Tuberculosis Surveillance: Data for Decision-Making

Descriptive review of tuberculosis surveillance systems across the circumpolar regions

BACKGROUND

Tuberculosis is highly prevalent in many Arctic areas. Members of the International Circumpolar Surveillance Tuberculosis (ICS-TB) Working Group collaborate to increase knowledge about tuberculosis in Arctic regions.

OBJECTIVE

To establish baseline knowledge of tuberculosis surveillance systems used by ICS-TB member jurisdictions.

DESIGN

Three questionnaires were developed to reflect the different surveillance levels (local, regional and national); all 3 were forwarded to the official representative of each of the 15 ICS-TB member jurisdictions in 2013. Respondents self-identified the level of surveillance conducted in their region and completed the applicable questionnaire. Information collected included surveillance system objectives, case definitions, data collection methodology, storage and dissemination.

RESULTS

Thirteen ICS-TB jurisdictions [Canada (Labrador, Northwest Territories, Nunavik, Nunavut, Yukon), Finland, Greenland, Norway, Sweden, Russian Federation (Arkhangelsk, Khanty-Mansiysk Autonomous Okrug, Yakutia (Sakha Republic), United States (Alaska)] voluntarily completed the survey - representing 2 local, 7 regional and 4 national levels. Tuberculosis reporting is mandatory in all jurisdictions, and case definitions are comparable across regions. The common objectives across systems are to detect outbreaks, and inform the evaluation/planning of public health programmes and policies. All jurisdictions collect data on confirmed active tuberculosis cases and treatment outcomes; 11 collect contact tracing results. Faxing of standardized case reporting forms is the most common reporting method. Similar core data elements are collected; 8 regions report genotyping results. Data are stored using customized programmes (n=7) and commercial software (n=6). Nine jurisdictions provide monthly, bi-annual or annual reports to principally government and/or scientific/medical audiences.

CONCLUSION

This review successfully establishes baseline knowledge on similarities and differences among circumpolar tuberculosis surveillance systems. The similarity in case definitions will allow for description of the epidemiology of TB based on surveillance data in circumpolar regions, further study of tuberculosis trends across regions, and recommendation of best practices to improve surveillance activities.

Tuberculosis case-finding in Cambodia: analysis of case notification data, 2000 to 2013

The routine tuberculosis (TB) surveillance system in Cambodia has been strengthened under the National TB Programme (NTP). This paper provides an overview of the TB surveillance data for Cambodia at the national level for the period 2000 to 2013 and at the subnational level for 2013. The proportion of the total population that were screened for TB rose from 0.4% in 2001 to 1.1% in 2013, while the smear-positivity rate decreased from 28.9% to 8.1% in the same period. The total number of notified TB cases increased steadily from 2000; this has stabilized in recent years with 39 055 cases notified in 2013. The proportion of all TB cases that were smear-positive decreased from 78% in 2000 to 36% in 2013. Case notification rates (CNRs) for all forms of TB and new smear-positive TB in 2013 were 261 and 94 per 100 000 population, respectively. Higher CNRs were found in the north-western and south-eastern parts of the country and were higher for males especially in older age groups. The increase in TB screening, decline in the smear-positive rate and decline in notified smear-positive TB cases likely reflect a long-term positive impact of the NTP. A negative correlation between the proportion of the population screened and the smear-positivity rate at the subnational level helped identify where to find undiagnosed cases. Subnational differences in case notification of the elderly and in children provide more specific targets for case-finding and further encourage strategic resource allocation.

Evaluation of tuberculosis underreporting in Greece through comparison with anti-tuberculosis drug consumption

Surveillance is an integral part of tuberculosis (TB) control. Greece has a low TB notification rate, but there are doubts about underreporting. Examining anti-TB drug consumption is a way to validate the results of surveillance and estimate TB burden in the country. We used surveillance data from 2004 to 2008 to calculate the average prescribed treatment duration with the first-line anti-TB drugs isoniazid, rifampicin, ethambutol and pyrazinamide. We then obtained the best available data on consumption of these drugs, and calculated the number of treated cases to which these quantities correspond. We thus estimated underreporting at around 80% (77-81%), and annual TB incidence at about 30 cases per 100,000 population, five times over the notification rate. Underreporting was found to be constant over the study period, while incidence followed a decreasing trend. In addition we estimated that one person receives chemoprophylaxis for latent tuberculosis infection (LTBI) for every three TB cases. These results indicate the need for a comprehensive plan to improve TB surveillance and TB contact tracing in Greece, especially in light of the economic crisis affecting the country since 2009.