Antiprotozoals Flashcards
What is parasitism?
• Parasitism is a non-mutual relationship between organisms of different species where one organism, the parasite, benefits at the expense of the other, the host.
What are ectoparasites? Give examples
Ectoparasites live on the outside of the host, either on the skin or the outgrowths of the skin.
They are directly transmitted between hosts. Examples include lice, fleas, and some mites.
What are endoparasites? Give examples
Endoparasites live inside the host. Endoparasites can exist in one of two forms: intercellular parasites (inhabiting spaces in the host’s body) or intracellular parasites (inhabiting cells in the host’s body). These include protozoa and helmints.
What is parasite infestation?
a group of disorders which are caused by invasion of the organism with other multicellular or unicellular organisms such as protozoa, helminths, ectoparasites
What are the three groups of antihelminthics?
a. antinematodes – against round worms b. antitrematodes – against flukes
c. anticestodes – against flatworms
What are the 3 groups of antiprotozoal drugs?
I. Anticoccidials
II. Antitrichomoniasis and antihistomoniasis drugs
III. Drugs used against malaria, babesiosis, theileriosis & trypanosomiasis
Define coccidia and list the 2 main genera.
Coccidia are endoparasites mainly of the small intestine, but also of other parts of GIT (caeca of chickens, bile duct of rabbits etc.), where they multiply and cause a destruction of tissue of various animals, in cattle, sheep, goats, pigs, cats, dogs, rabbits or poultry.
Poultry, livestock and young animals are the most affected however.
The 2 main genera are Isospora and Eimeria.
What 2 methods have been applied to minimize the risk of producing drug resistance?
- The shuttle program requires 2 or more drugs to be sequentially used during the bird ́s growth period.
- The rotation program involves the use of different classes of anticoccidials with subsequent crops of birds. The effectiveness of these methods is equivocal.
Name the 12 groups of anticoccidial drugs and their active substances.
- Ionophores (polyether antibiotics) monensin, lasalocid, narasin, salinomycin
- Benzeneacetonitriles (diclazuril, clazuril)
- Benzylpurins (aprinocid)
- Carbanilides (nicarbazin)
- Guanidines (robenidine)
- Dinitrobenzamides (dinitolmide-zoalene)
- Pyridines (clopidol)
- Quinazolines (halofuginone)
- Quinolines (decoquinate)
- Sulphonamides (sulphaquinoxaline, sulphaclosine, sulphadimidine)
- Thiamine antagonists (amprolium)
- Diaminopyrimidines (diaveridin, ethopabate, ormethoprim)
Which anticoccidial group is the most effective and widely used?
Ionophores
What was monensin used for in the past?
monensin was used as a growth promoter exclusively in cattle (in horses is poisonous), but since year 2006 it is prohibited to use this ATB for growth promotion.
Describe the mode of action of ionophores.
they interfere with the transport of ions through the membranes causing an increase of positively charged ions (cations), and osmotic disbalance of cells. Death of parasites.
Describe toxicity of ionophores.
Ionophores have a low therapeutic index and may be very toxic in certain species of animals. Equines e.g. are highly susceptible to monensin (lethal at very low doses 2-3 mg/kg) and they must not be mixed with other anticoccidials.
Use of monensin
It is highly therapeutically effective against all species of coccidia.
Used for broiler chickens and turkeys, cattle and sheep
Contraindications of monensin
Contraindications: in horses may be lethal, must not be given to chickens laying eggs
for human consumption.
Monensin withdrawal period
Withdrawal period: 3 days (for meat), but it heavily depends on producers composition of preparations.So for farmers is very beneficial.
Use of lasalocid
Like monensin it is widely used in the control of poultry coccidiosis against all species of Eimeria, including those, which have become resistant to monensin and narasin.
Contraindications and lasalocid withdrawal period
Contraindications: must not be used in other animals, only in broiler chickens. Withdrawal period: at least 5 days.
Narasin use
It is currently used only for the treatment of Eimeria spp. in broiler chickens and rabbits. It is effective against all intestinal and caecal coccidia if administered continuously in the diet.
Narasin contraindications and withdrawal period
Contraindications: It should not be given to egg-laying hens or to other species of birds or animals to which may be highly toxic.
Withdrawal period: at least 5 days
Salinomycin use, contraindications and withdrawal period
It is used for the prophylaxis of all species of coccidia in broilers.
Contraindications: It should not been used in other species of chickens.
Withdrawal period: 5 days
Maduramycin use, contraindications and withdrawal period
It has 12 – 24 fold greater potency than other ionophores and has shown a significant cross-resistance.
Contraindication: It should be dosed only to broilers.
Withdrawal period: 5 days.
Name ionophore active substances
Monensin, Lasalocid, Salinomycin, Narasin, Maduramycin