Sustainable control of parasites Flashcards
What are the main GI nematodes in sheep?
Teladorsagia circumcinta
Haemonchus contortus
Nematodirus battus
Do the main GI nematodes in sheep have direct or indirect life cycles?
Indirect
When does infection with teladorsagia usually occur?
First season lambs in late summer/autumn
How are nematodirus battus transmitted?
From lambs the previous year
When does infection with nematodirus usually occur?
A cold snap followed by temps above 10 C
What is the main mode of transmission of haemonchus contortus?
Hypobiosis and reemergence in ewes
What does in refugia mean?
leaving at least some of the parasite population unexposed to
anthelmintics
What are the 3 methods of anthelmintic control?
Prevention - chemoprophylaxis, treat all animals at start of grazing season
Evasion - dose and move
Dilution - decrease effective density of susceptible animals
What are some modifications of rotational grazing?
Creep grazing - young animals get clean pasture
Hoover effect - resistant adults on field first
How do you detect resistance?
Faecal egg count reduction test
What is the best method of treatment that wont cause resistance?
Targeted selective treatment - choose individual animals to treat
How do you detect the animals which have a high worm burden?
Faecal egg count Diarrhoea/dag score
Body condition
What is the intermediate host of fasciola hepatica?
Snail
What flukicide can be used to kill very young fluke/treat acute disease?
Triclabendazole
What flukicides will kill older fluke?
Nitroxynil
Closantel
What are the main GI nematodes in horses?
Cyathostomins
Strongyles
Parascaris equorum
Anoplocephala perfoliata
How do cyathostomins cause disease?
Encyst for >3 years
Mass emergence causing colitis
How does strongyles cause disease?
Clocks cranial mesenteric artery - arteritis
How does parascaris equorum cause disease and what does it affect?
Most significant in foals - blocks intestine
How can you diagnose nematodes in horses?
Faecal egg counts
Cyathostomin ELISA
Post mortem
When should you treat horses for nematodes?
200epg as a cut off from faecal egg count
What can you use praziquantel to treat?
Tapeworms - anoplocephala perfoliata
What drugs can treat a wide range of nematodes?
Ivermectin
Moxidectin
Pyrantel
BZ - Fenbendazole
How do you do a faecal egg count reduction test?
Do FEC
DOse
Do faecal worm egg count 14 days after
When is there resistance?
<90% result when difference divided by starting FEC
What are cyathostomins resistant to?
Benzimidazoles eg. fenbendazole
Pyrantel
What is parascaris equorum resistant to?
Macrocyclic lactone - ivermectin and moxidectin
What is the immunity like in cyathostomins, strongyles and parascaris?
Bad/incomplete in cyathostomins, strongyles
Good in parascaris
What methods of treatment can be used? Do they cause resistance?
Fixed interval dosing - causes resistance
Only when disease is proven - no but not regular so resurgence
Target dosing in responce to positive worm egg count - no, best method
