Phylum Arthropoda, Class Arachnida, Order Astigmata Flashcards
Astigmata meaning?
No stigmata and respires through cuticle
What are the general features of Sarcoptes Scabei?
Contains one species with many variants for the different species. Humans can become infected
Wide range of hosts
Infestations of sarcoptes specific to one host, on another host is limited in time. Can survive but cannot reproduce on the other host. Causes pathology.
Human health –> cattle, goat, pig, dog and horse parasites can temporarily infect humans. Cannot complete lifecycle on humans and signs disappear in 2-3 weeks unless have constant exposure.
Morphology
- Oval shape of body with ventral surface flattened and dorsal surface convex.
- Gnathosoma is almost square
- dorsal side of the idiosoma contains transverse striations, spines and triangular scales.
- 4 legs that are short and conical.
What is the lifecycle of sarcoptes scabei?
All stages occur on the host - cannot survive in environment long.
Takes 2-3 weeks to complete
The fecundated females burrow tunnels into the skin and lay eggs. Larvae hatch with 3 pairs of legs and move to surface of skin.
The larvae molt to protonymph and then tritonymphs, then adults.
Females mate, and burrow into the skin using their legs and enzymes produced. Females die after laying eggs.
Faeces, eggs and enzymes produced are important as they cause a hypersensitivity reaction –> itching. Once the females die within the tunnels, causes a nodular reaction and will be destroyed by the host immune system.
In very high populations, can cause many lesions that look like crustings. On pigs, have nodules on belly, on cattle = hair loss on neck, dogs = hair loss over body, horses = hair loss on face, neck and ears.
What are the general features of Notoedres cati?
Infects cats, rabbits and humans
Is smaller than sarcoptes scabei
Body is circular, on the dorsal side of idiosoma is concentrical striations (circle), spines and blunt scales
Legs are smaller and conical
Anus is dorsally located.
What is the lifecycle of Notoedres cati?
Similar to sarcoptes scabiei
Egg –> larvae –> 2 nymphal stages –> adults
All lifecycle stages occur on the host
Adult females burrow into the skin, lay eggs –> larvae, travel to surface –> nymph x 2 –> adults
What are the general features of Cnemidocoptes mutans?
Known as the scaly leg mite
Hosts –> domestic chicken, turkey, pheasant, older birds
Located under the scales of the legs –> scaly legs. If not treated, the bird could become crippled.
Circular body, short gnathosoma (shorter and wide - almost rectangular)
Dorsal surface has faint striations and in females it has a scaly aspect.
No Dorsal spines
Legs are short and stubby
What is the lifecycle of Cnemindocoptes mutans
Females give birth to larvae –> no egg, larvae form within the mite.
What are the general features of Cnemidocoptes gallinae?
Mites burrow into the feather shaft and the upper layer of the epidermis
Intense itch causes birds to pull out feathers = depluming itch
What are the general features of Cnemidocoptes pilae?
Known as the scaly face mite
infects budgies, rainbow lorikeets, parrots, etc.
Generates thick white crusts around the beak, eyes, face and legs. Can cause a deformity of the beak and difficulty breathing. Crusts are very thick and can cause bleeding lesions.
What are the general features of the Psoroptes species?
Hosts - many hosts, ruminants, horses
Located on the surface of the skin - do not burrow.
Common clinical signs in the cold season
Not present in Aus.
Look like spider.
Gnathosoma is long and conical
Most legs are long and protrude beyond the tip of the gnathosoma and the posterior margin of the body
Legs have 3 segments
Males have abdominal lobes and ventral suckers –> important for identification.
Posterior end of females are rounded
Posterior end of males contains a pair of lobes (each lobe has 5 setae - short) and a pair of copulatory (ventral) suckers.
What is the lifecycle of Psoroptes?
Eggs –> larvae –> 2 nymphal stages –> adults
All stages on the host
Lifecycle completed in 2 weeks
Larvae has 3 pairs of legs
Adults have 4 pairs
In sheep, lesions occur on shoulders, neck, thorax
In cows, lesions occur on shoulders, rump and base of tail (due to the cattle licking)
In goats and rabbits - located in the ears. In rabbits causes a severe disease and death.
In horses, lesions located on the mane and tail.
What is the general features of Chorioptes spp?
Hosts - Ruminants, horses
Located on the surface of the skin - no burrowing
All stages occur on the host
Gnathosoma is short, rounded
Legs are long.
Pretarsi are short, not jointed and the pulvilli are cup/bell shaped.
Posterior end of the male contains a pair of well developed posterior lobes with 2 long setae and 3 normal setae. Also contain copulatory suckers
Setae is used for mating and identification
Where are the lesions of Chorioptes spp. located?
Cattle (Chorioptes bovis) is located on the tail, peritoneum, udder, scrotum, hindlegs.
Horses - located on the lower legs and tail
What are the major differences between Psoroptes and Chorioptes?
Psoroptes
- contains a funnel shaped sucker
- pointed mouthparts
- rounded abdominal lobes in males (connected to setae)
- 5 short setae
Chorioptes
- Cup shaped sucker
- Rounded mouth parts
- squared posterior lobes in males
- 2 long setae, 3 short setae
What are the general features of Otodectes cynotis?
Known as the ear mite
Hosts - dogs, cats, humans
Located in the external ear canal and adjacent skin of the head
Gnathosoma is short and the length is the same as the width
4th pair of legs is very small (barely visible)
Posterior lobes in the males are reduced, copulatory / ventral suckers are present.
