DURING World War II, and precisely from 1941 to 1944, when Greece was under enemy occupation, a painless and feverless enlargement of the parotid glands which lasted for several months was observed in undernourished persons. This enlargement appeared in an epidemic form, particularly during the winter season, and we discovered more than 3,000 cases in a research at schools and factories. This enlargement gradually disappeared from the vast majority of patients with the first hot days in spring.
Various investigations were performed in order to elucidate the etiology of this syndrome. It was not a bacterial or virus infection, because fever or blood reactions were not observed. Since the first cases appeared in patients with epidemic louse-borne typhus fever, the rickettsial nature of the syndrome was excluded. Chronic virus parotitis was rejected because most patients already had had the infection, and orchitis as a complication during or after the syndrome
Katsilambros L. Asymptomatic Enlargement of the Parotid Glands. JAMA. 1961;178(5):513-514. doi:10.1001/jama.1961.73040440027014e