Blood Borne Viruses - HIV


The definition of a blood-borne disease is one that can be spread by contamination by blood. The most common examples are HIV, hepatitis B and C (HBV/HCV) and viral haemorrhagic fevers.

Acquired Immunodeficiency Syndrome (AIDS) is a blood-borne, sexually-transmitted disease in which the retrovirus (a type of virus that replicates itself in the host cell) known as the human immunodeficiency virus (HIV) invades the body. 

HIV can only replicate inside human cells and attacks the immune system by converting the body’s defender cells (T-helper cells).  The process typically begins when a virus particle interacts with a cell that carries a special protein (called CD4) on its surface.  Protrusions on the surface of the virus particle attach themselves to the CD4 protein and allow part of the particle (the viral envelope) to fuse with the T-helper cell membrane.  The contents of the HIV particle are then released into the cell, leaving the envelope behind.

As HIV infects more cells, the immune system becomes weaker; resulting in the condition we call AIDS.

The damage HIV causes to the immune system allows other infectious agents to invade the body and cause disease.  It may take several years for an HIV infection to develop into AIDS, and although the majority of untreated HIV infections will eventually progress to AIDS, in some instances, this is not the case.


  • HIV is spread through body fluids (excluding saliva), during sexual contact –primarily blood, semen and vaginal fluids. 
  • An HIV-infected woman can pass the virus to her foetus during pregnancy.  The virus may also be transmitted from mother to child during delivery or through breast milk.  Globally, this is the third most common way in which HIV is transmitted however in most cases, the neonate/ baby will avoid infection.
  • HIV is also transmitted by sharing needles, which can involve injecting with a used or discarded syringe previously used by a person who has come into contact with the virus and through contaminated blood/blood products.  

HIV is not transmitted by casual contact, by touching or shaking hands, by eating food prepared by a person infected with HIV, from drinking fountains, telephones, toilets or other surfaces.  It is not transmitted by insects, through air or in water.

The risk of being infected with HIV in non-using and non-intimate settings is very low and is most often associated with the transfer of blood from a person with HIV infection –primarily through needle-stick injuries.  The odds of transferring live virus into the circulatory system in these situations have been calculated as being less than 1%.  Any reaction to such an incident should however, not be dismissed based on these low odds.  The wound should be compressed outwards and the site run under water.

Signs and Symptoms

The initial period following the contraction of HIV is interchangeably called acute HIV, primary HIV or acute retroviral syndrome.  Many individuals develop a ‘flu-like’ illness 2-4 weeks post exposure, while others have no significant symptoms.  Symptoms most commonly include: a high temperature; swollen and tender lymph nodes, a sore throat; a skin rash; headache and sores in the mouth and/ or genitals.  The skin rash occurs in 20-50% of cases.  Some people also develop opportunistic infections at this stage.  Gastrointestinal symptoms such as nausea, vomiting or diarrhoea may occur.  The duration of the symptoms varies but typically last for one to two weeks.

The next stage is called clinical latency and its duration is determined by many variable factors including: the quantity and ‘quality’ of virus a person is exposed to; the strength of the immune system; age and other factors that are not entirely understood.  Some people move to this stage within a couple of years while others may resist it for decades even without treatment. 

The onset of AIDS is often accompanied by lymphatic swelling, profound tiredness, weight-loss, gastrointestinal problems, migraines and muscle pains.  Modern antiretroviral drugs are remarkably effective and with the correct treatment, many people can live far more functionally than was thought possible even 15 years ago when HIV was considered to be a terminal illness –albeit a potentially chronic one.  There is a small number of people infected with HIV who seem to have the ability to retain high levels of CD4+ T cells (T helper cells) without antiretroviral treatment.  Puzzlingly, another group of people with HIV appear to develop a reinforced immune response and maintain a low or undetectable viral load without requiring antiretroviral treatment.

Detection in the body

Most people infected with HIV develop specific antibodies where the immune system responds to the presence of the virus during what is known as the sero-conversion period –occurring within three to twelve weeks of the initial infection.  It is therefore futile to get tested immediately after you feel you may have come into contact with the virus.  If you are concerned about your status, it is vital that you get both pre and post-test counselling which should always be offered as opposed to a simple blood sample procedure.  It is worth considering whether a test offers you peace of mind and a degree of protection for the people you care about and potentially for those you may have had intimate contact with.  Due to the stigma surrounding the condition, many people deny the level of risk they may have put themselves at by minimising the true number of ‘casual’ partners they may have had (particularly in parts of the world where the incidence of BBV’s is much higher than the UK) or ‘forgetting’ rare or one-off experiments with drugs that may have occurred in the past.

The onset of AIDS is measured either in terms of the co-incidence of a drop in CD4+ T cell count to below 200 cells per µL/ blood and characteristic conditions including: pneumocystic pneumonia; rapid weight loss; muscle atrophy; fatigue; weakness; a loss of appetite often necessitating a high protein liquid diet that the person will have difficulty tolerating; oesophageal candidiasis (a ‘thrush’-like condition in the mouth and throat) and respiratory tract infections.  With the body’s immune system profoundly compromised, it may be overwhelmed by opportunistic infections. 

It is potentially a criminal offence to have unprotected sex (or share ‘works’) with someone if you are HIV positive, unless you inform your potential partner(s) of your status.  This is a very tricky area, where a standard test, based on circumstance and setting is imposed.  This test examines whether the person with HIV has acted intentionally, recklessly or if any potential infection was accidental.

Treatment and Prevention

To date, no vaccine is available to prevent AIDS and no antiviral drugs are available to cure it.  Some drugs however, have been found to inhibit the action of the virus, boost the immune system and fight certain types of opportunistic infections.  Research into the development of antiviral drugs and vaccines is ongoing; however there is irrefutable evidence showing that the virus can be controlled and managed in most patients and also that a vaccine may be developed in the not too distant future.  For the time being, treatment includes the use of multiple antiretroviral drugs in an attempt to control HIV infection.  There are several classes of antiretroviral agents that act on different stages of the HIV life-cycle.  The use of multiple drugs that act on different viral targets is known as ‘Highly Active Anti-Retroviral Therapy’ (HAART).  HAART treatment regimens are combinations of different compounds that work together to address the complex action of the virus, strengthen and maintain the functioning of the immune system and prevent the body’s lack of resistance succumbing to opportunistic infections that can frequently lead to death.

Prevention however, is currently the only approach to stopping the spread of the virus.

For IV drug users, this can be done by always using a new syringe for each injection and never sharing any injecting equipment; needles, syringes, spoons, cottons or cups of water.  As a last resort, a rinse through of the needle and syringe in (cold, clean) water followed by a rinse of bleach, then repeated should be sufficient to reduce the risk considerably.  The HIV virus is fragile but, similar to all viruses, it has the ability to adapt in order to survive.  Always prepare on clean surfaces, wash your hands and use alcohol wipes to sterilise the area thoroughly. 

‘Dead-space syringes’ are an advance in prevention and the virus is more vulnerable in certain mediums but is able to survive within certain room temperature ranges. 

Use protection for sexual intercourse.  Many drugs provoke a propensity for reduced sexual inhibition, so always be mindful of this.  Female protection and gels can help reduce risk.  For HIV positive mothers wishing to prevent the spread of virus to their child during birth, antiretroviral drugs have been medically proven to reduce the likelihood of the infection being