BACKGROUND
- USDA-ARS Southeast Poultry Research Laboratory, Athens, Georgia (prior to retirement in December, 2005)
- ELECTROSTATIC SPACE CHARGE SYSTEMS, LLC (2006 – present)
Electrostatic Space Charge System for Reducing Airborne Particulates: Pathogens, Dust, Smoke, etc and Electrostatic Sampling Device
REDUCING AIRBORNE PATHOGENS AND DUST:
An electrostatic space charge system (ESCS) was developed in cooperation with The Simco Co. and with BioIon, Inc. under Cooperative Research and Development Agreements, to reduce airborne dust and microorganisms in poultry areas. The object of the system is to transfer a strong negative electrostatic charge to dust and microorganisms in an enclosed space and to collect the charged particles on grounded plates or on specific surfaces of a room. By removing airborne dust, it is reasonable to expect airborne Salmonella and other potential pathogens would be reduced along with endotoxins, or fungi such as Aspergillus, and that ammonia and odors which are absorbed in the dust will also be reduced. The system has been shown to have effectiveness comparable to a 95% media filter for removing dust in laboratory experiments in hatching cabinets and equal or better effectiveness for removing airborne bacteria and Salmonella. Field studies in commercial hatchers have also shown the ESCS to be highly effective with reductions of dust averaging about 78% and reductions of pathogenic bacteria up to 96%. One of the studies involved testing the ESCS in a commercial Jamesway hatching cabinet and comparing it to a control cabinet with hydrogen peroxide disinfection. On the average in experiments ranging over 5 hatches, the ESCS system reduced Salmonella by four fold compared to the control, Enterobacteriaceae by 94% compared to the control, and dust by 77%. Salmonella transmission experiments with chicks exposed to Salmonella during hatching have shown that ESCS treatment of the hatching cabinet reduced cecal contamination at 7 days of age by an average of 3.4 logs. Airborne Salmonella enteritidis (SE) experiments conducted in controlled environment transmission cabinets with and without an ESCS showed chicks in an ESCS treated cabinet exposed to a naturally generated aerosol of SE beginning at one week of age had no cecal contamination 8 days later. Experiments conducted in a 15 x 22 ft (3300 ft^3) isolation room with SE infected caged layers showed reductions of airborne SE of approximately 95% over a test period of 10 days when the room was treated with the ESCS. A broiler-breeder house study showed the system reduced airborne dust, and ammonia by an average of 60%, and it reduced bird to bird transmission of Salmonella enteritidis (SE) as well as SE transmission to progeny. A study in a commercial broiler production house showed the ESCS reduced airborne dust by an average of 55%. Another effect of the space charge -- besides reducing dust and microorganisms which are already airborne, is to keep surface dust near its source. For example, loose dust on the floor of a treated room would tend not to become airborne because as soon as it left the floor it would be charged and re-attracted to the floor. Basic lab experiments indicate that within about 7 inches there is also a strong sterilizing effect of the charge which kills airborne and surface Salmonella. The kill rate on airborne and surface SE within about 7 inches has been shown to be 96% or more. The system has also been shown to reduce biofilms, developed from poultry carcass rinses on stainless steel surfaces, up to 99.8% when used within about 7 inches. Similar reduction efficiencies have been obtained with biofilms made from specific microorganisms including Camplobacter, E. coli, Salmonella enteritidis, Listeria, and Staphylococcus, and bacterial spore reductions up to 85% have been achieved. Biofilm reduction on plastic conveyor belt pieces within about 7 inches was approximately 6.7 logs.
The ESCS system has been patented (U.S. Patent No. 6,126,722), but licensing is no longer required. Applications to date have included installations in poultry hatcheries, commercial layer houses, commercial turkey breeder houses, and commercial swine houses. Recognition of the technology includes an ARS Superior Technology Transfer Award in 1999, a 2001 Federal Laboratory Consortium Award for Excellence in Technology Transfer, and inclusion as an intervention approach (Objective 7.1.4) in the President's Egg Safety Action Plan. The system works equally well for reducing airborne particulates and pathogens in any enclosed area. All of the applications have potential for improving human health as well.
The ESCS has also been tested with good results for its potential to reduce thick fire-generated smoke in stairwells, rooms, and other enclosed areas (see article at http://www.ars.usda.gov/is/pr/2006/060425.htm).
AIR SAMPLING:
A low-cost, simple, portable Electrostatic Sampling Device (ESD) was developed for high efficiency sampling of airborne bacteria, viruses, spores and other particulate. The compact, two pound ESD is battery operated and it is housed in a completely waterproof enclosure such that complete disinfection following use in highly infectious areas can be accomplished easily with a spray disinfectant. The ESD has good potential as an affordable and sensitive detection method for pathogenic strains of microorganisms which may be present in small amounts in animal housing or processing areas, etc. but difficult to recover by traditional methods such as drag swabs or serum samples. Since the ESD utilizes a generic technology, it could easily be applied to any area where high efficiency air sampling is needed.
Previous devices with good to high efficiency recovery were typically large and bulky, difficult to disinfect, or expensive -- ranging in price from $1,000 up to $25,000 each. Duplicated tests with the ESD for sampling of total and pathogenic bacteria at a poultry house exhaust outlet as well as in a caged layer room with birds infected with Salmonella enteritidis have shown up to 20 fold improvements compared to standard settling plates and better performance than a well known and widely used medium volume, laboratory-grade, portable impaction sampler costing approximately 100 times as much. Preliminary ESD tests with naturally generated viruses have shown that samples transferred to an RT-PCR allowed for consistent virus identification. Performance tests suggest the ESD -- if operated for 2 hours or more can provide the equivalent of a High Volume Air Sampler, and it can be operated for about 16 hours with two standard 9-Volt batteries. The ESD size makes it easy to transport and convenient to place in various locations throughout a space. Its low cost and simplicity would make it practical for routine use by hygienists, microbiologists, technicians, etc. The ESD can easily be configured for use with liquid media or metal collectors such that samples can be transferred to RT-PCR for rapid diagnosis of specific organisms (such as pathogenic strains of influenza). The potential market for the ESD should be world wide with applications ranging from routine monitoring of poultry and livestock to epidemiology, to processing areas, hospitals, monitoring of public areas for potential bioterrorism attack, and routine air quality surveys in office areas, schools, etc. Several ESD units have been loaned to various laboratories, research units, and companies for field evaluation. The ESD is patented (U.S. Patent No. 7,046,011 issued May 16, 2006) but licensing is no longer required.
