150 



is evidence to show that a process of bacterial selection occurs in the 

 fly's intestine. Some bacteria appear to flourish, but others are 

 rapidly eliminated. Among the latter must be numbered B. typhosus. 



Philip (W. M.) & Hirst (L. F.). A Report on the Outbreak of the 

 Plague in Colombo, 1914-1916.— J/, of Hygiene, Cambridge, xv, 

 no. 4, February 1917, pp. 527-564, 5 maps, 1 chart. 



The advent of plague in Ceylon occurred in January 1914 under 

 circumstances pointing to its introduction into Colombo by an infected 

 rat concealed in a bag of rice from South India. The deaths totalled 

 383 in 1914, and 128 in 1915. Nearly all the cases came from the very 

 poorest class of the population, living in the most insanitary parts of 

 the town. The rat has less difficulty in obtaining food in the poorer 

 quarters where waste food-stuffs are usually thrown into the yard. 

 The custom of sleeping on the earth em floor within easy reach of the 

 infected fleas from the numerous rat-holes also favours the spread of 

 plague. At Singapore, where there has been very little plague compa,red 

 with Colombo, rat-holes in houses are comparatively rare. Thirty 

 specimens of the Insectivore, Crocidura coerulea; the common shrew 

 of Colombo, were received in 1914, and 163 in 1915. The plague 

 infection among these was nil and subsequently the capture of 

 C. coerulea was forbidden and all that entered the traps were liberated. 

 Of Mus (Epimys) rvfescens, the local representative of Mtis rattus, the 

 total number examined in 1914 and 1915 for plague was 11,183 and 

 13,757 respectively, the gross percentage incidence being 1*13% and 

 0-23%. The corresponding figures for M. (E.) norvegicus were 3,891 

 and 5,129, with 2-72% and 0.58%. Of the infected M. rvfescens, 

 45-08% and 60-6% of the infection was of the septicaemic type, the 

 corresponding figures for M. norvegicus being 20-75% and 30%. 

 The most remarkable feature of the Colombo epizootic is this high 

 proportion of plague-infected M. rufescens showing the septicaemic 

 type. This feature is less marked in the case of M. norvegicus, but is 

 still very notable. As regards the relation between human and rat 

 plague it was observed that the discovery of the latter preceded that 

 of the former in 15 street-s of the town, thus enabling precautions to 

 be taken in advance. The rat plague when it appeared in new area^ 

 was almost always of the septicaemic type. 



The following species of parasites have been identified from Colombo 

 rats : The fleas, Xenopsylh, astia, Rothsch., and X. cheopis, Rothsch., 

 the mites, Dermanyssus muris, Hirst, Laelaps echidninus, Berl., and 

 L. nullalli, Hirst, and the louse, Haematopinus spinulosus. In view 

 of the exceptionally high degree of septicaemia in many of the Colornbo 

 cases of human plague, the question of the possibihty of transmission 

 from man to man by human parasites such as Pulex irritans (hominis), 

 Cirnex hemiptera {rotundatus) or Pediculus humanus (corporis) becomes 

 of practical importance. 



As regards seasonal incidence, there seems to be a more distinct 

 relation between the curve of humidity and the flea index than between 

 that of flea index and temperature. The curves showed a very close 

 correspondence between the periodicity of rat and human plague. A 

 sharp rise in the flea index in Jime 1915 was followed by a rise in the 

 curve of plague incidence among M. norvegicus. 



