16

Ingestion
Cysts form and rupture
Releases amoeboid trophozoites.
feed on bacteria and reproduce asexually in the colon.
Causes ulceration and that can mean the parasite enters blood vessels.

Question 17

What are the types of parasitic worms?

Answer 17

Flukes, tapeworms, roundworms, threadworms, hookworms, whipworms.

Question 18

What infections can worms cause?

Answer 18

Schistosomiasis.
Lymphatic filariasis (elephantiasis)
Onchocerciasis (river blindness)

Question 19

What are the symptoms of worms?

Answer 19

Stomach upset (pain, nausea or vomiting).
Reduced nutritional uptake.
Intestinal obstruction or bleeding.
Presence of worm in stools or vomit.
flu like symptoms (fatigue, fever)
skin rash
breathing difficulties if lungs affected.

Question 20

What does mebendazole treat?

Answer 20

Threadworm, roundworm, whipworm by inhibiting the synthesis of microtubules.

Question 21

What does praziquantel treat?

Answer 21

Tapeworm, whipworm, roundworm by increasing the permeability of the membranes causing paralysis.

Question 22

What are the drugs that treat worms called?

Answer 22

Anthelmintic.