62 APPLIED BACTERIOLOGY FOR NURSES 



before such an individual may be allowed to return to his 

 work. 



In smallpox the patient is invariably removed to the 

 isolation hospital of the Department of Health. Isolation 

 is maintained until all scabs have disappeared, including 

 the deep-seated ''seeds" beneath the epidermis of the 

 soles of the feet. 



In epidemic cerebrospinal meningitis isolation is main- 

 tained for fourteen days, for it has been found that menin- 

 gococci in the nasopharynx of convalescents are very rare 

 after the twelfth or fourteenth day. Whenever facilities 

 permit healthy contact carriers should be sought out and 

 isolated. 



In acute anterior poliomyelitis (infantile paralysis) the 

 minimum period of quarantine is six weeks, a period fixed 

 largely as the result of experimental work on animals. 



In yellow fever it is now well established that the pa- 

 tient's blood remains infective about three days. More- 

 over, after having been bitten by an infected mosquito it 

 requires about five days for symptoms to develop. (See 

 also page 133.) Isolation, therefore, is relatively short 

 and amounts, moreover, only to screening the-patient from 

 mosquitoes. 



In typhus fever recent work would indicate that isola- 

 tion need not be maintained for much beyond the return 

 of the fever to normal. Inasmuch as the disease is spread 

 by lice, care should be taken to destroy all lice by thorough 

 washing of the patient and disinfection of his clothing 

 and other belongings. 



In cholera the termination of isolation rests solely on 

 the result of the bacteriologic examination of the stools. 

 A minimum requirement is two consecutive negative 

 stools taken at intervals of five days after convalescence 

 is complete. 



