Table 1 Clinical characteristics of active tuberculosis cases
CaseClinical detailsGroup#
1Symptoms started July 2008
Smear and culture positive
Treatment started October 2008
Index case
2Friend of index case
No symptoms
IGRA positive December 2008
CXR: right mid-zone nodules
CT scan showed multiple small cavities
BAL smear and culture negative
Treatment started November 2009
Group 1
3Cough and sputum December 2008
Smear and culture negative
CXR and CT: small nodules right mid-zone Started treatment February 2009
Group 1
4No symptoms
Smear negative
IGRA positive
BAL culture positive, same genotype
Treatment started April 13, 2009
Treatment completed October 2009
Group 2
5Smear negative
IGRA positive
CXR in April 2009: right upper zone multiple cavities
BAL culture positive, same genotype
Treatment started April 2009
Group 2
6In same tutor group as another case
IGRA positive
Onset of cough and weight loss in April 2009
Sputum smear negative
Culture positive, same genotype
CXR normal
Treatment started May 2009
Group 2
7No symptoms
IGRA positive
CXR February 2009 and CT scan: left hilar gland and left hilar shadow
Treatment started May 2009.
Group 2
8No symptoms
IGRA positive
CXR and CT scan: left upper zone shadowing
BAL culture negative
Treatment started June 2009
Group 2
9Cough, fever, night sweats and weight loss since December 2008
GP presentation
Had indeterminate IGRA in April 2009
Pleural biopsy histology: caseating granulomata
PCR negative
Treatment started May 2009
Group 3
10Cough, weight loss
CXR and CT: left hilar glands
Smear and culture negative
Extended family of index case
Treatment started April 2009
Group 3
11Eye symptoms from June 2009
Choroid tubercles seen
IGRA positive
CXR normal
Treatment for eye TB started July 2009
Group 3
12No symptoms
CXR parenchymal changes and CT scan showed left apex changes
BAL smear negative and culture positive, same genotype
Treatment started September 2009
Group 3
13Attended school for a few hours in January and May 2009
Diagnosed through GP with cough, sputum, haemoptysis and night, sweats which started in April 2009
Smear and culture positive, same genotype
Treatment started August 27, 2009
Group 3
14No respiratory symptoms
Cervical node biopsy in Hong Kong, China
Smear and culture not performed
Histological diagnosis
Treated in Hong Kong from April 2009
Group 3
15Cough, night sweats from June 2009
IGRA positive
CXR: cavities right upper lobe, sputum smear and culture negative, refused bronchoscopy
Treatment started July 2009
Group 3
16No symptoms
CT: left upper zone early cavitation
BAL smear negative and culture positive, same genotype
Treatment started July 2009
Group 3
17Diagnosed in July 2009 with lymph node disease
CT scan: left lower lobe changes
BAL: smear and culture negative
Treatment started July 2009
Group 3
18Cough, night sweats, weight loss
IGRA positive, pleural biopsy
Smear positive
PCR negative
CXR: effusion
Culture positive, same genotype except last digit missing
Group 3
19Cough, weight loss in November 2008
Attended college 2007–2008
CXR and CT: cavities and enlarged hilar nodes
Sputum smear and culture positive, same genotype
Treatment started April 2009
Other
20Fever, night sweats, weight loss, no cough from January 2009
Friend of index case but attended a different college
IGRA positive
CXR and CT scan: hilar node and parenchymal changes; left lower lobe apical nodule
Treatment started July 2009
Other
  • IGRA: interferon-γ release assay; CXR: chest radiography; CT: computed tomography; BAL: bronchoalveolar lavage; GP: general practitioner. #: group 1 included those who shared classroom groups with cumulative exposures >2 h with the index case and friends of the index case, group 2 included students who attended the same general studies group with exposure time between 1 and 2 h in a large hall setting, and group 3 included the rest of the college.