Foodborne Disease Overview
Primarily, we study the foodborne pathogens
Escherichia coli O157:H7
(O157), Salmonella enterica serovar Typhimurium definitive type 104 (DT104), and
jejuni. These bacteria inhabit the gastrointestinal tracts of a large variety
of species. Water trough sediments, soil, and animal bedding can also harbor
O157 and DT104. This wide range of habitats and reservoirs, ranging from stagnant
ponds to insect guts to domestic pet intestines, makes complete eradication of these
pathogens very unlikely.
Animals infected with these bacteria excrete them in feces. This
feces is then transferred by insects, water, or other contact to food products.
Humans ingest the fecal material, and the bacteria along with it. We call this the
fecal-oral route of infection.
Generally, an adult human must ingest a large number of bacteria to cause
clinical disease. The actual number varies between bacteria. The infectious
dose of Salmonella is between 1,000,000 and 10,000,000,000 organisms. The
infectious dose of E. coli O157 can be as low as 10 organisms.
Children, elderly, and immunocompromised individuals need to ingest fewer
organisms to cause disease. These groups have less active immune systems.
Infants are especially susceptible because their gastrointestinal tracts are not fully
developed, and they have no normal flora to compete with the invading bacteria.
Symptoms of these diseases are described more fully in the research
section dealing with the organism.
The association of Feed and Water
with Salmonella and E. coli O157 prevalence in cattle: A study funded by an
FDA grant focuses on feed and water as sources of E. coli O157 and
the epidemiology and ecology of Salmonella typhimurium DT104 in and around
farms. The ultimate goal is to develop strategies to prevent entry of infection to
the farm and to mitigate zoonotic risk
Escherichia coli O157 and Campylobacter:
Studies on zoonotic bacteria
Salmonella, Campylobacter jejuni and
E. coli 0157. Recent human problems with E. coli 0157 have elevated the
need for a descriptive epidemiology, determination of risk factors for herd status, and on