MANAGEMENT OF AN OUTBREAK OF TUBERCULOSIS IN A SMALL COMMUNITY

Objective: To investigate an outbreak of tuberculosis, determine the n umber of active cases and infections, and examine efforts to control t he spread of disease. Setting: A small town in Maine, in which no case s of tuberculosis had been reported in the previous 3 years. Design: E pidemiologic investigation of an outbreak of tuberculosis infection an d disease. Measurements: A patient with an active case of tuberculosis was defined as a resident of the town or the surrounding area or an e mployee of the local shipyard who had a culture of sputum or tissue th at was positive for Mycobacterium tuberculosis between June 1989 and M ay 1992. A case of tuberculous infection was defined as a positive tub erculin skin test result in a person with no previous positive test re sult. Results: 21 active cases of tuberculosis occurred among shipyard workers and persons residing in the affected community between 1989 a nd 1992. One patient was the source of the outbreak; 8 months lapsed b etween the onset of this patient's illness and appropriate diagnosis a nd treatment. The M. tuberculosis strains isolated from this patient a nd from six other patients belonged to phage type I, auxiliary 14. All isolates were susceptible to drug treatment. Of 9898 persons who were tested, 697 (7%) were newly infected. Because isoniazid prophylaxis w as not routinely offered to infected persons older than 35 years of ag e, only 341 (49%) infected persons completed isoniazid prophylaxis. Co nclusions: Many secondary cases of tuberculosis occurred throughout th is small Maine community because of delayed diagnosis and treatment of the source patient, delayed outbreak investigation, and failure to pr omote isoniazid prophylaxis to all persons infected during the outbrea k. Aggressive efforts to identify persons with new infection are of li mited value in controlling tuberculosis unless they are accompanied by an equally aggressive use of isoniazid prophylaxis.