40 



NATURE 



[May 14, 1908 



This is shown on this diagram (Fig. 2). 



Distrihiilion of Malta Fever among the Civil Popiila- 

 tion. — Another important fact is the distribution of Malta 

 fever among the civil population. Until recently it was 

 supposed by many of us that it was restricted to the 



MALTA r£VER iMTHc CARRISON 

 fiAT/O per /OOO. 



Fig. 2. — Incidence in officers, men, and women for 1897-1905. 



inhabitants of the cities surrounding the Grand Harbour. 

 This was in the days when the theory was held that the 

 poison which causes this fever was found in the air. As 

 the Grand Harbour at that time was in a very dirty con- 

 dition, the drainage of Valletta and the three cities falling 

 into it. there was some excuse for this belief. 



Malta fever is now known to occur in every part of 

 the island, and, in fact, the general dis- 

 tribution of this disease is very striking. 

 It is not the cities round the Harbour 

 which are struck most heavily, some of 

 the inland towns and villages showing a 

 much higher fever-rate. 



This is illustrated by the following 

 diagram ^Fig. 3). 



SuM.M,\Rv OF Epidemiological Evidence. 

 What, then, have we learned from the 

 study of this fever from the general point 



of vil.'W? 



We have found that Malta fever depends 

 on no local conditions, as it occurs in many 

 parts of the world. It cannot have any 

 great dependence on climatic conditions, as 

 it occurs in the cool and rainy months 

 almost as frequently as in the hot, dusty, 

 and rainless. 

 . Poverty and insanitary surroundings do 

 not predispose; in fact, the well-to-do 

 classes have been shown to be more liable 

 to take the fever than the poor. It has no 

 connection with water supply or systems of 

 drainage,, as it breaks out as frequently in 

 the smallest country villages as in the large 

 cities. 



\\'liat, then, is the cause of this fever? 



Study of Malta Fever by the 

 experi.mental method. 

 Vliacovcry of the Parasite. — Let us 

 approach this problem from the experi- 

 mental 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 microscopically 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 dis- 

 covered by an army medical officer that a minute organism. 



to which the name of Micrococcus vieliteiisis was given, 

 is the cause of this disease. 



Description of the Micrococcus melitensis. — Theie is not 

 much to be said about this micro-organism, except that it 

 is very minute, only becoming visible under a magnifica- 

 tion 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 example, 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 somewhat shorter 

 period. 



The important thing to be noted is that it does not 

 increase outside the body; it merely survives for some , 

 time and then dies off, and, if exposed to direct sun- 

 light, 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 

 Ic.-ivcs .-md how it gains entrance to the body. 



y^" 



'<? 



Map of MdlU and Cozo. -ho' 



10 itie various Towros and 



lOg the Distribution. ol Malta Tevet 

 Viltages of the two Islands 



Fig. 3.— Incidence in civil population. 



How 130ES THE Micrococcus melitensis leave the Body? 



In regard to the first of these, it is conceivable that it 



might leave the body by way of the expired air, in the 



saliva, in mucus from the lungs, as in consumption, in 



the secretion of the skin, as in scarlet fever, in the renal 



NO. 201 I, VOL. 



78] 



