Staphylococcus hyicus

Synonyms

Exudative Epidermitis (Greasy pig disease)

Introduction

Exudative Epidermitis is a worldwide disease of pigs under 3 months of age caused by Staphylococcus. hyicus. Infections are generally sporadic and adn can cause noticable losses in non- immune herds.

Staphylococcus. hyicus is highly contagious and persists in the environment for long periods of time, making control and prevention difficult. S.hyicus works by producing an exfoliative toxin that causes separation of cells in stratum spinosum resulting in rapid intraepidermal spread of organisms.In piglets morbidity can range from 20- 100% and mortality can reach 90%. Older pigs can also be infected but only mild clincal signs will occur.

The disease is usually brought into the herd and then passed on to non-immune sows, whose litters will then develop the disease. S.hyicus is found on the nasal and vaginal mucosa and from the skin of the ears and snout in healthy animals. It is spread by transmission into skin abrasions, such as that caused by mites, rough bedding or bite wounds and is predisposed to if the piglet is weak or has had a failture of passive transfer.

 

Clinical Signs

It's presentation is very similar to “scalded skin syndrome” in human neonates, due to skin infection by exfoliative toxin-producing Staphylococcus aureus. There are three different syndromes that occur with this disease:

Peracute - greasy, brown exudate on face, esp. behind ears, vesicopustular eruptions esp. coronets; epidermal splitting; becomes generalised over back and abdomen with the exudate causing matting of the hair. There is no pruritis. Systemic signs such as depression, fever, anorexia and possible septicaemia will then ensue and death will usually occur within 3-5 days.

Acute - signs as for the peracute disease but also skin thickening and crusting of the skin; death 4-8 days.

Subacute - lesions on the head and ears and may also involve the limbs; pigs may recover spontaneously but usually are stunted.

In adult pig, mild skin lesions can develop, but no severe signs or systemic effects will occur.

Diagnosis

Clinical signs and the age of the pig usually are enough to make a presumptive diagnosis.

Differential diagnoses include mange (Sarcoptes scabiei var. suis),swine parakeratosis (zinc and essential fatty acid deficiency), porcine juvenile pustular psoriasiform dermatitis (collarettes or rings typically on the ventrum of young pigs), dermatosis vegetans (associated with a giant cell pneumonia) and dermatophytosis (most commonly Microsporum nanum).

Post mortem finding will show a thickened epidermis and scaling and when examined microscopically will see subcorneal pustular dermatitis extending to hair follicles leading to superficial suppurative folliculitis. Also in later stages of the disease will observe hyperplastic epidermis, thick keratin crusts with cocci, microabscesses.

Bacteriological samples can be taken from the skin lesions and sent to a laboratory for isolation of S. hyicus from these lesions.

Treatment and Control

If caught early, it can be treated with antibiotics, such as fluroquinolone, ampicillin, amoxycillin, ceftiofur and sulphonamides. Treatment must be carried out for at least 5 days and there is no gurantee that piglets will return to full health, with some remaining stunted for life.

Rehydration solutions and electrolytes are necessary and piglets should be washe din a mild disinfectant solution such as cetrimide. Disinfection of all farrowing crate and pens and other housing should be performed to try and eliminate the risk of further outbreaks.

Prevention measures include clipping of teeth in neonates, providing soft bedding and treatment for mites. Sows should be washed before entering the farrowing crates and all areas should be disinfected thoroughly before sow or litter are placed in there.

References

Cowart, R.P. and Casteel, S.W. (2001) An Outline of Swine diseases: a handbook Wiley-Blackwell
Jackson, G.G. and Cockcroft, P.D. (2007) Handbook of Pig Medicine Saunders Elsevier
Straw, B.E. and Taylor, D.J. (2006) Disease of Swine Wiley-Blackwell
Taylor, D.J. (2006) Pig Diseases (Eighth edition) St Edmunsdbury Press ltd