People who inject drugs (PWID) and Risk of Infectious Disease

Injecting Drug User 

Injecting drug use is widespread in developed countries. In 2014, it was estimated that there were between 18,720 and 21,454 problem opiate users in Ireland, with just over 70% of these living in Dublin.

People who inject drugs (PWID) are at special risk of developing a range of infectious diseases because of the dangers posed by contaminated injection needles, syringes and drugs. In addition, PWID engage in risk-taking behaviour and tend not to look after their health, leaving them at risk of contracting diseases such as sexually transmitted infections and tuberculosis. Some PWID may have severely suppressed immune systems and be at risk of disease produced by microorganisms that do not normally cause disease in humans.

The following are infections associated with PWID:

  • Injection site infections: caused by bacteria such as staphylococci and streptococci. One of the most serious types of injection site infection is wound botulism, caused by Clostridium botulinum.
  • Bacterial bloodstream infections: caused by bacteria such as staphylococci and streptococci (but also rarer pathogens such as Pseudomonas and Serratia) and leading to conditions such as:
    • Endocarditis: complicated by the damaging effects of talc and other contaminants,
    • Pulmonary infections (including lung abscess and septic pulmonary emboli),
    • Bone and joint infections.
  • Viral Hepatitis: PWID are at increased risk of being infected with Hepatitis C and Hepatitis B, which can lead to chronic hepatitis and liver failure. However, new highly-effective hepatitis C treatments, using direct acting antiviral drugs, are now available in Ireland and should have a significant impact on hepatitis C-related morbidity and mortality. PWID are also at increased risk of contracting Hepatitis A and vaccination against hepatitis A is recommended.
  • HIV: Sharing of needles and other injecting paraphernalia is a major risk factor for HIV infection
  • Tuberculosis: Tuberculosis tends to be endemic in PWID particularly those with weakened immune systems and especially in those infected with HIV.
  • Pneumocystis carinii pneumonia: this is much more common in PWID especially those living with HIV.
  • Toxoplasmosis: Toxoplasmosis is more common in severely immunosuppressed PWID.
  • Human T-Cell Leukaemia/Lymphoma: caused by HTLV-2 is more frequently reported in PWID that in the general population.
  • Anthrax: PWID may become infected with anthrax when heroin is contaminated with anthrax spores.
  • Opportunistic viral infections: these include infections cases by Herpes simplex virus, Varicella-Zoster virus, cytomegalovirus and Epstein-Barr virus in PWID who have severe immunosuppression.

Last updated: 20 September 2018