Sources of infection in childhood tuberculosis in a region of east Croatia.

Possible sources of tuberculosis (TBC) infection in children have been assessed in a retrospective epidemiological study covering a north-east region of Croatia in which the incidence of childhood tuberculosis has been increasing since the war in 1991-1995. During the past decade (1993-2003), 271 children up to 18 years of age have been referred for hospital care because of known contacts with tuberculosis (142 children, group A) or because of indicative clinical signs and symptoms (129 children, group B). Possible sources of infection were identified on the basis of medical documentation and field investigations. Frequencies of source identification for different age groups were compared. In group A, the exposure took place most often within the family (parents, grandparents, siblings, 129 of 142 children, 90.87%). Relatives, neighbors, friends and schoolmates accounted for 9.2%. In group B, possible sources of infection were identified for 44 of 129 children (34.1%) and were within the family for 16 of those 44 (36.4%). Evidenced contact with tuberculosis was more usual among younger children (0-9 years of age, 65.5%) in group A than among the older ones (10-18 years of age, 34.5%). In group B, contacts with tuberculosis were equally distributed (50.0%) among younger and older children. High proportion of unrecognized contacts in children having clinical signs and symptoms indicative of tuberculosis (group B, 85 of 129, 65.9%) opens the possibility that extra-familial exposure to tuberculosis occurs more often than expected regardless of the age of children.