(PM3A) Parasitic Infection + Anti-Parasitic Drugs Flashcards
How does a parasite meet its nutritional needs?
Prolonged contact with another living organism
What is an example of a unicellular parasite?
Protozoa
What is an example of a multicellular parasite?
Helminths
What are the two classes of parasites?
(1) Endoparasites
(2) Ectoparasites
What are examples of endoparasites?
(1) Protozoa
(2) Helminths
What are examples of ectoparasites?
(1) Lice
(2) Leeches
(3) Scabies
(4) Fleas
What are the main anti-protozoal drugs?
(1) Anti-amoebics
(2) Anti-malarials
(1) What is the mechanism of action for pyrimethamine?
(2) What is pyrimethamine?
(1) Inhibits DHFR
(2) Anti-protozoal drug
(1) What is mechanism of action for sulphadiazine?
(2) What is sulphadiazine?
(1) Inhibits DHPS
(2) Anti-protozoal drug
What is the mechanism of action of doxycycline?
Inhibits protein synthesis in 30S ribosomes
What are the main anti-helminth drugs?
(1) Anti-nematodes
(2) Anti-cestodes
(3) Anti-trematodes
What is mebendazole?
Common anti-helminth drug
What is praziquantel?
Common anti-helminth drug
What is niclosamine?
Common anti-helminth drug
What is the mechanism of action of mebendazole?
(1) Binds to beta-tubulin in intestinal cells of nematodes
(2) Prevents microtubule synthesis
(3) Leads to block of glucose uptake
What is the mechanism of action of praziquantel?
(1) Increases membrane permeability to Ca2+
(2) Leading to contraction of muscle and paralysis
What is the mechanism of action of niclosamine?
(1) Uncouples oxidative phosphorylation
(2) Prevents ATP synthesis
What are protozoa?
- Unicellular
- Eukaryotic organisms
- Can use insect/ water vectors
Give examples of protozoal infections.
(1) Malaria
(2) Intestinal infections - amoebic dystentery/ toxoplasmosis
What is toxoplasmosis?
Infection due to a single cellular parasite
What is malaria?
Caused by parasitic protozoa
How is a malaria infection diagnosed?
(1) Blood film microscopy
(2) Antigen-based rapid diagnostic tests (RDT)
What infection is blood film microscopy often used for?
Diagnosing malaria
What infection is antigen-based rapid diagnostic tests (RDT) commonly used for?
Diagnosing malaria
What are the stages of malaria transmission?
(1) Mosquito bites + injects sporozoites
(2) Infects liver cells
(3) Development of a schizont.
(4) Schizont ruptures
(5) Releases merozoites -> Infect erythrocytes -> Immature trophyzoites
(6) Some immature trophozoites mature to develop more schizonts
(7) Some generate gametocytes - which are ingested by mosquitos
What is a schizont?
A protozoan cell which divides to form daughter cells
What are the symptoms of malaria?
- Fever/ chills/ sweats
- Headaches
- Nausea + vomiting
- Aches
- Malaiase
What can severe malaria cause?
- Cerebral malaria
- Organ damage
- Metabolic damage
How can malaria be prevented?
(1) Anti-malarial drugs
(2) Covering
(3) Mosquito nets
(4) Permethrin - insecticide
(5) Vaccine
What are the main malaria prophylaxis medications in the UK?
(1) Doxycycline
(2) Mefloquine
(3) Proguanil + atovaquone (Malarone)
What is 1st choice treatment for P. falciparum malaria?
(1) Clindamycin
(2) Proguanil + atovaquone (Malarone)
What is the 1st line treatment for malaria in pregnancy?
Quinine + clindamycin
What does malaria have widespread resistance to?
(1) Chloroquinine
(2) Anti-folates
What is the first line treatment for non-P. falciparum malaria?
Chloroquinine
What is amoebic dysentery?
Amoebiasis
Infection of amoeba
Causes diarrhoea
What is amoebiasis?
Amoebic dysentery
Infection of amoeba
Causes diarrhoea
How is amoebiasis transmitted? What else is it called?
Faecal-oral
Amoebic dysentery
How is amoebic dysentery transmitted? What else is it called?
Faecal-oral
Amoebiasis
What is the treatment for amoebic dystentery (amoebiasis)?
Often self-limiting
Metronidazole - for acute invasive amoebiasis
When can a toxoplasmosis infection be life-threatening?
If immunocompromised
What is the treatment for toxoplasmosis?
Often self-limiting
Pyrimethamine + sulphadiazine
What is cryptosporidiosis?
Parasitic infection
Causes diarrhoea
How is cryptosporidiosis transmitted?
(1) Swimming pools/ lakes
(2) Contaminated foods + surfaces
What are the symptoms of cryptosporidiosis?
- Watery diarrhoea
- Dehydration
- Weight loss
- Stomach cramps/ pain
- Fever
- Nausea + vomiting
When is cryptosporidiosis life-threatening?
If immunocompromised
What is the treatment for cryptosporidiosis?
Usually self-limiting and not treated
Nitazoxanide if required