Stopping Typhoid Mary

Mary Mallon was a cook in the early 1900s who never showed signs of illness, but through her contact with food, she is said to have directly infected more than 50 people — three of whom died. Perhaps you would better recognize Ms. Mallon by her nickname … Typhoid Mary. Typhoid Mary, who has been called the most dangerous woman in America, was the first identified asymptomatic carrier of Salmonella typhi — the typhoid fever pathogen.

Does your facility have a Typhoid Mary (or Martin)?
 

Infected food workers

According to Ewen C.D. Todd, a co-author of Food Safety Management: A Practical Guide for the Food Industry, a review of foodborne disease outbreaks worldwide shows that food workers have been responsible for many of these outbreaks. Additionally, the most frequently reported factor associated with the involvement of an infected worker was bare hand contact with the food, followed by failure to properly wash hands.

Additionally, many of the workers were, like Typhoid Mary, asymptomatic shedders or had infected family members, and/or used improper hygienic practices.

How are these bacteria transmitted? How and why can proper handwashing greatly reduce the potential for such contamination?

Todd explains in Personal Hygiene and Health, Chapter 28*:
 

Sources of pathogens. The human body has several means of transmitting infections from body orifices, primarily fecal, nasal and skin sources, because these are exposed to the external contaminated environment through air, water, food and contact with other humans and animals.

Pathogens of nose, throat, skin or fecal origin are most likely to be transmitted by the hands (particularly fingertips and palms), as hands are the parts of the body that frequently touch the mouth, skin and anal areas.

The pathogens most likely to be transmitted by food workers are norovirus, hepatitis A, Salmonella, Shigella, and Staphylococccus aureus. These pathogens can be in high numbers in or on the body during an infection, with incubation periods lasting as long as several weeks for some. Not only do longer periods mean more opportunity that the infected person will excrete the pathogen and potentially contaminate foods, family or fellow workers who are contacted can be infected to excrete the pathogen as well.

Although visible feces are not normally present on fingers or hands following normal defecation, it has been shown that fecal contamination does occur. Fecal contamination on the hands is linked to the limited effectiveness of toilet paper use, with studies showing the fecal mass on fingers after defecation can exceed one milligram, meaning that there could be up to 10,000 fecal coliforms on the hands when initially contaminated, and pathogens could be even higher on the hands of those who are sick or convalescing. For all these reasons, personal hygiene is critical in reducing the opportunities for pathogen transmission, with efficient, effective handwashing as a key factor.
 

Handwashing efficiency. Handwashing removes dead skin cells, sweat, sebaceous secretions, associated resident bacteria, transient microorganisms and any organic material adhering to the hands. Transients are most important in food plants as they include the pathogenic bacteria, viruses, and parasites obtained through human, environmental, or unprocessed food or ingredient contact with food-contact surfaces. For effective handwashing:

1. The first step is removal of visible dirt and contamination from proteinaceous material, blood, body fluids or foods, like meat protein. Most surface microorganisms are easily flushed off with washing, but some remain in cracks, crevices, skin folds, and nail regions.

2. Thorough rinsing is important because it removes potential skin irritants and contact sensitizers originating in food, soaps, metals and facility disinfectants that could lead to dermatitis.

3. Friction is known as one of the most important elements in handwashing, as it dislodges microflora from skin surfaces during both washing and rinsing.

4. Drying is an important component because moist hands transfer microorganisms more readily than dry hands. Effective hand drying includes enough time to remove moisture through absorption and microorganisms on surface skin layers through friction with single-use towels or electric air dryers.

Handwashing efficiency is affected by two aspects of handwashing: how well hands are washed (soaps, friction, duration) and how frequently hands are washed. The 2009 Food Code states that hands and arms must be washed for at least 20 seconds, with 10 to 15 seconds of vigorous scrubbing.

Although common sense would suggest that hands should be washed in as hot of water as can be comfortably tolerated, studies have shown that water temperature has no bearing on the outcome when soap is used. To encourage effective duration and frequency, however, it is recommended that water temperatures be maintained at a comfortable temperature.

Best practice tips. The front line of defense against hygienic contamination begins with proper handwashing and ensuring that all workers know and understand all guidelines, said Best Sanitizers National Account Manager April Zeman. “It may sound like a very simple program to implement, but it can be riddled with many challenges,” she said. Following are tips from Zeman on handwashing and communication:

• Complete coverage. The actual process of washing hands is frequently done incorrectly. Fingernails, cuticles, creases, and crevices of the fingers and hands are all areas where pathogens hide. These problem areas require special attention when washing.
   
• Step by step. Wash your hands correctly for at least 20 seconds:
  • Thoroughly wet hands.
  • Take an adequate amount of soap, then rub palms and back of hands, rub thumbs and interlace fingers.
  • Rub fingertips into palm of opposite hand, then rub the wrists.
  • Rinse well with running water.
  • Dry hands thoroughly with a paper towel.
     
• Choosing a hand soap. There are many choices when it comes to hand soaps. Those containing dyes and fragrances should be avoided in food processing plants. E2 rated soaps combine washing and sanitizing in one application. The active ingredient in E2 soaps will determine the level of efficacy you actually achieve and should be evaluated carefully.
   
• Hand sanitizer. Facilities seeking the greatest log reduction of harmful pathogens on hands will follow handwashing with an appropriate E3-rated hand sanitizer which can provide log reduction up to 99.9999 percent. In food processing sanitation, log reduction is a term used to identify the effectiveness of a sanitizer. The higher the log number, the better that product is at reducing pathogen colony forming units (CFUs). For example, a product with a kill claim of 99.99 percent is log 4, while a product with a kill claim of 99.9999 percent is log 6. Log 6 is 100 times better at reducing CFUs than log 4, so if you start with a contaminated area containing 1,000,000 CFUs, the log 6 product will reduce the CFUs down to 1 (one colony forming unit), whereas the product with log 4 will only reduce that initial 1,000,000 CFUs down to 100. In other words, there are 100 CFUs still remaining that can multiply every 20 minutes until you have a real problem. To better protect your plant from cross-contamination, choose hand sanitizers with the highest log number available.
   
• Communication and training. To help ensure that workers follow handwashing guidelines:
  • Conduct training programs on proper handwashing and sanitizing and document all training.
  • Post appropriate multilingual signage on proper techniques at each wash/sanitizing station. Promote a culture of cleanliness by rewarding employees who understand, practice, and teach others about hand hygiene.
  • Monitor hand health of production employees by checking for skin issues. If identified, review existing practices and products for possible modification. Any changes made should be done in a methodical, systematic process to effectively monitor results, positive or negative.
  • Periodically swab test hands and document results to verify the effectiveness of current programs.
  • Employee hygiene and food safety go hand in hand. Investing in employee hygiene programs and training should always be considered an investment instead of an expense.
     
• A second line of defense. There are multiple ways that pathogens and bacteria can get into the food processing environment, including poor employee hygiene and illness, said Pure Bioscience CEO Hank Lambert. A secondary defense against such contamination is the use of an antimicrobial disinfectant on surfaces. When the sanitation team sprays or wipes down surfaces with silver dihydrogen citrate disinfectant, the antimicrobial properties stay active for up to 24 hours, killing bacteria that may remain on an employee's hands that touch that surface, Lambert explained.
   

Employee hygiene is a critical aspect of food safety. Correct thorough, and regular handwashing can go a long way toward preventing contamination by a unsuspected — and unsuspecting — Typhoid Mary or Martin in your plant.

Lisa Lupo is the editor of QA magazine. She can be reached at llupo@gie.net.

*Excerpted from Food Safety Management: A Practical Guide for the Food Industry, Chapter 28: Personal Hygiene and Health by Ewen C.D. Todd, Elsevier Inc., 2014.