Erysipelas

Other names	Diamonds, Diamond skin disease, Measles,
Causal agent	A bacteria – Erysipelothrix rhusiopathiae. There are over 25 serotypes, however types 1 and 2 are the most common
Age group	The disease can affect any age group. However, most weaners below 12 weeks of age are protected from colostrum antibodies passed on from their mother
Clinical signs
	There are five phases of the disease recognized:
Peracute	Pig found dead with no clinical signs
Acute	The disease starts with a sudden onset.
The classic diamond lesions of erysipelas		The animals present with a high temperature (40-42C). The infected pig is often separated from the rest of the group and may appear chilled and cold (typical of a high fever). The pig is generally found lying down. When the pig is encouraged to rise, it will rapidly lie down again. The pig appears to have a sore abdomen, walks stiffly and tucked up. The pig generally appears very dejected. The pigs are often off their feed and may be constipated (although young animals may have diarrhoea). Sows may abort with the high temperature. Boars may become infertile, which may be permanent or last 6 weeks. 2 to 3 days after initially becoming infected pigs develop diamond skin lesions, which can be pink to dark purple. The lesions are not visible in the early stage of the disease.
The diamond lesions are generally raised, which may be the only way to diagnose the disease in black pigs. Pigs untreated may die or start to recover in 4 to 7 days. The skin lesions may go necrotic in the centre. The more severe the diamond lesions indicate a poorer prognosis.
Subacute	The pig presents with diamond lesions with few other clinical signs including no loss of appetite.
Chronic	Two forms: arthritis and endocarditis affecting the heart
Arthritis	3 weeks after infection the pig may present with a chronic lameness in one or two joints. It can affect the vertebrae and thus the pig has a sore back and difficult painful walking.
Endocarditis	The pig develops breathlessness and poor circulation especially after exertion. This can result in sudden death, especially after mating for instance. The pig’s ears and tails may go purple with the poor circulation.
Carrier	Some 20 to 50% of pigs may carry the organism on their tonsils without exhibiting any clinical signs

Infectivity
		Many pigs carry the organism on their tonsils without any clinical signs
		Soil, bedding, feces and drinking water can become contaminated
		Stressed pigs are more likely to show clinical signs, cases are more likely after pigs have become stressed - sudden changes in diet, sudden changes in temperature or introduction of other disease such as Swine Influenza
		The organism can cause problems in turkeys which can then cross-infect pigs
		The organism also lives in fish and fish meal – which can be an source of infection
		Poor vaccination may also result in unvaccinated pigs
Post-mortem Lesions
Peracute		May have very few lesions. Possibly an enlarge spleen
Acute		The skin lesions may be seen or felt. The spleen is generally very enlarged
Chronic-heart		The endocarditis is seen a cauliflower lesions growing on the heart valves. The heart may be enlarged associated with the poor circulation
- arthritis		Severe arthritis in one or more joints.
Pathogenesis (how diseases occur)
	The organism can gain access by many routes. Classically most infections are via the mouth from contaminated feed and water.
	In acute cases the disease enters the blood stream via the pharynx and infects the blood vessels hence the widespread clinical signs. The diamond lesions are actually an immune response. The circulation to the skin diamond lesions can be so compromised that the centre may die and become necrotic.
	In the chronic form arthritis can take months to develop and therefore diagnosis can be difficult as the lesions are sterile at the time of clinical examination.
Diagnosis
	Clinical signs
	Response to penicillin in suspected pigs. With penicillin the pig should response within 24 hours.
	Bacterial culture can be done on acutely infected pigs
	In chronic cases the organism can be difficult to isolate and serology may be useful.
Treatment
Acute/ subacute	Penicillin based medicines are very effective in the treatment of erysipelas.
Chronic	There is no practical treatment excluding treatment with painkillers in the arthritic form. Arthritis is generally permanent. Note vaccination is not protective against the arthritis form.
Prevention	Vaccination is a cheap and effective control measure
	Vaccination lasts about 6 months, therefore the following programme is recommended: Pigs over 3 months vaccinated once and again 3 weeks later
	Sows vaccinated either pre or post farrowing or every 6 months
	Boars vaccinated every 6 months, the boar is often forgotten
Common differentials
Acute	Swine Fever. Salmonellosis. Anthrax. Other causes of sudden death. Food allergic responses
Chronic	Arthritis – Mycoplasma arthritis. Endocarditis - Streptococcus
Zoonotic – human infections
	Erysipelas can infect humans and infection usually only results in a skin infection; however, the condition can be more severe.