Investigation of an Outbreak of Tuberculosis in a Small Community Setting

BACKGROUND/OBJECTIVES: Ashtabula County, Ohio has been a low-risk county for Tuberculosis (TB) based on the Centers for Disease Control and Prevention guidelines. Over the past ten years there has been an average of one or two cases of active TB a year in the county. METHODS: In 2005 over a three month period of time there were six cases of active TB identified in Ashtabula County. The index case presented to the health department in January 2005 with a pre-employment TB test (PPD) measuring 10 mm induration. The patient was asymptomatic at that time. A workup was completed and the patient was seen at the TB clinic and started on Isoniazid. Sputum smears for acid fast bacillus were negative. In February the patient was admitted to a local hospital with respiratory distress and a diagnosis of left plerual effusion. A DNA probe showed Mycobacterium Tuberculosis Complex. A contact investigation was started by the health department and the Ohio Department of Health was notified. The investigation and follow-up was complicated by the fact that the suspected source case likely had active disease for over three years and had some medical procedures performed at a healthcare facility in another county. This person was unaware of having TB and was identified through contact investigation and sent for testing. The investigation was further complicated because the index case did not reveal contact with the suspected source case although this was later confirmed throug investigation. RESULTS: After identification of each case, contacts were identified through interviews with the clients, physicians and healthcare facilities where clients were treated. The suspected source case was found through contact investigation of his mother. He was unaware of having TB although he was symptomatic and under the care of his primary care physician for chronic bronchitis. Fifty six contacts were PPD tested and there were eight conversions. Testing was repeated in three months on those testing negative and there were no further conversions. The Infection Control nurse at the out of county facility where the suspected source patient had been seen was notifed and she conducted TB testing at that facility. No conversions were found. CONCLUSIONS: Though the overall incidence of TB is declining in the U.S. increased awareness of TB, appropriate TB diagnostic work up and treatment, among healthcare professionals in low incidence areas is increasingly important. Tuberculosis can be difficult to diagnosis because the signs and symptoms are seen in other diseases. Primary Care physicians provide the critical first steps in reducing the incidence of active cases. Contact investigation of an active case of TB requires diligence and effective communication. Persistence is necessary when working with clients to gain adequate information regarding contacts.