Sustained intra- and inter-jurisdictional transmission of tuberculosis within a mobile, multi-ethnic social network: lessons for tuberculosis elimination.
BACKGROUND
A context-specific, spatial-temporal understanding of a chain of tuberculosis (TB) transmission can inform TB elimination strategy.


METHODS
Clinical, public health and molecular epidemiologic data were used to: 1) identify and describe a complex cluster of TB cases in Alberta, 2) elucidate transmission sequences, and 3) assess case-patient mobility. Socio-economic indicators in loci of transmission and the province at large were described. Factors seen to be fostering or hampering TB elimination were identified.


RESULTS
Over a 15-year period, 18 TB cases in Alberta and multiple cases in the Northwest Territories were determined to be due to the same strain. One patient was diagnosed at death; all others completed directly-observed therapy (DOT). Case-level analysis revealed that patients were highly mobile with transmission of the strain over 26,569 km2, an average of 2.8 different places of residence per patient during treatment, and contacts of sputum smear-positive cases spanning 9 of 17 regional health authorities. The majority of the contacts (57%) were attached to a single infectious case living in a homeless shelter. The three loci of transmission in Alberta were separated geographically but similar in terms of median incomes, rates of unemployment, levels of post-secondary education, and rates of population mobility (p < 0.0001).


CONCLUSIONS
Upon review of the experience, central oversight, intra- and inter-jurisdictional coordination and DOT were seen as fostering, and the absence of 'real-time' DNA fingerprinting, social network analysis, engineering controls in shelters and better determinants of health in loci of transmission were seen as hampering TB elimination.
Aspler
Anne
A
Tuberculosis Program Evaluation and Research Unit, University of Alberta, Edmonton, AB.
Chong
Huey
H
Kunimoto
Dennis
D
Chui
Linda
L
Der
Evelina
E
Boffa
Jody
J
Long
Richard
R
D000293:Adolescent; D000328:Adult; D000416:Alberta / Q000453:epidemiology; D016009:Chi-Square Distribution; D023801:Directly Observed Therapy; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015873:Northwest Territories / Q000453:epidemiology; D012307:Risk Factors; D012944:Social Support; D014376:Tuberculosis / Q000453:epidemiology / Q000208:ethnology* / Q000517:prevention & control / Q000635:transmission*