12 Antiparasitic agents Flashcards
what is a parasite
an organism that lives in or on an organism of another species (its host) and benefits by deriving nutrients at the other’s expense
protozoa or metazoa
what are the 4 main species of malaria and which are benign
1 Plasmodium falciparum
2 P. Vivax- benign
3 P. Ovale- benign
4 P. Malariae- benign
how do mosquitoes transmit malaria
the female anopheles mosquito spits out saliva into humans to clear their passage for blood, and in doing so transmit the parasite
what are hypnozoites
dormant forms in the life cycles of certain parasitic protozoa- stay in the liver and emerge later
describe the life cycle of a mosquito
mosquito->sporozoite->schizont (liver)->trophozoite (RBC)->merozoite (RBC)->gametocytes->mosquito
M-SSTMG-M
which is the most dangerous species of malaria
P, Falciparum
a parasite can either.. or .. when it enters the body
stay in the liver as hypnozoites or come out and multiply into blood stream and cause RBCs to burst open
describe the treatment for P. Falciparum malaria
combination therapy
severe= quinine (+doxycycline or clindamycin)
milder= atovaquone + proguanil
IV for severe
describe the treatment for benign species of malaria
chloroquine and primaquine to clear out liver so don’t get any trouble later from hypnozoites
describe the mechanism of action of chloroquine
in malaria, the plasma membrane invaginates and takes it in using transporters
the parasite imports it’s own transporters into membrane
haemoglobin is ingested by the parasitophorous vacuole and is broken up into globin and haem
free haem is toxic to plasmodium due to the high iron so it has an enzyme called haem polymerase which clots haem and neutralises toxicity
chloroquine neutralises haem polymerase so haem remains toxic to the parasite and is killed
describe chloroquine resistance
some parasites have transporters to efflux the chloroquine back out, so don’t get a chance to inhibit haem polymerase
describe how artemisinin derivatives started to be used against malaria
what is it used with
china looked back at ancient texts to see what herbs and plants used to be used in medicine
literature said qing hao (artemisia annua) was good for piles and fevers, tests showed it had anti-malaria activity
use in combination with lumefantrine
describe prophylaxis for different levels of risk for malaria
high= mefloquine, malarone, doxycycline
moderate= chloroquine and proguanil
low= chloroquine
very low= nothing
what is African trypanosomiasis
also known as African sleeping sickness when CNS is invaded: insect-borne parasitic disease
vector= tsetse fly
reservoir= cattle
treatment for African trypanosomiasis
stage 1= suramin, pentamidine
stage 2= melarsoprol, eflorithine, eflorithine and nifurtimox
stage 1&2= new drug- fexinidazole
describe how infection occurs in chagas disease
reduviid bug sleeps in cracks in walls, at night lands on exposed skin, breaks skin and sucks, defecates which makes sleeping person rub/itch, rubs it into broken skin causing infection
what causes leishmaniasis
sandfly
treatment for leishmaniasis
AmB but is IV so hard to give in poorer areas
miltefosine is widely used
describe toxoplasmosis in the immunocompetent
glandular like illness, infections settle by themselves
describe toxoplasmosis in the immunocompromised
can cause brain abscesses
use pyrimethamine, sulphadiazine and folinic acid
treatment for luminal protozoa (3)
metronidazole (good for anaerobic infections)
co-trimoxazole
nitazonxanide
which intestinal nematodes do mebendazole and albendazole treat and describe them
enterobius (pin or threadworm)- sheds eggs in perianal area
ascaris- can be found in cold meats in eastern Europe
trichuris (whipworm)- behaves like a corkscrew and burrows into submucosa leading to diarrhoea and stunted growth
hookworms- suck blood-> anaemia
which drug treats strongyloides
ivermectin
what transmits onchocerciasis
blackfly by fast flowing rivers, larvae migrate into eye and cause river blindness
what drug regimen is used in ivermectin
2 doses of ivermectin 6 months apart, for 3 years
combined with nodulectomy to remove adult worms and blackfly vector control
in lymphatic filariasis…is blocked
lymphatics
name 4 nematodes
intestinal, strongyloidiasis, onchocerciasis, filariasis
name 3 cestodes and their treatments
beef and pork tapeworm- praziquantel
hydatid disease- albendazole/surgery
name a trematode and it’s treatment
schistosmiasis- praziquantel
