Myiasis Flashcards
Define the 3 groups of myiasis producing flies
Primary myiasis - specific myiasis producers, larvae only found in living tissues
Secondary myiasis - semi-specific myiasis producers, eggs usually laid on dead tissues or decaying plant matter, but sometimes deposit larvae on living host
Tertiary myiasis - accidental myiasis, usually don’t develop in flesh, but can survive
What is a myiasis
A Dipteran that parasitizes as a larvae only, and not as an adult
What is the common term for Sarcophagidae
Flesh flies
General physical characteristics of sarcophagidids
About 2x as large as house fly, gray thorax with dark longitudinal stripes abdomen is checkered black and grey
Scientific name for blow flies
Other common names for blow flies
Calliphoridae
Bluebottle and greenbottle
Why are they called blow flies
Blow their larvae or eggs onto meat
What are common hosts of calliphorid myiasis
Rabbit
Scientific name for American screwworm
Cochliomyia hominvorax
What type of myiasis does the American screwworm produce
Primary myiasis
How are American screwworms controlled
X-radiation and release of sterile males
Where do American screwworm larvae pupate
Soil
What is the only known insect to eat the living flesh of warm-blooded animals
American screwworm
What countries have screwworms been eradicated from
USA
Mexico
Panama
Libya
What is the major cause of avian myiasis in North America
Blood sucking maggots of the genus Protocallifora
What families of fly are involved in obligate myiasis. (Besides screwworms)
As a group, what is their common name
Oestridae
Hypodermatidae
Gasterophilidae
Cuterebridae
Bot flies
Where can the host-specific site-specific parasites be found on their hosts (identify host and site)
Oestrus in nasal passages of sheep
Hypoderma in the dorsal subcutis of cattle
Gasteroplilus in the stomach of horses
Which bots occasionally affect humans, and how
Oestra deposit larvae in the eyes of shepherd
Hypoderma and Cuterebra migrate subtaneously
What is a distinct feature of adult bot flies
Have vestigial mouthparts and energy is deprived from that which was stored when the fly was a larva
What time of day are Oestrus most active
During warm times of day, or intervals of sunshine
Life history of Oestrus ovis
Larvae deposited I sheep nostril
Larvae crawl to mucosa of nasal passages (2wk). Halt development until warm weather
Migrate to frontal sinus where they mature to 3rd stage larvae
What types of signs do Oestrus ovis cause in sheep
How do you treat it
None in mild infections
Sneezing nasal discharge and partial blockage of nasal passages in heavy infection
Tx with ivermectin
Name some other nasal bots and their hosts
Rhinoestrus purpureus - horse
Cephalopina - camels
Cephenemyia - cervids
Genus and species of gad fly or heel fly
Hypoderma bovis
Hypoderma lineatum
What is a warble
Walnut sized lumps on the backs of cattle formed by Hypoderma in the subcutis
Life history of Hypoderma
Females glue their eggs to hairs on the legs
H. Lineatum present in winter, H. Bovis present in summer
Eggs hatch and larvae burrow into skin
- h.lineatum present in esophageal tissues 5 mo later
- h.bovis present in spinal canal
Larvae ultimately migrate to sub-q tissues of back: molt twice, and grow larger
When fully developed, emerge and fall to ground to pupate
Which genus is associate with migrating lumps in people
Hypoderma
Where do different species of Gasterophilus deposit their eggs
G. Nasalis - hairs of intermandibular space
G. Hemorrhoidalis - hairs that adjoin the lips
G. Intestinalis - hairs of forelegs and shoulders
Where do first stage Gasterophilus larvae occur
Tunnels in epithelium covering dorsal surface of Rostropovich 2/3 of tongue and in pockets between molar teeth
(Second stage also in mouth in interdental pockets or base of tongue)
Where specifically are 3rd stage Gasterophilus larvae usually found
First ampulla of duodenum in horse (nasalis) Or stomach (intestinalis) above the fluid level
What are the preferred hosts of cuterebra species
Rabbits and rodents
What specific site are Cuterebra found on within the host
Under the skin
Do Cuterebra produce primary, secondary or tertiary myiasis
Primary
Life history of Cuterebra
Eggs deposited near animal burrows
Enter through natural body openings
Migrate to subcutaneous tissues, where development to third stage occurs
Larvae drop off host to pupate
How often to cuterebrae lay eggs
Once a year in north (univoltine)
Active. Year-round in south
Describe migration of cuterebra in the host
Enter natural opening Move to tracheal tissue Penetrate thoracic cavity Penetrate diaphragm Enter peritoneal cavity Enter sub-q tissue
Migrates around body 3-6 wks before making it to skin. Majority of growth occurs in sub-q
What affect do Cuterebra have on cats
Can develop warbles
Disease from migrating maggots (respiratory signs, neuro disease)
Genus species human bot fly
Dermatobia hominus
When do the larvae become. Bots
Large maggot stage
How are Dermatobia hominus eggs deposited
Eggs deposited on another fly’s body with hopes of contacting host… If no other fly, vegetation
What stimulates D hominus eggs to hatch
Heat from vertebrate host
Why can you not simply pull out a Dermatobia hominid when you spot the anterior end sticking out of a boil-like lesion
Maggot has large spine on its body that make it almost impossible to pull out the maggot without killing it or rupturing it (if maggot dies, increased risk if secondary bacterial infection)
Genus and species of the tumbu fly
Cordylobia anthropophaga
Where are tombu fly eggs deposited and what are their typical hosts
Eggs deposited in soil
Typical host is rodent. Can infect dog and human
What is one way that has been reported as a means for Cordylobia anthropophaga to acquire humans as a host
Hang clothes up to dry and do not iron them
Genus and species of Congo floor maggot
Auchmeromyia senegalensis
What is particularly unique about the Congo floor maggot
Does not penetrate the skin, instead fastens to the host to suck blood
What are common hosts of Auchmeromyia senegalensis
Wart hogs and other large burrowing mammals in Africa
What type if human habitations has Auchmeromyia become adapted to
Those with wooden floors
