Parasitology slide set 1 Flashcards
An animal or plant which lives in or upon another organism and draws its nutrients directly from it; definition might also include- exhibits some degree of adaptive structural modification, causes harm to host
parasite
Endoparasite
internal
Ectoparasite
external
Helminth
Worm
Parasitology includes
protozoa, nematodes, flatworms, arthropods
Helminths and arthropods are:
- complex multicellular organisms
- share many neurotransmitter and metabolic processes with vertebrate host, challenge is to affect parasite and not host
- drug’s effect usually determined by counting reduction in parasite numbers
Protozoa are
- single celled organisms
- drug’s effect often measured by ability to reduce clinical signs
- some antibacterial drugs also used for protozoa
-cide
kill; e.g. parasiticide, insecticide, nematocide
Anthelminitic
drug used for treatment and control of worms
Dose
the quantity to be administered at one time
Dosage
the determination and regulation of the size, frequency, and number of doeses
Half life
time required for one half of an administered dose to be cleared from the blood
Mode of Action
how the drug works to kill an organism
Spectrum of action
organisms affected (broad spectrum vs. narrow spectrum)
Efficacy
how effective the drug is against an organism (usually measured in % reduction for multicellular parasites)
Residual activity
length of time drug maintains efficacy after administration
Safety (therapeutic) margin (index)
max tolerated dose/effective (usually the marketed) dose
the higher the safety margin, the…
less likely for toxicity from drug
Withdrawal time
amount of time after drug administration that potential food products must be held to avoid drug resides entering human food
Subtherapeutic
does not have desired effect
Dose limiting parasite
when a product is marketed for more than one parasite, the dose limiting parasite determines the dose required for treatment; usually is the highest concentration
Treat or remove
90% reduction, minimum
Repel
EPA; fewer organisms after short period
Prevent
FDA- don’t get “mature” infection
EPA- ???- possibly means don’t get powerful infestation
Control
FDA- couldn’t quite meet the standard for treatment (don’t use this on new products)
EPA- when already on board, the pesticide keeps numbers low
Prescription only
from veterinarian or prescribed by veterinarian
Ethical channel sales
doesn’t require a prescription, but drug company chooses to market through veterinarians
Over the counter
freely available to public; most large animal parasiticides, many products for insects, ticks, and mites
Treatment objective in small animals
- goal is eradication from animal
- many products from vet
- cost less important
Treatment objectives in food animals
- goal is managing parasites, prevention of economic loss
- product usually not from vet
- cost very important
Treatment objectives in horses
aspects of small animals and food animals, depends on owner
Resistance
heritable characteristic
results from random mutation always present in population
use of a drug acts as a selection factor for resistant alleles and increases their frequency in the population
Ways an organism could be resistant (a few examples)
change in drug uptake
change in drug receptor
change in drug metabolism by parasite
refugia
pool of parasites not exposed to the drug
What factors influence the rate of development of resistance?
frequency of treatment, efficacy, refugia, half life, genetics
