128 



The author gives the following summary of observations made upon 

 rats and rat fleas. 



During April 1912, several cases of pneumonic plague were detected 

 on vessels from Hongkong and Amoy. Investigation of these cases 

 and of all subsequent arrivals failed to show any connection between 

 them and the first cases of plague on the 17th June in Manila. The 

 disease was probably introduced by plague rats or insects present 

 in cargo from infected poits which was not unpacked until it was 

 distributed in the city. Rat-catching was carried on in Manila during 

 the entire time that plague was absent, but no case of rat-plague was 

 found until the 31st August 1912, in spite of the fact that over 

 14,000 rats had been caught in districts in which human cases had 

 occurred since 17th June. Plague w^as found in rats, cats, bed-bugs 

 and fieas. A serious human outbreak occurred in October, in which 21 

 cases were traced to the goods warehouse at the Azcarraga railway- 

 station. The grey rats were found to be the commonest. The per- 

 centage of plague among rats had been very small, less than 0-002, 

 whereas in cities in which plague occurs at least 2 .per cent, of the 

 rats are usually infected. Of the 48 infected rats which were encoun- 

 tered, only one sick of plague and another that had died of plague 

 were found. The transmission of plague by fleas was definitely shown 

 by guineapigs contracting plague from fleas from the bed of a human 

 victim and by finding infected fleas in the desk of another patient. 

 Multiple house infection occurred only three tim.es, and all of the 

 cases Avere within the incubation period of the disease. Seasons 

 apparently had no influence upon the number of cases, whereas in 

 the near-by ports of Hongkong and Amoy seasonal prevalence is 

 most marked. 



The only place in the Philippines in which plague occurred outside 

 of Manila was Iloilo. The sanitary measures employed consisted 

 in the isolation of the plague victim in a plague hospital. The rat- 

 catching and rat-proofing measures were begun at the periphery of 

 a zone which extended three blocks on each side of the house in which 

 the plague infection had occurred, and this was apparently successful 

 in preventing extensive spread of plague among rats. Further par- 

 ticulars of the campaign undertaken against rats are given. 



ScHUBERG (A.). Naturschutz und Muckenbekampfung. [Nature pro- 

 tection and combating mosquito larvae.] — Arb. Kaiseii. Gesund- 

 heitsamte, Berlin, xlvii, no. 2, 1914, pp. 252-290. 



Experiments w^ere carried out to discover to what degree substances 

 poured on ponds and pools to destroy the larvae of mosquitos, etc., 

 were injurious to other animal hfe in the water or to birds and mammals 

 drinking it. It was found that while Saprol, phenol-free Saprol, 

 " Larviol A " and " Larviol B " were to a certain extent poisonous, 

 petroleum was only harmful to those organisms of w^hich it choked 

 the breathing apparatus. The results of experiments carried out 

 on birds and mammals to test the effects of a film of petroleum or 

 Saprol on their drinking water were negative, and no ill-efi'ects were 

 observed. 



