No abstract

Data collected by the CDC through a collaborative surveillance program for collection and periodic reporting of data concerning the occurrence and causes of foodborne disease outbreaks (FBDOs) are reviewed for the period from January 1988 through December 1992. An FBDO is defined as the occurrence of two or more cases of a similar illness resulting from the ingestion of a common food. Before 1992 only one case of intoxication by chemical or other nonbacterial toxin, marine toxin, or Clostridium botulinum toxin as a result of the ingestion of food was required to constitute an FBDO. Since 1992 two or more cases have been required. State and local public health departments have primary responsibility for identifying and investigating FBDOs. State and territorial health departments report these outbreaks to CDC on a standard form. During the 1988–1992 period a total of 2,423 outbreaks of foodborne disease were reported (451 in 1988, 505 in 1989, 532 in 1990, 528 in 1991, and 407 in 1992). These outbreaks caused a reported 77,373 persons to become ill. Among outbreaks for which the etiology was determined, bacterial pathogens caused the largest percentage of outbreaks (79%) and the largest percentage of cases (90%). Salmonella serotype Enteritidis accounted for the largest number of outbreaks, cases, and deaths; most of these outbreaks were attributed to eating undercooked, infected eggs. Chemical and other nonbacterial agents caused 14% of outbreaks and 2% of cases; parasites, 2% of outbreaks and 1% of cases; and viruses, 4% of outbreaks and 6% of cases. The number of FBDOs reported per year did not change substantially during the first four years but declined in 1992 as a result of the revised definition of an outbreak. During this reporting period S. Enteritidis continued to be a major cause of morbidity and mortality. In addition, multistate outbreaks caused by contaminated produce and outbreaks caused by Escherichia coli O157:H7 became more prominent.

Almeno tre bastoncini sporigeni Gram-positivi sono noti come causa di intossicazione alimentare: Clostridium perfringens (welchii), C. botulinum e Bacillus cereus. L'incidenza delle intossicazioni alimentari causate da ognuno di questi microrganismi è associata al consumo di specifici alimenti, come avviene per le intossicazioni alimentari in genere. Intossicazione alimentare da Clostridium perfringensL'agente eziologico di questa sindrome è un bastoncino Gram-positivo, anaerobio e sporigeno, ampiamente diffuso in natura. Se ne riconoscono tre tipologie, sulla base della capacità di produrre particolari enterotossine: A, B, C, D ed E. I ceppi responsabili di intossicazione alimentare appartengono al tipo A, come pure i classici ceppi che causano gangrena gassosa ma, a differenza di questi ultimi, sono generalmente termoresistenti e producono solo tracce di alfa tossina. Alcuni ceppi di tipo C producono enterotossina e possono causare una sindrome da intossicazione alimentare. I ceppi classici che causano intossicazione alimentare si distinguono da quelli di tipo C in quanto non producono beta tossina. Questi ultimi, che sono stati isolati da tessuto intestinale necrotico (enterite necrotizzante), sono confrontati nella tabella 24.1 con i ceppi termolabili e termostabili di tipo A. I ceppi termoresistenti di tipo A producono theta tossina, la perfringolisina O (PLO), un'emolisina attivata da tioli, simile alla listeriolisina O (LLO) prodotta da Listeria monocytogenes (discussa nel capitolo 25). Analogamente a LLO, anche PLO ha un peso molecolare di 60 kDa ed è stata sequenziata e clonata.Sebbene C. perfringens sia stato associato alla gastroenterite sin dal 1895, la prima chiara dimostrazione del suo ruolo eziologico nelle intossicazioni alimentari si deve a

The objective was to evaluate foodborne outbreaks of undetermined aetiology by comparing them to pathogen-specific epidemiologic profiles of laboratory-confirmed foodborne outbreaks. National foodborne outbreak data reported to CDC during 1982-9 were categorized by clinico-epidemiologic profiles based on incubation, duration, percent vomiting, fever and vomiting to fever ratio. From the pathogen-specific profiles, five syndromes were developed: a vomiting-toxin syndrome resembling Bacillus cereus and Staphylococcus aureus; a diarrhoea-toxin syndrome characteristic of Clostridium perfringens, a diarrhaeogenic Escherichia coli syndrome, a Norwalk-like virus syndrome, and a salmonella like syndrome. Of 712 outbreaks, 624 (87.6%) matched one of five syndromes; 340 (47.8%) matched the Norwalk-like syndrome and 83 (11.7%) matched the salmonella-like syndrome. After combining information on known pathogens and epidemiologic profiles, only 88 (12.4%) outbreaks remained unclassified. Norwalk-like virus outbreaks appear as common as salmonella-like outbreaks. We conclude that profiling can help classify outbreaks, guide investigations and direct laboratory testing to help detect new and emerging pathogens.