Enhanced chlamydia surveillance indicates more screening needed

To the Editor: Chlamydial infection is the most common bacterial sexually transmitted infection in Victoria and Australia, and notifications are increasing significantly. Most chlamydial infections are asymptomatic and, if untreated, lead to significant morbidity.1 The direct costs of these infections to the Australian healthcare system have been estimated at $90–$160 million annually.2 Chlamydial infection has been implicated in as many as 50% of cases of infertility.3 Widespread screening is cost effective and reduces both the prevalence of infection and the rate of complications.4 Screening is recommended in a number of countries and in the recently released Victorian Chlamydia Strategy.2

To determine if there has been an increase in the proportion of women tested for chlamydial infection who are asymptomatic in Victoria, we analysed notification and enhanced surveillance data. Since 1997, the Department of Human Services has collected enhanced surveillance data using a standard questionnaire distributed by laboratories to clinicians. The forms record information on risk factors and the reason for testing. Data from the Health Insurance Commission were obtained to provide an indication of trends in testing through Medicare.

The number of notifications almost doubled between 1997 and 2001, from 2059 to 3977 notifications (Box). In 2001, enhanced surveillance data were available on 2300 notifications (58%). Symptomatic presentation remained the major reason for testing (53%), with no significant change in the proportion tested for this reason since 1997. However, when data for the two sexes were analysed separately, the proportion of men who were symptomatic fell significantly between 1997 and 2001, from 77% to 65% (P = 0.02), while there was no change in the proportion of women who were symptomatic — 42% in 1997 and 41% in 2001 (P = 0.35) (Box).

From 1997 to 2001, the number of positive chlamydial tests notified relative to the number of tests conducted has remained constant (9.7%, 8.8%, 11.8%, 11.5% and 9.8% in consecutive years, respectively), despite the increase in number of tests performed. However, even if all tests had been performed in the 20–30-year-old age group, they would represent only 10% of the population in that age group tested each year.

Our data suggest that the reasons for testing over the past 5 years have not changed, and, in particular, that there has been no change in the proportion of women tested who are asymptomatic. Chlamydial infection meets the World Health Organization criteria for a screening program,5 and screening for this infection is cost effective.4 Although chlamydial infections are a significant public health concern for women, targeted screening is not occurring widely.