Cuterebra spp. (1)

Question 1

What are the common names?

Answer 1

Rodent Bot Fly

Rabbit Bot Fly

New World Skin Bot Flies

Question 2

What are the hosts?

Answer 2

Rodents

Rabbits

Dogs

Cats

Squirrels

Chipmunks

Mice

Rarely Humans

Question 3

Describe adults

Answer 3

Large - 20-30 mm

Bee-like

Stout-bodied

Short-lived

Cannot feed or bite - Mouthparts vestigial

Question 4

Describe the third instar

Answer 4

2-4 cm long

Dark brown

Covered with spines

Question 5

Explain the life cycle

Answer 5

Female fly lays eggs along rabbit runs/near rodent burrows

Infestation as they pass through contaminated areas

Eggs hatch in response to heat from a nearby host

1st stage larvae hatch instantaneously

Enter body via mouth or nares during grooming or open wounds

Larvae migrate to various subcutaneous locations

Develop and communicate with air through a breathing pore

One month later, larvae exit skin, fall to soil, pupate

Duration of pupation - depends on environmental factors

Question 6

What are the sites of infestation?

Answer 6

Subcutaneous tissue

Aberrant sites

 - Mouth
 - Nose
 - Brain

Question 7

Describe the Pathogenesis

Answer 7

Hair matted at affected area

Fibrotic cyst forms - larva in subcutaneous tissue

Migration of larvae in cat brain -> INFARCTION (tissue death due to
obstruction of blood
supply) and
FELINE ISCHEMIC
ENCEPHALOPATHY (deficiency of
blood because
of obstruction
of blood vessel
to brain)

Question 8

What are the clinical signs?

Answer 8

Lumps in neck

Fur constantly wet

Hole drips fluid

Question 9

How do you diagnose?

Answer 9

Seasonally - Dog/cat presents with lump in neck/legs, fur constantly
wet, hole drips clear fluid

Second instar larvae

 - 5-10 mm long
 - Gray/cream in color

Third instar larvae - most commonly seen by vets

Definitive diagnosis - Finding and identifying larva

Question 10

How do you treat and prevent?

Answer 10

Larva removed by enlarging breathing hole and carefully removing with forceps

Care taken not to crush larva
- Squashing larvae may result in severe tissue reaction from Type I
hypersensitivity type reaction

Wound heals slowly
- Secondary bacterial growth or leakage of Cuterebra antigens

MCLs heartworm prevention, imidacloprid, fipronil protect but not approved for this claim

Question 11

What is important about Cuterebra spp.?

Answer 11

It is ZOONOTIC