Foodborne outbreak of gastroenteritis possibily of multiple bacterial etiology

Routes of Transmission in the Food Chain

More than 250 different foodborne diseases have been described to date, annually affecting about one-third of the world's population. The incidence of foodborne diseases has been underreported and underestimated, and the asymptomatic presentation of some of the illnesses, worldwide heterogeneities in reporting, and the alternative transmission routes of certain pathogens are among the factors that contribute to this. Globalization, centralization of the food supply, transportation of food products progressively farther from their places of origin, and the multitude of steps where contamination may occur have made it increasingly challenging to investigate foodborne and waterborne outbreaks. Certain foodborne pathogens may be transmitted directly from animals to humans, while others are transmitted through vectors, such as insects, or through food handlers, contaminated food products or food-processing surfaces, or transfer from sponges, cloths, or utensils. Additionally, the airborne route may contribute to the transmission of certain foodborne pathogens. Complicating epidemiological investigations, multiple transmission routes have been described for some foodborne pathogens. Two types of transmission barriers, primary and secondary, have been described for foodborne pathogens, each of them providing opportunities for preventing and controlling outbreaks. Primary barriers, the most effective sites of prophylactic intervention, prevent pathogen entry into the environment, while secondary barriers prevent the multiplication and dissemination of pathogens that have already entered the environment. Understanding pathogen dynamics, monitoring transmission, and implementing preventive measures are complicated by the phenomenon of superspreading, which refers to the concept that, at the level of populations, a minority of hosts is responsible for the majority of transmission events.

Food safety: review and implications for dietitians and dietetic technicians

Section 103 (d) of the Americans with Disabilities Act directs the secretary of health and human services to identify, publish, and annually review a list of pathogens transmitted via food contaminated by infected food handlers. The secretary is also directed to publish means by which diseases on the list are transmitted. The intent of the list is to protect disabled food handlers when they become ill and to provide managers with information for determining when to remove or reassign disabled food handlers who have infectious or communicable diseases to jobs that do not involve handling food. Pathogens often transmitted via food contaminated by infected food handlers are Salmonella typhi, Shigella species, Staphylococcus aureus, Streptococcus pyogenes, hepatitis A virus, and the Norwalk and Norwalk-like viruses. This article discusses section 103 (d) and for each of the six pathogens describes characteristics and growth requirements, types of foods involved in outbreaks, factors that contribute to foodborne outbreaks, and prevention and control measures. Human beings are the only reservoir of Sal typhi. The source of Shigella species is the intestinal tract of human beings and other primates. Human beings are the common reservoir of Staph aureus and Strep pyogenes. Staph aureus is frequently found in the nose and on the skin of healthy people, whereas Strep pyogenes is carried in the throat of infected or asymptomatic carriers. Foodborne viruses of public health concern originate in the human intestine. Foods that favor the multiplication of Sal typhi are often foods that require no cooking. Many outbreaks of foodborne disease attributed to Shigella species and viruses have been associated with salads. Moist, high-protein, and salty foods that have been cooked are most often involved in outbreaks of staphylococcal foodborne illness. Foods usually implicated in Strep pyogenes outbreaks are predominately composed of milk, eggs, or meat. Dietitians and dietetic technicians can use three approaches to reduce the incidence of foodborne disease attributed to food handlers: conducting training and education programs, implementing a Hazard Analysis and Critical Control Points system, and supporting certification of foodservice managers.

The relationship between infecting dose and severity of disease in reported outbreaks of Salmonella infections

The relationship between size of the infecting dose and severity of the resulting disease has been investigated for salmonella infections by reanalysis of data within epidemics for 32 outbreaks, and comparing data between outbreaks for 68 typhoid epidemics and 49 food-poisoning outbreaks due to salmonellas. Attack rate, incubation period, amount of infected food consumed and type of vehicle are used as proxy measures of infecting dose, while case fatality rates for typhoid and case hospitalization rates for food poisoning salmonellas were used to assess severity. Limitations of the data are discussed. Both unweighted and logit analysis models are used. There is no evidence for a dose-severity relationship for Salmonella typhi, but evidence of a correlation between dose and severity is available from within-epidemic or between-epidemic analysis, or both, for Salmonella typhimurium, S. enteritidis, S. infantis, S. newport, and S. thompson. The presence of such a relationship affects the way in which control interventions should be assessed.

Traveler's diarrhea at sea: two multi-pathogen outbreaks caused by food eaten on shore visits

In 1976 and 1981, two outbreaks of gastrointestinal illness aboard cruise ships occurred within 24 hours following onshore visits to Haiti and Mexico, respectively. Three hundred eighty-six of 600 (64 per cent) and 98 of 260 (38 per cent) passengers became ill following luncheons in Port-au-Prince, Haiti, and Cozumel, Mexico. No increase in illness was observed among those passengers who did not attend the onshore luncheons. In both outbreaks, unrefrigerated seafood dishes served at outdoor buffets were epidemiologically incriminated as the vehicles of transmission. Several species of Vibrion, Salmonella, and toxigenic Escherichia coli were recovered from stool specimens of ill passengers in both outbreaks. In addition, invasive Escherichia coli and Shigella were isolated from stool specimens of ill passengers who ate at the Haitian buffet. Previous investigations of outbreaks of gastrointestinal illness aboard cruise ships have implicated exposures on board as the source and have involved only a single pathogen.