An increase in recently acquired HIV in PWID has been noted in Dublin since early 2015. We have defined recently acquired HIV infections as those in which the person tests positive using a combined HIV antigen/antibody screening assay, negative or indeterminate on a confirmatory immunoblot assay and is p24 antigen positive, or has had a HIV negative test within the 12 months prior to the positive test or who suffers an acute HIV sero-conversion illness. 

A multidisciplinary incident team has been set up by the Director of Public Health in Dublin to investigate and respond to the increase. The team includes public health and HIV Physicians, GPs providing services for drug users and homeless populations, HSE social inclusion, addiction clinicians, clinical virologist and HPSC. An epidemiological investigation is underway. Clinicians from the drug services are concerned that the increase is linked to injection of a synthetic cathinone PVP, street name Snow Blow, with consequent more frequent injecting, and unsafe sexual and needle sharing practices. This has mainly been seen in chaotic drug users, who report polydrug use, and are often homeless.

Evidence to date indicates that the increase has been occurring since June 2014. Fifteen cases of recently acquired HIV infection (confirmed cases) and one case with epidemiological link to a recently acquired HIV infection (probable case) have been diagnosed in PWID in Dublin from June 2014 to June 2015. Of the 15 cases, seven are p24 antigen positive indicating very recent infection. A further 16 possible cases in PWID are currently under investigation and new cases continue to be detected. Amongst the 16 confirmed and probable cases, 11 are male and five are female, and the mean age is 35 years (range; 24 to 51 years). A case control study is underway to identify any association between use of Snow Blow leading to an increase in unsafe injecting practices, and at-risk sexual behaviour, and acquisition of HIV.

Figure 1: Number of confirmed and probable HIV diagnoses in PWID in Dublin by month of first diagnosis, June 2014 to June 2015 (n=16)

HIV has been a notifiable disease in Ireland since 2011. The rise in cases of recently acquired HIV among PWID comes on the back of an increase nationally in the number of all cases of HIV notified annually, with a 11% increase noted from 2013 (n=341) to 2014 (n=377). In 2014, there were 27 (7%) new diagnoses among PWID, the highest number reported in this risk group since 2009. Between 2010 and 2013, the numbers reported nationally ranged from 16 to 23.

The following immediate control measures are being implemented:

• Provision of antiretroviral therapy to PWID diagnosed with HIV, where possible, and contact tracing to detect any additional cases among sexual or drug sharing partners
• Review of clients attending drug services, to identify those most at risk, and offering urgent HIV testing
• Pilot point of care testing (POCT) of PWID clients attending the Safety Net homelessness services
• Enhanced surveillance to identify new HIV cases as early as possible, including mode of transmission
• Awareness raising among  clients, clinicians, networks of PWID and other stakeholders
• Provision of greater access to needle exchange and other preventive activities within the drugs, homeless hostel services and prisons.  The need for additional measures, including the provision of extended opening hours for needle exchange, is being evaluated 
• Development and distribution of communications material, aimed at raising awareness of the risk of HIV among PWID posed by unsafe injections and unsafe sex. This is available on the HPSC website.
• Active case finding including Recent Infection Testing of possible cases
• Phylogenetic analysis of cases

The current upsurge in notifications of recently acquired HIV infection among PWID is a cause of concern, particularly given the circumstances surrounding recent outbreaks of HIV among PWID internationally, including in Romania in 2011, Greece in 2012 and Israel in 2012-13.[1,2] In this latter outbreak in Tel Aviv, approximately 45 cases were recorded in long-term heroin injectors who had switched to using cathinone derivatives, also known as ‘bath salts’.[1]

The injection of cathinone derivatives is associated with a number of features which mean that this activity is particularly high risk. These products are cheaper than heroin, however they are also shorter acting, and are therefore associated with higher frequency of injection.[3] In addition, in contrast to heroin, cathinones do not need to be heated as part of the mixing process, thereby removing any potential sterilising effect that heating might have had. Furthermore, cathinone injecting tends to be a highly social activity, and the use of these drugs has also been associated with risky sexual practices.[3] 

In Indiana, USA this year, a large outbreak of HIV occurred in a rural population, historically at low risk for HIV[4]. Infection spread rapidly within a large network of persons who injected prescription opioids. In a population of 4200, as of 21^st April, 135 (3%) were infected with HIV. Those interviewed reported an average of nine syringe-sharing partners, sex partners, or other social contacts who might be at risk for HIV infection. The reported daily numbers of injections ranged from four to 15, with the reported number of injection partners ranging from one to six per injection event.

Recency assays and the application of Recent Infection Testing Algorithms are not currently used on a routine basis for all HIV diagnoses in Ireland, although a pilot project to review suitable assays and develop a system to integrate this on a systematic basis with relevant clinical data alongside national epidemiological data is currently underway. If the pilot project is successful, in future this type of information may be of benefit in interpreting increases in HIV such as this one, and in monitoring trends in incident infections over time.

Authors
Ronan Glynn1, Coralie Giese2, 3, Orla Ennis1, Zorina Gibbons4, Kate O’Donnell2, Caroline Hurley1, Mary Ward1, Derval Igoe2, Margaret Fitzgerald1 on behalf of the PWID HIV Control Group

PWID HIV Control Group Members
Department of Public Health Dublin1: Orla Ennis, Margaret Fitzgerald, Caroline Hurley, Ronan Glynn, Mary Ward
National Drug Treatment Services4: Zorina Gibbons, Eamonn Keenan, Shay Keating, Seamus Noone
Addiction Services: Des Crowley, Deirdre Dowdall
Safety Net Homeless Service: Austin O’Carroll
HSE Social Inclusion: Joe Doyle, Joe Barry
National Virus Reference Laboratory: Jeff Connell, Susie Coughlan, Cillian de Gascun
GUIDE St James’s Hospital: Fiona Lyons, Sinead Murphy, Georgina Nagle
Mater Misericordiae University Hospital: Paddy Mallon, Deirdre Morley, Gerard Sheehan
Health Protection Surveillance Centre2: Coralie Giese, Derval Igoe, Kate O’Donnell
European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, (ECDC), Stockholm, Sweden3: Coralie Giese

References

1. Katchman E, Savyon M, Chemtob T, et al. An Outbreak of Primary HIV Infection among Injecting Drug Users in Tel Aviv, Israel Associated with Changes in the Illicit Drug Use Practices, abstract PS11/4. In. 14th European AIDS Conference, Brussels; 2013
2. Joint EMCDDA and ECDC rapid risk assessment HIV in injecting drug users in the EU/EEA, following a reported increase of cases in Greece and Romania. In: European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and the European Centre for Disease Prevention and Control (ECDC); 2012
3. Perspectives on Drugs: Injection of synthetic cathinones. In: European Monitoring Centre for Drugs and Drug Addiction (EMCDDA); 2015
4. Community Outbreak of HIV Infection Linked to Injection Drug Use of Oxymorphone — Indiana, 2015.  MMWR Weekly. May 1, 2015 / 64(16);443-444