VACCINES AND SERA 281 



the bones and joints and on early cases of pulmonary tubercle 

 (checking the fever and improving the general condition). 



SERO VACCINATIONS. 



When a vaccination per se involves a certain risk it may be 

 associated with a specific serum : the combined treatment is 

 equivalent to an active immunization under cover of a passive 

 protection. 



Sheep-pox. 1 In France the law enjoins the vaccination 

 against sheep-pox of all the flocks in the affected regions, 

 whereas it forbids it in the regions free from the scourge. In 

 Algeria sheep-pox is endemic, and the Algerian sheep are 

 much more resistant than the French sheep. In consequence, 

 Algerian sheep, which are imported in great numbers, may be 

 landed apparently healthy, yet may induce a malignant 

 epidemic in a French flock. Nowadays only vaccinated sheep 

 may be imported. 



Borrel, who perfected the method of vaccination by showing 

 how to prepare cheaply large quantities of pure virus, has 

 prepared an active anti-serum by " charging " with virus sheep 

 which had recovered from the disease. When injected into a 

 sheep twenty-four hours before the virus this serum prevents 

 the development of the disease (in a dose of 20-30 c.c.), and 

 even inhibits the inoculation pustule. By graduating the dose 

 of serum it is possible by inoculating the virus simultaneously 

 to produce simply an immunizing pustule without any risk of 

 a general infection. 



The serum employed alone is sufficiently active to render 

 certain a prophylactic treatment of the disease by curative and 

 preventive injections in a flock. It permits of the importation 

 of Algerian sheep without danger of infecting French territory. 

 The sheep to be imported receive the serum three weeks 

 before shipment. Inspection eliminates those which were 

 incubating the disease at the time of inoculation, and which 

 might therefore be shipped while still ill. This serotherapy is 



1 Non-existent in Great Britain. Translators' note. 



