# 1911 Encyclopædia Britannica/Actinomycosis

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​ACTINOMYCOSIS (Streptotrichosis), a chronic infective disease occurring in both cattle and man. In both these groups it presents the same clinical course, being characterized by chronic inflammation with the formation of granulomatous tumours, which tend to undergo suppuration, fibrosis or calcification. It used to be believed that this disease was caused by a single vegetable parasite, the Ray-Fungus, but there is now an overwhelming mass of observations to show that the clinical features may be produced by a number of different species of parasites, for which the generic name Streptothrix has been generally adopted. In 1899 the committee of the Pathological Society of London recommended that the term Streptotrichosis should be used as the appropriate clinical epithet of the large class of Streptothrix infections. And since that year the name Actinomycosis has been falling into disuse, and in any case is only used synonymously with Streitotrichosis. For a further account of these parasites see the articles on Bacteriology and on Parasitic Diseases.
Pathological Anatomy.—The naked-eye appearance of the different organs affected by Streptothrix infection varies according to the duration and acuteness of the disease. In some tissues the appearance is that of simple inflammation, whereas in others it may be characteristic. The liver when affected shows scattered foci of suppuration, which may become aggregated into spheroidal masses, surrounded by a zone of inflammation. In the lungs the changes may be any that are produced by the following conditions. (1) An acute bronchitis. (2) A phthisical lung, grey nodules being scattered here and there almost exactly simulating tuberculous nodules. (3) An acute broncho-pneumonia with some interstitial fibrosis and a tendency to abscess formation. The most characteristic lesions are ​in the skin. These appear as nodules, sarcomatous-looking, soft and pulpy. Their colour is mottled, yellow and purplish red. The skin over them is thinned out, and broken down in places to form one or two crateriform ulcers from which a clear sticky fluid exudes. The size varies from that of a pea to a small orange. The pus is characteristic, varying in consistency though usually viscid, and containing numerous minute specks.
The disease is more common in males than in females, and more prevalent in Germany and Russia than in England. The infection is probably spread by grain (corn or barley), on which the fungus may often be found. In a great number of recorded cases the patient has been following agricultural pursuits. The disease can only be transmitted from one individual to another with considerable difficulty, and no case of direct transmission from animal to man has yet been noted.
Clinical History.—The course of actinomycosis is usually a chronic one, but occasionally the fungus gets into the blood, when the course is that of an acute infective disease or even pyaemia. The symptoms are entirely dependent on the organ attacked, and are in no way specially characteristic. During life a diagnosis of phthisis is continually made, and only a microscopic examination after death renders the true nature of the disease apparent. The nature of the skin lesion is the most evident, and here the parasite can be detected early in the illness. The only drug which appears to have any beneficial influence on the course of the disease is potassium iodide, and this has occasionally been used with great benefit. Surgical interference is usually needed, either excision of the part affected, or, where possible, a thorough scraping of the lesion and free application of antiseptics.