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
Name benzeneacetonitrile active substances
Diclazuril, Clazuril
What is Clazuril used for?
is purely sold in tablets for treatment of pigeon coccidiosis. Dosage: 2.5 mg (1 tbl.) per bird per month.
Diclazuril use
It is very safe and effective in poultry (broilers, turkeys) and mammals including horses.
Diclazuril is highly potent against coccidia in turkeys, chickens and rabbits. It is well tolerated by various species of birds and all mammals. It is effective against all species of Eimeria.
Diclazuril contraindications
It is compatible with all therapeutics and feed additives.
Diclazuril withdrawal period
Zero days!
What is an active substance of benzylpurines?
Aprinocid (is not used anymore)
What is an active substance of carbanilides?
Nicarbazin
Nicarbazin use
after 27 years of its use a resistance of coccidia was reported. It is still used, today particularly is popular in shuttle program.
Used in the past
What is an active substance of Guandines?
Robenidin
Robenidin mechanism of action. It’s use.
Inhibits oxidative fosforylation and has coccidiostatic but also coccidiocidal activity against first and second generation of schizonts.
It is used to control of all turkey, chicken and intestinal coccidia of rabbits by
continuously administration.
Robenidin contraindications and withdrawal period.
Contraindications: not use in laying hens and mixed with other coccidials.
Withdrawal period: 5 days (for meat
Name an active substance of dinitrobenzamides.
Dinitolmid (zoalene)
Use of dinitolmid
It was very widely used in broiler, calves and lambs. It is effective against second- generation merozoites, i. e. it does not suppres the immunity formation.
Action: Dinitolmid has a moderate to good activity against chicken coccidia Therapeutically is effective against coccidia of lambs and calves.
What is the active substance of pyridines?
Clopidol
Use and withdrawal period of Clopidol.
It belongs among anticoccidials which do not allow natural immunity to develop because is acting against the first generation stage of coccidias.
Withdrawal period: 5 days in all species of animals.
Name an active substance of quinazolines
Halofuginone
Use of Halofuginone
It is a derivative of a plant extract, very potent against all coccidia of chicken and turkeys. It is very effective against the early developing stages of parasite – suppressing the immunity.
Contraindications and advantage of using Halofuginone
Contraindication: Laying birds and other species of animals should not be treated. Advantage: It is effective against resistant strains of E. tenella to clopidol, amprolium
and robenidine.
Name an active substance of quinolines
Decoquinate
Use and mechanism of action of Decoquinate
Decoquinate acts on the sporozoite stage of the life cycle. The mechanism of action for decoquinate is to disrupt electron transport in the mitochondrial cytochrome system of coccidia.
It is used for prevention of coccidiosis in broilers caused by Eimeria
Contraindications and withdrawal period of Decoquinate
Contraindications: not used in turkeys and laying hens.
Withdrawal period: 3 days for meat
Name the active substances of sulfonamides
Sulfaquinoxalene, Sulfaclozine, Sulfadimidine, Slufadimethoxine
Sulfonamides combined with other drugs can be very active against protozoa
Use and withdrawal period of Sulfaquinoxalene
used for treating intestinal and caecal coccidiosis in chickens, turkeys and rabbits, but today is more used as a mixture with amprolium.
Withdrawal period is 10 days for meat .
Use of sulfaclozine
It is effective for treating coccidiosis of chickens. It is suitable also for rabbits
Use and withdrawal period of sulfadimidine
It is used only for the treatment in all species of animals usually potentiated by diaveridine.
Withdrawal period is 15 days for eggs and meat
Use of sulfadimethoxine
It is used usually potentiated by ormethoprime for treating coccidiosis in chickens and turkeys.
Name an active substance of thiamine antagonists
Amprolium
Use and withdrawal period of amprolium
It was introduced predominantly for a prophylactic use with activity mainly against caecal coccidiosis. Amprolium has been used also for the treatment of coccidiosis in chickens, turkeys and ruminants. It is usually
mixed with ethopabate or sulphaquinoxaline.
Withdrawal period is zero days but for laying hens 3 days
Mechanism of action of amprolium
It inhibits the uptake of thiamine by coccidia, but also it is a thiamine antagonist of the host, but the parasite is 50 x more sensitive to this effect. Amprolium acts upon the early first generation schisonts depressing natural immunity formation.
Name the active substances of diaminopyrimidines
Diaveridine, Ormethoprim, Ethopabate
What are diaminopyrimidines used for and what’s their mechanism of action?
They are used to potentiate some anticoccidials. Their action is based on the inhibition of the dihydrofolate reductase, which catalyses the reduction of folic acid to folinic acid. Folinic acid is necessary for coccidia reproduction.
Diaveridine use
It has anticoccidial activity in chickens and some mammals (rabbits). It potentiates the activity of sulphonamides by decreasing a folinic acid formation. It is well tolerated by animals, does not influence the eggs production.
Ormethoprim use
It is used to potentiate the action of sulphadimethoxine for prophylactic purpose in chicken and turkeys.
Ethopabate use
It has only weak activity against coccidia, but is important for potentiation of amprolium and dinitolmide.
Give examples of active substances in antitrichomoniasis and antihistomoniasis drugs
Metronidazole, Ornidazole, Flunidazole, Ipronidazole
Give examples of active substances in drugs against babesiosis, malaria, trypanosomiasis and theileriosis.
Where are these diseases often found?
Diminazene, Pentamidine
Metronidazole and Ornidazole can also be used.
frequent especially in tropical areas and very often also in teritoria round equatorial parts of globe.
