Difference between revisions of "Psoroptic Mange"
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'''Life cycle''': Egg- Larvae- Nymph- Adult is confined to the skin surface. This life cycle takes around 10 days to complete. Adult female life expectancy is around one month and she lays 2-3 eggs per day, hence a mite population on an animal can expand rapidly. The mite can survive off the host and so transmission via housing and bedding is possible. Most transmission occurs from direct contact such as at markets or in livestock transporters. | '''Life cycle''': Egg- Larvae- Nymph- Adult is confined to the skin surface. This life cycle takes around 10 days to complete. Adult female life expectancy is around one month and she lays 2-3 eggs per day, hence a mite population on an animal can expand rapidly. The mite can survive off the host and so transmission via housing and bedding is possible. Most transmission occurs from direct contact such as at markets or in livestock transporters. | ||
| − | '''Predilection site''': Lesions are most common on flanks, neck, back and shoulders | + | '''Predilection site''': Lesions are most common on flanks, neck, back and shoulders |
This mite is found worldwide, but has been eradicated from Australia and New Zealand. | This mite is found worldwide, but has been eradicated from Australia and New Zealand. | ||
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== Pathogenesis == | == Pathogenesis == | ||
| − | The mite is active in the keratin layer of the skin and has abrasive mouthparts. It feeds on exudate of lymph, skin cells and bacteria caused by a hypersensitivity reaction to antigenic mite faeces, by the host. This causes intense pruritus, leading to self trauma, crust and scale formation and inflammation. | + | The mite is active in the keratin layer of the skin and has abrasive mouthparts. It feeds on exudate of lymph, skin cells and bacteria caused by a hypersensitivity reaction to antigenic mite faeces, by the host. This causes intense pruritus, leading to self trauma, crust and scale formation and inflammation. |
The disease is most prevalent in autumn and winter months, however does still occur in the summer, especially in sheep that have not been shorn. | The disease is most prevalent in autumn and winter months, however does still occur in the summer, especially in sheep that have not been shorn. | ||
| − | Psoroptic mange in sheep is a '''notifiable disease '''in the UK | + | Psoroptic mange in sheep is a '''notifiable disease '''in the UK |
<br> | <br> | ||
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*Evidence of self-trauma (loss, damage or staining of wool) | *Evidence of self-trauma (loss, damage or staining of wool) | ||
*Inflammation with exudate followed by a yellow crust | *Inflammation with exudate followed by a yellow crust | ||
| − | *Weight loss or reduced weight gain in young stock | + | *Weight loss or reduced weight gain in young stock |
*Secondary bacterial infection or Blowfly strike | *Secondary bacterial infection or Blowfly strike | ||
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*Skin scraping to microscopically identify mites (low magnification). Mites are found under scabs and in skin folds | *Skin scraping to microscopically identify mites (low magnification). Mites are found under scabs and in skin folds | ||
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| − | + | == Treatment/ Control == | |
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| − | + | Infestations are difficult to eliminate from a flock so a key factor in control is to not allow it to enter. | |
| − | * | + | *New stock should be isolated for at least three weeks before mixing with the main flock |
| + | *Plunge dipping is curative and preventative<br>- dip must contain the Organophosphate diazinon or the Synthetic Pyrethroid cis-cypermethrin<br>- plunge dipping must last for at least one minute and the head should be fully submerged twice during this time<br>- the sheep must be kept moving when in the dip as the movement displaces air from in the fleece allwing better penetration | ||
| + | *Can treat with avermectins or milbemycins by injection | ||
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*Cattle, horses and rabbits | *Cattle, horses and rabbits | ||
Revision as of 14:15, 1 March 2011
Synonyms
- Sheep Scab
- Psoroptic scabies
- Psoroptosis
Introduction
Psoropitc mange is the disease caused by the non-burrowing mite, Psoroptes ovis (common name Scab mite), which affects sheep.
Other species of Psoroptes mite affect a variety of species including Cattle, Goats, Horse, Rabbit, Camelid, however, all mites are host specific and will be discussed later.
Description: The mite looks very similar in appearance to Chorioptes, being oval in shape with long legs, but is almost visible to the naked eye. It has pointed mouthparts and jointed pedicles which have suckers on the distal aspect.
Life cycle: Egg- Larvae- Nymph- Adult is confined to the skin surface. This life cycle takes around 10 days to complete. Adult female life expectancy is around one month and she lays 2-3 eggs per day, hence a mite population on an animal can expand rapidly. The mite can survive off the host and so transmission via housing and bedding is possible. Most transmission occurs from direct contact such as at markets or in livestock transporters.
Predilection site: Lesions are most common on flanks, neck, back and shoulders
This mite is found worldwide, but has been eradicated from Australia and New Zealand.
Pathogenesis
The mite is active in the keratin layer of the skin and has abrasive mouthparts. It feeds on exudate of lymph, skin cells and bacteria caused by a hypersensitivity reaction to antigenic mite faeces, by the host. This causes intense pruritus, leading to self trauma, crust and scale formation and inflammation.
The disease is most prevalent in autumn and winter months, however does still occur in the summer, especially in sheep that have not been shorn.
Psoroptic mange in sheep is a notifiable disease in the UK
Clinical signs
- Severe pruritus
- Evidence of self-trauma (loss, damage or staining of wool)
- Inflammation with exudate followed by a yellow crust
- Weight loss or reduced weight gain in young stock
- Secondary bacterial infection or Blowfly strike
Diagnosis
- History and clinical signs
- Skin scraping to microscopically identify mites (low magnification). Mites are found under scabs and in skin folds
Treatment/ Control
Infestations are difficult to eliminate from a flock so a key factor in control is to not allow it to enter.
- New stock should be isolated for at least three weeks before mixing with the main flock
- Plunge dipping is curative and preventative
- dip must contain the Organophosphate diazinon or the Synthetic Pyrethroid cis-cypermethrin
- plunge dipping must last for at least one minute and the head should be fully submerged twice during this time
- the sheep must be kept moving when in the dip as the movement displaces air from in the fleece allwing better penetration - Can treat with avermectins or milbemycins by injection
- Cattle, horses and rabbits
- No licensed product for horses in the UK
- Cattle and rabbits can be treated with avermectins, milbemycins or topical acaricides