The enemy within

New challenge of eradicating bedbugs
Thursday, March 8, 2012
By Dave Hedman

Recent research has found that bedbugs can carry bacteria that have historically proven lethal to humans. This has raised the bar for integrated pest control providers. They now must kill the bedbugs and the potentially deadly microbes they carry.

“After careful laboratory analysis and a two-year field study, we’ve determined that structural pasteurization, coupled with filtration, proves an effective solution to bedbugs and their associated pathogens,” says Sean Abbott, a senior biologist with Natural Link Mold Lab (NLML) in Reno, Nevada.

Convincing evidence of pathogen transfer
Published in 2011, a study by NLML found that bedbugs were able to transfer live Staphylococcus aureus (staph) cells from a culture to a sterile plate, demonstrating their potential as a bacterial vector.

On theorizing how pathogen transfer occurs, Abbott says, “While a bedbug doesn’t inject its saliva into the host as does a mosquito, its mandibles act like a pair of sharp forceps, piercing and tearing the skin, so the potential exists for surface bacteria to enter through the bite. This evidence underscores the urgency for employing effective solutions against the pathogens sooner rather than later.”

Heat as an effective management tool against pathogens
The NLML study examined the efficacy of high temperature pasteurization of buildings for reducing levels of viable bacteria in indoor environments. Results demonstrated this heat process as the most effective modality for killing microbial pathogens carried by bedbugs.

“In one case, we subjected some adult specimens and one nymph to a temperature of 122 F (50 C) for four hours,” explains Abbott. “All the bedbugs were dead following the heat treatment. More importantly, no bacteria were isolated from the heat treated specimens.”

Abbott further explains the mechanism that enables heat to be so effective, especially when compared with traditional chemical means of killing bedbugs.

“We already know that bacteria can develop a resistance to antibiotics, so chemical solutions can’t guarantee eradication of the bedbug and its associated bacteria,” he says. “On the other hand, bacteria can’t mount a resistance to heat. When properly applied, which includes filtration, heat kills both bedbugs and any resident pathogens.”

Abbott adds that heat pasteurization destroys the entire bedbug life cycle. This includes bedbug eggs, which are ordinarily protected from chemicals by their outer shell. The heat actually denatures the proteins within the egg, making the process especially capable of killing eggs. Hence, single applications of structural pasteurization prove effective, obviating the need for repeat visits required of chemical processes.

Structural pasteurization process
Structural pasteurization employs engineer-controlled convective dry heat to sanitize buildings and is typically used in both pest control and restoration applications. It can provide significant hygiene benefits by reducing overall levels of insects and micro-organisms in indoor environments.

In structural pasteurization, super-heated, dehumidified air is produced via clean-burning propane or energy-efficient electric heaters, which is then ducted via Mylar tubing into the rooms or structures requiring de-infestation. Since the thermal death point for organisms such as insects and bacteria is a function of temperature and duration, digital thermometers, thermal imaging cameras and probes become a necessary adjunct to efficacy.

Considerable documentation cites the temperature and time correlations necessary to kill bedbugs and their eggs. Adults, nymphs and eggs die within 15 minutes at temperatures greater than 113 F (45 C) applied over a 60-minute period. Raising room temperatures above that thermal death point and maintaining that temperature for two to three hours helps secure the elimination of a bedbug infestation.

Structural pasteurization goes beyond those levels to kill pathogens. Thermal death for bacteria occurs rapidly at temperatures of 140 F (60 C) or higher for durations as short as 15 minutes but no longer than four hours.

The effectiveness of this process comes from the fact that these high levels of heat get transferred equally to carpets, cracks, crevices, voids and mattresses – where bedbugs typically reside – by the thermodynamics of rapidly moving air. Heated molecules bang against substrate and quickly transfer the heat via convection from the air to the structures.

While highly effective at transferring energy, the resultant turbulent airflow stirs up billions of particles such as dust, cellulose, fungi and allergens that subsequently become airborne. To prevent this particulate matter from being inhaled by technicians, careful monitoring with laser particle monitors should always be a part of structural pasteurization. At the same time, the placement of HEPA filtration devices must occur in parts of the structure to be treated.

Dave Hedman is CEO of ThermaPure and president of E-Therm Inc., one of the licensing companies for ThermaPure.

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