Epidemiology of Salmonellosis
The primary reservoir of salmonellae is in the
intestinal tract of humans and animals, particularly
in poultry and swine. As intestinal forms, the
organisms are excreted in feces from which they
may be transmitted by insects and other creatures to
a large number of places such as to water, soil and
kitchen surfaces. Eggs, poultry and raw meat
products are the most important food vehicles of
Salmonella infection in human, with S.
Typhimurium and S. Enteritidis being the most
frequently isolated food borne serovars (Jay, 1992).
Salmonella infection is usually acquired by the oral
route, mainly by ingesting contaminated food or
drink. Any food product is a potential source of
human infection. Salmonella can be transmitted
directly from human to human or from animal to
human without the presence of contaminated food
or water, but this is not a common mode of
transmission. The true incidence of Salmonella
infection is difficult to determine. Reported cases
represent only a small proportion of actual number
because it is only large outbreaks that are
investigated and documented. Hence, sporadic cases
are under reported because it is only patients with
protracted diarrhea that take cases for
microbiological evaluation (Hanes, 2003).
Infectious diseases spread through food or
beverages are common, distressing, and sometimes
life-threatening problem for millions of people
around the world. The Center for disease Control
and Prevention (CDC) estimates 76 million people
suffer food borne illnesses each year in the United
States, accounting for 325,000 hospitalizations and
more than 5000 death. Food borne disease is
extremely costly. Health experts estimates that the
yearly cost of all food borne diseases in the United
States is five to six billion dollars in direct medical
expenses and lost productivity. Infections with
Salmonella alone account for one billion dollars