Fundamental Food Microbiology, Third Edition - Fuad Fathir

IMPORTANT FACTS IN FOODBORNE DISEASES 339
The rates from serovar Typhimurium were constant between 1996 and 1999 (ca.
3.7%), but rates for serovar Enteritidis declined. The incidence of Lis. monocytogenes,
Vibrio spp., and Yer. enterocolitica remained unchanged during the 4-year period.
During the last 3 years, the incidence of Cyclospora declined, but that of Cryptosporadium
remained almost unchanged. 6
C. Estimated Foodborne Illnesses
For a long time, opinions differed on the actual number of foodborne illness cases
vs. the number of cases reported annually in the U.S. The average number of ca.
20,000 cases reported annually was thought to be too low. A realistic figure was
estimated to be anywhere from 5 to 25 million, and some thought it to be as high
as 80 million.
Recently, a group of researchers published a report on the estimated number of
cases of foodborne illnesses from both known and unknown causes. 7 They compiled
and analyzed the information gathered by several surveillance systems (e.g., Food-
Net) and other relevant sources. According to this report, the total number of
foodborne illnesses from known and unknown causes was estimated to be 76 million
annually, with 325,000 hospitalizations and 5000 deaths in the U.S. Among these,
the known pathogens account for an estimated 14 million illnesses, 60,000 hospitalizations,
and 1800 deaths (Table 23.14). About 75% of these deaths were caused
by Salmonella, Listeria, and Toxoplasma.
The report indicated that via different surveillance programs, an accurate number
of illnesses associated with outbreaks caused by some pathogens was available.
However, data for sporadic illnesses, especially for pathogens such as Bac. cereus,
Clo. perfringens, and Sta. Aureus, are not accurately available through such programs.
For these pathogens, the outbreak-related cases were multiplied by 10 to
obtain the total number of illnesses through sporadic and outbreak incidences. The
basis of using this multiplier was from data in which both sporadic and outbreak
illnesses were available, such as for Salmonella and Shigella.
Some other important aspects mentioned in this report are that even with the
current surveillance programs, the foodborne illnesses are underreported. any pathogens
that are transmitted through food can also be transmitted through water and
person to person, thus obscuring the role of foodborne transmission. Also some of
the current foodborne illnesses are caused by pathogens that have not yet been
identified. 7
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V. CONCLUSION
Foodborne diseases, either sporadic or outbreaks, can be caused by different pathogenic
microorganisms, some of which are more predominant than others. The different
parameters associated with the predominant factors (pathogenic bacteria and
viruses) are also described. Finally, the sequence of events necessary for a foodborne
disease to occur is discussed. This information will be helpful in understanding the
material presented in following chapters.