Lice As Parasites Flashcards
Lice
Arthropods Flattened dorso ventrally abd wingless Permanent obligate parasites Mallophaga Anopleura
Mallophaga
Biting/chewing lice
Mouthparts spec to bite a skin and pelage
Dont pierce the skin
Move quickly and difficult to diagnose if only small numbers present
Head is broader than thorax and is flattened
Smaller claws for looser attachment and grazing
Anopleura
Sucking lice
Mouthparts pierce the skin and suck blood from capillaries in epidermis or lymph
Head much narrower than thorax
Larger claws for more permanent attachment to aid with blood feeding
Finding a meal
Have well dev antennae to locate feeding sites through combo of smell and warmth
Some feed in clusters so use pheramones to attract each other
Patjogenesis
Heavy infestation of sucking lice can cause anaemia, worse affected when already debilitated
Chewing lice in large no can cause large irritation as they feed - skin reaction can cause hair to loosen and be displaced
And can cause hide dam/cockle
Pruritic cattle can cause significant enviro damage
Lifecycle
All spent on host, transmission by close contact (once removed die within a week)
Adult F lay eggs glued to hair shaft which hatch in 1-2wk into nymphs which mature through 3 stages to become adults that live for several weeks, mate on host and F lay eggs
Adults are easily displaced by rain and cycle takes 2-3wk dep on strain host tine of yr and is quickest in long coated or housed animals as lice prefer rough surf and warm dark enviro
Repro
Some species eg bovicola can swith between sexual and asexual repro tonincr rate of pop growth
Feeding
Take repeated small meals
Survival against host d
Strong Legs and curved claws and spines enable tight contact with pelage and reduced removal by grooming
Eggs glued to pelage and res to dessication and grooming
Highly host spec and adapted to digestion of hist tissue
Evolved saliva and feeding mechanisms to evade imm resp
Bovicola ovis
Chewing in sheep
Infection spread is slow as transfer req close contact
Dont drop off or survive long in enviro
Host spec so no interspecies spread
Irritation cause foot stamping displacement of wool tufts and rubbing and biting flanks etc
Chewing lice diagnosis
Rel large so see in hair or wool partings with naked eye or magnifying glass
Microscopy to ID species with clinical signs and history to help
Also ID lice antigens in wool samples
Chewing lice economic cost
Little evidence showing negative effect on prod
Heavy infestation can red wool quality
Cockle
Key differential for sheep scab
Lice management (large animals)
Pyrethroid pour ons
Disperse around body in wool grease and amount of grease determine effective conc of pour on
Most effective applied off shears
High dose req for long wool treatment
Req 6 wk to disperse around body and kill lice
Res problems
Wool residue probs
Single off shears application in sunmer can give all year round protection
Felicola subrostratus
Only species that infest cats
Broad yellowish chewing lice short slender legs with single claws and triangular heads woth a longitudinal groove tgat fits around host hair
Trichodectes canis
VECTOR!!!
Broad pale yellow chewing lice
Dogs
Broad head short stout legs with single claws to grasp base of hair mainly over head neck and tail
Similar lifecycle to linognathus vituli and bovicola bovis
Potentially harmful for puppies and old debilitated dogs
Very active and cause skin irritation causing matted coats skin dam and alopecia
Cluster around body orifices and moist wounds
Vector of diphlidium caninum (ingested during grooming)
