I440 



UNDULANT FEVER 



water, neither have any of these in a natural way been proved 

 capable of spreading the disease. It is, however, true that dust, 

 infected with damp organisms from a culture, has infected monkeys, 

 as have suspensions of the organism when applied to mucosae of the 

 nose or throat. It appears, however, to be best conveyed to 

 animals in food, especially milk. 



The organism has also been found by the serum reaction to be 

 present in 50 per cent, of the goats examined in Malta, and has also 

 been obtained from the milk of 10 per cent, of the goats investi- 

 gated, and, when looked for, it has been found in the blood of goats 

 and other animals. The milk of such animals contains agglutinins 

 for the germ (Zammit's lacto-reaction). Notwithstanding this 

 infection, the animals are quite healthy, though a chronic mastitis, 

 as observed by Neri, may occasionally be noted. It appears to be 

 conveyed to man by infected milk, the best evidence in favour of 

 which is the infection of a ship's crew by the milk of goats, which 

 were being conveyed from Malta to America, 53 per cent, of which 

 were found to be infected. 



The distribution of the disease, therefore, depends upon the con- 

 sumption of infected goat's milk, for people who use this milk will 

 be more liable to infection than others — ^hence its occurrence in 

 Malta and the Mediterranean districts, in South Africa and India. 

 This is also the reason why the richer classes are more affected than 

 the poorer, and why individual institutions are picked out. It also 

 explains why there is no age or sex incidence, why infants rarely 

 suffer, and why occupation and surroundings have but little in- 

 fluence. 



How the disease spreads from goat to goat is not known. Brumpt 

 states that they drink human and animal urine if deprived of salt, 

 and in this way the infection may be kept up. The percentage 

 of infected goats has been found to be 3-4 per cent, in Algeria, 

 29 per cent, in St. Marthal, 307 per cent, in Tunis, 34*2 per cent, 

 in Marseilles, and 50 per cent, in Malta. 



Mules, asses, horses, oxen, cows, dogs, rabbits, and fowls, are all 

 apparently capable of spreading the infection, while often they do 

 not show any sign of disease. 



The question of the human carrier is only just coming forward 

 with any degree of prominence as a factor to be considered in the 

 spread of the disease, but Shaw has drawn attention to this possi- 

 bihty in Malta, where many of the dock labourers showed agglu- 

 tinins in their blood for M. melitensis, and Missiroli has obtained the 

 micrococcus from the blood of an apparently healthy man who 

 subsequently developed the fever typically in fifteen days. 



The carriers and ambulant human cases may pass the Micrococcus 

 melitensis in the urine, infecting the soil, and in this way may convey 

 indirectly the malady to other persons. 



Four modes of infection are described: (i) By the alimentary 

 canal, which is the usual method; (2) by the respiratory system> 

 inhaling dust contaminated by goat's urine, which is rare; (3) by 



