Now, researchers are making discoveries that may hold
the promise of immunity from disease and a safer food supply.
With funding from USDA's Cooperative State Research,
Education, and Extension Service (CSREES) National Research Initiative (NRI),
scientists in California determined that human strains of
Salmonella
are
different from those derived from animal sources.
Contaminated
food consumptionSalmonella
is most commonly transmitted through
consumption of food products that have been contaminated with animal waste. In
human patients, Salmonella causes salmonellosis, a form of food poisoning
characterised by the sudden onset of abdominal pain, vomiting, diarrhoea, and
fever.
There are more than 2,300 strains of Salmonella. Although
antibody-based classification of these strains has been useful
epidemiologically, it provides limited information concerning bacterial
diversity, evolutionary relatedness, and disease-causing potential. Many of
these strains are also becoming resistant to powerful
antibiotics.
Commercial livestock
The presence of
Salmonella
in commercial livestock production systems presents a potential risk
to the food supply, and the prospect of a bacterial strain emerging that is more
suited to human infection than animal infection is a major cause of
concern.
Michael Mahan and colleagues at the University of California,
Santa Barbara determined that strains of Salmonella collected from human
salmonellosis patients are distinct from Salmonella strains obtained from
animals.
Until now, scientists had not been able to describe the
relationship between virulence and the degree of disease-causing potential of
animal vs. human Salmonella isolates. However, Mahan's new research findings
could significantly affect the development of treatment methods to reduce
food-borne illness in humans.
Mice researchMahan's researchers tested in mice the
virulence capacities of 184 human and animal strains of Salmonella. Results
showed that 21 of 21 strains of Salmonella derived from animals were virulent in
mice, compared to only 16 of 41 Salmonella strains collected from human
salmonellosis patients.
These studies suggest that Salmonella isolates
derived from human salmonellosis patients are distinct from those of animal
origin. The researchers believe that characterization of these bacterial strain
variants may provide insight into the relative disease-causing ability of
Salmonella and the development of treatment and prophylactic strategies for
salmonellosis.
This project brings scientists one step closer to
developing a promising live Salmonella vaccine. Such a vaccine would provide a
protective immune response across the animal-human realm, resulting in improved
animal well-being, a safer food supply, and increased public
health.
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