1908] on the Extinction of 3Ialta Fever. 19 



Study of Malta Fever by the Experimental 

 Method. 



Discovery of the Parasite. — I^et us approach this problem from the 

 experimental side. The first step to be taken is to discover if any 

 parasite or micro-organism is associated with this fever. To do this 

 we examine the blood and the tissues of the various organs, both 

 microscopicallj and by means of cultivation, on suitable media, to 

 find out if anything can be seen or grown. In this way, as long ago 

 as 1887, it was discovered that a minute organism to which the name 

 of iMicrococciis melitensis was given, is the cause of this disease. 



Description of the Micrococcus Melitensis. — There is not much to 

 be said about this micro-organism, except that it is very minute, only 

 becoming visible under a magnification of 1000 diameters. It is 

 round or oval in shape, and non-motile. It is found in every case of 

 Malta fever, and if injected under the skin of monkeys gives rise in 

 them to a fever similar to that in man. 



Characteristics of the Micrococcus Melitensis. 



Behaviour outside the Body. — Now, having found the micro- 

 organism, it is necessary to study its characteristics. 



It is found to survive outside the body for some time. For ex- 

 ample, it can retain its vitality and virulence in a dry condition in 

 dust or on clothing for at least two or three months. It can also live 

 in a moist condition ; in water — tap-water or sea-water — for a some- 

 what shorter period. 



The important thing to be noted is, that it does not increase out- 

 side the body ; it merely survives for some time, and then dies off ; 

 and that, if exposed to direct sunlight, it disappears in a few hours. 



Many attempts were made to discover it outside the body, under 

 natural conditions. As the generally accepted theory was that it was 

 conveyed in air, naturally the air of fever wards or of places where 

 cases had occurred was examined with great care. It was also looked 

 for in the dust of suspected places and in the water of the harbour ; 

 but with no success. It is evidently what is known as a facultative 

 parasite, or one which depends on a host for its existence. 



Thus, then, the first important step in our discovery of a means 

 of preventing Malta fever has been taken. We now know the cause 

 of the disease, and can look with some chance of success for the source 

 whence man obtains it. 



The next steps are to find out how this micrococcus leaves, and 

 how it gains entrance to the body. 



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