Transmitting HIV through contaminated blood
Did you know that HIV can be transmitted by unsterile or dirty instruments used for circumcision? There are many other ways that HIV is transmitted though contaminated blood.
The HI virus can be transmitted from one person to another when
- A person receives HIV-contaminated blood in a blood transfusion,
- When a person is exposed to needles that are contaminated with HIV-infected blood in the process of injecting drugs,
- When a person (eg a health care worker) is injured with blood-contaminated needles, syringes, razor blades or other sharp instruments
- Unsterile or dirty razors, knives, needles or other instruments are used during cultural practices such as circumcision, scarrification, or blood letting.
How safe is our blood supply in South Africa?
Blood in our country is fortunately very safe. All transfusion services in South Africa test for Hepatitis B, Hepatitis C, syphilis, HIV1-2 Antibodies and p24 Antigen (HIV). The P24 antigen reduces the window period of HIV to 14 to 16 days.
One of the reasons why it is possible to keep the blood supply relatively safe, is because we make use of volunteer blood donations - we do not pay people for blood. It is a huge problem in countries where, for example, injecting drug users sell their blood for drug money.
Although blood is currently far safer than it was in the past, the “window period” (the period after infection but before antibodies are formed) still creates problems for blood transfusion services.
Because infected blood which is donated during the window period does not show up as HIV positive, it slips through the net and is therefore not destroyed. Although the risk of HIV infection via a blood transfusion is very low, there is, unfortunately, no such thing as “no-risk blood”. It is therefore the moral and ethical responsibility of people who engage in high-risk sexual activities and high-risk drug using activities not to donate blood.
Blood transfusions should only be administered to patients when it is necessary to do so to save their lives. Under certain circumstances, it is possible for patients to donate their own blood for storage and later use during and after a scheduled operation.
The danger of sharing contaminated needles
To share needles to injects drugs, or to “shoot up”, is extremely dangerous. The HI virus is highly concentrated in blood, and a drop or two of blood always remain in the hollow needle after injecting blood.
If the next person uses the same needle, infected blood is injected into this person’s bloodstream - an ideal method for passing on the virus. People who inject drugs not only put themselves at risk; they also put their sex partners at risk.
How great is the risk of HIV transmission when one person has been accidentally exposed to the blood of an infected person?
Doctors, nurses and other health care workers who care for HIV-infected patients, are often concerned about the risk of contracting HIV.
All known cases of HIV transmission in health care settings have occurred in the context of accidents.
The average risk of HIV infection following “through the skin” exposure to HIV-infected blood, is 0,3% (or approximately one chance out of 300). The risk of HIV infection after a needlestick injury with an HIV-contaminated hollow-bore needle, is approximately 0,37% (or one chance out of 370).
PEP (or post-exposure prophylaxis) (that is antiretroviral treatment (ART) after possible exposure to HIV through needlesticks, after forced sex or rape, and after condom breakage) lowers the risk of infection significantly.
It is, however, important to start the treatment as soon as possible after the incident - within two hours if possible, but many sources give a time bracket of two to 72 hours after the incident.
The sooner treatment with ART is started, the bigger is the change of eradicating the virus before it establishes itself in the body. Note that the medication (ART) should be taken for 28 days.
For how long can the virus survive outside the body?
We should distinguish between the lifespan of HIV when
- It is outside the body and outside body fluids, and
- When it is outside the body but still present in body fluids like blood.
As soon as the HI virus is no longer in the context of a body fluid, it is extremely fragile or weak - especially when it is exposed to oxygen, heat and dryness in the atmosphere.
While HIV cannot survive outside body fluids for very long, it can probably live outside the body for many hours if it is body fluid like blood, or fluids containing blood.
Body fluid spills should always be handled with extreme care. Wear latex gloves, flood the spillage with a 1:10 solution of household bleach (e.g. Jik) and water, and clean with disposable paper cloths.
Revision date: July 5, 2011
Last revised: by Jorge P. Ribeiro, MD