Background and objective: The aim of the present study was to analyze the characteristics of families with microepidemics of tuberculosis.
Patients and method: We included family studies examined in the Center for Tuberculosis Control and Prevention of Lleida during the period 1991-97. A microepidemic was defined as the appearance of two or more new cases in the same family study. The association between the detection of new cases among family contacts and the prevalence of tuberculosis infection was analyzed.
Results: Prevalence of families with microepidemics was 1.4% (6/437). Families with microepidemics generated 15 out of 39 newly diagnosed cases (38.5%). We observed a higher prevalence of tuberculosis infection in families with one new case (OR = 1.67; CI 95%, 1.19-2.34) and in families with microepidemics (OR = 2.67; CI 95%, 1.28-5.62).
Conclusions: Study of microepidemics of tuberculosis is very important because a small percentage of families with microepidemics (1.4%) generate a large number of secondary cases who are diagnosed during the screening of tuberculosis contacts (38.5%).