Drug-related infectious diseases

Overview of the data

The index below lists the tables in the bulletin, the supplementary down-loadable tables and the associated graphics in the section dealing with drug-related infectious diseases, along with a brief, summary overview. See also the main overall index for all sections of the statistical bulletin.

Table INF-1, Table INF-2 and Table INF-3 are summary tables by country of the latest results held at EMCDDA, for prevalence of HIV, HCV and HBV infections among injecting drug users, showing the numbers of tests made and the percentage infected, the broader aspects of the study setting, and references to the original reports listed in the section's bibliography, Table INF-0 part (i) and Table INF-0 part (ii).

In the supplementary tables, tables INF-4 to INF-6 report information on newly diagnosed or notified HIV, HCV and HBV cases respectively, giving medium-term historical data on the number of reported cases. Table INF-4 gives additionally the rate per million population for HIV infection and Table INF-5 (Excel format) and Table INF-6 (Excel format) give the IDU percentage among the cases that have information on the presumed transmission category.

A small number of countries report incidence data for HCV from follow-up studies of IDUs at a city level. Table INF-7 (Excel format) reports the number of IDUs followed, the number of sero-conversions, follow-up time, the incidence rate per 100 person-years and a reference to the source study in the section's bibliography, Table INF-0 part (i) (Excel format).

Fuller information on which the summaries above are based as well as prevalences among young injectors and new injectors can be found among the supplementary downloadable tables (all in Excel format): Table INF-8, Table INF-9 and Table INF-10 for HIV; Table INF-11, Table INF-12 and Table INF-13 for HCV; and Table INF-14 and Table INF-15 for HBV current infection (HBsAg) prevalence and HBV antibodies (aHBc, aHBs) prevalence, respectively.

Summary points

• AIDS and HIV infection

• AIDS incidence rates among IDUs are available for all EU members and show strong declines in the old EU member countries, although there are increases in some of the new members.

• The decline in AIDS incidence in the late 1990s is generally thought to be not only the result of reduced transmission, but also due to the introduction of highly active antiretroviral treatments (HAART) in 1996 that delay or prevent the development of AIDS.

• Estimates of the coverage of highly active antiretroviral treatment made by WHO–Euro suggest that in the EU Member States and the candidate countries over 75 % of persons in need of treatment have access to HAART. A significant improvement of the situation has taken place in this respect in the past 3 years, before which the Baltic states and the candidate countries had only a partial coverage of HAART. However, a problem still remains that the coverage estimates specific to IDUs are not available, and studies show that IDUs are often at higher risk for inadequate access to HAART than people infected by other routes. Reference: WHO Regional Office for Europe, 2006 (Figure INF-14 part (iii) and Figure INF-14 part (iv)).

• A lack of decline or a late decline among IDUs can indicate a lack of coverage or late introduction of these treatments for IDUs.

• AIDS incidence in IDUs in affected countries peaked in the early 1990s – in some countries somewhat later. Some countries report recently increasing AIDS incidence for IDUs.

• AIDS incidence data show that IDUs have been the most important transmission group for HIV and AIDS until 2002. Since then heterosexual transmission has become the largest category of new cases (Figure INF-1 part (ii))

• Rates in the general population of newly diagnosed HIV cases who are IDUs have strongly increased in the Baltic states, but have remained low in other EU countries with the exception of Portugal.

• Data on newly diagnosed cases of HIV infection shows high peaks of HIV transmission as recently as 2001 in some EU Member States and elsewhere in Eastern Europe. See Figure INF-2 part (ii).

• Seroprevalence data are an important complementary source of information to HIV case reports. HIV seroprevalence data, mostly from studies of IDUs in drug treatment, suggests that long-term the prevalence of HIV among IDUs has decreased in the most affected countries but has in most cases stabilised since the mid-1990s.

• Since 1997/8 however new increases are seen in the available national level seroprevalence data in several countries.

• In 2003 and 2004, the HIV prevalence among IDUs shows wide variation in regional studies both within and between countries, ranging from 0 % in some of the newer members to a high of 90 %, with several studies reporting prevalence in excess of 20 %. Recent local data are however not available from some of the most affected countries and areas.

• Some local studies among young IDUs (aged <25) and new injectors (injecting less than 2 years) found high prevalence of HIV infection (greater than 20 %), suggesting recent transmission of HIV. Data for young or new injectors is also lacking from several countries and regions which have a high prevalence overall, making it more difficult to evaluate the extent of recent transmission (Figure INF-3, Figure INF-4, Figure INF-5).

Hepatitis B and C infections

• HCV prevalence among IDUs (mostly IDUs in drug treatment) is in general extremely high but shows wide variation within and between countries, ranging from 10 % in some national data to 97 % in one regional study.

• National data are missing for many countries and in two countries data relate to problem drug users in treatment, not restricted to injectors, and may thus underestimate prevalence among IDUs. Even so, data for 2003 to 2004 show high prevalence in several national samples.

• Data on local/regional HCV prevalence levels are also unavailable for several countries, but high regional or local prevalence levels (exceeding 60 %) among IDUs have been found for 2003 to 2004 in studies in some countries. Lower prevalence (less than 40 %) has also been found in national and local samples in other countries.

• HCV prevalence data from young IDUs (aged <25) are available from few countries only, with levels in excess of 40 % in some studies and less than 20 % in others.

• Availability of data on prevalence in new injectors (injecting < 2 years) is very limited, but similar high levels are found, with the lowest levels falling below 10 % in a few countries.

• The sparse trend data that are available suggest a slowly decreasing prevalence over time in most countries that provided data, with some exceptions (Figure INF-6, Figure INF-7, Figure INF-8).

• A positive test result for HCV antibodies is a useful epidemiological indicator of having been infected with the virus and reflects well e.g. risk behaviours. However, antibody prevalence does not show how many of these (ex)injectors are still currently infected and are able to infect others. Recent studies suggest that the presence of virus (being RNA positive) may be confirmed in roughly 40 to 90 % of those with antibody positivity.

• The genotypes of the hepatitis C virus most frequently found in European studies of IDUs are types 1 and 3. Information on the prevalence of HCV genotypes is highly policy relevant as genotype is a major determinant of anti viral treatment outcome. There are six main genotypes of HCV of which types 1 and 4 are very difficult to treat (probably less so for type 6) while types 2 and 3 (and probably 5) are much easier to treat and can be eradicated (Figure INF-9 part (i), Figure INF-9 part (ii) and Figure INF-9 part (iii)).

• The prevalence of HbsAg, the marker for current infection with HBV, among IDUs (mostly in drug treatment) shows similar wide variation, ranging from 0 % in one country’s sub-national sample to 20 % in another sub-national sample. This may relate to variation in the combined effect of risk behaviours among IDUs (sexual risk and needle sharing) and of (lack of) vaccination against HBV.

• The highest prevalences are in excess of 5 % whilst some countries have less than 2 % prevalence. However as few countries are providing data on HBsAg the picture is far from complete.

• The prevalence of specific antibodies against HBV (especially anti-HBc), which indicate a history of infection, also varies strongly within and between countries. Several countries, both old and new EU Member States, have sample studies showing relatively low rates of less than 20 %, but at the same time more than 60 % prevalence is found in local samples in some countries. The prevalence of antibodies against HBV appears to vary more than the prevalence of HCV, both within and between countries, which may reflect variability in HBV vaccination coverage.

• Some countries show consistently high figures across HIV, HCV and HBV, both in the total samples and in young and new IDUs, suggesting current transmission of these infections among injecting drug users.

• Trends data for HBsAg are only available from six countries, and these show mixed results.

• Trends in HBV antibody prevalence show varying changes over time, with some minor increases and falls in recent years. There were declines in the last few years in Belgium and Norway, while a relatively stable situation in other countries reporting data (Figure INF-11 part (i) and Figure INF-11 part (ii)).

• Data on the notification of hepatitis are not reliably comparable indicators across countries, due to differences in case definitions and high proportions of asymptomatic cases that are not notified. They may however provide information on the direction of time trends, that might be more comparable. In addition, the proportion of IDUs among all notified cases with known transmission category may give an indication of the relative importance of drug injecting for acquiring these diseases.

• Absolute numbers of IDU related hepatitis C notifications show a variety of trends with no overall consistent patterns discernable. Countries that show increasing trends might need to review the effectiveness of their prevention measures.

• In many countries that provided data, the HCV notifications for 1992 to 2004 suggest that the large majority of new cases of hepatitis C (mostly considering acute cases only) are IDUs. However, in some countries this proportion is relatively low, suggesting that other routes of transmission may have not been effectively prevented.

• Proportions of IDUs among notified cases of hepatitis C vary from less than 50 % in some countries to over 75 % in most others. Where trends in numbers are sufficient to permit a percentage interpretation, they do in the main show some slight decrease (Figure INF-8 part (i), Figure INF-8 part (ii) and Table INF-5 part (i)).

• Hepatitis B notification data 1992 to 2004 for the countries with data available (only acute cases) suggests that the proportion of IDUs has been increasing during the 1990s.

• Absolute numbers of cases of IDU-related hepatitis B show strong variations in trends. Even the countries with past increases tend to show more recently declines in the past three to four years, both in absolute numbers and in percentage terms (Figure INF-12 part (i), Figure INF-12 part (ii) and Table INF-6 part (i)).