Myiasis Flashcards
What is the name of greenbottles? What do they do?
Lucilia seratica. Lay maggots into dogs, humans. Affects the poorest people.
What is the old world screw worm?
Chrysoma bezziana.
What is the new world screw worm?
Cochliomyia hominovorax
How could the eradication of screwworms occur? (I.e. how has this already been achieved in Florida Keys)?
- Animal inspection on highways
- Treatment points for animals
- 2 million sterile flies released twice a week
What are the three types of myiasis? (In terms of what they feed on)?
- Accidental: ingestion of eggs or larvae with food
- Facultative: by carrion or live hosts
- Obligate- only on live hosts.
Where are the three main locations of pathology in myiasis?
The intestinal tract, urogenital tract, respiratory tract
What are the three main families of myiasis causing fies? Are they obligate or facultative?
- Oestridae (botflies)- obligate only
- Calliphoridae (blowflies)- obligate or facultative
- Sarcophagidae (flesh flies)-obligate or facultative
What is interesting/ unique about oestridae?
Their alimentary canal is vestigial- their energy, therefore, goes into egg production rather than feeding.
What are the infestation sites of oestridae, calliphoridae and sarcophagidae?
Oestridae- skin, respiratory tract (i.e. nasal passages)
Calliphoridae and sarcophagidae- mainly cutaneous
What is the lifecycle of myiasis flies?
Egg–> 3 larval instars –> third instar shrinks and adult pupates –> mating following pupation.
Which characteristics do we look at to identify the different species of myiasis flies? (Larvae)
- Head end (notches of mouthparts)
- Posterior spiracles (3 in L3 and 2 in L2)
- Spine bands
- Crop with food in
Which characteristics do we look at to identify the different species of myiasis flies? (Adults) (How many segments of each part of the body are there?)
- One head segment duh
- 3 thoracic segments
- 8 abdominal segments
As well as molecular tools being used for identification, how can landmark analysis separate lineages?
By looking at where veins intersect.
Which oestridae is found in the UK and how does it infect sheep?
Oestris ovis. Squirts out larvae in flight into sheeps nostrils, they snort it out and they pupate in the soil.
What is the camel nostril fly bot?
Cephalophora titilator.
Why/ how can oestridae infect humans? How does human infection present?
As they cannot feed, they must find their host quickly and lay eggs, if they cannot find the primary host, they will simply find a secondary host.
Human infection is usually resolved fairly quickly and may present as mild conjunctivitis.
Describe the lifecycle of hyperdermatinae (subfamily of oestridae).
Flies lay EGGS –> eggs attach to hairs of host –> larvae hatch and migrate through the animal –> warble formed in the dermis –> they feed and evacuate and fall out onto the ground –> they then pupate into an adult.
Which Oestridae reside in the digestive tract? Why?
Gastrophilinae. For the warm temperature and constant food supply.
Describe the lifecycle of gastrophilinae.
Eggs laid on hairs–> larvae get to the mouthparts (e.g. by licking) –> develop in gut –> pass out in faeces–>pupate in soil
Which drug is used to treat all horses in the UK for gastrophilinae?
Avermectin.
Cuterebra is a new world oestridae that likes dermal tissue. What is its lifecycle?
Drops onto the host –> penetrates skin –> subcutaneous migration –> forms a warble.
How does dermatobia hominis indirectly infect humans? How are they removed?
Catches flies and lays their eggs on them (e.g. mosquitos, tabanids) eggs hatch when they detect warmth from the insect landing on a human. Eggs hatch and burrow into host- backwards pointing spines aid in retention.
Surgical removal or occlusion of the wound so the maggot crawls out to breathe.
Where do sarcophagidae penetrate? What is an example of a sarcophagidae?
Are cutaneous but can penetrate further.
Wohlfahartia magnifica.
What is cordylobia (i.e. what is its common name) and what does it preferably feed on? Where does it lay its eggs?
Is a tumbu fly. Is anthropophagic. Lays eggs on sites of urine contamination. They burrow into soil until animals lie on top.
Give one example of an auchmeromyia (genus). What does it feed on?
Auchmeromyia senegalensis. Blood (10 blood meals in larval development). After each blood meal, the larvae drop off and continue development.
Other than auchmeromyia, which other flies are sanguinivorous?
Calliphorias and muscias.
What conditions does lucilia seratica require from the host for infection?
Needs a predisposing condition e.g. fleece contamination with faeces or urine. They feed on healthy tissue once everything else has run out.
What are the three ways we can control myiasis flies?
- Control and eradication (sterile insect technique, insecticide spraying, odour attractants to catch and kill them)
- Avoidance (vaccines?, prophylactically treating animals)
- Treatment (removal of maggots, difficult due to spine bands).
Why should we treat animals?
- Pain/ suffering
- Secondary infection
- Death
