Læknablaðið - 15.07.1995, Blaðsíða 36

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LÆKNABLAÐIÐ 1995; 81
Discussion
Facilities for diagnosing infections caused by
C. trachomatis were introduced for routine use
in Iceland after a study had indicated that the
prevalence might be significant (8). It soon
became obvious that these infections constitu-
ted a significant health care problem (9,10).
Diagnostic efforts where steadily intensified,
with increasing number of cases diagnosed un-
til 1988, when the number of cases began to
level off. In 1990 the number of diagnosed
cases dropped for the first time, raising hopes
that the prevalence of the disease was decreas-
ing (11). The drop in diagnosed cases may be
explained in part by the introduction of the
blocking assay which eliminates false positive
Chlamydiazyme® tests. As can be seen in fig-
ure 4, there was a marked increase in diag-
nosed cases in the Department of Obstetrics
and Gynaecology in 1988 when Chlamydia-
zyme® was introduced. This may have been
caused in part by increase in diagnostic efforts
but false positive tests undoubtedly contrib-
uted. False positive Chlamydiazyme® tests
have been shown to be most common in speci-
mens from asymptomatic low risk wonten (12).
The number of positive cases dropped below
the previous level when the blocking assay was
introduced in 1990.
In 1991 and 1992 the total number of diag-
nosed cases increased again only to drop again
in 1993. In 1994 the number of diagnosed cases
rose again although the number of examin-
ations declined (figure 1). The most likely ex-
planation for this was the introduction of the
PCR assay for routine use. The Amplicor®
PCR has been shown to be significantly more
sensitive than culture and vastly more sensitive
than Chlamydiazyme® (13-15).
There has been a significant increase in pa-
tients diagnosed in the STD Clinic after 1990.
The clinic moved to a new facility in the begin-
ning of 1991 and contact tracing efforts were
intensified and counselling for various youth
organisations was initiated. There was also a
significant change in the population attending
the clinic. Women traditionally accounted for
one third of the patients attending the clinic,
but by 1992 they constituted 50% of the patient
population. The number of diagnosed cases
increased correspondingly to the increase in
the number of tests but the positivity rate de-
clined. In 1994 the number of examinations
increased as did the number of positive tests
and the positivity rate rose after the introduc-
tion of PCR. The reasons for this are unknown
but an increased willingness to come to the
clinic for examination has observed after the
introduction a urine test in stead of the more
invasive tests used previously.
Because of the changes in the diagnostic ef-
forts and tests, care must be taken in interpret-
ing the data. Little can be said with certainty
about changes in the prevalence of Chlamydial
infections in Iceland. However, it seems un-
likely that the dramatic 40% decrease in preva-
lence reported from communities like Uppsala
in Sweden (3) has taken place in Iceland. Judg-
ing by the experience in Uppsala, a major re-
duction in diagnosed cases in Iceland might
have been expected. The Department of Mi-
crobiology at the Academic Hospital in Up-
psala and the Department of Microbiology at
the National University Hospital in Reykjavík
serve populations of similar size. During the
six year period between April 1985 and March
1991, 84,844 examinations were performed in
Uppsala (3). During a six year period 1987 to
1993 the number of examinations performed in
Iceland was 61,240. In Uppsala more emphasis
was placed on screening asymptomatic individ-
uals, such as those attending maternity and
family planning clinics. The screening in youth
clinics in Sweden has been credited for a signif-
icant proportion of the decline in prevalence
(16). When diagnostic facilities became avail-
able, screening asymptomatic women in ma-
ternity clinics was recommended. The Depart-
ment of Obstetrics and Gynecology at the Na-
tional University Hospital, where approx-
imately 60% of Icelandic children were born,
started screening pregnant women, and the
effort increased steadily until 1987. The preva-
lence of Chlamydial infections in this popula-
tion was 3.9% (17) and a decision was then
made to stop general screening of pregnant
women but it was still recommended that
women under 24 (prevalence 5.6%) be
screened. However, screening decreased
steadily after 1987 (figure 5), and in 1994 the
only asymptomatic population that was consis-
tently screened were women seeking termina-
tion of pregnancy, a group known to have a
high prevalence rate of C. trachomatis infec-
tions (18).
Comparisons of the experiences observed in