INCUBATION PERIOD OF DISEASE 



269 



The following table shows important facts about some com- 

 mon diseases. 





Means op 



Incubation Period (Approximate) 



Disease 



Communication 



AND Early Symptoms 



■ 



Chicken pox . . 



Discharges from nose 

 or throat of a pa- 

 tient 



21 days. Rash. 



Diphtheria . . 



Nose or throat dis- 

 charges; sometimes 

 infected milk 



2 to 5 days. Begins like a cold. 



Measles . . . 



Nose or throat dis- 



9 to 11 days. Begins like a cold. 





charges 



Reddish spots appear on the 

 third day. 



German measles . 



Nose or throat dis- 



Unknown, though longer than 





charges 



measles. 



Mumps .... 



Nose or throat dis- 



Unknown, probably about 2 





charges 



weeks . Pain in sal ivary glands . 



Infantile paralysis 



Nose, throat, or bowel 



Not known. Fever, headache. 





discharges of pa- 



vomiting, weakness of one or 





tient or carrier 



more muscle groups. 



Scarlet fever . . 



Discharges from nose. 



2 to 7 days. Begins like a cold; 





mouth, ears. In- 



in 24 hours evenly diffused 





fected milk 



bright red spots under skin. 



Smallpox . . . 



All discharges of a pa- 



About 12 days. Fever and back- 





tient; particles of 



ache. Red shothke pimples on 





skin or scabs 



face and hands, become blisters. 



Septic sore throat . 



Discharges from nose 

 or mouth 



Varies with resistance. 



Whooping cough . 



Discharges from nose 



14 days. Cough ; worse at night. 





or mouth 



"Whooping" develops in about 

 two weeks. 



Incubation Period of Disease. — Quarantine regulations often 

 affect not only the person having the disease, but also all those of 

 the family who were " exposed " ; that is, who came in personal 

 contact with the person who has the disease. If, for example, you 

 have measles, the doctor will keep at home the other children in the 

 family who have not had the disease. The period of quarantine 

 for measles lasts in most states fifteen days. Why this precaution ? 



Consider what we already know of germs. We found it took a 

 certain length of time for colonies of germs to appear in a culture 

 medium after exposure. In the same way it takes a certain 

 amount of time in the case of a disease for the germs to become 



