Typhoid Mary in Flight

At about the same time that Mary Mallon was unwittingly infecting civilians with typhoid (See Does Your Facility Have a “Mary (or Martin) Mallon,” page 18), it was discovered that the cause of typhoid epidemics among U.S. and British soldiers was Typhoid Musca domestica … or, the common housefly. As cited in the 2006 paper “Winged Sponges” by V.J. Cirillo, “The experiences of the American and British armies finally convinced the medical profession and public health authorities that these insects conveyed typhoid. The housefly was now seen as a health menace. Military and civilian sanitarians waged fly-eradication campaigns that prevented the housefly’s access to breeding places (especially human excrement), and that protected food and drink from contamination.”

As anyone in a food safety or sanitation positions knows, such campaigns are an ongoing challenge today. Additionally, flies now have been found to transmit disease-causing agents for Shigella, Salmonella, E. coli, and Vibrio, through both bodily contact and fluid regurgitation for ingestion.

With summer just around the corner, now is the ideal time for food safety, quality assurance, and sanitation managers to inspect your facility and step up the campaign to prevent fly entry before the spring awakening and summer invasion.
 

Fly Prevention.

In preparing for the onslaught of flies, P+L Systems General Manager of the Americas Steve Jackson said, a food facility can look at a three-zone approach:

1. Perimeter (50 to 500 feet away from the facility)
   • Remove potential breeding sites such as any dead or decaying organic matter.
   • If perimeter rodent management is in place, look for dead rats or mice in snap traps and glueboards or killed by bait consumption, and remove the carcasses.
   • Look for and remove other animal carcasses along the road ways or around the perimeter or fenceline.
   • Clean up any animal waste regularly, such as that from guard dogs.
   • Clean refuse collection containers and sites with applicable bacteria and/or enzymatic cleaner. The ground around these areas should also be sanitized.
   • Secure dumpsters/compactors with lids/covers.
   • Ensure that septic systems, if present, are operational with no leaks, and that there are no broken sewage/waste lines.
     
      
2. Exterior of structure
   • Sanitize the walls and grounds adjacent to the structure with the same bacterial or enzymatic products used to spray or foam the dumpsters.
   • Install electric grid fly lights in areas with overhead cover.
   • Install air doors (blowing downward) or large commercial fans (blowing outward).
   • Repair any broken windows or doors, sealing large openings at the top and bottom, and installing sweeps if needed.
   • Use fly-bait hanging devices around the exteriors of doors and windows and in garbage areas.
   • Apply residual insecticide to door and window frames.
   • Keep loading dock doors closed whenever possible.
     
      
3. Interior
   • Station floor and ceiling fans to move air away from critical food processing areas to deter flies from entering.
   • Install glueboard fly-light devices as needed to handle the size of facility, taking into consideration the layout, competing light sources, obstructions (such as walls, pallet racks, and barriers), and air movement. Place the fly lights in such a manner as to intercept flies from their points of entry to the food areas. If floor fans are used, place fly lights downwind.
   • Use a sponge applicator to place a residual insecticide on door and window frames and around hanging light fixtures.
   • Remove food waste/garbage from breakrooms and locker rooms on regular basis.
   • If facility has a cafeteria, install glueboard fly lights and maintain garbage bins and regular removal.
   • Install decorative fly lights in the office/reception areas.
     
     
      

Facility Management.

Insect-0-Cutor Vice President Jack Harris authored a chapter of Insect Management for Food Storage and Processing detailing additional preventive controls for flying insects, use of insect light traps (ILTs). Following are Harris’ recommendations:

• Exclusion. Exclusion of insects from a facility should be a priority. In addition to the above, strategies can include temperature-controlled vestibules; positive facility air pressure; window and door screening (for both personnel and truck doors); screening of housings for air intake and exhaust fans; caulking of structural gaps at the foundation, roof, door jambs, and walls; and either strip curtains (plastic or chain) or air doors for active doorways.
• Lighting. Interior and exterior lighting can play an important role in flying insect control. Most industrial facilities rely upon mercury vapor and high-discharge lamps, but both of these produce significant amounts of insect­attracting light. Whenever and wherever possible, facilities should consider the use of sodium vapor lighting for exterior purposes and in interior areas where light may be visible from outdoors. These lamps, characteristically known for their orange or golden color rendition, emit low levels of ultraviolet light and thus minimize insect attraction.
  Additionally, for exterior entrance lighting, a facility should consider placing fixtures 10 to 15 feet from the doorway. This placement is near enough to illuminate the area but distant enough to minimize insect attraction and congregation at the entrance. If it is necessary to place lighting directly above an active entrance, the use of lamps with low levels of ultraviolet emissions, such as sodium vapor and metal halide lamps, should be specified. Such fixtures also can be relayed to a timer or a daylight-sensitive photocell to minimize unnecessary use.
  Exterior lighting also may be used to proactively lure flying insects out of a facility. For this type of application, lamps with ultraviolet emissions are placed away from the building. Typically, the lamps are partially shrouded to direct light only toward the facility. The shrouding eliminates insect-attracting ultraviolet emission into the surrounding property.
• Window tinting. For facilities with evening operations, window tinting can reduce the amount of insect-attracting light shown through windows.
• Exterior structure color. Insects also are thought to be responsive to certain colors, primarily white and yellow. This probably is due to the reflective qualities of these colors. If possible, minimize these colors both on exterior structures and in critical interior areas. If the colors are already present, try to minimize the amount of light shown on or reflected from the painted areas.
• Grounds. Minimizing insect-friendly habitats, travel corridors, and attractions surrounding a building can reduce insect ingress and contamination. Generally, all standing water should be eliminated. Grasses and low-lying vegetation should be closely cropped. When possible, dumpsters should be located away from frequently used doorways. If a trash-staging area exists, structural controls such as roll-up doors or a vestibule should be considered to control the access of flying insects from the staging area into more critical areas.
  
   

Interior Fly Control.

For those flies that defeat all your efforts and make their way into your facility, interior trapping can provide a final defense. The old phrase “like a moth to a flame” captures a characteristic that has been known for quite some time; many flying insects are phototropic (i.e., responsive to light).

This simple observation has spawned a multitude of developments over several decades, including the design and development of lighting fixtures for pest control applications, all of which have relied on a two-part process:

1. Lure an insect with light energy.
2. Trap or contain the insect.
    

Initial light-trap designs relied upon standard incandescent light bulbs for insect attraction. If such bulbs were not available, then both gas and candle power were acceptable light substitutes. If no light source was available, then other attractants such as honey or decaying fruit were employed. Electrocutor-type designs for an insect light trap appeared in the 1920s, but it was not until the 1950s that insect light traps regularly incorporated fluorescent lamps as their insect attractant The primary advantage of using a fluorescent lamp instead of an incandescent lamp is the ability to control the type of light, and therefore energy, emitted from the fluorescent lamp.

Many flying insects are known to be phototropic, that is, positively responsive to certain energy or light wave­ lengths, and it became possible to emit those specific insect-attracting wavelengths from fluorescent lamps.

Improvements are still being made on the basic idea of combining fluorescent lighting with an electrified grid for insect trapping. Electrocuting traps are now available for a variety of installations and applications, including wall-mounting, ceiling-hanging, post-mounting, portable, stand-alone, exterior, interior, splash-proof, and scatter­proof. Complementing the standard electrocuting insect light trap is a non-electrocuting fixture. These devices employ an adhesive-coated board for insect trapping. Upon being lured to these glueboard fixtures, the flying insect is trapped on a disposable, adhesive-coated board.

Insect light traps are an important component of any integrated pest management program. When used and maintained judiciously, insect light traps can provide effective, economical control and monitoring of the potential contamination risks associated with flying insects within food processing and storage facilities.

The author is Editor of QA magazine. She can be reached at llupo@gie.net.

Material reprinted, by permission, from Harris, J. E. 2006. Insect light traps. Pages 55-66 in: Insect Management for Food Storage and Processing, 2nd ed. J. W. Heaps, ed. AACC International, St. Paul, Minn. (www.aaccnet.org/insectmanagement)