This article, the sixth in a series reviewing the role of food workers in foodborne outbreaks, describes the source and means of pathogen transfer. The transmission and survival of enteric pathogens in the food processing and preparation environment through human and raw food sources is reviewed, with the main objective of providing information critical to the reduction of illness due to foodborne outbreaks. Pathogens in the food preparation area can originate from infected food workers, raw foods, or other environmental sources. These pathogens can then spread within food preparation or processing facilities through sometimes complex pathways and may infect one or more workers or the consumer of foods processed or prepared by these infected workers. The most frequent means of worker contamination is the fecal-oral route, and study results have indicated that toilet paper may not stop transmission of pathogens to hands. However, contact with raw foods of animal origin, worker aerosols (from sneezes), vomitus, and exposed hand lesions also have been associated with outbreaks. Transfer of pathogens has been documented through contaminated fabrics and carpets, rings, currency, skin surfaces, dust, and aerosols and though person-to-person transmission. Results of experiments on pathogen survival have indicated that transmission depends on the species, the inoculum delivery route, the contact surface type, the duration and temperature of exposure, and the relative humidity. Generally, viruses and encysted parasites are more resistant than enteric bacteria to adverse environmental conditions, but all pathogens can survive long enough for transfer from a contaminated worker to food, food contact surfaces, or fellow workers.
A lack of understanding in many food service settings concerning the transmission and growth of pathogens (80, 195, 199) can lead to potential foodborne outbreak situations. Similar issues are associated with food prepared in households and served at home or used in home-catering situations, but problems in these settings are much less likely to be reported (80). Such lack of understanding or ignoring the risks of contamination is illustrated by a hepatitis A virus (HAV) outbreak involving an ice-slush beverage contaminated by an infected employee in a convenience market (30). The utensils for the beverage machine used by the infected worker were kept beside the toilet bowl. This gross error in hygiene should have been identified by the management, and appropriate information should have been relayed to employees. Outbreaks also have been caused by workers changing diapers on infants with diarrhea before going to work. Sick children at home are a risk factor for foodborne illness, and effective hand washing practices must be taught and adhered to (113). Even healthy family members may transmit pathogens. For instance, a higher carriage rate for ß-hemolytic streptococci occurs in children, up to 47% in normal school populations (95). In numerous reports from countries where sanitary facilities are lacking, food has become contaminated by unwashed hands and exposure to temperature abuse. Contamination can be transferred to and from workers through raw food, hands (including dirty fingernails, rings, and other jewelry), clothing, aerosols, fomites, food soil, food packages, and other environmental sources and pathogens can survive for extended periods of time on many surfaces, including skin.
TRANSFER OF CONTAMINATION ASSOCIATED WITH FOOD WORKERS
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Dr. Ewen Todd is a Food Safety Expert with over 45 years of knowledge and experience in general food safety and Food Microbiology Issues. Specifically, he has extensive experience the reporting and surveillance of Foodborne Disease, as well as development of analytical methods for identifying foodborne pathogens. As a result of his work with the industry and his knowledge of foodborne disease, Dr. Todd has influenced research programs and regulatory approaches taken by the Health Protection Branch of Health Canada. In the US, he held the position of Director of the National Food Safety and Toxicology Center and the Food Safety Policy Center at Michigan State University.
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