Flies ( Myiasis)

Front 1

define myiasis and the possible outcomes

Back 1

the invasion of a living vertebrate tissue by fly larvae. ( obligate, faculative or accidental).

tissue damage often with a putrid ( smell of decay ) discharge which will attract other flies./ ulcers/ loss of tissue function./secondary infections/ death.

Front 2

describe the genera of importance in the ostridae family of flies. what type of myiasis do they do. describe their morphology and whether they are host specific.

Back 2

oestrus, hypoderma and gastrophilus genera all in the family osetridae.

MORPHOLOGY- large and hairy and the adults have non functional mouth parts.

Front 3

state the genera and sp of the sheep nasal bot. describe their morphology and life cycle.

Back 3

oestrus ovis.

MORPHOLOGY- large ( 1cm ) and hairy ( short brown hairs). gray colour with black spots on ab. non functional mouth part .

LIFECYCLE- females lay live L1 around 1mm long (viviparous) in packages of around 25 directly into nostrals- the L1 begin to migrate toward the frontal sinus and they feed on mucus- L1-L2 molt in nasal passages- the l1 or l2 may overwinter in nasal passages- l2 enters frontal sinus then molts to L3 - L3 continues to grow to around 3 cm- l3 migrate back towards the nostral and are sneezed out due to the irritation from their hooks and spines- l3 burrows in to the ground and pupates- finds sexual partner and mates.


NOTE -dont feed and only live for around 2 weeks and which makes sense if you dont feed!! can produce around 200 larvae with up to 2-3 generations per yr. most infections are light (10-20)

Front 4

labble the picture ...

Back 4

1.Inter-segmental spine bands 2.Hooks on margins of body
segments 3.Oral hooks 4.Cephalopharyngeal skeleton

Front 5

describe the pathology caused by the sheep nasal bot ( oestrus ovis)

Back 5

IRRITATION-main effect. it interrupts feeding and weight gain. ( may run with muzzle near ground, sneeze, stamp feet, rub nose on static objects, shake head or form circles when flies are most active.

NASAL DISCHARGE- clear and mucoid often bloddy.

INFLAMMATION OF SINUS AND BRAIN- circling and lack of corrdination and will kill the sheep.

Front 6

you are called out to a farmer who suspects his sheep have nasal bot. He has found what they have been sneezing out of their nose. If it is nasal bot what will this be and what will it look like ?

Back 6

L3s are sneezed out.

3cm long/ yellow to white colour with dark transverse bands / taper at one end

Front 7

what is the genera of oestridae family which are commonly called warble flies and what sp are important. what animals do they affect. what is their morphology and lifecycle. where in the world ae they found

Back 7

hypoderma bovis and hypoderma lineatum. i/e derma for skin!!
most significant in cattle although infect man, sheep and horse rarely. found in N.Hemisphere ( not UK)

MORPHOLOGY- large ( 1cm ), hairy bee like. again the adults dont have mouth parts and they have a short lifespan.

LIFECYCLE- senn in summer ( calm weather and bright sun ideal ) cement eggs to hair of cattle. - egg take 1 week to hatch - L1 penetrate the skin via the hair folicles- L1 migrate through flesh using their enzymes and oral hooks making tracks of gelatinous ' butchers gelly'. within 5-9 m they have migrated through the flesh to reach just under the skin on the back - they then develope from l1-l3 in 1-2 months. L3 is the 'warble' and is large ( 2-3 cm)- L3 penetrates the skin to breath - L3 drops to the ground and pupates then adult emerges.

Front 8

describe the pathology and treatment of warble flies ( hypoderma)

Back 8

PATHOLOGY- cattle panic when they hear the fly- this worry causes reduced weight gain./ hide damage due to L3 penetrating skin - reduced value of hide/ butchers jelly tracts reduces the valve of the carcus.

TREATMENT-systemic insecticides ( eg ivermectin)

Front 9

what genera of the oestridae family is called the horse bot and what sp are significant and which is the most common. where in the world are they found. what is the morphology of the larvae and adults and what is the lifecycle

Back 9

Gasterophilus intestinalis ( most common), gasterophilus nasalis and gasterophilus haemorhoidalis.

found throughout the world.

MORPHOLOGY- large ( 1-2 cm ), hairy and wasp like with a pointed Ab. larvae red-orange, barrel shaped and rows of spines.

LIFECYCLE-again adults only live for a few weeks- mate usually near horse faeces where there have been many pupae -lay eggs on hairs ( like warble fly - hypoderma)-eggs hatch to L1 and are eaten by horse or move towards it mouth - larvae attach to the mouth - molt to L2 in mouth and go via the GIT to the stomach - molt to L3 which attaches to the stomach mucosa with oral hooks for 8-10 months- release hold and are passed out in faeces- pupate in soil for around 1 month.

note entire cycle takes 1 yr

Front 10

how do you differentiate between the sp of horse bot

Back 10

gasterophilus intestinalis - is found on almost any body hair but esp the forelimbs and the larvae in the stomach a red colour.

Gasterophilus nasalis- eggs are found in the throat region and the L3 in the stomach are a lighter ( yellow ) colour.

Gasterophilus Haemorrhoidalis - eggs are found on the nose or lips.

Front 11

describe the pathology caused by the horse bot ( gasterophilus intestinalis ) and the treatment

Back 11

if low numbers will have few signs

worry - of horses causes irritation

toung ulcers (rare) - cause pain on eating.

stomach ulcers and inflammation

owners concer about L3 in faeces

treat with ivermectin

Front 12

what are the flesh flies

Back 12

obligate myiasis flies which feed on sugerical liquids. larvae feed on dead animals, and wounds. causes traumatic Myiasis.

Front 13

what is the name of the group of flies which are do faculative myiasis and which genera and sp are significant in the UK and which animals do they mainly affect. which is the most common in the UK

Back 13

blow flies.
Lucilia sericata- green bottle ( most common in UK)
phormia terranova- blackbottle
calliphora sp- bluebottle

mainly afftect sheep and rabbits

Front 14

what does 'blow' and 'strike' and 'primary and secondary' flies with regards to blow flys mean.

describe their life cycle

Back 14

blow flies are undergo facultative myiasis.

DEFINITIONS -'blow'- laying of eggs. eg' fly blown meat'
'strike'- development of larvae
primary flies ( green and black bottles ) can initiate their own strike whereas secondary ( blue bottles) need to lay their eggs on a damaged area.

LIFECYCLE- adults are attracted by the smell of wet fleese, existing wounds, faeces or dead tissue -eggs laid on fleece- hatch within 12 hours- larvae grow ( 1mm-1cm over 3 days)- develope oral hooks and produce enzymes which digest tissue-larvae drop to the ground after around 5 days - burrow into the soil and pupate for 14 days.

takes 3-4 weeks usually may- september with 3-4 generations per yr with the final generation pupae overwintering. Adult flies live for about 30 days.

Front 15

how are the types of blow fly strike defined and which is the most common in the UK.

describe the pathology of blow fly strike.

Back 15

by body region ....

body (common in UK)
breech ( the back of the hind legs)
penile sheath
tail
poll ( horns)

PATHOLOGY - the lesion produced is very irritating causing interupted feeding and self trauma / secondary bacterial infection can lead to septicaeimia.
If not treated severe blow fly strike can kill sheep.

Front 16

describe the epi of blow fly strike

Back 16

EPIDEMIOLOGY...

TEMPERATURE- OFF HOST- soil temp of > 9 required for the pupae to develop ( hence they are overwintered and are seen again in late spring). the temperature on the host remains at a high ( > 31)

CLIMATE AND RAINFALL- less of a problem in northern UK do to lower temperatures and less wool rot. ( rain wets the wool and warm conditions result in 'wool rot' which attracts the female flies to lay their eggs causing 'body strike').

BREED- fine wool breeds are more susceptible to wool rot ( merino or rambouillet) / any wrinkles or folds are also more susceptible to wool rot eg the narrow breech of the merino. / horned sheep will have open wounds where their horns are growing.

DIARRHOEA- attracts flies around breech and tail leading to breech and tail strike.

WOUNDS- fighting in horned breeds or barbed wire or bushes or foot rot will all attract flies.

Front 17

describe the control of blow fly strike in sheep

Back 17

prevent diarrhoea by controling worms with antihelmintics

clip wool from around breech and general shearing removes the warm moist environment which attracts flies

pooled breeds/ breed for less susceptible sheep.

remove dead animals

tail docking

Front 18

blowfly can also affect rabbits which fly is mainly responsible for this and where do they commonly get fly strike on their body. what is the usual outcome.

Back 18

significant mortality.
usually around breech.
mostly lucilia sericata ( green bottle)