How it began
In 1887 the British Army surgeon David Bruce, working at the Station Hospital in Valletta, first isolated a bacterium from the spleens of patients who had died of Malta fever. He named it Micrococcus melitensis; it was later renamed Brucella melitensis. How people caught it stayed unknown. In 1904 the Maltese doctor Themistocles Zammit joined the Mediterranean Fever Commission. He fed cultures of the bacterium to goats from September 1904 and found their blood reacted. On June 14, 1905 he found that five of six goats bought from local herds tested positive.
Before it existed
After a year of work the Mediterranean Fever Commission had made little progress on how the fever spread. Other routes, including mosquitoes, were under study. Local health officers had noticed cases among people living on farms that kept milch goats supplying Sliema, and in 1904 a newspaper reported a family of five falling ill after drinking goat milk. A navy surgeon who injected a goat in July 1904 could not find the bacteria in its milk or urine.
How it works
Zammit used an agglutination blood test to show that goats were susceptible to the infection and that natural infection was very frequent. About half the goats in Malta were found to be positive. He isolated the organism from the blood, urine and milk of infected goats that showed no signs of disease. People were infected mainly by drinking the milk, and also through foods made with it.
Who pushed back
Credit was contested. David Bruce called the finding an accident, and an obituary of Bruce said Zammit "happened to examine the blood of a goat". Major W. H. Horrocks reported the result to Bruce in terms that took the credit for himself. A 2005 paper in the Journal of the Royal Society of Medicine argues that the discovery followed months of deliberate experiments by Zammit. A 1996 Lancet paper also records the controversy.
What changed first
The finding led within a few years to the elimination of the disease among British servicemen in Malta. In May 1906 the senior medical officer G. Caruana Scicluna published a government pamphlet on the milch goat as a factor in spreading the fever, in English, Italian and Maltese.
What lasted
The discovery that apparently healthy goats could carry the disease has been called one of the greatest advances in the study of epidemiology, and it changed ideas about animal carriers of human disease. The bacterium and the disease now carry Bruce's name, and a blood test devised by Zammit was used by other researchers.
