Abstract
OBJECTIVES: Tuberculosis (TB) was a major cause of morbidity and mortality in Canada early in the 20th century. Elderly populations in Canada remain at high risk for TB disease. Elderly patients may present atypically, with the result that many active cases can remain undiagnosed. We present an outbreak of TB that occurred in a Residential and Long-Term Care (LTC) facility in Ontario.
METHODS: Case finding was carried out through the conventional concentric circle approach. Three rounds of tuberculin skin testing were conducted at 8–12 week intervals. Laboratory analysis was conducted at the Public Health Ontario Laboratories. An indoor air quality assessment was conducted to determine whether inadequate engineering controls were a transmission risk factor.
RESULTS: A case of active pulmonary TB was confirmed in May 2010 in a staff member at the facility. By January 2011, 3 additional active cases and 24 latent tuberculosis infections among residents and staff had been identified. Genotyping methods confirmed that the 4 active cases were infected by an identical strain. Nine of 15 locations tested in the facility had air exchange rates below published guidelines.
CONCLUSION: Prompt reporting of the initial case allowed for a quick initiation of the epidemiologic investigation. Given the epidemiology of TB in elderly populations, outbreaks should remain a concern for LTC facilities and physicians, even in jurisdictions of low TB incidence. Baseline and annual TB screening for residents and staff, early diagnosis of active TB, and adequate ventilation are important to reduce the incidence of disease.
Key words: Epidemiology, outbreaks, tuberculosis, long-term care
Résumé
OBJECTIFS: La tuberculose était l’une des grandes causes de morbidité et de mortalité au Canada au début du 20e siècle. Les populations âgées du Canada présentent encore un risque élevé de contracter la tuberculose-maladie. Ses manifestations peuvent être atypiques chez les patients âgés; de nombreux cas actifs peuvent donc rester non diagnostiqués. Nous présentons une éclosion de tuberculose survenue dans une maison de soins infirmiers en Ontario.
MÉTHODE: Nous avons procédé à la recherche des cas selon l’approche classique des cercles concentriques. Trois cycles de tests cutanés à la tuberculine ont été menés à intervalles de 8 à 12 semaines. L’analyse a été faite dans les laboratoires de Santé publique Ontario. Une évaluation de la qualité de l’air à l’intérieur a permis de déterminer si des mesures d’ingénierie inadéquates étaient un facteur de risque dans la transmission de la maladie.
RÉSULTATS: Un cas de tuberculose pulmonaire active a été confirmé en mai 2010 chez un membre du personnel de l’établissement. En janvier 2011, 3 autres cas actifs et 24 infections latentes à la tuberculose avaient été détectés parmi les résidents et le personnel. Des méthodes de génotypage ont confirmé que les quatre cas actifs étaient infectés par une souche identique. Neuf des 15 endroits testés dans l’établissement avaient des taux d’échange d’air inférieurs aux lignes directrices publiées.
CONCLUSION: La déclaration rapide du cas initial a permis d’amorcer rapidement l’enquête épidémiologique. Étant donné l’épidémiologie de la tuberculose dans les populations âgées, les maisons de soins infirmiers et les médecins doivent rester à l’affût des éclosions, même dans les provinces et les territoires où l’incidence de la tuberculose est faible. Le dépistage initial, puis annuel de la tuberculose chez les résidents et le personnel, le diagnostic précoce de la tuberculose active et une ventilation adéquate sont d’importants facteurs pour réduire l’incidence de cette maladie.
Mots clés: épidémiologie, flambées épidémiques, tuberculose, soins longue durée
Footnotes
Conflict of Interest: None to declare.
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