The small and medium-sized arteries are affected and it involves most organs. In half the cases, there is an acute onset with fever, aching in the limbs and abdominal pain.
While this also is thought to be an auto-immune disease, some researchers believe it to be a hypersensitivity reaction to infection, particularly to recent infection with the streptococcus germ. This is the common cause of tonsillitis and the skin disease, impetigo.
Rheumatic fever, which affects the joints and sometimes the heart, and acute nephritis, an inflammation of the kidneys, are believed to be hypersensitivities to the streptococcus.
Cortisone can relieve the acute symptoms of polyarteritis but does not appear to alter the course of the disease.
There are a number of other collagen disorders, perhaps the most important of which is Giant Cell Arteritis.
This is a sub acute inflammation of the larger arteries and the temporal artery which lies in the scalp is the most commonly affected.
This form of collagen disease affects the elderly, usually at around 70. There is often a slow, insidious onset, with fever, tiredness and weight loss. The temporal artery may become thickened, easily felt and tender. While this is the most noticeable feature, many other arteries of the body may also be affected.
Early recognition is important, as the retinal arteries which supply the eyes may be involved and this can impair vision.
Cortisone is most effective in this condition. Early treatment results in settling of the inflammation with relief of symptoms, and can save the sight.