Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis?
<h4>Background</h4>New immigrants to Canada with a history of tuberculosis or evidence of old healed tuberculosis on chest radiograph are referred to public health authorities for medical surveillance. This ostensible public health protection measure identifies a subgroup of patients (re...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Public Library of Science (PLoS)
2019-01-01
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| Series: | PLoS ONE |
| Online Access: | https://doi.org/10.1371/journal.pone.0212706 |
| _version_ | 1819142368823083008 |
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| author | Richard Long Leyla Asadi Courtney Heffernan James Barrie Christopher Winter Mary Lou Egedahl Catherine Paulsen Brenden Kunimoto Dick Menzies |
| author_facet | Richard Long Leyla Asadi Courtney Heffernan James Barrie Christopher Winter Mary Lou Egedahl Catherine Paulsen Brenden Kunimoto Dick Menzies |
| author_sort | Richard Long |
| collection | DOAJ |
| description | <h4>Background</h4>New immigrants to Canada with a history of tuberculosis or evidence of old healed tuberculosis on chest radiograph are referred to public health authorities for medical surveillance. This ostensible public health protection measure identifies a subgroup of patients (referrals) who are at very low risk (compared to non-referrals) of transmission.<h4>Methods</h4>To assess whether earlier diagnosis or a different phenotypic expression of disease explains this difference, we systematically reconstructed the immigration and transmission histories from a well-defined cohort of recently-arrived referral and non-referral pulmonary tuberculosis cases in Canada. Incident case chest radiographs in all cases and sequential past radiographs in referrals were re-read by three experts. Change in disease severity from pre-immigration radiograph to incident radiograph was the primary, and transmission of tuberculosis, the secondary, outcome.<h4>Results</h4>There were 174 cohort cases; 61 (35.1%) referrals and 113 (64.9%) non-referrals. Compared to non-referrals, referrals were less likely to be symptomatic (26% vs. 80%), smear-positive (15% vs. 50%), or to have cavitation (0% vs. 35%) or extensive disease (15% vs. 59%) on chest radiograph. After adjustment for referral status, time between films, country-of-birth, age and co-morbidities, referrals were less likely to have substantial changes on chest radiograph; OR 0.058 (95% CI 0.018-0.199). All secondary cases and 82% of tuberculin skin test conversions occurred in contacts of non-referrals.<h4>Conclusions</h4>Phenotypically different disease, and not earlier diagnosis, explains the difference in transmission risk between referrals and non-referrals. Screening, and treating high-risk non-referrals for latent tuberculosis is necessary to eliminate tuberculosis in Canada. |
| first_indexed | 2024-12-22T12:09:15Z |
| format | Article |
| id | doaj.art-3f936e6bff634962a9ab78c0713ce68b |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-22T12:09:15Z |
| publishDate | 2019-01-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS ONE |
| spelling | doaj.art-3f936e6bff634962a9ab78c0713ce68b2022-12-21T18:26:20ZengPublic Library of Science (PLoS)PLoS ONE1932-62032019-01-01143e021270610.1371/journal.pone.0212706Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis?Richard LongLeyla AsadiCourtney HeffernanJames BarrieChristopher WinterMary Lou EgedahlCatherine PaulsenBrenden KunimotoDick Menzies<h4>Background</h4>New immigrants to Canada with a history of tuberculosis or evidence of old healed tuberculosis on chest radiograph are referred to public health authorities for medical surveillance. This ostensible public health protection measure identifies a subgroup of patients (referrals) who are at very low risk (compared to non-referrals) of transmission.<h4>Methods</h4>To assess whether earlier diagnosis or a different phenotypic expression of disease explains this difference, we systematically reconstructed the immigration and transmission histories from a well-defined cohort of recently-arrived referral and non-referral pulmonary tuberculosis cases in Canada. Incident case chest radiographs in all cases and sequential past radiographs in referrals were re-read by three experts. Change in disease severity from pre-immigration radiograph to incident radiograph was the primary, and transmission of tuberculosis, the secondary, outcome.<h4>Results</h4>There were 174 cohort cases; 61 (35.1%) referrals and 113 (64.9%) non-referrals. Compared to non-referrals, referrals were less likely to be symptomatic (26% vs. 80%), smear-positive (15% vs. 50%), or to have cavitation (0% vs. 35%) or extensive disease (15% vs. 59%) on chest radiograph. After adjustment for referral status, time between films, country-of-birth, age and co-morbidities, referrals were less likely to have substantial changes on chest radiograph; OR 0.058 (95% CI 0.018-0.199). All secondary cases and 82% of tuberculin skin test conversions occurred in contacts of non-referrals.<h4>Conclusions</h4>Phenotypically different disease, and not earlier diagnosis, explains the difference in transmission risk between referrals and non-referrals. Screening, and treating high-risk non-referrals for latent tuberculosis is necessary to eliminate tuberculosis in Canada.https://doi.org/10.1371/journal.pone.0212706 |
| spellingShingle | Richard Long Leyla Asadi Courtney Heffernan James Barrie Christopher Winter Mary Lou Egedahl Catherine Paulsen Brenden Kunimoto Dick Menzies Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? PLoS ONE |
| title | Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? |
| title_full | Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? |
| title_fullStr | Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? |
| title_full_unstemmed | Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? |
| title_short | Is there a fundamental flaw in Canada's post-arrival immigrant surveillance system for tuberculosis? |
| title_sort | is there a fundamental flaw in canada s post arrival immigrant surveillance system for tuberculosis |
| url | https://doi.org/10.1371/journal.pone.0212706 |
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