History and Geography

Among the fevers plaguing the Mediterranean peoples since antiquity, a low type with regular remis sions or intermissions has been recorded since the time of the Hippocratic writings. Its geographic origins are indicated by many synonyms of which the best known are Malta fever and Mediterranean fever, although other variants involve Naples, Constantinople, Crete, and Gibraltar. A differential description of Malta fever as distinct from other fevers was first given by J. A. Marston in 1863; he called it "gastric remittent fever" and described several cases including his own ("a mild case of gastric remittent fever"). In 1887, Bruce, a surgeon attached to the Malta garrison like Marston before him, recorded his discovery of a small microorganism in the spleen of fatal cases. He proceeded to establish its causal role and called it Micrococcus melitensis, although in the 1920s it was changed to Brucella melitensis in his honor. Returning from duty in Malta, Bruce taught at the Army Medical College at Netley; among his students was Matthew Louis Hughes who, posted to Malta in 1890, enthusiastically embraced Bruce's interest in the prevailing fever. He wrote, both alone and in collaboration with Bruce, several papers dealing with the disease during the next decade, until he died under enemy fire while tending casualties in South Africa at Ladysmith in December 1899. It was Hughes (1897) who published a definitive clinical description of Malta fever, which is still quoted today as a model of its kind.

Since the time of Bruce, and because of the presence of British troops in the island, the disease and its epidemiology have received particular attention in Malta, culminating in the work of the British Mediterranean Fever Commission, which began reporting in 1905. During this work, Themistocles Zammit was able to establish the presence of the disease in local goats and the role of goats' milk in transmitting the disease to the human population. The results of his research caused the British army and navy to prevent troops from drinking goats' milk; within a year the disease had all but disappeared from the British forces in Malta (see Figure VIII.20.1). As already mentioned, for social and economic reasons control of the disease in the civilian population proved far more difficult to achieve; only the advent of pasteurization could eventually solve this problem, although it should be noted that the disease in goats is still resisting control.

B. melitensis infections had been observed and described in the late 1800s, following Robert Koch's epoch-making demonstration of the methods for isolating and identifying specific disease agents. It was Bruce, however, who isolated the causal microorganism in 1887. Nearly two more decades were to elapse

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Figure VIII.20.1. Graphs illustrating the dramatic reduction in the incidence of brucellosis in the British garrison in Malta from 1905 to 1907, following the ban on the use of goat's milk. (From D. Bruce 1908.)

before the goat was identified as the natural host of B. melitensis and the mechanism of transmission to humans became clear. In the case of B. abortus infections, the historical sequence of events was rather different. The disease in cattle had been described by several authors during the first half of the nineteenth century. In the context of the times some considered it contagious, others not. Its transmissi-bility was demonstrated in pregnant cattle in 1878; and just before the turn of the century Bernhard Bang in Copenhagen was able to isolate and identify the causal agent. It was only in 1918, however, that Evans noted a close morphological and biochemical similarity between B. melitensis and B. abortus; within a few years B. abortus had been shown to be pathogenic for human beings and to give rise to cases of undulant fever in many areas around the world where raw cows' milk rather than goats' milk was consumed, and where epizootic abortion of cattle was a common occurrence.

Last of the major types of undulant fever to attract attention was that caused by B. suis. The first case to be diagnosed appears to have been in the United States in 1922, although even then the identity of the agent was not immediately recognized. Clinically (and bacteriologically) the disease is similar to the two other major types although it is less extensively distributed in either pigs or humans. B. suis infection of swine first began to cause concern in the large hog-raising areas of the midwestern United States in the 1930s. The disease has since been reported to be present in a number of other countries, but cases appear to be mostly sporadic, with only a few recognized outbreaks in the United States, and one in Denmark in 1929.

Lise Wilkinson

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