Contamination of environmental surfaces by genital human papillomaviruses (HPV): a follow up study

• human papillomavirus
• environmental contamination
• polymerase

In a previous study we investigated the contamination of environmental surfaces with human papillomavirus (HPV) DNA in two genitourinary medicine (GUM) clinics.¹ This study was intended to review the GUM clinic in which HPV DNA was found to be present. Cleaning with “general purpose neutral liquid detergent” (detergent) (Youngs Detergents, Lancare Ltd, UK) and water, or 2% Clearsol (disinfecting detergent, 40% VV Tar Acids; Coventry Chemicals Ltd, Coventry, UK) in 70% methylated spirits (Clearsol) was performed following the results of the previous study.

Twenty samples were collected from two treatment rooms and patients’ toilets at each time of sampling. Samples were tested and typed as described previously.¹ Surfaces sampled, and accumulation of HPV DNA during a single day, are listed in table 1. Sampling was performed at 08.30 on two consecutive days and a third set of samples was collected at 16.30, the end of the clinic hours, on day 2.

Following cleaning with detergent and water at the end of the working day (sampling 1), nine of the 20 surfaces tested were contaminated. It was decided to clean surfaces with a more stringent agent. After subsequent cleaning with Clearsol solution HPV DNA was present on one surface at the beginning of the day, and on four at the end of the day.

β Globin DNA was detected in all HPV DNA positive samples, indicating HPV was cell associated, and in a further five samples taken at the end of the day from HPV DNA negative surfaces.

Compared to our previous study a 50% reduction in surface contamination with HPV DNA was found after cleaning with detergent and the number of types detected was reduced. Only HPV types 6, 11, 16, and 58 were detected on the nine different surfaces. This is also a 73% reduction in the number of types detected in our previous study.¹ HPV types 6, 11, and 16 were still the most common types found (all types in table 1).

Three of the samples positive for β globin DNA but negative for HPV DNA were from the patients’ toilets and or the male clinic examination couch. On the examination lamp switch and the edge of the examination couch in the patients treatment room, DNA was probably from the doctors’ gloves, whereas β globin DNA detected on the surfaces sampled in the patients’ toilets was probably the result of cells shed naturally.

Cleaning with Clearsol was more effective then cleaning with a detergent, which was more effective than no cleaning, but not sufficient.

Early in the 20th century Ignaz Philipp Semmelweis showed that hand washing with soap/water was not as effective as washing with ethanol.² It has also been shown that alcohol based disinfectants have a better efficacy than antiseptic soaps.^3,4 Different antiseptics and decontaminants, whether water or alcohol based, may have different viricidal efficiencies.^5,6 There are few data on environmental decontamination; however, this study suggests cleaning with Clearsol/methylated spirit is reasonably effective at decontaminating environmental surfaces, but contamination will recur unless cleaning is performed regularly.