Protective vaccinations 491 



horses treated for a long period with cultures of the plague bacillus 

 and with the toxin of the same organism. Treatment is begun by 

 injecting plague coccobacilli killed by heat (70 C.). These injections 

 are made into the veins, with the object of avoiding the local lesions 

 which are observed after the subcutaneous introduction of micro- 

 organisms. When the horses have been rendered refractory by this 

 treatment with dead micro-organisms, the next step is to inject (also 

 into the veins) small quantities of living cultures. The doses of these 

 cultures are gradually increased, and end by conferring upon the animal [514] 

 a very strong immunity, which is strengthened by injections of 

 products of cultures passed through a Chamberland filter. 



Calmette and Salimbeni 1 injected prophylactically more than 

 600 persons menaced by plague at Oporto. These comprised the 

 doctors and the staffs of the laboratories of hygiene and of the 

 disinfection services, the firemen who removed the sick persons and 

 the dead, the families of those who were attacked, the members of 

 the French colony, etc. Into each person 5 c.c. of serum was injected 

 below the skin of the abdomen. These vaccinations in some cases 

 caused nettle-rash, eruptions similar to those so often observed after 

 the injection of the other kinds of serums. Of the total number in- 

 jected two persons contracted plague : the unfortunate Doctor Camera 

 Pestana and his assistant. The former succumbed to the disease, but 

 the second only contracted a very mild form of it. The study of 

 these 600 cases, as well as of experiments on animals, demonstrated 

 that the immunity conferred by the antiplague serum is set up 

 immediately after its injection but is not of long duration. It is 

 probable that it lasts for 8 or 10 days, or at furthest a fortnight only. 



Similar results were obtained at Glasgow. Van Ermengem 2 , who 

 has published a report on the epidemic in this town, mentions that 

 more than 70 persons in good health were inoculated with the serum ; 

 each one received 10 c.c. beneath the skin of the belly. Of these 

 70 persons one was attacked with a fairly mild plague 8 days after 

 the vaccination, and another, a housekeeper, was attacked, 9 days after 

 the injection, with a congestion of the cervical glands induced by the 

 plague bacillus. Both cases recovered. All the other vaccinated 

 persons, in spite of constant exposure to the plague infection, 

 remained unaffected. Van Ermengem was of opinion that the two 



1 Ann. de VImt. Pasteur, Paris, 1899, t. xm, p. 902. 



2 Bull. Acad. roy. de med. de Belg., Bruxelles, 1900. 27 Octobre. 



