310 HUMAN PHYSIOLOGY CHAP. 



have been exposed to any of the dangerous communica- 

 ble diseases. The pupil who was sick and all other 

 children living in the same house should not attend 

 school until the placard has been removed and the 

 house disinfected by the health authorities. It is best 

 to require a certificate from the proper authorities before 

 the pupils are permitted to return. 



If a child sick with a dangerous contagious disease 

 attends school even for a part of a day, the school 

 should be closed and the room thoroughly disinfected. 

 Whenever a contagious disease is likely to gain a strong 

 foothold in a community, it is best to close the school 

 entirely to keep the disease from spreading. The spread 

 of so many communicable diseases can be traced directly 

 to the schools, that parents and teachers should exercise 

 the utmost vigilance to forestall epidemics. 



219. Disinfection. The process of killing disease 

 germs and spores by physical means or by chemical 

 agents is known as disinfection. We have already 

 learned that adequate ventilation and abundant sunlight 

 are important means of checking the growth of disease- 

 producing organisms. When disease germs are present 

 in large numbers, more radical measures must be 

 employed to destroy them. We have learned that the 

 excretions of patients suffering from some of the com- 

 municable diseases, as well as the sick rooms, clothing, 

 bed linen, furniture, etc., may contain vast numbers of 

 disease germs, which, if not destroyed, are sources of 

 danger to the public. 



The chief agencies used in disinfecting are heat.. 



