liver parasites Flashcards
outline the general lifecycle of fasciola spp.
list the polymorphic forms of flukes
- adult fluke
- encysted metacercaria
- cercaria
- redia
- miracidium
- egg
discuss how fasciola gigantica affects different species
- causes chronic fascioliosis in cattle (buffalo no as susceptible)
- acute and often fatal in sheep
outline the clinical presentation of fasciolosis
discuss immunity to fasciolosis
- strong parastie specific IgG and IgE
- prolonged eosinophilia
- large quantities of IL-4 IL-10 but NOT IFN-gamma, all of which point to a dominate T helper 2 or Th2 (humoral) reponse
- Th2 repsonse that develops is beleived to be non-protective
how are liver fluke infections diagnosed
- fecal egg count using mcmaster slide
- plasma enzymes which signal liver or bile duct damage (GGT)
- generally, on condemnation of liver or following necropsy
- ELISA
how are fluke diseases treated
- fasinex (triclabendazole) is drug of choice and gets both adults and juveniles)
- albex (albendazole high dose) treats both adults and juveniles
- mebadown (mebendazole/closantel) A+J
- combinex (levamisole/triclabendazole) = A+J
- ## droncit (praziquantel) = A+J
how is F. hepatica treated
- of fluke is present, treat with triclabendazole in sept/Oct and again in Jan if FEC is positive
- treat against adult only stages in May/june for preventing pasture contamination
- do not use same treatment at sept/oct, Jan or may/June for preventing pasture contamination
- treat additionally in particularly wet years
- isolate and treat all new animals brought into herd
- fence off wet areas
- increase soil drainage
- control of wildlife reservoirs of fasciola where possible and legal
outline the lifecycle of dicrocoelium dendriticum
what happens in the host in a dicrocoelium dendriticum infection
- does not penetrate the liver capsule or tissue or gut wall as with F. hepatica. instead, metacercariae excyst in duodenum and travel via ampulla of vater (where pancreas and bile duct empty their secretions) where they enter the bile duct
clinical disease of dicrocoelium dendriticum is more likely to occur in sheep or cattle
sheep
heavy infection of dicrocoelium dendriticum manifests as which clinical observations
- anemia
- oedema
- liver fibrosis
- hepatic damage
list epidemiological factors of dicrocoelium dendriticum
- eggs quite resistant (can survive many months on pasture)
- may lead to exposure of land snails and ants to large number of eggs
- wild life may act as reservoirs
- resistance to flukicides
name the 2 intermediate hosts of dicrocoelium dendriticum
- land snail
- ant (contracts by eating slime balls)
what is the most common snail host for liver flukes in europe
Lymnaea truncatula
