Popular Disinfectants May Not Kill HPV in Hospitals

Human papilloma virus (HPV) is one of the most common sexually transmitted infections (STIs).  HPV can cause a range of conditions, from genital warts to several forms of cancer.  It is sufficiently serious that in the UK, girls between 12 and 13 are offered vaccinations by the NHS to protect against cervical cancer.  A recent press release from researchers at Penn State University warns that HPV may be more prevalent in hospital environments than previously thought.  While less common, HPV can be transmitted non-sexually, and hence patients could potentially be infected without realising it.  This might seem quite shocking – surely doctors and nurses are aware of this?

What did the Researchers Say?

In their paper in the Journal of Antimicrobial Chemotherapy, the authors note that producing HPV samples in the lab is very difficult, and that an assay for the virus (i.e. a test to determine whether it is present) is a recent innovation.  This is why hospitals have been less able to track the virus than one might naively expect.  As a result, it has been difficult to test whether standard disinfectants, which are extremely effective on cold and flu viruses, are effective on HPV.

Using new techniques to produce large numbers of HPV particles, the authors were able to carry out tests on how different disinfectants reduce the “infectivity” of the virus.

The disinfectants tried were: ethanol, isopropanol, glutaraldehyde (GTA), ortho-Phthalaldehyde (OPA), Phenol, Peracetic Acid with added silver (PAA-Silver), and Hypochlorite.  Ethanol and isopropanol are commonly found in hand sanitising products; GTA is found both in medical and dental environments as both a disinfecting and sterilising agent.

The virus was then mixed with disinfectant, and left to incubate for 45 minutes at room temperature.  This mixture was then added to HaCaT cells, which are derived from a line of skin cells that, thanks to mutation, are immortal.  After 48 hours of incubation, the cells were then tested for the presence of the virus’ RNA.

The researchers found that, out of all the disinfectants tested, only those using PAA-silver and hypochlorite were effective at disinfection, reducing the infectivity of the virus by around 99.99%.  The other disinfectants only reduced the infectivity of the virus by 10% or less.

What does it Mean?

There are quite a few types of virus that are resistant to popular disinfectants.  Generally speaking, these more pernicious viruses are also more susceptible to PAA-Silver and hypochlorite based products, so this result appears to be consistent.  There are many strains of HPV, and the research focused only on one: HPV-16.  This is a sensible choice, as it is responsible for 60% of the cancers HPV strains can cause, but until the other strains are tested, we won’t know for sure whether ethanol/isopropanol products will be ineffective on them as well.

The fact that hand sanitisers are ineffective against HPV-16 is worrying, as one of the few ways that HPV can be transmitted non-sexually is from fingers previously in contact with genitals.  If hospitals are to defend against transmission in this way, then the hand sanitisers in use must reflect the weaknesses of HPV.

Meyers J., Ryndock E., Conway M.J., Meyers C., Robison R. (2014).“Susceptibility of high-risk human papillomavirus type 16 to clinical disinfectants”. Journal of Antimicrobial Chemotherapy, published online, doi: 10.1093/jac/dku006.