Antiparasitic agents

Question 1

Types of parasites

Answer 1

Protozoa (unicellular)

• Blood
• Tissue
• Intestine
• Genital

Metozoa (multicelluar)

• Nematodes (roundworms), intestinal, tissue
• Cestodes (tapeworms)
• Trematodes (flukes)

Question 2

Species of malaria

Answer 2

Question 3

Life cycle of malaria

Answer 3

vivax and ovale species can remain latent in liver for severla years as Hypnozoites

Question 4

Malaria epidemiology

Answer 4

• 2000 pa in UK
  
  • 75% falciparum
  • under 10 deaths pa
• 219 million clinical episodes worlwide
  
  • 3 million complicated cases.
  • 0.44 million deaths
  • Children more at risk, less immunity

Question 5

Treatment for falciparum

Answer 5

• artemisin bderivatives +
  
  • ​another drug e.g. Lumefantrine
• OR Quinine+Doxycycline or Clindamycin
• (OR Atovaquone+Proguanil)

Question 6

Treating bening malaria species

Answer 6

• Chloroquine or Primaquine

Question 7

Important concepts in malaria management

Answer 7

Combination therapy

Complete the course

IV for severe malaria

Question 8

Mechanism of chloroquine (and Quinine)

Answer 8

• Paraiste invades and becomes envoleped by membrane; parasiophorous vacuole
• RBC transporters, on vacuole import Hb and utilises globin
  
  • Free haem is toxic to parasite; clumps in into haemozoin by haem polymerase
  • Chloquine diffuses across surfaces of vacuole and inhibites haempolymerase; toxic accumulation

Question 9

Chloroquine resistance

Answer 9

• P. falciparum resistant
  
  • Benigng species still sensitive

Increases chlowoquine removal from vauole by PGH-1 transporter

• P. falciporum generally sensitive to quinine

Question 10

Artemisin quality is not regulated in some parts of world so varying effectiveness, and breeds resistance

Question 11

Prophylaxis regiments for malaria

Answer 11

• High risk areas
  
  • mefloquine, malarone, doxycycline
• Moderate
  
  • risk chloroquine + proguanil
• Low risk
  
  • chloroquine

Balance risk vs side-effects of drug, rather work on bite prevention

Question 12

African trypanosomiasis

Answer 12

• Bloodstream, unicellar.
• Tetse fly
• CNS invasion, sleepiness by
• Treatments are toxic and IV
• FExinidazole

Question 13

American trypanosomiasis

Answer 13

• Romana’s sign
• Heart targeted
• Smooth muscle of Gi
• ORAL BENZIDAZOLE

Question 14

Leishmaniasis

Answer 14

• Cutaneous, mucocutanoues, visceral
• Sodium stibogluconate - im
• Amphotericin B - iv
• Miltefosine - oral

Question 15

Toxoplasmosis

Answer 15

can be from cats

Immunocompetent:

• Lymphoadenopathy, glandular fever like. settles

IMmunocompromised e.g HIV

• Brain abcess

Question 16

EXAM: Luminal protozoa

Answer 16

• Metronidazole for some luminal protozoa
  
  • E. histolytica
  • Giardia
  • Trichomona

Question 17

Intestinal nematodes management

Answer 17

Mebendazole or albendazole

Question 18

Strongyloides management

Answer 18

• Capable of long term infection, harbour parasites, and may become a problem later if immunocompromised e.g. steroids, HIV
• Hyperinfection in the immunocompromised
• Death from gram negative sepsis
• Ivermectin

Question 19

Onchocerciasis

Answer 19

I:E River blindness

• Black fly
• Two doses of ivermectin 6 months apart, repeated every 3 years
• Side-effects associated with killing of microfilaria
  
  • Fever, itch, oedema, arthritis, lymphadenopathy
• Ivermectin combined with nodulectomy to remove adult worms and blackfly vector control

Question 20

Cestodes (tapeworks)

Answer 20

Pork tapeworm can cause cysts

Question 21

Schistosomiasis

Answer 21

Adults killed with praziquantel