Public Health Significance Of Salmonella

Why is Salmonella important to public health safety?
Salmonella and the medical condition that it causes,
Salmonellosis is one of the most commonly and widely distributed
foodborne diseases This disease in the past has caused
tremendous cost to society in many countries worldwide Millions
(2-4) of cases have been reported annually and yet a significant
number of cases has been unreported worldwide In the United
States it is estimated that the total cost of human
salmonellosis is estimated at US$ 3 billion In Denmark, the
total cost of human salmonellosis is estimated at US$155
million In general the costs of foodborne diseases are
difficult to acquire and generally not available from developing
countries
One of the highlights that made Salmonella significant is that
the European Commission has reported a 20-fold increase in
Salmonellosis from 1980s to 1990s in a number of countries This
has resulted in an increased spread of two strains, namely
Salmonella Enteritidis and Salmonella Typhimurium, causing much
public health concern Since as early as 1990s strains of
Salmonella showed increased resistance to a range of antibiotics
creating serious problems of treatment and recovery This has
led to tremendous human suffering, morbidity and mortality
What is Salmonella?
Salmonella belongs to the genus of gram negative infective
bacteria The organism is transmitted through poultry, eggs,
meat and other sources Three species are recognized; salmonella
typhi, salmonella choleraesius and salmonella enteriditis It is
estimated that over 2,500 serotypes exist Salmonella typhi
causes typhoid fever while salmonella typhimurium causes
gastroenteritis or inflammation of the stomach and small
intestines
What is the incubation period for Salmonellosis?
The incubation period for Salmonellosis is between eight to
forty-eight hours The disease or infection lasts three to seven
days if detected and treated promptly The infection may be
prolonged if diagnosis and treatment are delayed or if the
bacteria become multi-resistant to antibiotics
What are the symptoms of Salmonellosis? Symptoms of
Salmonellosis include: 61607; Fever 61607; Abdominal
cramps 61607; Diarrhea 61607; Headache 61607; Chills
61607; Prostration 61607; Nausea 61607; Pain
How is Salmonellosis diagnosed?
Salmonellosis is diagnosed by clinical observations and also by
pathological confirmation of the pathogenic bacteria Salmonella
in the blood and the feces Blood and feces analysis are often
considered essential tests in the positive identification of
Salmonellosis
How can Salmonella enter the food chain?
Salmonella can enter the food chain in three main ways: (i)
Animals harbor Salmonella on their bodies and in their
intestines Animals that are reared under unsanitary conditions
coupled with poor hygiene of food handlers provide an easy route
for the transfer of Salmonella along the fecal-oral path
Allowing pets and other animals into food preparation areas may
lead to cross-contamination of food being prepared Petting or
touching animals and pets without washing hands can lead to the
transfer of Salmonella from animals to the food being prepared
(ii) Manure, feces and litter are rich sources of Salmonella
Animals that are infected with Salmonella often pass out large
amounts of Salmonella in their feces which can directly or
indirect contaminate food
(iii) Cross-contamination may occur through poor personal
hygiene, poor sanitation, poor food handling and cooking
practices Of these practices hand washing is often the main
culprit Hands that are not washed before every new task, during
the task, and after performing the task and when changing to
another task, pose a serious risk of contamination Cutting
boards which are not frequently cleaned and sanitized between
tasks and when changing use from meat to vegetables or from raw
to processed or to cooked foods lead to the spread of Salmonella
and cross-contamination of foods
How is Salmonellosis treated?
Treatment usually takes the form of anti-diarrheal drugs and/or
antibiotics such as fluoroquinolones, chloramphenicol,
ampicillin and trimethoprim-sulfamethoxazole How can Salmonella
acquire antimicrobial resistance? Research suggests that
Salmonella may acquire antimicrobial resistance through the
following: 61607; Uptake of new genetic material 61607;
Mutation in the bacterial chromosome How can the different
types of antimicrobial resistance be detected? Different types
of antimicrobial resistance have been detected using known
“marker antibiotics” For example: 61607; Uptake of new
genetic material is displayed by Salmonella bacteria showing
resistance to ampicillin, trimethoprin-sulfamethozazole and
chloramphenicol 61607; Mutations in bacterial genome are
displayed by Salmonella bacteria showing resistance to
fluroquinolones What are some of the common foods associated
with Salmonellosis? Any food can become contaminated with
Salmonella if prepared using poor hygienic practices, under
unsanitary conditions and if not cooked thoroughly at the proper
internal temperature for a specified time Some common foods
associated with Salmonellosis include but are not limited to:
61607; Raw meats 61607; Poultry 61607; Eggs 61607;
Milk and dairy products 61607; Fish 61607; Shrimp
61607; Yeast 61607; Coconut 61607; Sauces 61607;
Salad dressing
How eggs become contaminated with Salmonella?
Eggs may become contaminated with Salmonella enteritidis in two
main ways: (i) Salmonella enteritidis may silently infect the
ovaries of healthy appearing hens and contaminates the eggs
before the shells are formed
(ii) Salmonella enteritidis is normally present in the feces
that can contaminate the outer egg shells and may penetrate
cracks in the shell
Who is at increased risk?
Healthy adults and children are at risk for egg-associated
Salmonellosis, but the elderly, infants and persons with
impaired immune systems are at increased risk for serious
illness In these persons, a relatively small number of
Salmonella bacteria can cause severe illness Most of the deaths
caused by Salmonella enteritidis have occurred among the elderly
in nursing homes Egg-containing dishes prepared for any of
these high-risk persons in hospitals, in nursing homes, in
restaurants, or at home should be thoroughly cooked and served
promptly
What you can do to reduce risk?
Eggs, like meat, poultry, milk and other foods, are safe when
handled properly Shell eggs are safest when stored in the
refrigerator, individually and thoroughly cooked, and promptly
consumed The larger the number of Salmonella present in the
egg, the more likely it is to cause illness Keeping eggs
adequately refrigerated prevents any Salmonella present in the
eggs from growing to higher numbers, so eggs should be held
refrigerated until they are needed Cooking reduces the number
of bacteria present in an egg; however, an egg with a runny yolk
still poses a greater risk than a completely cooked egg
Undercooked egg whites and yolks have been associated with
outbreaks of Salmonella enteritidis infections Both should be
consumed promptly and not be held in the temperature range of 40
to 140 ºF for more than 2 hours
What proactive measures can be taken to reduce Salmonellosis?
(i) Vaccination of laying chickens (ii) Avoid indiscriminate
use of antibiotics as growth promoters that will minimize the
appearance of new Salmonella resistant serotypes (iii) Use
probiotics to competitively exclude Salmonella form the small
intestines Feed should be supplemented with yeast or chickens
should be sprayed with mucosal starter culture and/or feed the
culture through water This procedure will serve to
competitively exclude Salmonella from the crop and ceca of the
small intestines (iv) Adopt and use HACCP food safety
management system (v) Use irradiation to kill Salmonella (vi)
Use heat processing to kill Salmonella (vii) Reduce water
activity to inactivate and kill Salmonella (viii) Use low pH or
acidification to inactivate and kill Salmonella (ix) Use salt
and sugar in processing to reduce water activity thereby
reducing the activity of Salmonella (x) Freezing may inactivate
and destroy Salmonella (xi) Adopt chemical disinfecting of
seeds such as alfalfa sprouts to eliminate Salmonella and/or
reduce to acceptable levels (xii) Use recommended sanitizers
such as chlorine used at a concentration of 20, 000 ppm to
sanitize floors, walls, ceiling, equipment and table tops to
ensure Salmonella free environment (xiii) Thoroughly cook foods
at the proper internal temperatures Use a food thermometer to
verify that the correct internal temperature has been reached
(xiv) Keep eggs refrigerated at a temperature between 0 to 5 ºC
(xv) Discard cracked or dirty eggs as they may be a source of
contamination (xvi) Wash hands thoroughly with soap and then
with sanitizer before, between tasks and after completing tasks
(xvii) Eat eggs promptly after cooking Do not keep eggs
standing for more than 2 hours after cooking (xviii) Do not eat
raw eggs because of the possibility of becoming infected with
Salmonella
What else is being done to curb the incidence and future
outbreaks of Salmonellosis?
61607; US Government Food Protection Agencies and other
agencies worldwide have taken steps to reduce Salmonella
enteritidis outbreaks These steps include the challenging task
of identifying and removing infected flocks from the egg supply
and increasing quality assurance and sanitation measures
61607; The Centers for Disease Control in US and Ministries
of Health in various countries have advised health departments,
hospitals and nursing homes of specific measures to reduce
Salmonella enteritidis infection Some states in US and other
countries worldwide now require refrigeration of eggs from the
producer to the consumer The US Department of Agriculture has
implemented regular testing of breeder flocks that produce
egg-laying chickens to ensure that they are free of Salmonella
enteritidis The US Food and Drug Administration has issued
guidelines for safe handling of eggs in retail food
establishments
61607; Research by these agencies and the egg industry is
addressing the many unanswered questions about Salmonella
enteritidis, the infections in hens and contaminated eggs
Informed consumers, food-service establishments and public and
private organizations are working together to reduce and
eventually eliminate, disease caused by this infectious organism
61607; Increased training and awareness through the
implementation of educational programs on television, radio,
printed media and electronic media at all education levels
(primary, secondary and tertiary, post-graduate) would all serve
to reduce, eliminate and prevent Salmonellosis
Summary
Salmonellosis is now being described by scientists as an
emerging public health problem Poor hygienic practices, poor
sanitation, poor food handling practices and poor cooking
practices have all contributed to Salmonella becoming
uncontrollable in both developing and developed countries,
leading to preventable morbidity and mortality Increased
resistance of Salmonella to known antibiotics have made
treatments even more challenging The best control of Salmonella
is to adopt effective proactive measures that would eliminate,
reduce or control Salmonella from farm to consumer in the food
chain cycle Such proactive measures would entail developing
effective training programs that would educate the consumer, the
public and householder about safe food preparation techniques
such as the importance of and proper personal hygiene, good
sanitation and good cooking practices For the farmers good
agricultural practices should be adopted and implemented
together with vaccination, active surveillance and monitoring
Future research should focus on new, simple, realistic and
practical methods of controlling multi-resistant strains of
Salmonella Heating processing and simply cooking eggs, poultry
and meats at a safe internal temperature of 75 ºC still remain
the only acceptable safe method of destroying Salmonella
References
61607; Christian, J Greger, J (1994) Nutrition for
Living Benjamin/Cummings Publishing Company, Fourth Edition
61607; Global Salm-Surv (GSS)
Website:http://wwwwhoint/salmsurv/en/ 61607; Jay, JM
(2000) Modern Food Microbiology Aspen Publication: Maryland
61607; Scientific Status Summary Bacteria Associated with
Foodborne Diseases (2004) Institute of Food Technologists:
Chicago 61607; The Medical Impact of Antimicrobial Use in
Food Animals: Report of a WHO Meeting, Berlin, Germany (1997)
WHO/EMC/ZOO974 61607; US Food and Drug Administration,
Center for Food Safety and Applied Nutrition, Foodborne
Pathogenic Microorganisms and Natural Toxins Handbook, The Bad
Bug

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