Methodological Notes – Infectious Disease Incidence Module

Updated: October 2011

Concepts and Definitions

Although the public health significance of infectious diseases has decreased substantially in the past half century, the overall burden of infectious diseases in the Arctic remains high, especially among the indigenous populations in some regions. Disease surveillance is an integral part of public health practice in the national and regional health care systems of circumpolar countries. The Circumpolar Health Observatory (CircHOB) tracks the incidence of two specific infectious diseases – tuberculosis (TB) and gonorrhea. These are two socially and epidemiologically important diseases which are reported consistently and regularly by all the regions, and information on them is publicly available.

Infectious diseases are defined on the basis of their causative microorganisms, which in the case of the two selected diseases are the bacteria Mycobacterium tuberculosis and Neisseria gonorrhœae. There are, however, operational case definitions used by public health agencies for the purpose of surveillance – see, for example, the ones used by the Centers for Disease Control and Prevention (CDC) of the United States [Case definitions for infectious conditions under public health surveillance].

Inclusion and exclusion criteria do vary across different jurisdictions, and in the absence of laboratory confirmation, cases defined on the basis of clinical signs and symptoms and other investigations (such as X-ray) may not be completely comparable internationally. CircHOB accepts as confirmed cases those that are reported by the various public health agencies and released to the public. This is adequate for the purpose of showing broad spatial patterns and temporal trends.

The annual incidence rate of a disease = (number of new cases reported in Year X) / (mean population of year X)

This is usually expressed as the number of cases per 100, 000 persons.

Data Sources and Limitations

United States

United States and Alaska all-race data are available from the CDC On-Line Tuberculosis Information System and Sexually Transmitted Disease Morbidity, both accessible from the CDC Wonder interactive website.

Canada

The Public Health Agency of Canada publishes the report Tuberculosis in Canada annually. Reported cases and rates of gonorrhea by province/territory and sex from 1980 to 2009 are tabulated online.

Greenland

Data for Greenland are available from the annual report (Årsberetning) of the Chief Medical Officer (Landslægeembedet, formerly Embedslægeinstitutionen i Grønland) under the heading: Opgørelse over smitsomme sygdomme. The report is available on the website.

Faroe Islands

Faroe Islands data are published in the annual report Sundhedsberetning (formerly Medicinalberetning) of the Chief Medical Officer (Landslæknin í Føroyum).

Iceland

The Directorate of Health (Landlæknisembættiđ) provides on its website an annually updated spreadsheet containing all notifiable communicable diseases.

Denmark

Tuberculosis data are available from the Statens Serum Institute’s disease monitoring tables and graphs in its interactive website (in Danish only) [Statens Serum Institut. Smitteberedskab. Overvågning i tal og grafer]. For gonorrhea, the number of cases have to be extracted from the weekly bulletin Epi-News (separate Danish and English editions), which provides an epidemiological update for this disease in an issue each year. Note that Denmark surveillance data do not include cases from Greenland or Faroe Islands.

Norway

Both tuberculosis and gonorrhea are among the diseases listed in the Surveillance System for Communicable Diseases (Meldingssystem for smittsomme sykdommer, or MSIS) interactive website of the Norwegian Institute of Public Health (Folkehelseinstituttet).

Sweden

Cases of TB reported by counties are tabulated in the report Tuberculosis in Sweden (and its predecessor prior to 2003 The Swedish Tuberculosis Index) jointly published by the Swedish Institute for Infectious Disease Control (Smittskyddsinstitutet, or SMI) and the Swedish Lung Association [Tuberkulos i Sverige – Sammanfattande analys av tuberkulosstatistiken]. The number of cases of gonorrhea is retrievable from SMI’s statistical database.

Finland

Communicable disease surveillance is the responsibility of the National Institute of Health and Welfare (Terveyden ja hyvinvoinnin laitos, or THL), which merged the former National Public Health Institute (KTL) and the National Research and Development Centre for Welfare and Health (STAKES). The number of reported cases is available from the THL interactive statistical database.

Russian statistical data are available from the Federal State Statistics Service (Federal’naia sluzhba gosudarstvennoi statistiki), commonly referred to as Rosstat. The chief source of publicly available information on disease surveillance in Russia and its regions is the report Health in Russia, published in 2001, 2005 and biannually thereafter [Zdravookhranenie v Rossii: Statisticheskii sbornik]. A continuous series of trend data for the Russian Federation as a whole are available for all years, but for the regions, only data for the one year prior to the year of publication are available (i.e. 2000, 2004, 2006 and 2008).

For the Nenets, Taymyr, Evenki, Koryak and Chukotka AO, data for additional years are reported in Economic and Social Indicators of Regions of Residence of Numerically Small Peoples [Ekonomicheskie i sotsial’nye pokazateli raionov prozhivaniia korennykh malochislennykh narodov Severa], and for the Khanty-Mansi and Yamalo-Nenets AO in the Economic and Social Indicators in the Far North and Similar Areas [Ekonomicheskie i sotsial’nye pokazateli raionov krainego Severa i priravnennykh k nim mestnostei].

Since 2005, the Central Research Institute of the Department of Health and Social Development (Central’nyi nauchno-issledovatel’skii institut organizatsii i informatizatsii zdravoohranenija Ministerstva zdravoohranenija i social’nogo razvitiia Rossiskoi Federatsii) has released biannually statistical tables on “socially important” diseases, which include TB and gonorrhea, in its website Mednet.