Animal Health - ectoparasites

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ectoparasite

an org that spends part or all of its life on the outside of the host animal

either:

• damage host directly

• act as carriers of other pathogens

5 types of ectoparasites

• athropods:

• insects: flies, fleas, lice

• arachnids: mites, ticks

Insects

• head

• thorax

• abdomen

arachnid

• cephalothorax

• abdomen

Arachnids

• mites

• ticks

arachnids - mites and ticks

• two body parts

• four pairs of legs

• no antennae

• mouthparts - chelicerae (paired cutters) and palps (paired sensory organs)

Mites (mange)

• infest a wide variety of animals and birds (inc man)

• small <0.5mm

• some are v host specific, others not

• transmission is mainly via direct contact

• prolonged period of time in contact w host skin

• most required a microscope to be seen and identified

basic lifestyle - mites

• egg

• larvae

• nymph

• adult

common UK mange mites

• chorioptes (tail head mange)

• posoroptes (sheep scab)

• sarcoptes

• demodex

chorioptes

• tail head mange

• cattle

• sheep

• horses

• goats

• rabbits

psoroptes

• sheep scab

• sheep

• goats

• occasionally cattle

sarcoptes

• pigs

• cattle

• goats

• dogs

• cats

• foxed

• humans

three diff forms of mites

• under the top skin layer in skin burrows

• on the skin surface

• inside hair follicles

• cause intense itching predisposing areas to to 2ndary infection + allergic reactions

sheep scab - psoroptes ovis

• the entire life cycle take place on the host

• eggs -adult about 10 days - pops can build very quickly = heavy infestations

psoroptes ovis sheep scab - when

• during spring/summer - mites are quiescent

• found in ears, groin, axilla

• as fleece thickens for winter the mite becomes active and spreads over the fleeced area

sheep scab - psoroptes ovis - cause

• non burrowing, feed on tissue fluids

• can cause skin damage (on skin surface)

• intense irritation + loss of condition

• cannot replicate away from sheep

• lives for max 2-3 weeks when not on sheep

• mite faeces act as allergens

psoroptes ovis - signs of it

• thick dry scabs

• fleece may become detached

• most prevalent in winter but can occur at any time

• sheep should be treated on welfare grounds

psoroptes ovis - sheep scab - control

• dipping

• pour on/spray on formulations + injections

• easier to apply, less traumatic to sheep

• possibly not as effective

• resistance to some pour ons and injectables

sarcoptic mange - sarcoptes scabiei

• affects all mammals

• burrowing mite - lives under surface of skin in burrows

• most commonly found neck, face, back

• most severe type of mange

lifecycle of sarcoptic mange

• fertilised female burrows into upper layer of epidermis

• feeds on resultant diseased tissue

• eggs laid within burrow hatch in 3-5 days

• larvae which hatch burrow into ‘moulting pockets’ - develop through nymph stage to adults

• adult male emerges + seeks out females

• mating takes place + female seeks out new burrow to lay eggs

• lifecycle takes 17-21 days

sarcoptic mange of dogs

• predilection sites:

• ears, muzzle, face and albows

• extremely intense itching, scaling and crusting followed by alopecia

• very contagious - spreads between dogs, foxes, other animals inc humans

• can be very bad - euthanasia

diagnosis of sarcoptic mange

• groups of animals often affected

• intense itching, rubbing and scratching - ears - Pedal-Pinna reflex

• skin scrape by vet

treatment of sarcoptic mange

• acaricidal spot-on treatments

• weekly bathing with acaricidal preparation

• all dogs kept together must be treated

demodectic mange - caused by demodex canis

• lives in hair follicles - cigar shape

• common form of mange in dogs:

• immunosuppression

• young dogs under 12 months

two forms of demodectic mange

• mild

• severe (generalised)

mild demodectic mange

• localised to head (eyelids, corners of mouth etc)

• patches of hair loss

• slight itching

severe (generalised) demodectic mange

• widespread hair loss over body

• intense itching

• secondary infection

• pus filled pimples

demodectic mange treatment

• mild cases may clear up within a month

• severe cases must be supervised by vet as drugs are highly toxic

• in severe cases treatment may be prolonged and unsuccessful

ear mites - otodectes cynotis

• psoroptidida mite

• lives on skin surface

• most common mange of dogs + cats also foxes ferrets

• lives in inner ear + feeds on ear debris

• causes head shaking, ear scratching, aural heamatomas

ear mites - otodectes cynotis - caused by

• pruritus caused by irritation + saliva of the mites - secondary bacterial infection

• cats - can get infection on tail from sleeping curled up

otodectes cynotic - ear mites treatment

• ear drops to kill mites

horse mites - chorioptic mange - chorioptes equi

• host specific surface mite w an entire lifecycle carried out on the host. transmission by direct + indirect contact

• typically affect feathered distal limbs of heavy horses and cobs more common in winter

sings, diagnosis + treatment of chorioptic mange

• signs: foot stamping + self trauma

• diagnosis: skin scrapings (collected from fresh lesions on clipped legs)

• treatment: as for lice (permethrin) + topical ivermectin + fipronil (unlicensed)

equine mites - dermanyssus gallinae

• small red mites - usually found on chickens

• may infest horses in contact w poultry

equine mites - psoroptic mange - psoroptes equi and psoroptes communis

• un-common + not found in the UK

• surface mites commonly found around the mane and tail

• diagnosis: skin scrapes

ticks

• two families:

• ixodidae (hard ticks)

• argasidae (soft ticks)

• important vectors for:

• protozoa

• bacteria

• viruses

ixodidae

hard ticks

argasidae

• soft ticks

tick lifecycle

• female lays eggs

• larvae - feeds on small mammals

• nymph - feeds on small + medium

ticks - life + host

• most of life spent in the environments

• on host - live on surface + feed on blood

• hard ticks insert their mouth parts into the skin + anchor themselves at the point by secreting a ‘cement’

ticks - clinical effects

• blood loss + weight loss in heavy infestations

• transmission of various pathogenic microbes

what is the predominant tick in the uk

• ixodes ricinus (sheep tick) which can transmit:

• babesia divergens (red water in cattle)

• ehrlicha phagocytophilia (tick borne fever in sheep)

• louping ill (sheep) virus

• lyme disease (dogs, humans) - bacteria

ixodes ricinus distribution UK

• when the tick is active/on host:

• northern uk - spring

• southern uk - spring + autumn (temp dependent)

control of ixodes ricinus

• dips, spot ons

• environmental control - ixodes prefers scrubby habitat → pasture improvement

ixodes ricinus - 3 host parasite

• temporary parasite:

• usually 2-3 yrs to complete lifecycle but can take between 1-6

• only 26-28 days feeding in total

• peal periods:

• march - june

• aug - nov

ixodes ricinus - survival

• dependent on ticks requirement for water

• must have relative humidity greater than 90%

• common in wet areas

insects

• lies

• fleas

• flies

lice

• mallophaga - chewing lice

• anoplura - sucking louse

mallophaga

• chewing lice

anoplura

• sucking louse

lice species in Uk - sheep

• bovicola ovis

bovicola bovis

• cattle louse

linognathus vituli

• long nosed cattle louse

haematopinus eurysternus

• short nosed louse

solenoptes capillatus

• little blue cattle louse

pig louse species UK

• haematopinus suis

equine biting louse

• damalinia equi

equine sucking louse

• haematopinus asini

lice lifecycle

• adult lice lay eggs (nits) close to the hair root

• eggs hatch on host

• 3 nymph stages

• egg - egg = 2-3 weeks

lice in poultry

• common chicken louse

lice - impacts

• blood feeders (sucking) → heavy infestations can cause anaemia

• both types cause skin irritation + pruitis → behavioural change

lice - control

• thorough treatment of all animals w insecticidal dips, spots on or endectocides

• removal from infested areas for a week allow lice to die off

• prevention thru approp nutrition, stocking densities + stress management

lice in dogs

• uncommon

• generally affect vulnerable animals

• environment - dirty + overcrowded

trichodectes canis

• dog chewing louse

linognathus setosus

• dog sucking louse

Fleas

• dogs

• cats

• poultry

• humans

• suck blood - anaemia

• flea allergic dermatitis

fleas - animals to humans

• bartonella henselea - cause of cat scratch disease in humans

• mycoplasma haemofelis - cause of feline infectious anaemia - affects red blood cells

• feline leukaemia virus

symptoms of fleas

• scratching

• itching

• self trauma

• hair loss

• flea dirt

commonly affected areas of fleas

• back

• ventral abdomen

• inner thighs

• most of life spent in environment - need to kill those on host + in enviro

cat flea lifecycle

flies

• biting flies + midges e.g. horseflies - tabanus spp

stomoxys spp

stable fly

culicoides spp

midges (bluetongue)

musca spp

• house flies + face flies

• disease transmitters

hydrotea spp

• head fly - sheep

haematobia spp

• horn fly - sheep + cattle

lucilia sericata

• blow flies

hypoderma spp

• warble flies

fleas - clinical effects

• irritation - may lead to self trauma

• behavioural change

• disease transmission

• fly strike

• warbles

fly life cycle

• eggs - 8-24hrs

• larvae - 4-7 days

• pupa - 10-20 days

• adult

blowflies - calliphoridae

• myiasis = infestation of a living animal w larvae of dipteran flies

• blowfly strike

• eggs laid on host

• larvae hatch + feed on host skin

• sheep + rabbits

2 major species of blowflies in england

• lucilia cuprina/sericata - greenbottles

• calliphora erythrocephla - bluebottles

blowfly lifecycle

• up to 3,000 eggs laid

• 12 hours eggs hatch

• moult 3 times in 3-10 days

• maggots drop to ground and pupate

• adult emerge and mate

• female lays eggs

blowfly strike - primary

• lay eggs on wool

• larvae hatch, crawl down wool + lacerate skin

blowfly strike - secondary

• attracted by odour

• lay eggs on or around rotting flesh

blowfly strike - symptoms

• areas usually affected - breech and tail

• body + poll also

• 2dary bacterial infections of damaged skin

• dull, depressed, off food, isolation, damp foul smell

• enzymes released by larvae are toxic

• can result in death

blowfly - treatment + control

• clip wool around area, remove larvae manually if possible + treatment w a suitable insecticide

• antibiotics ± fluid therapy for septicaemia

• control:

• using pour on products or by dipping before risk period

• control infections e.g. foot rot, PGE

• crutch out dirty sheep

flies impacting horses

• culicoides spp (midges)

• tabanus spp (horse flies)

• stormoxys calcitrans (stable fly)

• adult females are the problem - bit the animal to feed on blood

• act as vectors for disease such as African Horse Sickness

• may cause a hypersensitivity reaction in sensitised horses, known as ‘sweet itch’

control of flies in horses

• fly rugs

• fly masks

• topical preparations

• diet (?)

• breeze

• kept away from natural water sources

gastrophilus spp

3 main species:

• gastrophilus intestinals (most common)

• gastrophilus nasalis

• gastrophilus haemorrhoidalis

• bot flies

gastrophilus spp info

• adults lay sticky yellow eggs on horses legs

• these are licked during grooming + larvae ingested

• larvae attach to the stomach lining + may survive for 10-12 months when passed in faeces

• pupate + adult flies emerge

hyopderma bovis

• warble fly

• notifiable disease - only in Scotland

• exotic to uk - risk from imported cattle

• compulsory treatment

warble fly lifecycle

• eggs laid on the hair of legs + ventrum

• larvae penetrate hair follicles + migrate to oesophagus or spinal canal

• moving to the skin of the back in early spring where they develop as warbles, before dropping to the ground to pupate

• hide damage

• carcass damage

Keds

• melophagus ovinus

• wingless flies

• spend entire life on the sheep

• a nearly fully developed larva is laid in fleece - develops into a pupa + and then adult fly

• adult lives for several months

Keds - causes

• feed on blood → heavy infestations can lead to anaemia

• mostly cause behavioural change, leading to fleece + skin damage

• damage to skin may attract to blowflies

• shearing + dipping easily treats them