Drug related infectious diseases

Irena Klavs, Tanja Kustec, Lina Berlot, Andrej Kastelic, Zdenka Kastelic, Sandra Kosmač, Edita Eberl-Gregorič

1.3.1 Main drug-related infectious diseases among drug users – HIV, HBV, HCV

Drug-related infections among persons who inject drugs (PWIDs) that are transmitted through exposure to infected blood, mostly while sharing injecting equipment, include HIV, hepatitis C virus (HCV) and hepatitis B virus (HBV) infections. HIV, HBV and to a much lesser extent HCV infections are also transmitted through sexual intercourse. Thus, these infections can be spread through unprotected sexual intercourse to the partners of PWIDs. All three infections can also be transmitted from infected mother to the new-born child before, during or after the birth. HBV infection can be prevented by vaccination. Since there is no vaccine against infections with HIV and HCV, the prevention is based on prevention of risky behaviour, promoting behavioural changes, harm reduction programs, early diagnosis and treatment of those infected.

HIV, HBV and HCV infections surveillance is coordinated by NIJZ. It is based on regular collecting, analysing and interpretation of data about diagnosed cases. All three infections diagnoses must be reported according to the Contagious Diseases Act and Healthcare Databases Act. To ensure comparability of data European surveillance case definitions are used. The data about notified diagnosed cases usually underestimate the true incidence of these infections. With the exception of diagnosis of HIV, information on the transmission route (e.g. PWIDs) is only available for a minority of reported HBV and HCV infection cases. Therefore, we can not reliably estimate the proportion of notified cases of new diagnoses which is related to injecting drug use.

This surveillance information is complemented by monitoring the prevalence of HIV, HBV and HCV infections in convenience samples of clients of Centres for the Prevention and Treatment of Illicit Drug Addiction who are entering for the first time or re-entering treatment during different calendar years by collecting available information about voluntary confidential tests results in the past. Centres for the Prevention and Treatment of Illicit Drug Addiction report data to NIJZ within annual monitoring of Treatment Demand Indicator. When interpreting this data, the limitations of methodology must be taken into consideration. Estimated percentages do not represent estimates of the prevalence of infections among those entering for the first time or re-entering treatment, but rather the proportion among those for whom the results of any previous tests at the time of entering or re-entering the treatment were documented in the medical records.

During the past five years (2016 - 2020) the Centres for the Prevention and Treatment of Illicit Drug Addiction reported data for 655 PWIDs who entered for the first time or re-entered treatment - 187 in the year 2016 (11 for the first time), 157 in 2017 (24 for the first time), 125 in 2018 (five for the first time), 110 in 2019 (seven for the first time) and 76 in the year 2020 (seven for the first time). Proportion of PWIDs with any result of tests for HIV, HBV or HCV infections reported to NIJZ ranged from the highest of 44% in the year 2016 to the lowest of 22% in 2020.

Since 1995, the prevalence of HIV is monitored also in other convenience samples of PWIDs. During the period from 2016 to 2020, the convenience samples of PWIDs were among clients of five nongovernmental harm reduction programmes - in Ljubljana (2016 - 2019), Koper (2016 - 2020), Maribor (2016 - 2020), Celje (2018 - 2020) and Nova Gorica (2018 - 2019). Saliva specimens for unlinked anonymous HIV testing were voluntarily provided by clients of the aforementioned needle-exchange programmes visiting for the first time during the period of sampling, which was one month each year during most recent years.

HIV Infection

For the period from 2016 to 2020, the NIJZ received the data for a total of 224 PWIDs entering for the first time or re-entering treatment within the national network of Centres for Prevention and Treatment of Illicit Drug Use in different years and for whom the results of previous voluntary confidential testing for HIV infection were available in the medical documentation (in the year 2016 for 79 PWIDs, in 2017 for 62, in 2018 for 29, in 2019 for 39 and in the year 2020 for 15 PWIDs).

To ascertain the number of PWIDs with diagnosed HIV infection we took into account results of screening and/or confirmation tests for HIV antibodies (anti-HIV) available in the medical documentation – screening tests of third and fourth generation and confirmation tests Western blot and Immunoblot.

During this period, the number of PWIDs with diagnosed HIV infection before treatment demand ranged from none among PWIDs who entered or re-entered the program in years 2017, 2018, 2019 and 2020 to one among PWIDs who entered or re-entered the program in 2016. Respective HIV prevalence estimates ranged from the lowest 0% in 2017, 2018, 2019 and 2020 to the highest 1% in 2016. When interpreting these results, it is important to take into consideration that these estimates for respective years were based on the results of tests conducted before entering for the first time or re-entering treatment.

More reliable estimates of the proportions of currently HIV infected PWIDs can be derived from data from unlinked anonymous HIV testing of small convenience samples of PWIDs at first treatment demand during different calendar years, which has been conducted for HIV surveillance purposes in five harm reduction programmes run by NGOs in Ljubljana, Koper, Maribor, Celje and Nova Gorica. Among 610 tested PWIDs during the period from 2016 to 2020 none were HIV positive (Table 8).

Table 8.Proportion of HIV infected PWIDs among clients of five harm reduction programmes, 2016–2020 Year Number of

Source: Unlinked anonymous testing for HIV for surveillance purposes, 2016–2020

During the period from 2016 to 2020, the reported HIV infection incidence rate in the Slovenian population ranged from the highest 3.0/100,000 population in 2016 to the lowest 1.3/100,000 population in 2020. During the last five years (2016 - 2020), four cases of a new HIV diagnosis in individuals with a history of injecting drug use were reported to the NIJZ, one in 2016 and 2020 and two in 2019. At least two of these individuals had a history of injecting drug use abroad. Since 1986, when the national HIV surveillance, based on mandatory notification of all diagnosed HIV infection cases was initiated, a cumulative total of 25 new HIV diagnoses were reported among PWIDs. Majority of these individuals had a history of injecting illegal drugs abroad. It has to be noted that not all HIV infections are diagnosed.

According to all available surveillance information, extensive spread of HIV infection has not started yet among PWIDs in Slovenia.