New York Codes, Rules and Regulations
Title 10 - DEPARTMENT OF HEALTH
Chapter I - State Sanitary Code
Part 2 - Communicable Diseases
Isolation, Quarantine and Restriction
Section 2.30 - Diphtheria

(a) Isolation of case, quarantine of children of household and modified quarantine for adult household contacts. Whenever a case of diphtheria shall come to the attention of the city, county or district health officer, he/she may, according to his professional judgment, isolate the patient and establish and maintain quarantine for the periods hereinafter stated. When isolation on the premises is impracticable, the health officer may cause the removal of the patient to a suitable hospital.

(b) The patient shall be isolated until two successive cultures taken from the nose and throat at intervals of not less than 24 hours and not less than 24 hours after cessation of antimicrobial therapy, have been found free from diphtheria bacilli in an approved laboratory, or in the laboratory of the State Department of Health, the first of such cultures being taken not less than one week from the date of the onset of the disease; except that if diphtheria bacilli continue to be present in cultures, the health officer in his discretion may release the patient from isolation 30 days after clinical recovery, provided the mucous membranes appear normal and there are no abnormal discharges from the nose, throat or ears or after 14 days following antibiotic treatment.

(c) Personal contact(s) of a case of diphtheria whose occupation involves handling food, providing health care to patients, or close association with children, shall be prevented by exclusion from that work until bacteriological examination proves such case not to be a carrier.