This surveillance report is a follow-up of two previous articles published in the EpiNorth Journal describing surveillance systems, epidemiological trends and prevention strategies for some important diseases in the Barents- and Baltic Sea region (1,2). This report provides an overview of the current epidemiologic situation and trends for some important infectious diseases in this area of Europe.
The EpiNorth project started as an international project for communicable disease control in Northern Europe in 1998. The project has from the beginning included several activities including EpiNorthData and EpiNorth Journal. Regional and national surveillance data have been collected since 1999. The data are collected directly from the national or regional centres for infectious disease control in the Nordic and Baltic countries and in the Northwest Russian regions. EpiNorth’s secretariat is located at the Norwegian Institute of Public Health.
The area described in this report (the “EpiNorth area”) covers over 3,800,000 square kilometres with a total population of almost 42 million inhabitants. The Nordic countries include Denmark, Finland, Iceland, Norway and Sweden. The Baltic countries include Estonia, Latvia and Lithuania. The official northwestern division of the Russian Federation (with a total of approximately 14.5 million people) includes seven oblasts or regions (Murmansk, Arkhangelsk, Vologda, Kaliningrad, Leningrad, Novgorod, Pskov), two republics (Komi and Karelia), Nenets autonomous okrug and the city of Saint Petersburg. Surveillance data presented in this report include all these regions, except Komi, Pskov, Novgorod and Vologda. From 2008, EpiNorthData will also include surveillance data from these regions, and hopefully from other neighbouring countries, like Belarus, Ukraine and Poland.
Figure 1. Countries / regions and population cooperating within the EpiNorth project in the Baltic- and Barents Sea area.
Epidemi¬ological data presented in this report have been collected from the EpiNorthData (3). Incidence rates 2006 for the most important infections in the region are presented as maps of the region, and trends in the incidence rates are for some infections presented as graphs with incidence curves covering the period 1999-2006. In these graphs, the area has been divided into groups of countries or regions, i.e. the Nordic countries, the Baltic countries and Northwest Russia. The countries or regions in these groups may vary from disease to disease depending on available data. In addition, the general epidemiological situation for each of the diseases in the area is briefly discussed.
Comparing epidemio¬logic data from national surveillance systems in different countries is a challenge since case definitions and methods of data collection often vary across countries.
For this reason, some precaution is also called for when interpreting the comparisons. Since the surveillance systems in the various countries and regions systems are not measuring exactly the same things in exactly the same way. It can always be argued that for some diseases the comparisons are not “just”. This is true, but a rough comparison using the best data available is still worthwhile, since it gives at least some picture of the differences throughout the region. The trends should also be more reliable than the figures for any one given year as long as the surveillance systems are stable over time.
A further complication is that, cases diagnosed in prisons and in military institutions are not always included in the official statistics in Russia. Data from such institutions can only be provided for some infectious diseases by some Russian regions. Military personnel are not included in the Estonian data. These limitations will influence the true incidence rates of HIV, hepatitis and tuberculosis in these countries.
Figure 2. Number of cases of tuberculosis (all types) notified in 2006 per 100 000 population
Figure 3. Number of cases of tuberculosis (all types) notified per 100 000 population 1999-2006 by groups of countries or regions. Saint Petersburg, Komi, Pskov, Novgorod and Vologda regions not included
In the Nordic countries, incidence rates for tuberculosis have for many years remained low and stable. Two main risk groups for developing tuberculosis are recognized; elderly persons born in the Nordic countries with a reactivation of latent of infection contracted earlier in life, and younger persons emigrating from high endemic areas, in particular from some African countries (4). Tuberculosis is in general rarely spread among native citizens in the Nordic countries. The few cases of multi-drug resistant tuberculosis (MDR-TB) diagnosed to date in the Nordic countries have primarily been seen among the immigrant population (4, 5).
In Northwest Russia and the Baltic countries tuberculosis is regarded as a major public health problem. In the early 1990s the deteriorating health and social conditions resulted in a growing number of tuberculosis cases, especially among males. Several factors contributed to this increase; economic recession, worsening nutritional status, poor living conditions and overcrowding in prisons. Disruption of the health services, severe shortages of drugs and laboratory supplies also contributed to inadequate tuberculosis control. Institutional infection control programmes and prison reforms may have contributed to improvements in many places. The direct observed therapy short course strategy (DOTS) has been introduced in most regions and laboratory facilities have improved. Reforms in the penitentiary systems have resulted in a reduction in the number of prisoners, regular supplies of anti-tuberculosis medication and better living conditions for inmates. Incidence rates have now decreased in the Baltic countries while they remain high in Northwest Russia. There may be many reasons for the continuing high rates in Northwest Russia. Tuberculosis cases diagnosed in prisons as well as re-treatment cases have been increasingly included in the notifications. In addition, more effective services have probably resulted in more case detections.
MDR-TB has been and continues to be a serious problem in the Baltic countries and Russia, and presents a major challenge of treatment at the individual level and in the infection control at the population level. Drug resistance surveys in the Russian Federation have shown that 7 – 16% of tested Mycobacterium tuberculosis isolates are primary MDR (6). Co-infection with HIV is an increasing problem among tuberculosis patients in both the Baltic countries and Northwest Russia.
Figure 4. Number of cases of newly diagnosed HIV infection notified in 2006 per 100 000 population
Figure 5. Number of cases of newly diagnosed HIV infections notified per 100 000 population 1999-2006 by groups of countries or regions. Komi, Pskov, Novgorod and Vologda regions not included
The Nordic countries experienced during the 1990s and early 2000s stable and comparatively low figures for newly diagnosed HIV infections, with exception of Finland where an outbreak of HIV among injecting drug users was reported in 1999-2000 (7). A large part of HIV cases in these countries are immigrants who were infected in a highly endemic country of origin before arriving in the Nordic countries. The majority of HIV-infected immigrants arrives from Sub-Saharan Africa, but for the last few years an increasing number comes from Southeast Asia.
Men who have sex with men represent the other major group of people living with HIV. As in many other western European countries, an increasing number of newly infected men who have sex with other men are reported in most of the Nordic countries (8–10). The HIV incidence rates among injecting drug users have remained low and stable in all the Nordic countries, although outbreaks in this group have been reported in Finland in the late 1990s and most recently in Sweden (7,11).
The epidemiological situation of HIV/AIDS in Northwest Russia differs dramatically from that in the Nordic countries. In Russia, a sharp rise of newly diagnosed HIV cases started in 1998, especially in the Northwest region, and a peak was observed in 2001. Injecting drug users have dominated among the diagnosed cases since the start of the epidemic and this trend continues (12,13). The highest incidence of diagnosed cases of HIV is found in the Saint Petersburg, Leningrad, Murmansk and Kaliningrad regions. During the last few years, most regions in Northwest Russia have reported an increase in the numbers of diagnosed HIV cases. This is mainly caused by an increase in the spread of HIV among women and to some degree children. The majority of these cases in women are seen among sex partners of infected drug users, and there are as yet no signs of a generalised heterosexual epidemic. At present, men who have sex with men do not account for a large proportion of the reported cases in Northwest Russia, but stigmatisation faced by men who have sex with men may lead to an underreporting of this transmission route. The high incidence of other sexual transmitted infections in Northwest Russia represents a potential risk factor for a wider heterosexual spread of HIV. Like tuberculosis, a substantial number of HIV cases occur among prison inmates (12). Many of these inmates have been transferred to regions in Northwest Russia from other parts of the Russian Federation.
In Estonia and Latvia, the situation is very similar to the situation in Northwest Russia. Estonia is one of the countries with the highest HIV prevalence rates in the WHO European region. The overwhelming majority of the infections are among drug users, especially in the eastern part of the country bordering Russia. Likewise, Latvia has experienced a rapid increase in the number of infected drug users (14). An increasing number of men who have sex with men are diagnosed in both Estonia and Latvia. In contrast, relatively few cases are diagnosed in Lithuania. As in Northwest Russia, there is no data available to support the idea of a generalised heterosexual HIV epidemic in any of the Baltic countries.
Acute hepatitis B
Figure 6. Number of cases of acute hepatitis B notified in 2006 per 100 000 population
Figure 7. Number of cases of acute hepatitis B notified per 100 000 population 1999-2006 by groups of countries or regions. Iceland, Komi, Pskov, Novgorod and Vologda regions not included
The vast majority of notified acute cases of hepatitis B in the area occur among injecting drug users (IDUs). While introduction of vaccines and HIV preventive measures such as clean syringes and users’ equipment resulted in a dramatic fall of hepatitis B in the early 1980s, many of the countries in the area experienced a surge in incidence rates in the 1990s. This was mainly caused by outbreaks among groups of non-immune IDUs and coincided with an increase in the number of young people injecting drugs in many of the countries in the area.
The number of newly diagnosed cases has dropped considerably in the eastern part of the area. A combination of effective preventive measures and decrease in numbers of susceptible drug users may have contributed to this improvement. From 2006, as a part of the presidential National Priority Project in Public Health, Northwestern Russian regions will vaccinate several hundred thousands individuals against hepatitis A. The spread of hepatitis B among drug users has resulted in a growing number of sexually transmitted cases among IDUs’ sex partners, usually women. As a consequence, preventing newborn hepatitis B has become a concern in most of the countries in the area. Transmission of hepatitis B by routes other than needle sharing and sex is rare in the Nordic countries, while nosocomial infections may still occur in the eastern part of the area (15). Likewise, health care workers in the eastern part of the area are at greater risk of contracting hepatitis B than in the Nordic countries.
Figure 8. Number of persons with anti-HCV positive tests notified in 2006 per 100 000 population
Figure 9. Number of persons with positive anti-HCV tests notified 1999-2006 by groups of countries or regions. Denmark, Norway, Komi, Pskov, Novgorod and Vologda regions not included
Hepatitis C is a chronic disease which is rarely symptomatic in the acute stage. It is thus a disease that is difficult to monitor and the number of newly infected persons are difficult to estimate. Most countries in the area report the number of diagnosed anti-HCV positive cases without differentiating between acute or chronic cases. Therefore, the reported incidence rates of hepatitis C do not always reflect the true incidence of the disease. This is especially the case in the Nordic counties and to a lesser extent true for Northwest Russia and the Baltic countries where the hepatitis C epidemic probably started in the 1990s.
Injecting drug users represent by far the most important risk group for contracting hepatitis C in the entire area. Ever since hepatitis C serology was introduced in the late 1980s, an increasing number of anti-HCV positive cases has been diagnosed in this group throughout the entire area. In the Nordic countries, many of these cases were previously diagnosed in older age groups who were infected while injecting drugs in the 1970s and 1980s (16). In contrast, most cases in the eastern part of the area have been diagnosed among young, active IDUs’ many of who are co-infected with hepatitis B. The number of reported cases of hepatitis C was drastically reduced in Northwest Russia in the early 2000s. A combination of effective preventive measures and a decrease in numbers of susceptible drug users may have contributed to this improvement. The same is probably true for the Baltic countries (16).
There are signs that the spread of hepatitis C is decreasing in drug communities, and treatment is becoming more available in many parts of the area. The extent of sexual and nosocomial transmission of hepatitis C is to a large extent unknown in most parts of the region.
Figure 10. Number of cases of gonorrhoea notified in 2006 per 100 000 population
Figure 11. Number of cases of gonorrhoea notified per 100 000 population 1999- 2006 by groups of countries or regions. Komi, Pskov, Novgorod and Vologda regions not included
In the Nordic countries, gonorrhoea is, compared with the situation in the 1970s and 1980s, a rare disease. It is mostly seen among men who have sex with men and in heterosexual males who are infected abroad, notably in Thailand and other popular tourist destinations (17).
Among females, the infections are mainly domestically acquired.
In the Baltic countries and Northwest Russia heterosexual transmission dominates with a high number of cases among the young and unemployed. In the early 1990s the Baltic countries and Northwest Russia experienced record high incidence rates of gonorrhoea. This may be attributed to political and social changes, resulting in changing sexual behaviour patterns and delays in treatment that caused patients to remain infectious for longer periods. In Northwest Russia, the incidence peaked around 1993-94. For the three Baltic countries, the incidence has decreased since 1999. The incidence rates in the eastern part of the area are still high compared with the western part of the region. This is especially the case for the younger age groups. Antibiotic resistance is a growing problem in the Nordic countries, and quinolone-resistant strains are often seen in patients who contract the disease in the Far East. Less is known about resistance patterns in the eastern part of the region.
Figure 12. Number of cases of syphilis notified in 2006 per 100 000 population
Figure 13. Number of cases of syphilis notified per 100 000 population 1999- 2006 by groups of countries or regions. Komi, Pskov, Novgorod and Vologda regions not included
Like gonorrhoea, syphilis is now a rare disease in the Nordic countries and is mostly seen among men who have sex with men and in heterosexual males who are infected abroad, notably in Thailand and other popular tourist destinations. A high proportion of men who have sex with men who have contracted syphilis during the last few years have also been HIV-positive (17).
The situation has been very different in Northwest Russia and the Baltic countries. In the early 1990s, this part of the area experienced record high incidence rates of syphilis. This was probably due to political and social changes, resulting in changing sexual behaviour and delays in treatment that caused patients remaining infectious for longer periods. The syphilis epidemic in the eastern part of the area reached its peak around 1995-96, and the incidence rates are still dropping The overwhelming majority of cases in the Baltic countries and Northwest Russia are among heterosexuals with a high number of cases among the young, the unemployed, substance users and sex workers.
Genital chlamydial infections
Figure 14. Number of cases of genital chlamydial infections notified in 2006 per 100 000 population
Figure 15. Number of cases of genital chlamydial infections in the Nordic countries notified per 100 000 population 1999- 2006
Chlamydia is the most commonly reported bacterial sexually transmitted infection in Europe. While testing for genital chlamydial infections is common practise in the Nordic countries and some of the Baltic countries, this pathogen is at present rarely looked for in most of the regions in Northwest Russia. Therefore, little is known about the true incidence of the disease in Northwest Russia.
In the Nordic countries incidence rates of chlamydila infection have gradually increased in the past years. Chlamydia infections mainly affect young heterosexuals, especially young women. The highest incidence is reported in the age group 15–24 years (4,18,19). In 2006, a new genetic variant of Chlamydia trachomatis was reported in Sweden (20). Patients infected with this variant of C. trachomatis received a false negative result if tested by one of the most commonly used diagnostic tests. At the moment, the spread of this variant seems to be restricted to Sweden.
Figure 16. Number of cases of hepatitis A notified in 2006 per 100 000 population
Figure 17. Number of cases of hepatitis A notified per 100 000 population 1999-2006 by groups of countries or regions. Komi, Pskov, Novgorod and Vologda regions not included
The Nordic countries are considered a non-endemic area for hepatitis A and most cases are diagnosed among travellers to endemic areas. However, since the mid-1990s outbreaks of hepatitis A among injecting dug users have been reported from Sweden, Finland and Norway (22-24). In 2004, outbreaks among men who have sex with men were reported from Denmark and Norway (25). In contrast, Northwest Russia has long been considered an endemic area, with mostly domestically acquired cases involved in occasional water- or food-borne outbreaks. The incidence rates of hepatitis A in Northwest Russia have decreased considerably during the last 15 years. Improvements in water quality and sewage systems are important contributing factors. The fall in incidence rates are even more striking in the Baltic countries, and the incidence rates are now similar to the rates in the Nordic countries. In Northwest Russia non-immune school children and children in day care centres are the most vulnerable groups, and nosocomial infections have been reported in pediatric wards. Adults in the general population in Russia and the Baltic countries have a much higher prevalence of serological evidence of prior hepatitis A virus infection than adults in other parts of the region.
Salmonellosis (excluding typhoid and paratyphoid fevers)
Figure 18. Number of cases of salmonellosis notified in 2006 per 100 000 population
Figure 19. Number of cases of salmonellosis notified per 100 000 population 1999- 2006 by groups of countries or regions (1). Komi, Pskov, Novgorod and Vologda regions not included
In Norway, Sweden, Finland and Iceland the majority of reported cases of salmonellosis are contracted abroad (26) and Salmonella enteritidis dominates. This serotype is the most commonly occurring in most European countries outside the Nordic region. S. Typhimurium is the most common serotype isolated from patients domestically infected in the Nordic countries. Distinct clones of S. Typhimurium have been established in the Nordic countries among wild birds and wild animals (27).
Control programmes have documented that live cattle, swine and poultry as well as domestically produced food products of animal origin are virtually free from salmonella in all the Nordic countries except Denmark. In Denmark, the majority of cases are domestically acquired and contaminated egg products have been a major problem in the country. The number of egg-associated cases has decreased considerable in the last few years in Denmark, which is believed to be the result of special control programmes (28). In Russia and the Baltic countries, the overwhelming majority of cases are domestically acquired and the majority of cases are probably caused by contaminated domestically produced food products or imported poultry products.
Figure 20. Number of cases of shigellosis notified in 2006 per 100 000 population
Figure 21. Number of cases of shigellosis notified per 100 000 population 1999- 2006 by groups of countries or regions. Komi, Pskov, Novgorod and Vologda regions not included
The Nordic countries have for many years had low and stable incidence rates of shigellosis with very few domestically acquired cases. In Northwest Russia, and to some degree in the Baltic countries, shigellosis is endemic and has been a major public health problem for many years. This is partly caused by unsatisfactory hygienic and sanitary conditions. Nosocomial trans¬mission and outbreaks may occur. Outbreaks in childcare centres still occur in Northwest Russia. Incidence rates in the eastern part of the area may fluctuate depending on local outbreaks but, in general, incidence rates have for the past few years decreased considerably.
Figure 22. Number of cases of campylobacteriosis notified in 2006 per 100 000 population
Campylobacteriosis is a growing problem in the area. Since the late 1990s campylobacter has surpassed salmonella as the most common cause of bacterial enteritis in the Nordic countries. The vast majority of the cases are caused by Campylobacter jejuni. In Finland, Norway and Sweden, about half of the cases are contracted abroad, while in Denmark and Iceland the majority of cases are contracted within the country (28). Consumption of poultry products and untreated surface water are believed to be major risk factors in most Nordic countries (27). In the eastern part of the region, nearly all the diagnosed cases are domestically acquired. The low incidence figures from the eastern countries of the region compared to the Nordic countries are probably due to underreporting and varying use of laboratory services for the diagnosis of these infections.
Figure 23. Number of cases of yersiniosis notified in 2006 per 100 000 population
Yersinia enterocolitica is the dominating species occurring in Denmark, Norway, Sweden and Iceland. Yersinia pseudotuberculosis is much more common in Finland and Northwest Russia. The most important reservoir for Y. enterocolitica is pigs, and rodents, hares, deer and birds for Y. pseudo-tuberculosis. Several outbreaks of Y. pseudotuberculosis infections have been reported in Northwest Russia and Finland (29).
Risk factors for infections with Y. enterocolitica are consumption of pork and untreated drinking water. Outbreaks related to Y. enterocolitica are very rare in the Nordic countries.
The incidence rates of yersiniosis are fairly stable in the region, and the majority of cases are acquired domestically. In Norway, a decreasing incidence has been noted since the late 1990s. This decline coincided with the gradual introduction of improved slaughtering routines that resulted in reduced Y. entero¬colitica contamination on the surface of pig carcasses.
Vaccine preventable diseases covered in national immunisation programmes
Figure 24. Number of cases of diphtheria notified in 2006 per 100 000 population
In the early 1990s, a sharp increase in reported cases of diphtheria was observed in the Baltic countries and Northwest Russia. This increase was caused by a drop in the vaccination coverage. In most of the countries in the eastern part of the region, the epidemic reached a peak around 1995. Massive vaccination campaigns in the most heavily affected regions have greatly improved the situation. However, in Latvia and some of the Northwest Russia regions, a second wave of increasing diphtheria incidence has been observed. Diphtheria still remains a serious public health problem in Latvia where most cases occurs in non-vaccinated adults (30). During the last decades, very few cases of diphtheria have been diagnosed in the Nordic countries and most of the cases have been imported from Southeast-Asia. Non-immune children and adults, especially alcoholics and homeless people, are at the highest risk of contracting diphtheria in the region.
Figure 25. Number of cases of measles notified in 2006 per 100 000 population
Due to very high vaccination coverage, measles has been a rare disease in the entire region for many years. Sporadic cases are, however, still reported. In the Nordic countries small outbreaks have been reported in groups of non-vaccinated children. Non-immune children living in communities where general opposition to vaccination is widespread are at special risk if a case of measles is introduced in the community.
Figure 26. Number of cases of mumps notified in 2006 per 100 000 population
As a result of high vaccination coverage, mumps are rarely diagnosed in the Nordic countries. In contrast, lower vaccination coverage in the early 1990s in parts of the eastern part of the area resulted in an unstable situation with periodic outbreaks. Changes in vaccination schedule and vaccination campaigns have improved this situation.
Figure 27. Number of cases of rubella notified in 2006 per 100 000 population
Thanks to the high vaccination coverage, rubella is now a rare disease in the Nordic and Baltic countries. As rubella vaccination has not been a part of the programme in Russia, the disease is still endemic in Northwest Russia, and cases of the congenital rubella syndrome occurs. From 2006, as a part of the presidential National Priority Project in Public Health, Northwestern Russian regions introduce rubella vaccine and aim to control the disease.
Figure 28. Number of cases of pertussis notified in 2006 per 100 000 population
In 1997, Norway experienced a sharp, epidemic-like increase in reported cases of pertussis. This rise was not related to a fall in vaccination coverage, and the overwhelming majority of cases were diagnosed among older children and adults. These high rates may be partly explained by an increased awareness about the disease. Incidence rates remain exceptionally high in Norway (4). The same trend has not been observed in the other Nordic countries. In Northwest Russia, vaccination coverage fell in the early 1990s resulting in local outbreaks. Improved regional vaccination campaigns have since led to a considerable decrease in the number of reported cases among the youngest children in Northwest Russia. However, the number of cases in older children remains high.
Tick-borne encephalitis (TBE)
Figure 29. Number of cases of tick-borne encephalitis notified in 2006 per 100 000 population
The TBE virus persists in so-called natural foci where it circulates among vertebral hosts, mainly rodents, and infects humans through tick bites. These foci are usually stable and exist in most of the Baltic Sea region, especially the Baltic countries, Åland Islands, mainland Finland, the Republic of Karelia and the south-eastern costal parts of Sweden (31). In recent years new, small foci have been identified on the Bornholm Island in Denmark and within a limited area on the southern coast of Norway. The reasons for the spread remain unknown.
Figure 30. Number of cases of meningococcal disease notified in 2006 per 100 000 population
During the last years the incidence rates of reported meningococcal disease in most of the countries have been relatively stable with incidence rates usually below 5 per 100,000 population. Except for Iceland, infection with serogroup B has dominated in the region followed by serogroup C.. In the early 2000s an increase in cases caused by serogroup C was observed in Iceland. Following a vaccination campaign aimed at children and youths under 19 years of age, the incidence of meningococcal disease group C has fallen in Iceland (32).
Compared with the situation in the late 1990s and early 2000s, the epidemiological situation for most communicable diseases in the Barents- and Baltic Sea area has improved considerably. The decrease in incidence rates has been most striking in the eastern part of the area, especially with regard to blood-borne and sexually transmitted infections such as HIV and viral hepatitis. A combination of effective preventive measures and decrease in numbers of susceptible drug users may have contributed to this improvement. The increasing number of women diagnosed with HIV in Northwest Russia probably reflects increased sexual transmission within the drug use communities, and not the start of a generalised heterosexual HIV epidemic. The continued high incidence of syphilis and gonorrhoea in Northwest Russia, especially among young people, the unemployed, substance users and sex workers, is of concern because it is well-documented that the presence of other sexually transmitted infections increases the risk of contracting HIV through unprotected sex (33). In addition, the growing number of newly diagnosed HIV cases among men who have sex with men, especially in the Nordic countries, is of great concern.
In contrast to most other communicable diseases, the incidence of tuberculosis has remained high in the area, both in terms of reported number of cases and proportion of multi drug-resistant strains. The spread of tuberculosis and HIV infection still represent one of the most important public health challenges in the Barents and Baltic Sea area.
The favourable epidemiological situation for most of the communicable diseases in the region may be attributed to many factors. One important factor is the extensive collaboration and exchange of experience and expertise between health authorities, infectious disease control professionals and non-governmental organisations across the national borders in the area. This is of special importance in the development of infection control programmes and other preventive measures. In addition, the exchange and dissemination of surveillance data within the region is of vital importance in the fight against communicable diseases.
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