Erysipelas - Turkey

Introduction

Erysipelothrix rhusiopathiae is the only agent thought to cause Erysipelas in avian species. It is a non-spore forming, non-motile, gram-postive rod, which does not stain acid-fast.

It is a common disease in turkeys but is rare in the fowl.

Erysipelas is of economic importance in turkey farming as it not only causes death in the flock, but also causes infertility in the male.

In humans that work with poultry, the disease is of public health significance due to its zoonotic effect. A predisposing cut can cause infection by the organism, resulting in localised infection or septicaemia and death in people.

The organism is thought to be transmitted by contaminated material as the source of the infection, entering the bird via breaks in the mucous membrane or skin. Fish or fishmeal has been cited as the most likely causes of infection for turkeys. The bacteria can also be transmitted in the semen of the male turkey (tom). Research into vectors of the disease has shown that the poultry red mite (Dermanyssus gallinae) can act as a reservoir for the bacteria.

Clinical Signs

A sudden outbreak is characteristic of Erysipelas with birds of all ages affected. Males are predominantly affected, but if a female has been artificially inseminated in the last 4-5 days she is likely to die suddenly if the semen contained the bacteria.

Many birds will have no clinical signs and may be found dead, but some will have an unsteady gait and appear weak.

A dark, purple, swollen snood is commonly seen in affected males, however, many farmers are now removing these at birth making diagnosis in this case more difficult.

Pathology

Gross: An enlarged friable liver, spleen and kidney are present. All lesions are concurrent with septicaemia and congestion. Petechial haemorrhage in abdominal fat and haemorrhage in heart muscle are also seen. Arthritis and vegetative endocarditis, along with emaciation is common in chronic infections.

Microscopic: Again, all findings are concurrent with haemorrhage and congestion, such as sinusoidal channels and blood vessel engorgement in most organs and aggregations of fibrin and bacteria in capillaries and venules. Oedema and haemorrhage in lungs and heart are found due to congestion as well as necrosis of parenchymal cells in the liver, spleen and kidney.

Diagnosis

A presumptive diagnosis based on history, clinical signs and post mortem along with gram-stained smears of liver, kidney, spleen and bone marrow is usually enough for a vet to begin a treatment course. Whilst treatment has begun, samples of the dead bird will be sent to a laboratory for culture to confirm the presence on E.rhusiopathiae. 

Prevention/ Management

Husbandry measures such as rotating turkeys from contaminated areas and disinfecting equipment with 1-2% Sodium hydroxide (this has been proven to be effective against E.rhusiopathiae) are recommended. Prompt removal of dead birds and other carrion, as well as trying to limit stress in the flock at all times also greatly help in the prevention of this disease.

Vaccination - A formalin inactivated E. rhusiopathiae bacterin is used. Doses are:

breeding turkeys - 2 doses, one at 16-20 weeks and the second just prior to laying

meat turkeys - single dose SC

Treatment

Prevention is better than treatment but in the case of an outbreak the veterinarian should prescribe a rapidly-acting form of penicillin, as this is thought to be most efficient, as either a one-off I.M. injection or in drinking water for 4-5 days. The erysipelas bacterin (vaccine) should also be given.

Prognosis

Prognosis is poor in unvaccinated stock.

Immunised stock have good - guarded prognosis with mortality ranging from 1% to 50%.

References

Quinn, P.J., Markey, B.K., Carter, M.E., Donnelly, W.J., Leonard, F.C. (2007) Veterinary Microbiology and Microbial Disease Blackwell Publishing 

Randall, C.J, (1985) Disease of the Domestic Fowl and Turkey, Wolfe Medical Publications
Saif, Y.M, (2008) Diseases of Poultry, Blackwell Publishing