430 MICROORGANISMS 



is unable to produce smallpox when introduced into the 

 human body, but is still able to stimulate the body to build up 

 its defenses against the virulent form of the organism. 



497. The Effectiveness of Smallpox Vaccination. The com- 

 parative rarity of smallpox in recent years in most countries 

 as compared with the eighteenth century is ample evidence of 

 the effectiveness of vaccination as a preventative of the disease. 

 More striking evidence, however, can be found in countries 

 in which vaccination is made obligatory. In 1870-71, during 

 the Franco-Prussian war, the armies of both Germany and 

 France were attacked by smallpox. Vaccination had been 

 compulsory in the German army since 1834 but was not 

 compulsory in the French army. As a consequence, the 

 French lost 23,000 soldiers from smallpox and the Germans 

 lost only 273 from that cause. Vaccination has been com- 

 pulsory in Sweden since 1810. From 1774 to 1801, smallpox 

 had caused an annual death rate of 2,050 per million of in- 

 habitants in that country. During the years from 1810, 

 when vaccination was made compulsory, to 1855, this death 

 rate had fallen to 169 per million, and in the period from 1884 

 to 1894, the average annual death rate was only 2 per million. 

 This shows that, if all countries would follow the example of 

 Germany and Sweden in requiring that every citizen be 

 vaccinated, smallpox might entirely disappear from the earth. 

 It shows further that as long as frequent outbreaks of the 

 disease are allowed to occur as they do every winter in this 

 country, an individual is very foolish if he does not submit to 

 vaccination as often as it will take. 



498. How Often Should One be Vaccinated? In a report 

 of the Board of Health of the city of Berlin, the following 

 sentence may be found: "Vaccination in infancy, renewed 

 at the end of childhood, renders the individual practically as 

 safe from death from smallpox as if that disease had been 

 survived in childhood, and almost as safe from attack." In 

 a recent report of the Illinois State Board of Health, occurs the 

 following sentence: "A recent successful vaccination is a 



