Class : Arachnida
Order : Acarina
Mites
By
Assist. Lecturer Maytham A. Alwan
4/13/2015
Phylum: Arthropoda
phylum
Class
Order
Arthropoda
Arachnida
Acarina
Ticks
Mites
Insecta
Diptera
Phthiraptera
Siphonaptera
flies
lice
fleas
Others
e.g. Hemiptera
bed bugs
Acarina : Mites
• The parasitic mites are small, most being less than 0.5 mm long, though a few
blood-sucking species may attain several mm when fully engorged. causing various
forms of the condition generally known as mange.
• Although, like the ticks, mites are obligate parasites, they differ from them in the
important respect that most species spend their entire life cycles, from egg to adult,
on the host so that transmission is mainly by contact.
• The mites have a complex taxonomy, occupying at least eight different families, and
for veterinarians. Mites can be divided into two major groups: sarcoptiform and
nonsarcoptiform mites. Nonsarcoptiform mites includes demodecidae (Demodex
canis)
• The sarcoptiform mites can be subdivided according to their location on the host as
burrowing(Tunneling)
Mites
Burrowing Mites
The three important burrowing genera, Sarcoptes, Notoedres and
Knemidocoptes, belong to a single family, the Sarcoptidae
Non-burrowing (surface dwelling) mites (Psoroptes, Chorioptes,
Otodectes), belong to a family, the Psoroptidae
classification
Order : Acarina
Family: Sarcoptidae
Genus: Sarcoptes
Sarcoptes
• Sarcoptes is well known in both human and veterinary medicine as a
cause of mange, the disease in man being generally known as scabies.
• Hosts:
• All domestic mammals and man.
• Species:
• S. scabiei var hominis (human), S. scabiei var. canis ( dogs), it can also
infest other mammals, including cats, pigs, foxes, rabbits and guinea
pigs for varying periods of time. S. scabiei var. suis ( pigs), S. scabiei
var bovis ( cattle), S. scabiei var. equi ( horses), S. scabiei var ovis (
sheep), S. scabiei var caprae ( goats).
• Distribution: Worldwide.
Sarcoptes
Morphology
Adult scabies mites are spherical(rounded) ,
dorsoventrally flattened up to 0.4 mm in diameter,
and the cuticle is striated bearing a central patch
of raised scales with four pairs of short legs
having suckers on a long unjointed stalk on pairs
1st and 2nd in the case of female and on pairs 1st,
2nd and 4th in male. The remaining legs all
terminate in long, hair-like setae.
Female of Sarcoptes-scabiei
Order :Mesostigmata mite
Sarcoptes
life cycle
Sarcoptes scabiei mites complete their entire four-stage
life cycle : egg, larvae, nymph and adult on the host,
and do not survive for long periods in the environment.
Male and female mites breed on the skin surface. Males
do not burrow into skin. The females penetrate the
keratinized layers of the skin and burrow tunnels through
the epidermis over a 10-15 day period. The female
deposits 40 to 50 eggs within the tunnel. After egg
deposition, the female dies. Six-legged larvae emerge
from the eggs in (3-10) days and exit the tunnel to wander
on the skin surface. These larvae molt to the eight-legged
nymphal stage within tiny pockets called molting pouches
in the epidermis. Nymphs become sexually active adults
in 12 to 17 days and the life cycle begins again.
Sarcoptes
Clinical Signs
In sheep, Sarcoptes scabiei variety ovis affect the nonwoolly skin, and the lesions typically start on the lips or
nostrils. The lesion on the nostrils also extends around the
eyes, the supraorbital fossae and in some cases over entire
face and head.
The clinical signs can be summarized in itch , intense
pruritic erythematous dermatitis and papular rash as the
alopecia spreads. The rash often becomes generalized
leading to hair loss due to which animals loose much of the
grazing time and hence loose general body condition
(weight loss), secondary bacterial infection where severe
untreated cases can be fatal , death is usually the result of
secondary bacterial infections.
Scabies Rash
Sarcoptes
• Pathogenesis
Sarcoptes female Mites burrow into the epidermis and
feed on tissue fluids. The burrowing and feeding of the
mite cause irritation and consequential scratching,
leading to inflammation and exudation to form crusts .
If left untreated, the skin wrinkles and thickens with
proliferation of the connective tissue followed by
depilation. Death of the animals may occur in severe
mite infestation.
Non burrowing mites
Including: psoroptes, chorioptes, otodectes
Family : Psoroptidae
Genus : Psoroptes.
Species : P. communis var ovis.(sheep)
P. communis var caprae (goat)
P. equi (equine)
P. natalensis ( cattle and horses)
P. cuniculi (ear mite of rabbits, goats, horses and sheep)
Psoroptes
• Mites of the genus Psoroptes are obligate, non-burrowing, astigmatid
ectoparasites of mammals, of particular economic importance in domestic animals
where they cause clinical psoroptic mange.
• Morphology
•
Mature female Psoroptes up to 0.75 mm, with a striate cuticle. A noticeable
anterodorsal cuticular plate is present behind the mouthparts, and the midventral
ovipore is an inverted U-shape. Males are about one-fourth smaller, and they have
a pair of posteroventral adanal suckers, and two terminal posterior lobes, each
equipped with four setae of varying lengths and structures. Nymphs and larvae are
somewhat similar to adults but progressively smaller, and all Psoroptes are pearly
white in color.
In all stages, the anterior two pairs of legs are thicker and more robust than the
posterior pairs, which are thinner, and in the male, shortened in the fourth pair. Legs I
and II terminate in pretarsal empodial suckers on long, segmented pedicels in both
sexes, with similar structures on legs IV of the female and legs III of the males. The
female’s third tarsus ends in two long, whip-like setae, and the male has a single short
seta on tarsus IV.
Male of psoroptes
female of psoroptes
Psoroptes
life cycle
The life cycle begins with the deposition of the eggs on the skin at the
margin of the lesion. These hatch in 1 to 5 days producing 6-legged
larvae. The larvae feed for 2 to 3 days and then molt and become 8legged nymphs. The nymphal stage lasts 3 to 4 days when they molt
and become mature males and females which mate immediately. The
fertilized female molts and then lays eggs. The cycle from egg to
adult is compeleted in 12 days. Females may live as long as 42 days
on sheep.
Psoroptes
Clinical signs
Psoroptes mites usually affect the shoulders, back, sides, lower cervical and
upper thoracic region. Sheep scab is characterised by intense itching and
pruritus. The flock may be seen repeatedly rubbing their shoulders and
flanks along the ground or against fences, foot stamping, clawing at their
flanks, or biting their shoulders and sides. Early cases of sheep scab are
characterised by red sores with serous exudation, yellow/orange staining
wool fibres and displacement of small tufts of wool. As the disease
progresses, the serous exudation increases in severity and extent, extending
over the shoulders to the chest wall, back and flanks.
Diagnosis
1. Clinical manifestations
They are summarized by hair loss, crusty or scaly skin lesions, dermatitis, thickened skin,
blisters, scurf, and pruritus.
2. Laboratory tests : which include two methods
a. Direct method: the skin scraping place in a test tube and add 5-10 ml of KOH 10%. The
tubes are placed in a water bath with 60-80˚c for 15 minutes then transported to a centrifuge
in a speed of 1500-2000 rounds per minute for 5 minutes then the supernant is discarded by
an automatic pipette and the sediment is mixed well in a test tube. Then some drops are
drawn from the sediment with a pipette and placed on a glass slide covered with a cover
slide and examined under microscope with power 10 x, 40 x, 100 x to confirm the presence
of parasite.
b. Indirect method:
1. ELISA
2. Polymerase Chain Reaction (PCR)
Treatment
• in animals mite infestations are treated with
• 1. acaricides including lime sulfur, the animal may be bathed first
with an antiseborrheic shampoo to remove crusts and debris.
• 2. Ivermectin is used to treat some mites, and doramectin has been
used for sarcoptic mange. Selamectin has recently been reported to
be effective for sarcoptic mange. If the mites can survive for more
than a few days in the environment, the animal’s surroundings must
also be treated with an insecticide or acaricide .
some differences between Ticks & Mites
Mites
Ticks
1.
Large in size, can be seen by the
naked Eyes
2.
All of them parasitic
3.
Covered by scutum
1.
Microscopic in size
2.
Some of them free living & other
parasitic on plants
3.
Scutum not present and the skin is
leathery
4.
Armed hypostome
4.
not armed hypostome
5.
Parts of it's lifecycle is free living
5.
All it's lifecycle on the body of the host
6.
Lay it's egg on the ground in cracks
6.
Lay it's egg in tunnels at the site of
infection on the body of the host
or under the rocks
7.
Body is not covered by hair
7.
Body is covered by hair