17. Exposure Control Plan to Prevent Infections with Blood-borne Pathogens

HIV

The risk of contracting HIV from work in the clinical or research laboratory setting is defined by OSHA as a "small, but real risk." As of December 1996, 52 cases of workplace exposure have been documented in the U.S. by the CDC; another 111 cases are considered "probable" but anecdotal since the data available is incomplete. However, all 163 seroconverted are AIDS cases.

Hepatitis B

Approximately 8,000 to 10,000 health care workers seroconver (develop antibodies) to Hepatitis B every year before vaccination is applied. Approximately 10% of those who seroconvert become chronic carriers, able to transmit the virus by sexual or prenatal routes. Ultimately, approximately 200 health care workers a year die of acute or chronic Hepatitis B infection, because of cirrhosis or liver cancer.

A safe effective vaccine against Hepatitis B is provided by the Institute at no cost to the worker.

Hepatitis C

Some evidence exists that Hepatitis C virus presents an occupational risk for health care workers. A few examples of transmission by needle stick have been documented.

Other Blood-borne Pathogens

In addition to the above mentioned pathogens, there are other Hepatitis viruses that are blood-borne. They are Hepatitis D, E, GBV-A, GBV-B, and GBV-C. A few human retroviruses can also be transmitted by blood: HTLV-1, HTLV-II, HIV-2, and HTLV-V. For some of these viruses occupational infections have been documented.

Other pathogens may also be implicated in occupational exposure through skin or mucous membranes to blood. Some documented cases involved syphilis, malaria, borrelia, lepra, Rocky Mountain spotted fever, and some hemoragic fever viruses like Lassa, Marburg, Ebola and Congo-Crimlan.

Another group of pathogens which has a potential for occupational infection includes: Babesia, Brucella, Cytomegalo virus, Trypanosomae, and Parvo virus B-19.

Risks of infection from a single exposure

The rate of seroconversion after a contaminated needle stick is:

< 0.4% HIV positive needle stick
~ 30% HBV positive needle stick
~ 3% HBC positive needle stick

Exposures to blood-borne pathogens in the laboratory may involve:

• Needle stick or cut from a sharp object known to have been in contact with blood or body fluids.
• Exposure of mucous membranes with blood or body fluids.
• Contact of non-intact skin (chapped, abraded, or afflicted with dermatitis) with blood or body fluids.
• Contact of intact skin or mucous membranes with high-titer HIV materials (cell cultures or culture supernatants from laboratories working with HIV).

If a workplace exposure occurs:

• Eye splash: Use the eye wash for 15 minutes, holding the eye open.
• Hands or other exposed skin: Wash with antiseptic or soap.
• Report immediately for antiviral prophylaxis

Prevention - Universal Precautions

Use universal precautions (BL2 work practices) with ALL materials of human origin, without regard to any information about the sample which may be available: the source, serological results, or even information such as heat inactivation. A safe and effective vaccine against Hepatitis B is available and strongly recommended. In addition:

• Prevent needle sticks by NOT recapping needles.
• Prevent mucous membrane exposures by wearing your safety glasses and a mask or a face shield.
• Keep contaminated gloves away from the face.

Spill Clean Up

Clean up blood or body fluid spills according to the following procedure:

• Contain spill promptly by placing absorbent paper towels over the spill.
• Wear utility gloves, discard contaminated towels in biohazard bag, and wash the contaminated area with detergent.
• Flood the area with freshly prepared 0.5% bleach solution for a 10 minute contact time. Clean and rinse the area.

Protection of vacuum system from contamination

• Be sure that collection tubes extend at least 2 inches below the aspirator outlet.
• Try to locate the collection flask in the biosafety cabinet so that the liquid level can be seen easily and the flask emptied before it overflows. The second (overflow) flask may be located outside the cabinet.
• Never use a glass flask at floor level unless it is shielded by a plastic container.
• In BL2 laboratories, plastic suction flasks are preferred.
• Add disinfectant to the flasks so that the final concentration will be effective (i.e. 1/10 flask volume of chlorine bleach. If chlorine bleach is used, replace disinfectant daily).
• A hydrophobic filter should prevent fluid and aerosol contamination of central vacuum systems or aspiration/suction systems. The filter will also prevent hazardous microorganisms from being exhausted by a vacuum pump into the environment.