Published time: 23 June 2015
Authors: Marie Hagbom, Johan Nordgren, Rolf Nybom, Kjell-Olof Hedlund, Hans Wigzell and Lennart Svensson
Keywords: Airbone-transmission, health care, PCR
There is an urgent need for simple, portable and sensitive devices to collect, eliminate and identify viruses from air, to rapidly detect and prevent outbreaks and spread of infectious diseases1. Each year, infectious diseases cause millions of deaths around the world and many of the most common infectious pathogens are spread by droplets or aerosols caused by cough, sneeze, vomiting etc.2,3,4,5. Knowledge of aerosol transmission mechanisms are limited for most pathogens, although spread by air is an important transmission route for many pathogens including viruses6.
Today no simple validated technology exists which can rapidly and easily collect viruses from air and identify them. The problem is not the analyzing technique, since molecular biological methods such as real-time PCR enable a sensitive detection system of most pathogens7,8,9. The difficulty is to develop an effective sampling method to rapidly collect small airborne particles including viruses from large volumes of air. Furthermore, the sampling method should be robust with easy handling to enable a wide distribution and application in many types of environment. At present, the most commonly used techniques aimed to collect pathogens from air are airflow and liquid models10,11,12,13,14,15. These systems are complex, and their efficiency has not been thoroughly evaluated.
Spread of infectious diseases in hospitals can be most significant16,17,18. In many situations there is a need for a pathogen- and particle-free environment, e.g. in operation wards, environments for immunosuppressed patients as well as for patients with serious allergies. This makes it desirable to have a method not only for collection and identification19, but also for eliminating virus and other pathogens from air20. Ozone gas has been shown to inactivate norovirus and may be used in empty rooms to decontaminate surfaces, however in rooms with patients ozone should not been used due to its toxicity21. Generation of negative ions has previously been shown to reduce transmission of Newcastle disease virus22,23 and several kind of bacteria24,25 in animal experimental set-ups.
The ionizing device used in this study operates at 12 V and generates negative ionizations in an electric field, which collide with and charge the aerosol particles. Those are then captured by a positively charged collector plate. For safety reasons, the collector plate has a very low current, less than 80μA, however the ionizer accelerates a voltage of more than 200,000 eV, which enables high production of several billion electrons per second. Moreover, this device does not produce detectable levels of ozone and can thus be safely used in all environments.
This technique is known to effectively collect and eliminate cat-allergens from air26. Aerosolized rotavirus, calicivirus and influenza virus particles exposed to the ionizing device were attracted to the collector plate and subsequently identified by electron microscopy and reverse transcription quantitative real-time PCR techniques. Most importantly, we demonstrate that this technology can be used to prevent airborne-transmitted influenza virus infections.
Ionizing air affects influenza virus infectivity and prevents airborne-transmission