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Index
Sr.no Index # of slides
1 Classification of Osteridade
2
Introduction to
Hypodermatinae
3 Life cycle
4 Pathogenesis
5 Control and Dx
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Economical significance
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Introduction
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Hypodermatidae
• Warble fly, Gad fly,
• Heel fly, cattle grub
• Larvae live s/c ,Nature .. Obligate
• Warbel anglo Saxon for boils.
• Occurs usually on Northern
hemisphere b/w 25 to 60℃.
• Host cattle, deer, sheep,
reindeer, and horses.
• Nasopharyngeal and skin
boils(warbles).
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Other hypodermatinae
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• Przhevalskiana … goat warbles
• Oestroderma pikas
• Oestromyia mice and marmots
• Pallasiomyia sagia antelope
• Pavlovskiata Goitered gazelle
• Portschinskia ..mices and pikas
• H. diana parasite of deer
• H. tarandi parasite of Reindeer
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Differences
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• Flies most active on warms days.
• Mid July to early September.
• Rage ..5 km
• Predilection sites, subcutaneous tissue and spinal tissue.
• H.bovis 15 mm, H.linatum 13mm
• Egg singly, batches
• Larave posterior spiracular plates surroundings the button has a narrow
funnel-like channel.
• Posterior spiracular plates surrounding the button has a broad channel.
• Epidural fat of spinal cords vs submucosa of esophagus.
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Conti..
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• Europe, the US, and Asia.
• Gadding about
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Hypodermatidae
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Hypodermatinae ( subfamily)
Genus 9
Species 32
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Cattle grubs ( Hpodema larvae)
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Genus Hypoderma H. Bovis, H. lineatum warble fly, Heel fly
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Morphology
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H. Bovis 15 mm
H . Lineatum 13mm
Vestigial mouthparts
Dense hair, light dark
color.
DDx
Thorax of H. Bovis
hairy,
Both lack Palps.
Both Mouth parts
small.
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• Bumble-bee like flies with reddish yellow pile at the end of abdomen.
• In H. bovis whitish yellow or reddish yellow hairs are present on anterior of
suture while black on posterior of suture.
• In H. lineatum white or yellow hairs are present white on anterior and yellow on
posterior.
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Morphology
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• H. Bovis; Spiracular plates, marked with spines on the posterior side.
• Funnel-like channel.
• Posterior spiracular plates having broad channels in H. lineatum.
• this is present in 3rd stage larvae.
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Life cycle
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warble fly
Overwinter
Oviposition
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eggs
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• Egg attach firmly to the host hair.
• In case of H.bovis eggs are laid during flight or walking over the host body (causing gad to
cattle) .
• In H. lineatum eggs are laid without disturbing the host.
• In H. bovis single egg is attach on rump and upper part of hind leg.
• In H. lineatum several eggs on single shaft of host hair on legs and lower parts of body.
• Eggs hatched within a week after that 1st larval hatches which is less than 1mm.
• Crwaling towards hair or skin, H.bovis penetrate into skin nerves and spinal tissues in thoric and
lumber region.
• H. lineatum submucosa the of the esophagus and over winter.
• Next spring, 9 month resume its distance and come back to skin surface
• Warble. Small swelling formed on either side of midline and completed two moultings.
• Egg hatch in 4 days in both species.
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larvae
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• Extensive internal larval migration
• Crawl down and penetrate the skin using proteolytic enzymes (mid gut)
+spines+ hooks • May take several months to reach final site
• In H.lineatum migrating larvae are found in wall of oesophagus
• In H. bovis larvae are in epidural fat of spinal canal
• Larvae reach the spinal canal by migrating along nerve trunks or through
muscle
• Larvae move on final site on back area 25 cm around the mid line from
shoulder to tail
• Immature larvae are 15 mm in length
• Ist larval instar moults into 2nd while reaching the back area
• Cut hole in host skin for respiration and moults into 3rd larval instar
• Mature larvae are 30 mm in length and convex on ventral surface and flat on
dorsal surface
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Continue
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• Anterior row of large , backwardly directed spines
• Posterior band of smaller forwardly directed spines
• In H. lineatum spiracles are flat, crescent shape
• Considerable gaps between the arms of the crescent
• In H. bovis spiracles are funnel shaped and smaller gaps b/w arms In H. bovis
numerous openings are present on spiracles as compared to H. lineatum
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Pupa
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• 4-11 weeks
• Yellowish brown Pupa emerge through breathing hole on skin
• Burrowing beneath loose soil
• Dropping of pupa depend upon the temperature in cooler condition during noon
while in moderate conditions at early morning
• Can survive - 15 ͦ C during early period after dropping and can survive -28 ͦ C
during late period after water loss
• Humidity level for H. lineatum is 98% while in case of H. bovis it is 76% and
above 20 ͦ C pupal development is independent of RH
• Duration of pupal stage varies from 3-10 week
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Adult
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• Adult appear after 4 weeks in H. lineatum earlier than H. bovis
• One generation in a year
• Active during sunny days when temperature is above 18 ͦC.
• April to June H. lineatum
• Mid –June to early September H.bovis.
• Unable to feed
• Can live 3-5 days
• In presence of suitable host adult do not fly but are capable to fly up to 16 km
in H.lineatum
• Adult emerge early in the morning and mate after one hour of emergenc
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• Lays eggs 300-600/cycle , singly H.bovis and batches of 15 in H. lineatum.
• Attachment organ
• 3rd stage larvae having posterior spiracular plates with spines.
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Pathogenesis
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• Devaluation of hides, breathing holes,
• Inflammation & edema at the entry of 1st stage larvae.
• Butcheres jelly, H. Lineatum, 1st stage larvae produces, yellow, greenish
gelatinous, oedematous areas, having high eosinophils.
• Anaphylactic shocks, hypersensitivity
• Weight gain.
• Younger > Older , more resilient why?
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Pathogenesis
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• Gadding, The characteristics noise, and persistent ovipositing behavior is
avoided in cattle.
• Abortion ,
• Wound
• Myasis
• Retarded growth
• Poor BCS
• Milk production
• Heel fly . series of silent hops along the ground.
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Economic significance
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The disease is present globally.
40-90% of cattle are affected by warble fly.
60-600 US$ loss annually reported in Europe.
Prevalence in the UK, Ireland, Canada, and the USA.
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Pathogenesis
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• Gadding during ovipositioning in H. bovis.
• Reduce weight gain and 10 -15% loss in milk production.
• Jelly like tracks in muscle due to larval migration.
• Anaphylaxis.
• Hide malfunction due to hole formation.
• Rarely infect humans causing creeping myiasis due to wandering larval stage
Abscesses
• Eye damage.
• Abnormal host (brain invasion in horse in USA led to death ).
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Dx
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Identification of larvae
underneath skin
Eggs
Immunodiagnostic
tests
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Treatment and control
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• Organophosphate insecticides (migrating larvae) and macrocyclic lactones.
• Ivermectin, Doramectin, eprinomectin, moxidectin,
• Vaccine using antigen from Ist larval instar.
• PBZ
• Adernaline
• Atropine
• 3% H2O2
• Application
• How to apply
• Pour on
• s/c injections.
• Control strategies
• September, October, and November @ single Rx given in Europe.
• Condition larvae
• Uk
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• Legislation in UK, Eire, 40%
• Denmark, Netherlands.
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Discussion
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• Differences b/w H. bovis and H. lineatum.
• Mutilation
• DDX
• LSD
• Dermatitis
• Sporotrichosis presents as a chronic infection of skin and
subcutaneous lymphatics, developing after a primary inoculation
such as a rose thorn puncture ( subcutaneous mycosis).
• Filarial dermatitis
