Ectoparasites Flashcards
what is the difference between endo and eco parasites
endo= live inside the host
ect= live on the surface of the host
fish gill parasites an intermediate between ecto and endoparasites as the gill is both an internal and external organ
which ectoparasites are vectors of various pathogens and parasites
fleas
ticks
mites
lice
outline the morphologies of the ectoparasite the flea which make it easily identifiable
- laterally compressed bodies
- wingless
- 3 pairs of powerful jumping legs
- conspicuous black eyes
outline some characteristics of the flea
few are pests or parasites to humans
94% of fleas bite mammals and 6% birds
worldwide distribution but species specific
can be zoonotic, generalist or specific
outline the chigoe/jigger flea aka Tunga penetrans
a flea which secretes proteolytic enzymes resulting in the formation of a callus where they feed and lay eggs
the formation of callus makes it hard to notice presence as unable to feel it= only when cyst begins to press on nerves surrounding the callus is it noticable but by then the eggs are released from the skin
outline the lifecycle of Tunga penetrans aka chigoe/jigger flea
1) females lay eggs once they leave the host in debris such as sand, or they may lay them whilst on host
2) eggs are coated with a sticky substance allowing accumulation of dirt and debris = camouflage, hatch after 5-6 days
3) larvae (made up of 13 segments and dark head capsule) spin a silk cocoon where it pupates, can live in this cocoon for 4-12 months
4) adults emerge following environmental cues such as heat/co2 looking for blood meal
what are the two different types of ticks
class = Arachnida
soft ticks = family Aragasidae
hard ticks = family Ixodidae
= different ecologies, forms and functions
how to hard and soft ticks differ
soft
- no scutum (sheild)
- mouthparts not visable
- eggs laid in small batches
- 4-5 nymphal larval stages
- rapid feeding of 20-30 mins
- tick borne releapsing fever
hard
- scutum present
- mouthparts visable
- eggs laid in one large batch
- 1 nymphal stage
- slow feeding 1-4 weeks
- attach to host for long time
- lyme disease, typhusus
outline some characteristics of mites
infest the skin of a variety of animals including humans
Scarpotes scabei = highly infectious and causes mange
- caused by adult females burrowing into the skin by the release of proteolytic enzymes being spat forming a channel for it to use
- lays eggs in this channel
- causes itching releasing eggs
outline some characteristics of the ectoparasite lice
common name for 3000 wingless insects
- obligate ectoparasites of every avian and mammalian order
- some feed on secretions and blood
- eggs= nits
most are highly species and site specific
what species of lice infect humans
1) prediculus humanus humanus= hair
2) pediculus humanus capitis = body
3) pthuris pubis =pubic hair
= very site specific, wont be found anywhere else on the body but where it is adapted to
outline the ectoparasite bedbugs
not vectors of disease but are ectoparasites of humans
causes rashes and allergic reactions
outline the ectoparasite myiasis
invades organs and tissues of verterbrates by dipteran larave which feed on the living or dead tissue
different types depending on the affected body part
what are the different types of myiasis
1 )cutaneous
- creeping/ eruption myasis = surface layers of skin
2) urogenital
3) ophthalimic/ ocular
4) nasaopharangeal
5) intestinal
what are warble flies
genus = Hypoderma
parasitic on cattle and deer mainly but also in horses, cats dogs
eggs laid on the forelegs of large animals
larvae burrow into the skin through connective tissues or the oesphogus
after a few months the larvae migrate to the skin causing swelling (warbles)
= eradicated in uk in 1990s due to economic impact on livestock
what are the three different dipteran families
1) calliphoridae = metallic and non metallic
2) Sarcophagidae
3) Oestridae
outline the characteristics of non-metallic flies from the dipteran family calliphoridae
e.g. Mango fly
- found in Africa and Saudi Arabia
-adults are robust large flies dull yellow and brown in colour
- females lay 100-300 eggs in the soil in the presence of urine, soiled nappies/ washed clothes
- larvae hatch and use powerful hooks to burrow into host tissue
- spiracles used to breath protrude from host
outline the characteristics of the newworld metallic flies from the family calliphoridae
new world screwworm
found in southern states of USA, Mexico and central America/south America
- limitied range due to successfull eradication programme (mass release of sterile males)
- adults 8-10mm long, metallic green/blue in colour
- lay 100-400 eggs on the edges of wounds, scabs, eyes and mucous membranes
- larvae burrow into healthy flesh for 4-12 days
- if distrubed they burrow deeper
outline the characteristics of the old world metallic flies from the family calliphoridae
obligatory parasite of living tissues
found in tropical africa, indian subcontinent, most of SE asia
introduced to west coast of perisian gluf and iraq
adult flies and larvae simialr to new world flies expect larvae have 4-6 finger like protuberances on the arterial spiracles
- massive economic damage as affect cattle, goats and horses
outline the medical importance of metallic blue bottle flies
- dirty habits - potential vectors for a number of pathognes
- faculative myiasis, infest wounds
- maggot therapy
raise flies and maggots in sterile conditions which can be used to treat ulcers, pressure sores and infected surgical wounds as they feed on dead tissue not living
outline some characteristic of the dipteran family sarcophagidae
aka flesh flies
- they lay no eggs just first instar larvae
two genus
1) sarcophaga = falculative myasis
2) wohlfahrita = furuncular myiasis
outline some characteristics of the dipterian family oestridae
bot flies
when on flesh they secrete ammonia which damages skin and surrounding tissue = ammonia poisoning
economic impact = damages fleece of livestock such as sheep
outline some characteristics of the subfamily cuterebrinae from the oestridae family (botflies)
found in north argentina and south mexico
- lowland forests espcially along paths and margins of forests
- females lay 6-30 eggs
eggs can either be glued to body of another arthropod or layed directly onto the hsot
larvae matures inside egg but doesnt hatch until in contact with the host
outline some biological control of dipteran flies
- release of sterile insects which have been irradiated with gamma radiation to kill sperm before being released into the wild
successfull in
= mexican fruit fly
=Medfly
= melon fly
future targets = anopheles and aedes mosquitos, Tstes fly and painted apple moth
what are the advantages of sterile male techniques
- highly specific
- no pesticide so no residue
- it works
- opens the door to genetic modification e.g. using GM mosquitos to stop breeding instead of radiation
what are the disadvantages of using sterile male techniques to control pest populations
- no residue means repeated treatment needed
- sex seperation needed which can be hard
- radioactive elements used which may provide selective disadvantage to sterile males
- if irradiation doesn’t work just released a batch of healthy males
- high cost as requires dedicated facilities
