Dangerous Diamonds!

Michaela Giles explains the ins and outs of Erysipelas, the serious threat it poses and how best to deal with it

In 2016, the government’s disease surveillance group observed an increase in the disease diagnosis rate for Erysipelas; this was reported by the Animal and Plant Health Agency (APHA) in its quarterly UK surveillance data.

Anecdotally, those of us who exhibit our pigs also seemed to have ‘heard’ of a case across the UK last year. The reason for the upward trend hasn’t been fully explained, but a few ideas have been postulated and published (APHA 2016).

Erysipelas can be a serious disease for a pig and, although there’s a common misconception that it’s ‘easily treated’ with penicillin, there can be very significant, knock-on effects.

Widely-found

Erysipelas in pigs is caused by a bacterium, Erysipelothrix rhusiopathiae. It can be detected at most if not all pig farms, with up to 50% of the herd carrying it, asymptomatically, in their tonsils. It’s often present in the pigs’ environment, as the bacteria is shed in saliva, urine and faeces, and can survive outside the pig for up to six months (especially in light-soil environments).

It’s nigh on impossible to eliminate Erysipelas from a herd, especially if it is a breeder-finisher unit, only from individuals within a herd. While E. rhusiopathiae alone can cause clinical disease, an outbreak within a herd may be triggered by a concurrent virus infection, such as Porcine Reproduction and Respiratory Syndrome virus (PRRSv), or influenza.

Clinical signs

Pigs are particularly sensitive to Erysipelas and, as the bacteria multiplies in the body, it invades the bloodstream, causing septicaemia. The rapidity of multiplication of the bacteria, and the level of immunity in the pig, are what then determine the clinical signs seen, of which there are four typical forms:

• Per-acute

This is when the onset of the disease is sudden, with the only sign being death.

• Acute disease

Disease is relatively uncommon in nursery and recently-weaned pigs, due to the protection provided by maternal antibodies from the sow, supplied via the colostrum. The most susceptible animals are growing pigs, nonvaccinated or poorly vaccinated pigs and up to 4th parity sows; although some infected pigs may show no outward clinical signs.

Clinical signs may include a high temperature of around 40-42°C (104-108°F) and sufferers will be obviously unwell and reluctant to eat. The Erysipelas organisms invade the circulatory system and block the tiny blood vessels to the skin over the back and sides of the body, causing blood clots (thrombosis). This restricts blood supply, causing small, raised areas that typically form a diamond shape measuring 1-5cm in size – hence the name Diamond Disease.

These are initially red in colour but, as the surrounding tissue dies through lack of blood supply, they gradually turn black. This tissue is raised and so can be felt for in the case of dark-coloured pigs, and most heal within 7-10 days. Death may occur due to septicaemia and/or heart failure.