a contact investigation was performed by local health authorities in central italy after a report in november 2008 of culture - positive pulmonary tb in a 3-year - old girl . she attended a kindergarten in a building that housed 3 schools ( kindergarten 1 , kindergarten 2 , and a primary school ) . initially , children in the girl s class ( kindergarten 1 , class c ) , her family contacts , and some staff were tested . a high percentage ( 34.6% , 9/26 ) of classmates were positive for tb by mantoux tuberculin skin test ( tst ) , and health authorities decided to test all school children and staff . this contact investigation was part of a routine public health response to a school outbreak and did not require ethics committee approval . persons with negative tst results were retested 10 weeks later . children with positive tst results for whom a diagnosis of active tb had been ruled out were prescribed isoniazid for 6 months . children < 5 years of age were prescribed isoniazid regardless of tst results if active tb was ruled out . those children with negative results at initial a total of 851 persons , of whom 817 ( 96% ) were born in italy , were screened ( table 1 ) . at initial testing , 53 ( 13.8% ) of 383 children had positive tst results . among 9 children with a positive result at follow - up , nineteen children had active tb ( 18 with pulmonary tb and 1 with extrapulmonary tb [ pott disease ] ) . no cases of active tb were identified among school staff and contacts of children with positive tst results . * does not include family contacts of the source case - patient . * tb , tuberculosis . p<0.001 by  test or , when appropriate , fisher exact test or  test for trend . in january 2009 , a case of smear - negative , culture - positive pulmonary tb with cavitary involvement of both upper lung lobes was reported to the same local health authorities by a hospital in southern italy . the case - patient was a 42-year - old woman born in italy who worked as an assistant in kindergarten 1 and was considered the presumed source of the outbreak . she reported a family history of tb ( son and father treated for pulmonary tb in 1996 and 1999 , respectively ) and positive tst results , but did not recall completing a chemoprophylaxis regimen with isoniazid . she also reported persistent cough for 1 year , which was treated with mucolytic and antimicrobial drugs by her family physician . during this time , she had frequent contact with many children , especially in kindergarten 1 , and occasionally worked as an assistant in kindergarten 2 . she had a negative tst result during the school contact investigation ; no chest radiograph was prescribed . she subsequently traveled to southern italy , where she consulted a respiratory physician who requested immediate hospitalization . gastric aspirate specimens were obtained from 18 children , and a vertebral abscess pus specimen was obtained from 1 child . ziehl - neelsen microscopy , direct amplification tests , cultures , and drug - susceptibility testing were performed according to standard procedures . specimens from 3 children were positive for acid - fast bacilli , and specimens from 9 children were culture positive for mycobacterium tuberculosis . all isolates were susceptible to first - line drugs against tb except 1 that was moderately resistant to isoniazid . dna fingerprinting showed that the strain isolated from the source case - patient belonged to the s family lineage and was identical to all strains isolated from children in this study . median age of children with active tb was 5 years ( 9 were girls and 15 had signs or symptoms ) . attack rates were significantly higher for children in kindergarten 1 than for those in kindergarten 2 and the primary school ( p<0.001 ) ( table 2 ) . differences in attack rates in 4 classes of kindergarten 1 were not significant . in the primary school , high attack rates were found among children in grade 1 ; no active tb cases and few children with positive tsts results were found in higher grades ( p<0.001 ) . most children in grade 1 , including the 3 with active tb , were in kindergarten 1 the preceding school year . all children except 1 ( lost to follow - up ) have completed treatment and are healthy . genotyping results confirmed that all cases were linked to the school assistant , and clinical and epidemiologic data suggest that she was the only source of infection . infected children in grade 1 the major factor that contributed to the outbreak was the delay in diagnosis of the source case , as in other reported outbreaks ( 36 ) . this finding indicates the need for increasing awareness of tb among primary care physicians and for improving their ability to recognize risk factors for infection and progression to active disease . also , if the school assistant had received appropriate treatment and follow - up at the times her son and father received diagnoses of tb , active disease might never have developed . this finding highlights the importance of appropriate follow - up of contacts in response to a case of tb . urgency was required because of the school setting , pressure by parents , and media coverage . as in other school - contact investigations , this urgency may have led to excessive screening of low - risk persons and difficulties in categorizing contacts by close and casual status ( 8) . also , information regarding risk factors for tb and previous tst results was not consistently recorded . nevertheless , the investigation had a high rate of test completion among children and staff . although tb among foreign - born persons is of increasing importance in many industrialized countries because of immigration from high - incidence areas , this outbreak highlights that tb is of concern not only for those of foreign origin ( 2 ) . tb was once a common disease in italy , and a pool of improperly treated persons may be at risk for reactivation of tb . a high proportion of school staff had positive tst results , probably because many were born at a time when the risk for tb was high . in italy , there are no specific requirements regarding tb screening of school employees . when screening is initiated in a low - prevalence population , it should focus on high - risk persons , and priority should be given to quality surveillance , follow - up , and containment activities . however , consideration should be given to administering a health questionnaire to school staff ( foreign and native born ) who have sustained contact with small children to identify high - risk persons , as is being conducted elsewhere in europe ( 3,9 ) .
an outbreak of tuberculosis ( tb ) in italy involved 19 schoolchildren with active tb and 43 with latent infection . 
 the source of the outbreak was a school assistant born in italy who had a family history of tb . 
 this outbreak highlights the need for maintaining clinical and public health expertise in countries with low tb incidence .