Hepatitis B Virus (HBV)

What is it? Why the concern?

What can be done about it?

A medical technologist collects blood from an incoherent E.R. patient for a STAT controlled substance screen. While transferring three filled, blood collection tubes to a plastic bag, a single tube tumbles end-over-end until it lands squarely on a white tile floor. The resulting mess seems too large for such a small tube of blood. The experienced technologist knows well the potential dangers that could be present in the glass shard/blood mixture. One that comes to mind immediately is HBV.

If an individual is infected with HBV, the relative highest number of infectious virions are present in the blood, they may also be present in saliva and semen. Blood and blood products are recognized as the main vehicles for Hepatitis B virus transmission. In the Northern Hemisphere, transmission occurs primarily in situations where blood leaves a body and is transferred to another directly. Direct transfer commonly occurs from needle-sticks, sharp instrument cuts, and exposure of mucosal surfaces to infective fluids via splashes, direct human contact or contaminated environmental surface contact. It does not take a large direct exposure to become infected. It has been shown that blood of an infected individual diluted 1 to 100,000,000 still contains enough virus to cause infection, if direct contact occurs. HBV can even remain viable in dried blood for a short period of time.

Areas in the healthcare setting found to be associated with an increased risk of HBV transmission include:· Clinical laboratories (chemistry, hematology, blood bank, microbiology)· Pathology departments· Emergency units· Hemodialysis units· Surgeries· Psychiatric clinics (believe it or not)Workers in these areas routinely work with blood, either directly, on floors or on other environmental surfaces. For safety, workers can be immunized against HBV. There must also be procedures and products available to disinfect HBV (and HIV), a requirement of the U.S. Occupational Safety and Health Administration (OSHA). OSHA indicated that tuberculocidal disinfectants or household bleach were needed for this purpose, since specific claims against HBV did not exist.

Disinfectant product claims against HBV were absent for a long time because of a preference by the EPA for a suitable infectivity-based efficacy test.An infectivity test measures disinfectant efficacy by exposing living cells (the host) to microorganisms treated by a product. If the cells become infected, the product was ineffective. Conversely, if the cells remain uninfected, the product worked. Scientifically sound infectivity tests for human HBV require the use of protected species (humans or chimpanzees) - obviously unsuitable to the EPA! A new method which measures destruction of HBV by means of a Morphologic Alteration and Disintegration Test (MADT) correlates with infectivity method results and has been accepted by the EPA. The MADT uses electron microscopy to study the structural integrity of HBV following contact with a disinfectant.Acceptance of the MADT by the EPA has allowed manufacturers to provide customers with HBV effective disinfectants: Products that have broad range antimicrobial activity including activity against HIV.

Cleaning up a blood spill still requires caution, fortunately it can now be done with the convenience and safety of quaternary disinfectants.