Reemergence of Gonorrhea in Sweden

GONORRHEA WAS ONE of the most common infectious diseases in Sweden during the 1970s. After many years of steady decline to a low level incidence,1 2.4 of 100,000 inhabitants in 1996 (211 cases), an increasing incidence has been seen for the first time since 1976. In the Swedish Act of Communicable Diseases it is stated that each case of gonorrhea has to be reported (age and sex) to the Swedish Institute of Infectious Disease Control and to the regional authority. Since 1997 a questionnaire is also sent from the Swedish Institute of Infectious Disease Control to the clinician reporting a case of gonorrhea which requests the mode of transmission (homosexual, heterosexual), where the patient was exposed (town, country), and susceptibility of the Neisseria gonorrhoeae strain for ciprofloxacin and β-lactamase production. During 1997 a total of 246 cases were reported, which is 17% higher than for 1996. The increase started during the first half of 1997 and was more pronounced during the second half, a trend that persists during the first half of 1998, as shown in Figure 1.Fig. 1: Number of clinically reported Neisseria gonorrhoeae in Sweden per 6-month period (1993-1998). (Mean population 8.8 million).The proportion of male cases has remained at a level of 80% since 1995 which is slightly higher than at the beginning of the 1990s when the proportion of men was 70%. The proportion of homosexually infected men has been stable since the middle of the 1990s, comprising about 25% of all infected men. Cases from the first half of 1998 were compared with cases from the first half of 1997 and show a significantly younger mean-age among women (30 to 21 years, P = 0.001). No significant change in mean-age for the men was seen (34 and 32 years, respectively). The proportion of heterosexually infected teenagers, i.e., 15 to 19 years old, increased from 1% to 11% of all cases during the same periods. The majority of these teenagers contracted their infection in the Stockholm area. An increase was also seen in heterosexual adults as well as homosexual men in the Stockholm area. Half of all patients diagnosed during the second half of 1997 and the first half of 1998 acquired their infection abroad which is a lower proportion than in previous years. A majority of these cases were heterosexually infected adults. Exposure in several countries all over the world was reported but most prevalent were countries in Asia (35%) or Western Europe (30%). Only a few cases (5%) reported exposure in the Baltic states and other ex-Soviet Union areas, a similar epidemiologic situation as during previous years. In the early 1990s the proportion of β-lactamase producing N. gonorrhoeae in Sweden was below 20%, but during 1997 31% of the strains were β-lactamase producing N. gonorrhoeae as measured by a rapid chromogenic cephalosporin test (Nitrocetin, AB Biodisk, Solna, Sweden). The majority of these cases acquired their infection abroad, but a few cases with β-lactamase producing N. gonorrhoeae were endemic. A decreased susceptibility to ciprofloxacin (minimum inhibitory concentration > 0.06 mg/l as measured by E-test, AB Biodisk, Solna, Sweden) was seen in 17% of the strains in 1997. The majority (62%) of these strains were isolated from cases infected abroad, mostly in Asia, but 16 patients reported Sweden as the place where they were exposed. All strains with decreased susceptibility against ciprofloxacin were from heterosexual patients. This increase of antimicrobial resistance has also been seen by others.2,3 The increase in cases of gonorrhea in Sweden during 1997 and the first half of 1998 was mostly due to an increase in domestic cases. This is alarming, especially the increasing incidence in teenagers and a tendency to endemic spread in Sweden. Every year 10,000 women and men in the age group 15 to 24 years are reported with genital Chlamydia trachomatis infection. Some of them are diagnosed with both gonorrhea and chlamydia, and it is easy to imagine the potential for a wider spread of gonorrhea. The increasing antibiotic resistance among N. gonorrhoeae strains isolated in Sweden is a matter of concern and shows the importance of using culture and antibiotic sensitivity testing. It is therefore no longer acceptable to use direct microscopy as the one and only diagnostic method for gonorrhea. The known Swedish strategy of culture for diagnosis of gonorrhea, effective antibiotic treatment, and contact tracing is still most important. The Swedish Institute of Infectious Disease Control will intensify the surveillance of N. gonorrhoeae to increase the knowledge of how different clones are spreading in the country. With better knowledge, the efforts against the spread of gonorrhea can be more effective, and Sweden may maintain the low rate of pelvic inflammatory disease.1