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SALMENOSIS
Author: Kevin Crawford
Dr. Phalen
HSCI 530
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Table of Contents
INTRODUCTION ............................................................3
IDENTIFICATION ..........................................................4
Description of the Agent .................................................4
Antigenic Structure .........................................................4
Laboratory Identification ................................................5
Testing ............................................................................5
Symptoms .......................................................................5
Natural Sources in the Environment ...............................6
Associated Foods ............................................................6
Occurrence in the United States......................................6
Reservoirs .......................................................................7
Modes of Transmission...................................................7
Infective Dose .................................................................8
Incubation Period ............................................................8
Methods of Control and Prevention ..................................8
Major Food-Borne Outbreaks .........................................10
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INTRODUCTION
Salmonellosis is an infection of the bacteria called Salmonella. It is known to be associated with
living in the intestinal tracts of warm and cold blooded animals. It is transmitted and derived
from infected animals and or contaminated feces. It is part of the family enterobacteriaceae and
has numerous known serotypes ranging up to 2500 different subspecies (Knechtges, 2012). The
two most concerned serotypes for humans are S. Typhimurium and S. Enteritidus.
The species itself has been around for hundreds of years. In the 1880’s the typhoid bacillus was
first observed by Eberth in sections of the spleen and mesenteric lymph nodes from a patient who
died from typhoid. He successfully cultivated this bacterium in 1881 which further lead to the
serodiagnosis of typhoid by 1896 (Todar, 2013).
Common symptoms include headache, abdominal pain, diarrhea, nausea, and vomiting. Some
serotypes can lead to more serious illness such as typhoid fever. Due to the range of mild to
severe cases of salmonella, and the fact that non industrialized countries do not have proper
reporting systems, the actual number of cases cannot be identified but it is estimated that 42,000
laboratory-confirmed cases happen in the U.S yearly (CDC, 2012).
Contamination and ingestion are the two most common ways for the disease to spread.
Unsanitary practices in food production ranging from the slaughtering of animals to
commercially preparing food can be used as a mode of transmission if any fecal matter were to
be involved (Todar, 2013).
This helps backup the idea that we must set preventive measures and control to ensure that large
and widespread occurrences do not happen. Establishing regulations on sanitary practices and
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ensuring the quality of products from livestock all the way to the consumer will help save lives
and prevent further occurrences (Heymann, 2004).
IDENTIFICATION
Description of the Agent
Salmonella is a motile bacterium, gram negative, facultative rod shaped bacterium in the family
enterobacteriaceae. It is non-spore forming and non-motile variants of the species do exist such
as S. Gallinarum and S. Pullorum (Hammack, 1998). It is commonly manifested by acute
enteroclotius which is an infection of the intestinal tract. 2500 Different serotypes are known
today between the two species S. Enterica and S. Bangori. S. Enterica consists of six subspecies
and includes most serotypes involving animal and human infection. These numerous serotypes
were named after the type of animal or carrier it was found in (Knechtges, 2012) .The two most
commonly reported types include S. Typhimurium and S. Enteritidus.
Antigenic Structure
Its DNA base composition is 50-50 mol% G+C, similar to that of Escherichia, shigella, and
citrobacter. Somatic antigens within salmonella are heat stable and alcohol resistant. Flagella
antigens are heat-labile proteins while surface antigens in salmonella may mask O antigens, and
the bacteria will not be angulated with O antisera (Todar, 2013). Most strains are prototrophic
meaning they do not require any growth factors. Auxotrophic strains do occur, meaning they can
synthesize their own organic compounds to help reproduce and thrive. These strains are found
especially in host adapted serovars so as Typhi and Paratyphi A.(Todar, 2013).
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Laboratory Identification
The most commonly used media selective for salmonella includes and not limited too; SS Agar,
bismuth sulfite agar, hektoen enteric (HE), brilliant green agar, and xylose-lisine-deoxycholate
(XLD) agar (Todar, 2013). Most salmonella strains are motile with peritrichous flagella while
non-motile variants may occur occasionally. Most strains grow on nutrient agar as smooth
colonies, 2 – 4 mm in diameter (Todar,2013).
Testing
Determining cause for salmonella requires laboratory testing which can be identified with a stool
sample, 3-10 grams of fecal matter should be inoculated (Heymann, 2004).
Symptoms
Symptoms for salmonellosis ranges due to type of infections that my happen. Depending on
serotype, more serious illnesses can occur such as typhoid and paratyphoid fevers from
respective strains S. Typhimurium and S. Paratyhphimurium (Hammack, 1998). Onset of
headache, abdominal pain, diarrhea, nausea and vomiting are all common with salmonella
infections and enteric disease. Typhoid fever can include high fevers from 103-104 degrees,
lethargy, gastrointestinal symptoms including abdominal pain, diarrhea or constipation,
headache, loss of appetite. Rash of flat, rose-colored spots sometimes occur. Paratyphi fever has
been known to be much more subtle and milder compared to typhoid (Hammack, 1998). Post
infectious irritable bowel syndrome, which is prevalent in an average of 15% among those who
have recovered from an intestinal infection, may occur. Symptoms include and sometimes result
in abdominal abscesses (Knechtges, 2012). Reiter’s syndrome; a condition which results when
the body’s immune system attacks its own tissues includes symptoms such as arthritis, eye
irritation and urinary tract problems (Knechtges, 2012).
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Natural Sources in the Environment
Salmonellae are disseminated in the natural environment through human or animal excretion.
These environments include water, soil, and even sometimes plants used as food and feed
(Todar, 2013). Infected farm animals by feeds and fertilizers have been pointed out as a source of
contamination which results in infected products such as meats and poultry.
Associated Foods
The salmonellae family has a large number of associated foods due to its ease of transmission
through fecal contamination. Animal products such as meats, poultry, eggs, fish and shrimp are
all susceptible (Hammack, 1998). Milk and dairy products if they have not been through a
pasteurization process, which brings the product to a specific temperature for a predefined length
and time to remove harmful pathogens, can be a probable source (Heymann, 2004). Raw veggies
such as alfalfa sprouts, tomatoes, peppers, cantaloupes, lettuce due to contaminated water supply
can result in salmonella. (Knechtges, 2012).
Occurrence in the United States
Extensive reporting has been done on salmonella in the United States and Europe due to better
reporting systems. In some industrialized countries, as few as 1% of cases actually get reported.
Incident rates are most common in children and elderly as they are the most susceptible
(Heymann, 2004). The incidence of foodborne Salmonella infection/toxication remains relatively
high in developed countries because of commercially prepared food or ingredients for food. Any
contamination of commercially prepared food will result in a large-scale infection (Todar, 2013).
According to the CDC, an estimated 1.2 million cases occur annually in the United States; of
these, approximately 42,000 are laboratory-confirmed cases which are reported (CDC, 2013). Of
these 1.2 million cases, an estimated 1,027,561 cases of domestically acquired nontyphodial
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salmonellosis occur while the CDC recently estimated that a mean of 1,821 cases occur annually
in the U.S. (Hammack, 1998)
Reservoirs
As mentioned earlier, salmonellae live in the intestinal tracts of warm and cold blooded animals.
Salmonella serovars can be found predominantly in one particular host, can be ubiquitous, or can
have an unknown habitat (Todar, 2013). Salmonellosis in these cases is transmitted through fecal
contamination of water and food, it must be noted that Typhi and Paratyphi A are strictly human
serovars (Todar, 2013).
Beef includes most individual outbreaks, while poultry and eggs consist of most of the
salmonellosis pandemics. Much wild game such as birds, hoofed animals can be transmitters
while even house hold pets such as cats, dogs, and reptiles (Knechtges, 2012). Municipal water
supplies can also carry salmonella strains if not properly treated with a recommended dose of
chlorine.
Modes of Transmission
The most commonly and frequently seen mode of transmission for salmonella is to be taken a
dose orally, that is ingesting of contaminated food, fecal particles or contaminated water
(Hammack, 1998). Surface contamination of meats during cooking usually has little to no
consequence if the person is properly cooking it, although handling of contaminated meat may
result in contamination of hands, tables, kitchenware, towels, and other foods (Todar, 2013).
Outbreaks have sourced from raw fruits and veggies as they do not go through any cooking
processes. Infected farm animals may have been a result of contaminated feed and fertilizers and
this infection can spread from the rearing and slaughter process (Heymann, 2004). Person to
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person transmission is possible while animal to human transmission is more likely. Typhi and
Paratyphi are strictly human serovars and are usually associated with cross contamination,
particularly in areas of poor sanitation (Knechtges, 2012).
Infective Dose
The infective dose, also known as virulence, varies greatly with the serotype and host resistance.
Its range is known to be as wide as 10 to 1,000,000,000 colony-forming units (Knechtges, 2012).
Susceptibility is increased by anchlorhydria, antacid treatment, and gastrointestinal surgery.
Severity is related to serotype; number of organisms ingested and host factors. Septicemia is
increased in those with sickle cell disease (Heymann, 2004).
Incubation Period
The incubation period of salmonellosis occurs relatively rapidly, after ingestion, the bacilli
colonize sites on the epithelium of the intestine, and within a manner of minutes, they invade
cells of the intestinal mucosa (Knechtges, 2012). Once infection occurs, onset of symptoms can
happen as soon as 6 to 72 hours, but this timeframe is most active around 12-36 hours. The
period of communicability includes through the course of the infection which can be from
several days to several weeks. Those infected can be temporary convalescent carriers for months.
1% of adults and 5% of children excrete the organism for more than a year, usually from typhoid
cases (Heymann, 2004).
Methods of Control and Prevention
Methods of control to help stop the spread of the disease as reported in the communicable
diseases manual, states that reporting your illness to a local health authority is the first step in
gauging the problem. Next, isolation and immunization of those in contact with disease may be
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needed to help prevent any further spreading. Next, quarantine and investigation of contacts and
source will help identify the issue. Finally, specific treatment and concurrent disinfection will be
needed to ward off the disease (Heymann, 2004). Preventive measures were further outlined in
the disease manual which stated we must educate food handlers and public handlers of proper
sanitary practices. Use pasteurized or irradiated egg products to prepare dishes. Exclude
individuals with diarrhea from food handling. Indoctrinate known carriers on washing hands
after using the restroom. Recognize that household pets can be carriers of salmonella and must
be handled carefully. Establish facilities and encourage irradiation of meat and eggs. Inspect and
supervise sanitation methods while also establishing salmonella control programs. Finally, all
foods should be adequately cooked or heat treated to ensure integrity of such foods from foreign
invaders (Heymann, 2004). National surveillance is conducted through the public health
laboratories for culture-confirmed cases and through the National Notifiable Diseases
Surveillance System (NNDSS). Active laboratory- and population-based surveillance is
conducted in FoodNet sites (CDC, 2013). Challenges outlined on the Centers for Disease
Control and Prevention website believes that identifying unrecognized major sources of
salmonella infections; determining the sources of infections in infants; preventing contamination
of vegetables with manure from concentrated animal feeding operations and preventing further
emergence of highly resistant strains through improved detection from collaborative efforts from
laboratories and trained state health department personnel are effective opportunities to help
reduce the spread of salmonellosis (CDC, 2013).
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Major Food-Borne Outbreaks
The CDC website has listed on their salmonella homepage all reported outbreaks from 2006 to
2013.
1. Multistate Outbreak of Human Salmonella Typhimurium Infections Linked to Live Poultry
June 6, 2013
A total of 224 persons infected with the outbreak strain of Salmonella Typhimurium have been
reported from 34 states. Epidemiologic, laboratory, and traceback findings have linked this
outbreak of human Salmonella Typhimurium infections to contact with chicks, ducklings, and
other live baby poultry purchased from multiple feed stores and sourced from multiple mailorder hatcheries. Mail-order hatcheries, agricultural feed stores, and others that sell or display
chicks, ducklings, and other live poultry should provide health-related information to owners and
potential purchasers of these birds prior to the point of purchase. This should include information
about the risk of acquiring a Salmonella infection from contact with live poultry.
2. Multistate Outbreak of Salmonella Typhimurium and Salmonella Newport Infections Linked to
Cantaloupe. October 5, 2012
A total of 261 persons infected with the outbreak strains of Salmonella Typhimurium (228
persons) and Salmonella Newport (33 persons) were reported from 24 states. Collaborative
investigation efforts of state, local, and federal public health and regulatory agencies indicated
that cantaloupe originating from Chamberlain Farms Produce, Inc. of Owensville, Indiana, was
the source of this outbreak.
(ALL OUTBREAKS SOURCED FROM http://www.cdc.gov/salmonella/outbreaks.html)
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1. Hammack, Thomas. "Salmonella Species." Foodborne Pathogenic Microorganisms and Natural
Toxins Handbook: The 'bad Bug Book' 2nd ed. [Washington, D.C.]: U.S. Food & Drug Administration,
Center for Food Safety and Applied Nutrition, 1998. 12-16. Print.
1. Identification and/or description of the agent
 Salmonella is a motile
 non-sporeforming
 Gramnegative
 rod-shaped bacterium in the family
Enterobacteriaceae and the tribe Salmonellae. Non-motile variants include S. Gallinarum and S.
Pullorum.
2. Associated disease or illness, including the following relevant information:
a. Name of disease or illness
Salmonella
b. Identification of the disease (e.g. signs and symptoms, medical tests)
Nontyphoidal Salmonellosis
 Nausea, vomiting, abdominal cramps, diarrhea, fever, headache.
Typhoid Fever

High fever, from 103° to 104°F; lethargy; gastrointestinal symptoms,
including abdominal pains and diarrhea or constipation; headache; achiness; loss
of appetite. A rash of flat, rose-colored spots sometimes occurs.
 Serological identification of cultural isolates from stool
c. Natural habitat or sources in the environment
 It can colonize the intestinal tracts of vertebrates, including livestock, wildlife,
domestic pets, and humans.
 May also live in environments such as pond-water sediment.
d. Associated foods
 fresh produce
 associated with animal products
 meats, poultry, eggs, milk and dairy products, fish, shrimp, spices, yeast, coconut
 sauces, unpasteurized salad dressings, cake mixes, cream-filled desserts and
toppings that contain raw egg, dried gelatin, peanut butter, cocoa.
e. Occurrence in the United States
Nontyphoidal Salmonellosis

(CDC) estimates that 1,027,561 cases of domestically acquired nontyphoidal
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salmonellosis occur annually in the U.S.
Typhoid Fever

CDC recently estimated that a mean of 1,821 cases occur annually in the U.S.
f.
Reservoirs
 S. Typhi and S. Paratyphi A are found only in human hosts.
g. Modes of transmission
 oral (e.g., ingestion of contaminated food, fecal particles, or
contaminated water)
h. Virulence (e.g. infective dose)
Nontyphoidal Salmonellosis

i.
As low as one cell, depending on age and health of host and strain
differences among members of the genus.
Typhoid Fever
 Fewer than 1,000 cells
Incubation period
Nontyphoidal Salmonellosis
 6 to 72 hours after exposure.
Typhoid Fever
 Generally 1 to 3 weeks, but may be as long as 2 months after exposure.
3. Major food-borne outbreaks (2-3)
 Outbreaks also have been linked to the handling of certain animals sometimes
kept as pets, such as turtles, frogs, and chicks.
 Notes from the Field: Multistate Outbreak of Salmonella Infantis, Newport, and
Lille Infections Linked to Live Poultry from a Single Mail-Order Hatchery in Ohio —
March–September, 2012
 Notes from the Field: Salmonella Bredeney Infections Linked to a Brand of Peanut
Butter — United States, 2012
 Outbreaks of Acute Gastroenteritis Transmitted by Person-to-Person Contact —
United States, 2009–2010
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2. Heymann, David L. “SALMONELLOSIS” ICD-9003. Control of communicable diseases manual. 18th Ed.
Washing, D.C: American Public Health Association, 2004. 469-73. Print.
1. Identification





Bacterial disease commonly manifested by acute enterocloitus.
Symptoms; onset of headache, abdominal pain, diarrhea, nausea, vomiting.
Dehydration in elderly & infants
Enterocolitus, fecal excretion persists after few days of acute effects.
3-10 grams of fecal matter should be inoculated
2. Infectious Agents



Numerous serotypes have been found pathogenic to both animals and people
Much variation & prevalence of serotypes from country to country
S. Typhimurium + S. Enteritidus most commonly reported
3. Occurrence






Extensively reported in US and EU due to better reporting systems
Foodborne disease mainly of animal origin, which is dominant mode of transmission.
In industrialized countries, few as 1% of clinical cases are reported
Incidence rate are highest in infants and young children
60 – 80% of all cases occur sporadically
Large outbreaks in hospitals, child institutions, restaurants are not uncommon arising from a
contaminated food source.


USA epidemic involving 25,000 cases resulted from non-chlorinated municipal water supply.
Largest single epidemic; improper pasteurized milk affected 285,000 persons
4. Reservoir



Domestic wild animals; poultry, swine, cattle, rodents
Pets such as dogs, cats, iguanas, tortoises, turtles, terrapins
Humans; ie. Patients and convalescent carriers.
5. Mode of Transmission


Ingestion of the organisms in food derived from infected animals or contaminated feces.
Contaminated raw and undercooked eggs, milk, water, meat/meat products, poultry/poultry
products
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




Outbreaks have sourced from raw fruits and veggies
Infected farm animals by feeds and fertilizers
Infection spreads from rearing/slaughter process
Cross-contamination during food handling
Person-person transmission
6. Incubation Period





From 6 to 72 hours, usually about 12-36 hours
Through course of infection
Several days to several weeks
Temporary carrier continues for months
1% of adults, 5% of children excrete the organism for more than a year
8. Susceptibility



Increased by anchlorhydria, antacid treatment, gastrointestinal surgery
Severity is related to serotype; number of organisms ingested and host factors.
Septicemia is increased in those with sickle cell disease.
9. Methods of Control
PREVENTIVE MEASURES
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
educated food handlers of sanitary practices
Educate public handlers of sanitary practices
Use pasteurized or irradiated egg products to prepare dishes.
Exclude individuals with diarrhea from food handling
Indoctrinate known carriers on washing hands after using restroom
recognition of salmonella in pets
Establish facilities and encourage irradiation of meat and eggs
Inspect and supervise sanitation methods.
Establish salmonella control programs
Adequately cook or heat-treat foods
10. CONTROL OF PATIENT
a)
b)
c)
d)
e)
f)
g)
Report to local health authority
Isolation
Concurrent disinfection
Quarantine
Immunization of Contacts
Investigation of contacts and source
Specific treatment
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3. Knechtges, Paul L. "Chapter 2 Foodborne Infectious and Microbial Agents; Salmonella Species and
Serotypes." Food Safety: Theory and Practice. Sudbury, MA: Jones & Bartlett Learning, 2012. 66-73.
Print.
4. Associated disease or illness, including the following relevant information:
a. Name of disease or illness
 2500 Different Serotypes
 Two species; S. Enterica and S. Bangori
 S. Enterica consists of six subspecies and includes most serotypes involving animal
and human infection.
 Group by O antigen similarities first, then further classified by H antigens.
 Species or serotype is named after the type of animal it was found in
 S. Typhi and S. Paratyphi are responsible for the serious diseases of typhoid and
paratyphoid fever.
b. Identification of the disease (e.g. signs and symptoms, medical tests)
 Typhoid Fever; Fever, headache, constipation
 Paratyphoid fever is generally milder compared to typhoid fever
 Enteric Disease; diarrhea, fever, vomiting, and abdominal cramps
 Post infectious irritable bowel syndrome, which is prevalent an average 15%
among those who have recovered from an intestinal infection; Symptoms include
abdominal pain, diarrhea, fever, and sometimes resulting abdominal abscesses.
 Reiters syndrome; condition results when the bodys immune system attacks its
own tissues; symptoms include arthritis, eye irritation, urinary tract problems.
c. Natural habitat or sources in the environment
d. Associated foods
 Red meats, poultry, eggs, unpasteurized milk, fruits, vegetables, and processed
products, alfalfa sprouts, tomatoes, peppers, cantaloupes, and lettuce.
e. Occurrence in the United States
 Typhoid Fever; before antibiotics, case fatality rate was 10-20%, but with proper
treatment it is now less than 1%.
 Considered endemic in regions of Asia, Africa, and Latin America.
f.
Reservoirs
 Convalescent carrier times can be quite prolonged, lasting months and possibly a
year in some cases.
 Warm and cold blooded animals
 Wild birds, hoofed animals, cats, dogs, rodents, reptiles, insects
 Food contact surfaces
 Beef includes most individual outbreaks, while poultry and eggs consists of most
of the salmonellosis pandemics
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g. Modes of transmission
 Typhoid; Control of disease transmission is very difficult due to unwary human
carriers.
 Human typhoid fever is associated exclusively with human carriers
and usually with contaminated food or water, particularly in areas
with poor sanitation.
 Animal-to-human contact
h. Virulence (e.g. infective dose)
 Varies greatly with the serotype and host resistance
 Ranges wide as 10 to 1,000,000,000 CFU’s
i.
Incubation period
 Occurs relatively rapidly, after ingestion, the bacilli colonize sites on the
epithelium of the intestine, and within a manner of minutes, they invade cells of
the intestinal mucosa.
5. Methods of control and prevention
 Treatment involves supportive care, rehydration, electrolyte replacement and
antibiotic therapy
 Medical clearance and good personal hygiene among food workers who have
recently recovered
6. Major food-borne outbreaks (2-3)
 Eggs implicated in 80% of the reported outbreaks in the united states by salmonella from 1985
through 1999.
 Year 2000 was estimated to be between 81,535 and 276,500 cases
 Two largest outbreaks caused by dairy products; 1985, cross contamination of pasteurized and
non-pasteurized milk led to 16000 culture confirmed salmonellosis cases and a total number of
cases estimated to be nearly 200,000 people(Illinois). 1994; contaminated ice cream estimated
in 224,000 persons were infected with s. enteritidis from ice cream premix.
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4. Todar, Kenneth, PhD. "Salmonella and Salmonellosis." Salmonella and Salmonellosis. Madison,
Wisconsin, n.d. Web. 29 May 2013. <http://textbookofbacteriology.net/salmonella.html>.
7. Identification and/or description of the agent
 Salmonella
 Gram-negative




8.
facultative rod-shaped bacterium
same proteobacterial family as Escherichia coli
the family Enterobacteriaceae
DNA base composition is 50-52 mol% G+C, similar to that of Escherichia,
Shigella, and Citrobacter.
Antigenic Structure



Somatic antigens are heat stable and alcohol resistant.
Flagellar antigens are heat-labile proteins.
Surface antigens in Salmonella may mask O antigens, and the bacteria will not be
agglutinated with O antisera.
9. Associated disease or illness, including the following relevant information:
a. Identification of the disease (e.g. signs and symptoms, medical tests)
 The most commonly used media selective for Salmonella are
 SS agar
 bismuth sulfite agar
 Hektoen enteric (HE) medium
 brilliant green agar and xylose-lisine-deoxycholate (XLD) agar
 Most Salmonella strains are motile with peritrichous flagella
 however, nonmotile variants may occur occasionally.
 Most strains grow on nutrient agar as smooth colonies, 2-4 mm in diameter.
 Most strains are prototrophs, not requiring any growth factors.
 auxotrophic strains do occur, especially in host-adapted serovars such as Typhi and



Paratyphi A.
symptoms appear (diarrhea, vomiting, fever) and last 2-5 days.
Salmonella strains may produce a thermolabile enterotoxin
antibiotic resistance and multiresistance of Salmonellaspp. have increased a great
deal.
o cause appears to be the increased and indiscriminate use of antibiotics in the
treatment of humans and animals
o Until 1972, Typhi strains had remained susceptible to antibiotics
b. Natural habitat or sources in the environment
 Salmonellae are disseminated in the natural environment (water, soil, sometimes
plants used as food) through human or animal excretion
c. Associated foods
 Contamination of meat (cattle, pigs, goats, chicken, etc.)
 most often it results from contamination of muscles with the intestinal contents



during evisceration of animals, washing, and transportation of carcasses.
Surface contamination of meat is usually of little consequence
as proper cooking will sterilize it (although handling of contaminated meat may result
in contamination of hands, tables, kitchenware, towels, other foods, etc.).
Infection may follow ingestion of any food that supports multiplication
of Salmonella such as eggs, cream, mayonnaise, creamed foods, etc.
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d. Occurrence in the United States
 The incidence of foodborne Salmonella infection/toxication remains relatively high in

developed countries because of commercially prepared food or ingredients for food.
Any contamination of commercially prepared food will result in a large-scale infection.
e. Reservoirs
 Salmonellae live in the intestinal tracts of warm and cold blooded animals
 Salmonella serovars can be found predominantly in one particular host, can be
ubiquitous, or can have an unknown habitat.


f.
Salmonellosis in these cases is transmitted through fecal contamination of water or
food.
Typhi and Paratyphi A are strictly human serovars
Virulence (e.g. infective dose)
 a large number of ingested salmonellae are needed to give symptoms.
g. Incubation period
 About 12-24 hours following ingestion of contaminated food

 Salmonella excretion by human patients may continue long after clinical cure.
 About 5% of patients clinically cured from typhoid remain carriers for months or even
years.

Salmonellae survive sewage treatments if suitable germicides are not used in sewage
Processing.
h. Discovery
 1880s, the typhoid bacillus was first observed by Eberth in spleen sections and


mesenteric lymph nodes from a patient who died from typhoid.
succeeded in cultivating the bacterium in 1881
Serodiagnosis of typhoid was thus made possible by 1896.
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5. Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious
Diseases (NCEZID), Division of Foodborne, Waterborne, and Environmental Diseases (DFWED)
Page last reviewed: May 14, 2013 Page last updated: May 14, 2013
http://www.cdc.gov/salmonella/index.html
6. FoodSaftey.gov, Salmonella, U.S. Department of Health & Human Services - 200
Independence Avenue, S.W. - Washington, D.C. 20201 Date Modified: June 10, 2013
http://www.foodsafety.gov/poisoning/causes/bacteriaviruses/salmonella/#.UbXtePmsh8E
7. Salmonella Infections, U.S. National Library of Medicine 8600 Rockville Pike, Bethesda, MD
20894 U.S. Department of Health and Human Services National Institutes of Health Page last
updated on 19 April 2013 Topic last reviewed 30 August 2012
http://www.nlm.nih.gov/medlineplus/salmonellainfections.html
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