Reported incidence of gonorrhoea and syphilis in East and West Germany 1990-2000 – effects of reunification and behaviour change
Numbers of cases of gonorrhoea and, to a lesser extent, of syphilis in Germany may have been drastically underreported in the past, according to a report in Germany’s national surveillance bulletin (1). It is hoped that a new notification system for syphilis, introduced on 1 January 2001, and a sentinel surveillance system for sexually transmitted infections (STIs) soon to be implemented will provide better quality data to estimate the incidence of STIs and find out whether they reflect the situation in other European countries (2-7).
The old notification system, in place until the end of 2000, provided only aggregated data stratified by sex, age group, and region of residence. According to the new notification system, of the bacterial STIs, only syphilis will remain notifiable, and notification will be carried out by laboratories. The new reporting system, based on anonymous single case reports, will provide additional data (for example, the mode of transmission). Data on gonorrhoea and other sexually transmitted diseases will have to be gathered by the new sentinel surveillance system.
In Germany, gonorrhoea is diagnosed and treated mainly by private practice doctors from a variety of specialist fields. For various reasons reporting of cases of gonorrhoea was incomplete and a large proportion (up to 90% of cases) may have gone unnotified, as indicated by:
The number of reported cases of gonorrhoea dropped from 4000 in 1995 (5.0/100 000) to 2000 in 2000 (2.8/100 000). Assuming that this drop reflects a real decline, a conservative estimate of the actual incidence would be in the range of 10 000-20 000 cases per year, due to the severe underreporting. The real incidence rate of gonorrhoea in Germany therefore may have been 12-25/100 000.
Trends and developments
Nationwide the number of notified cases fell appreciably between 1990 and 1995. The new states (former East Germany, including East Berlin) showed a dramatic decrease, probably because their (formerly stringent) notification system adapted to the poor reporting habits of the old states (former West Germany). There, the decrease in the reported incidence is less pronounced and can be explained with either a real decrease or changes in notifications or healthcare provision. Since 1995, the notified incidence has remained comparatively stable at a low level.
During the nineties the incidence of gonorrhoea in men was twice as high as in women. Some 60-65% of notifications in women related to women younger than 25 years, whereas in men, only 40% of notified cases occurred in those younger than 25.
In the past few years, discussion has focused on whether risky sexual behaviour in homosexual men is increasing as a result of improved treatment options for HIV infection. Since 1996, the proportion of male gonorrhoea cases has increased nationwide, suggesting – in the context of information from other sources – that the incidence of gonorrhoea in homosexual men has risen. The increase is more marked in the old states, which have more of the big cities that attract homosexual men.
A rising trend in gonorrhoea notifications is consistently reported from all five new states, affecting men as well as women, whereas in the old states the developments are heterogeneous. Whether these different trends in the new and the old states are real differences or whether a similar trend in the old states is masked by more selective reporting patterns and higher underreporting rates cannot be decided based on the currently available data.
Incidence of reported cases of gonorrhoea in West and East Germany, 1988-2000
Since 1994, each year about 1100 cases of syphilis (1.2-1.4/100 000) have been reported in Germany. Appreciable underreporting has to be allowed for in the number of notifications, but the proportion of unreported cases is probably considerably smaller than for gonorrhoea and is estimated at about 30-40%.
Trends and developments
After reaching a peak in 1978, the incidence of syphilis in West Germany has been decreasing. At the end of the 1980s the number of reported cases fell notably among men in the old German states; probably as a result of changed behaviour in response to the emerging HIV/AIDS epidemic. Since the early 1990s the reported incidence of syphilis has remained stable. A small peak at the beginning of the decade was due to regional outbreaks in individual states – the most notable of these in Bremen and Lower Saxony in 1992, and in Mecklenburg-Western Pomerania and Saxony-Anhalt in 1993. With the exception of the Bremen outbreak, most of the cases were in men. The outbreak in Bremen recorded an increase in the number of cases in both men and women.
Half of the female patients in Bremen were younger than 25, whereas half of the male patients were over 40, which suggests a probable association with prostitution. In Lower Saxony and Saxony-Anhalt, the notified cases in men were evenly distributed among the different age groups, whereas in Mecklenburg-Western Pomerania, 20-25 year old men dominated. In these three states there was no corresponding increase in female cases. Nevertheless, the most likely explanation for these outbreaks is that they also resulted from heterosexual transmission associated with prostitution.
Syphilis notifications, ratio of male to female cases, 1995-2000
Further localised outbreaks of syphilis have been noted in Hamburg from 1998 to 2000 and in Berlin since 1999. These are outbreaks among homosexual men. The age distribution among notified cases is typical for an epidemic among homosexual men, with most cases in the 30-40 year age group. According to a local study, a high percentage of cases in the Hamburg outbreak occurred among HIV positive homosexual men (8). The Berlin outbreak has intensified and is ongoing. The high number of cases notified through the new reporting system up to July 2001 for Berlin, Hessen, and Baden-Württemberg (in Hessen and Baden-Württemberg the outbreak is probably restricted to the greater Frankfurt region/Rhine/Main area), compared with the number of notified cases for 1999/2000, indicates large outbreaks in these two regions – even if considerable underreporting is taken into account under the old reporting system. More than one third of all syphilis cases in Germany reported up to July 2001 were reported from these three federal states. The two outbreaks (Berlin and Frankfurt/Main region) are, to our knowledge, the largest reported among homosexual men in Europe in the past decade. About one half of the syphilis cases in Germany currently occur among homosexual men.
Syphilis notifications in selected regions in Germany, 1999-7/2001
Discussion and conclusions
The slight increase in gonorrhoea cases in men and women in Germany’s five new states needs to be analysed further in the future on the basis of better data. The increase of STIs in homosexual men in the second half of the 1990s has been observed in almost all industrialised countries of the West. Risky sexual behaviour may have increased especially among people known to be infected with HIV as their wellbeing has improved with highly active antiretroviral treatment (HAART), and sexual activity of homosexual men overall is increasing. Transmission of gonorrhoea and syphilis may, however, occur during sexual practices that are considered as safe with respect to HIV transmission, so that only part of the increase in bacterial STIs may be attributed to unprotected anal intercourse. It will be one of the aims of the planned STI sentinel study to collect behavioural data to help to clarify these developments.