Abstract
As genital Chlamydia trachomatis (chlamydia) infection is often asymptomatic, surveillance of diagnosed cases is heavily influenced by the rate and distribution of testing. In 2007, we started supplementing case-based surveillance data from the Norwegian Surveillance System for Communicable Diseases (MSIS) with aggregated data on age group and sex of individuals tested. In this report, annual testing rates, diagnosis rates and proportion positive for chlamydia in Norway between 1990 and 2013 are presented. From 2007, rates are also stratified by age group and sex. The annual testing rate for chlamydia culminated in the early 1990s, with 8,035 tested per 100,000 population in 1991. It then declined to 5,312 per 100,000 in 2000 after which it remained relatively stable. Between 1990 and 2013 the annual rate of diagnosed cases increased 1.5 times from ca 300 to ca 450 per 100,000 population. The proportion of positive among the tested rose twofold from ca 4% in the 1990s to 8% in 2013. Data from 2007 to 2013 indicate that more women than men were tested (ratio: 2.56; 95% confidence interval (CI): 2.56-2.58) and diagnosed (1.54; 95% CI: 1.52-1.56). Among tested individuals above 14 years-old, the proportion positive was higher in men than women for all age groups. Too many tests are performed in women aged 30 years and older, where 49 of 50 tests are negative. Testing coverage is low (15%) among 15 to 24 year-old males. Information on sex and age-distribution among the tested helps to interpret surveillance data and provides indications on how to improve targeting of testing for chlamydia. Regular prevalence surveys may address remaining limitations of surveillance.
Highlights
Genital Chlamydia trachomatis infection is the most frequently reported sexually transmitted infection (STI) in Europe, in particular in Norway [1,2]
A trend test of the diagnosis rate showed an average increase of 2.2% each year from 1990 to 2013 (p-value < 0.001)
We have found that information on age group and sex among those who are tested for chlamydia helps us interpret the results obtained by the national surveillance system for chlamydia
Summary
Genital Chlamydia trachomatis infection (hereafter: chlamydia) is the most frequently reported sexually transmitted infection (STI) in Europe, in particular in Norway [1,2]. Diagnosis and treatment has been considered a major strategy to prevent complications and further transmission of chlamydia [3,4], and countries have tried various strategies to increase testing in target populations [5]. The evidence for the effect of early diagnosis and treatment of chlamydia on the population level is weak [6,7]. Since 1995 the following groups are recommended to be tested: any person below 25 years of age after each change of sexual partner, individuals with clinical symptoms compatible with chlamydia or epidemiological link to another case, women below 25 years of age during antenatal care and women undergoing legal abortion [8,9,10,11,12]. Recommendations for annual testing of chlamydia and other STIs in men who have sex with men were issued in 2005 [11]
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Schedule a callMore From: Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin
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