The Significance of Infections in the Origination of Psoriasis

Summary and ConclusionThe first of the investigations presented discloses that in a random-sampled psoriasis clientele (66 patients) the number of positive streptococcal O-agglutination tests in the titre range, 1:40 to 1:320, is seven times higher than in a simultaneously examined, random-sampled venereological clientele (68 patients). As a rule, the strongest reactions were noted in patients with guttate psoriasis. — The second, and above all, the third investigation relate to cases with eruptions of psoriasis following throat infections, but show in the first place that AST titres of 200 units and more are nearly three times more common in a case series (32 patients) with acute eruption of psoriasis than in normal subjects. — Again, the fourth investigation shows that of 65 patients with suddenly arising psoriasis, in particular guttate psoriasis, 64% had had infections of the upper respiratory tract, as a rule tonsillitis, 1 to 3 weeks prior to the eruption of psoriasis. Another 6 patients included in the series had elevated AST titres though being unaware of any infections.The collected evidence illustrates from various points of view the relationship between infections of the upper respiratory tract, principally by streptococci, and suddenly developing, extensive psoriasis chiefly guttate in type. The study was performed in different parts of the country and during different periods, shorter in summer as well as longer ones covering several years. Hence the results cannot be attributed to an occasional epidemic of throat infections.The separate observations tally well with one another, and in my opinion they show that acute eruptions of psoriasis, especially guttate psoriasis, in two-thirds of the instances are provoked by infections of the upper respiratory tract, in particular those due to streptococci. The high incidence of articular changes in psoriasis patients is hereby easily explained. The closer connexion is obscure. At any rate, one might venture to state that the same incitement can be present in both conditions.The question of whether penicillin is beneficial in cases of psoriasis, is likely to arise under such conditions. It should be borne in mind, however, that psoriasis is not a streptococcal infection of the skin, but that, in my opinion, it is an independent biologic process in the skin, which is started by the streptococcal infection. In certain occasional instances where there was evidence suggesting that the evoking infection had not yet subsided, the skin disease seemed to respond more readily to topical applications when the patient had been treated with penicillin. On the other hand, guttate psoriasis is often easily cured by topical treatment, provided that it is used carefully at first when the patient is sensitive. This might very well agree with the evoking throat infection already having completely subsided when these patients are seen by the physician.