=Definition.=—Malta fever is a septicaemic condition due to the presence of the specific organism, _Micrococcus melitensis_, in the blood and various organs, especially spleen. It runs a protracted course, averaging three or four months, but is attended with very slight mortality (2%). Rare cases may run an acute course and show a high death rate. The fever course resembles that of a typhoid fever with two or more relapses, in that a step-like rise of fever for ten or twelve days is followed by a similar fall during the succeeding week or ten days, an afebrile interval of a few days then ensuing, to be followed by a second or third or even tenth febrile wave with the separating days of apyrexia. The course of the disease may last for a year or more attended with progressive anaemia and manifestations of neurasthenia. Very characteristic are sudden swellings of various joints which subside in a few hours to entirely disappear in a few days. Neuralgic manifestations, especially sciatica, are prominent features of the disease. It is chiefly spread by the milk of infected goats and can best be prevented by boiling such milk. =Synonyms.=—Febris undulans (from the wave-like monthly accessions of fever). Mediterranean, Gibraltar or “Rock,” Neapolitan, Cyprus fever (from the geographical distribution). Febris sudoralis (from the night sweats). Mediterranean phthisis (from the bronchitis, anaemia and night sweats resembling phthisis). Melitensis septicaemia. Febris melitensis. HISTORY AND GEOGRAPHICAL DISTRIBUTION =History.=—It is generally considered that a disease described by Hippocrates, in which there was an irregular febrile course without crisis but showing relapses and running a very prolonged course, was probably Malta fever. In 1861 Marston showed on clinical and pathological grounds that the disease was different from typhoid fever. In 1887, Colonel Bruce isolated the causative organism from the spleen at autopsy and established the demands of Koch’s postulates by reproducing the disease in monkeys with cultures from the spleen and then recovering the organism from the monkeys. Our present accurate knowledge of the epidemiology of Malta fever and its connection with the use of the milk of goats is due to the work of a Commission appointed to investigate the disease—1904 to 1907. [Illustration: FIG. 74.—Geographical distribution of Malta fever.] =Geographical Distribution.=—It is usual to consider Malta as the focus of the disease, with the cities of the Mediterranean shores showing quite a degree of infection. It is probable that the spread of the disease has been in part connected with the importation of Maltese goats, these animals being desirable on account of their superior yield of milk. It is now known that outside of the Mediterranean basin the disease exists in India, East and South Africa as well as Northern Africa, China, North and South America and the West Indies.