Risk factors for recent transmission of Mycobacterium tuberculosis.
In recent decades, the decline of tuberculosis has stopped in Western Europe, mainly due to increased immigration from high-prevalence countries. The objective of the current study was to identify risk factors for developing tuberculosis following recent infection, in order to better target interventions. Strains from 861 culture-positive cases, diagnosed in Norway in 1994-1999, were analysed by use of restriction fragment length polymorphism (RFLP). A cluster was defined as two or more isolates with identical RFLP patterns. Risk factors for being part of a cluster were identified by univariate and multivariate analysis. A total of 134 patients were part of a cluster. These constituted 5% Asian-born, 18% Norwegian-born, 24% European-born and 29% African-born patients. Four independent risk factors for being part of a cluster were identified: being born in Norway, being of young age, being infected with an isoniazid-resistant strain and being infected with a multidrug-resistant strain. Transmission of tuberculosis may be further reduced by improving case management, contact tracing, preventive treatment, screening of immigrants and access to health services for the foreign-born population.
Division of Communicable Disease Control, Norway. einar.heldal@fhi.no
E
E
Heldal
U R
UR
Dahle
P
P
Sandven
D A
DA
Caugant
N
N
Brattaas
H T
HT
Waaler
D A
DA
Enarson
A
A
Tverdal
J
J
Kongerud
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D024901:Drug Resistance, Multiple, Bacterial; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D009664:Norway / Q000453:epidemiology; D012150:Polymorphism, Restriction Fragment Length; D012111:Residence Characteristics; D012307:Risk Factors; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology / Q000382:microbiology* / Q000635:transmission*