Royal College of Physicians

but the danger of more distant spread is steadily diminishing owing to the wider adoption of measures against " domestic " rodents (rats and mice) and the efficiency of techniques for the control of plague. Elimination of an endemic focus among wild rodents has only recently been attempted, and it has proved expensive and difficult. Measures for the control of plague may be directed towards the wild rodent reservoir, the domestic rodent, or to man in contact with these animals. Populations of domestic rats may be reduced by the use of poison baits or by gassing their burrows with chloropicrin or cyanide, and these methods have also been used successfully by Russian workers in an attack on the wild rodents in sylvatic foci of plague. The most rapidly effective control measure in epizootics or epidemics remains the destruction of vector fleas by means of insecticides applied to all surfaces over which rats may move. The susceptibility of man to infection can be reduced by vaccination, but the vaccines are not highly efficient, and in present circumstances this method of prophylaxis is best used to raise immunity progressively (by giving the vaccine annually) among communities in the neighbourhood of enzootic foci. Treatment of plague improved greatly with the introduction of the sulphonamides and antibiotics. Sulphamerazine is the most popular drug, but it is ineffective in pneumonic plague unless given very early. In this form of the infection streptomycim proved very effective both in treatment and prophylactically in contacts,3 but recently it has been reported that it is apt to produce a high degree of resistance in Pasteurella pestis. The tetracycline group of antibiotics have proved to be as active as streptomycin and more useful because they can be given by mouth and are less toxic. So long as enzootic foci persist in wild rodent populations plague remains a threat to human communities in contact with them. Owing to the effectiveness of control measures against domestic rodents international spread is now limited, and the use of preventive techniques to eliminate foci of wild rodent plague, successfully introduced by the Soviet Union,2 gives the hope that the world will be rid of this pestilential disease in the foreseeable future.