Salmonella

1
Salmonella

• Bhushan Jayarao
• Extension Veterinarian
• Department of Veterinary Science
• Pennsylvania State University
• University Park, PA

2
Salmonella

• PART TOPIC
• ________________________________________
• 1 Case Study The Hudson Farm
• 2 What Should You Know About Salmonella ?
• 3 Prevention and Control Strategies

3
PART ONEHudson Farm a Case Study
4
Hudson Farm
5
Meet the Hudsons !
Linda
Fred
Mary
Susan John
Jeff
Dave
6
The Hudson Dairy Farm

• History
• 1920 - Established
• 1956 - Upgraded
• 1981 - New structures equipment
• Employees
• Jeff Hudson, owner
• 1 farm worker
• 1 milker
• Dave, Linda, Fred
• Susan John feed the calves

Jeff Hudson Owner Since 1982
7
MS
Milk cow barn
Dry cow heifer barn
Feed barn
Holding area
Calf barn
B T R
Milking parlor
Tool shed
Hudson home
Grazing area
Hudson dairy farm layout
8
Dairy Herd Statistics

• HERD PERFORMANCE
• Grade A milk
• 4600- 4800 lbs of milk per day
• No antibiotic residue violations
• BTMSCC 200,000 - 500,000 last year.

• DAIRY CATTLE
• 12 calves
• 19 dry cows
• 20 heifers
• 87 cows in milk
• OTHER ANIMALS
• 4 stray cats 2 dogs
  1 pony
  3 ducks and
  8 chickens

9
People with whom Jeff interacts ...
Milk Agent Farm Worker
Cull Cow Farm Credit

Dealer Agent
Banker Salesmen
County Ext. Agent Veterinarian
10
So goes the story !
11
October 1, 7.00 am
Jeff, I have got a deal for you ! How about 3
calves for 90 ? IF you dont, I have someone
who will take it !
????
I take it !
12
October 1, 10.00 am
13
MS
Milk cow barn
Dry cow heifer barn
Feed barn
Holding area
Calf barn
B T R
Milking parlor
Tool shed
Hudson home
Grazing area
Theres no one to tell him where to put the
calves, so he leaves them in the calf barn !!!!!!
14
October 4
5.00 am 3 new calves, and 2 other calves have
high temp. and bloody diarrhea !
8.00 am The Vet examines the herd. He also takes
a swab sample for lab testing. He then
treats the calves, and then tells Jeff You
might have a serious problem
15
October 4
8.00 p.m. A total 7 out of 15 calves are now
sick. He treats the sick calves.
11.00 PM Jeff, has to take both
and to the County Hospital
emergency room --- abdominal cramps and high
temperature.
This has not been a good day for Jeff !
16
October 5
4.00 am Children admitted. Dave volunteers to
help
5.00 am 8 dead calves Dave loads the dead calves
on the UNI-LOADER and takes them to the
pit. 6.00 am The cows have just returned from
milking, he quickly TURNS AROUND hoses down the
uniloader, and picks up feed for feeding the cows
17
October 8

• Nothing much happening on the farm.
• The remaining sick calves nursed back to health.
• On October 8th, the children return home.
  Diagnosis Salmonellosis.

October 10

• The veterinarian calls to tell that Salmonella
  from his calves
• is a new type of Salmonella called DT104.

18
October 12

• 4.00 am
• 18 cows in milk are scouring !
• 9.00 am
• Sick cows are moved from the milk barn to the
  maternity /sick pen.
• 11.00 am
• The Vet examines the cows.
• Verdict Salmonellosis.
• 12.00 noon
• Mr. Smith a neighbor, who buys raw milk tells
  Jeff that they are going to host 24 Boy Scouts
  over the weekend on his game farm.

19
October 14

• 9.00 am
• Jeff learns, 18 of 24 boy scouts are
  hospitalized 2 in serious condition.
  
  
  
  
  
• 11.00 am
• The County Health Officer, the State Regulatory
  Veterinarian, The Milk Agent, his Veterinarian,
  FDA and USDA officials come to the farm.
  
  
  
  
  
• 11.30 am
• Herd is to be quarantined, till further notice.

20
All newspapers carry the outbreak story !
Milk makes kids sick Salmonella outbreak
traced to DAIRY farm .. Milk contains bugs that
makes people sick . Scientists say .. Dairy
farming ...... Dairy cows .. All infected with
dangerous bugs Killer bug on the loose dairy
cows responsible
21
How did Salmonella typhimurium DT104 get into
raw milk ?
22
Date Event October 1
Apparently healthy
calves brought
Apparently
clean looking truck
New calves




mixed with
other calves
23
Date Event October 1- 3
Incubation period
for Salmonella
(Children probably
infected) October
4 Clinical symptoms
in calves children

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Date Event October
5 Dead calves loaded onto uniloader
UNI- LOADER IS
CONTAMINATED WITH
SALMONELLA ! Uni-loader hosed down
with water
!!!!! Picks up feed---
FEED IS CONTAMINATED
WITH SALMONELLA !
SALMONELLA
25

• Date Event
• October 5 Cows infected with Salmonella
  Typhimurium DT104
• October 10 Salmonella Typhimurium DT
  104 Multiple antibiotic
  resistance Ampicillin
• Chloramphenicol
• Streptomycin
• Sulfonamides
• Tetracycline
• Incidence increasing in the US
• 3 human outbreaks reported !

26
Date Event October
5-12 Cows infected with Salmonella

27
Date Event October
12- Infected cows contaminate milking
stall, parlor and milk in bulk
tank
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Putting it all together !
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PART TWOWhat should you know about Salmonella ?
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Whats Salmonella ?

• Salmonella is a bacteria
• Rod shaped
• Appears pink to red when stained with Grams
  stain (Gram-negative)
• Belongs to a family Enterobacteriaceae
  (intestinal bacteria)
• Salmonella (genus)
• enterica ( species)
• serovar ( over 2200 serovars)
• Example Salmonella enterica serovar Dublin
  
  
  
  
  S. Dublin

Light Microscope
Electron Microscope
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DANIEL ELMER SALMON, D.V.M. (1850-1914)Father of
disease eradication Pioneer in public health
practice and medical researchDiscoverer of
salmonellaeExperimental Immunologist,
Epidemiologist, AdministratorBureau of Animal
Health Veterinary Medicine and Human Health,
C. W. Schwabe, 1969
Historical Perspective
One of the first veterinary students from Cornell
University, and holder of the first D.V. M.
degree (1876)
32
Where does Salmonella come from ?

• Inhabitant of intestinal tract of
  
  
  
  
  
• animals
• birds
• reptiles
• insects

Host adapted Human S. Typhi Cattle S.
Dublin Poultry S. Pullorum Pigs S.
Choleraesuis Non host adapted S. Typhimurium
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Whats Salmonellosis ?

• When Salmonella causes a physical illness in
  animals or human beings it is termed as
  Salmonellosis

Is Salmonella communicable between animals and
humans ?

• YES !
• Human outbreaks of Salmonellosis in the United
  States are frequently associated with food
  products of animal origin including eggs, meat,
  milk and milk products

38 Outbreaks, 14 (37) traced to products of
bovine origin !
34
Bovine Salmonellosis

• Magnitude of the problem
• National survey
  
• 2.1 fecal samples from 7.4 of farms
• Cull dairy cows
• 4.6 of cull cows (Washington State)
• Neonatal calves
• Ohio- 4.8 farms California- 16 farms
• Missing information
• Estimates of economic losses
• calf and adult cattle
• milk production
• contaminated raw bulk tank milk

Salmonella in raw milk
Wisconsin --- 4.7 Tennessee --- 8.9 South
Dakota - 6.1
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Bovine Salmonellosis

• Common serotypes isolated from cattle in the
  United States
  
  
  
  
  
• S. Dublin - ( group D) -------------
  Most
• S. Typhimurium - ( group B) --- common
• S. Newport
• S. Muenster
• S. Saintpaul
• S. Anatum
• S. Kentucky
• S. Montevideo

36
How does Salmonella gain access to a farm ?
Most important sources of infection
Replacement calves
trucks heifer/ cows
birds /pests feed water
visitors
37
Other routes of entry
38
Salmonella host interaction
Contaminated
feed
water
feces colostrum / milk
Animal
Intestine
OUTCOME ?
Salmonella
Environment
Microscopic picture of small intestine
39
Outcome of an Salmonella infection .
No Salmonella in feces and milk
No clinical signs
Salmonella infrequently present feces and or
milk
SYMPTOMLESS CARRIER
Salmonella present in the body but not excreted
recover
LATENT CARRIER
Fever, diarrhea, bloody stool, dehydration,
anorexia/ emaciation rapid breathing, sloughing
of skin from extremities
Clinical symptoms
Salmonella in feces and or milk
ACTIVE CARRIER
death
40
Salmonella carriers ?

• Animals with Salmonella infection that appear
  healthy and show no signs of disease make
• detection
• diagnosis
• prevention and control
• one of the most difficult tasks to achieve
  and provide the greatest challenges to the animal
  health industry.

ACTIVE CARRIER
LATENT CARRIER
SYMPTOMLESS CARRIER
41
How do healthy animals become infected ?
FECES AND DISCHARGE
Sick
Contamination of 1. Barn/ manure 2. Water
troughs 3. Feed 4. Run off waste 5.
Uni-loader 6. Other equipment
Sick but apparently look healthy
Feces
On farm newly purchased
Direct
Milk
Feces
colostrum
Indirect
Healthy cows
Healthy calves
42
Characteristics of Salmonella and Salmonellosis
--- points to remember
ONE Infection on a farm is maintained
primarily by transmission of Salmonella from
feces of infected animals ACTION Break the
links in the chain by minimizing opportunity for
fecal contamination of feedstuffs, feeding
surfaces, water troughs and equipment
Partly taken from John M. Gay,
Bovine Herd Salmonellosis http//
www.vetmed. wsu.edu / courses-jmgay/
fdiuherdsalmonella.htm
43
TWO Salmonella infection subsequent clinical
disease is a result of

• ACTION Maximize host resistance by paying
  careful attention to the transition of
  susceptible animals (periparturient cows newborn
  calves).

Organism Animal
serotype age
virulence immunity
No. of organisms nutrition
prior exposure
stress
44
THREE Salmonella infects anything in the
livestock environment that has an intestinal
tract

ACTION Initiate control programs 1. Rodent
proof and bird proof feed storage 2. Remove
nesting and roosting opportunities
45
FOUR Majority of Salmonella infections in a herd
over a period of time are symptomlessClinical
infections are only the tip of the iceberg, even
during clinical outbreaks of disease
ICEBERG EFFECT

• ACTION in an outbreak handle all animals as
  if they were shedding not just the sick ones.
  Reduce water and feed contamination.

Clinical Normal Subclinical
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FIVE Some symptomless animals shed Salmonella
through saliva, nasal secretions, urine, milk and
feces

• Such animals POSE THE GREATEST PROBLEM in
  controlling spread of Salmonella infection as
  they contaminate
• water bowls
• nipples
• oral treatment equipment (balling guns,
  esophageal feeders)
• human hands
• ACTION Clean all equipment with Chlorhexidine (
  3 oz. / gal) and other items such as boots and
  mats with orthophenylphenol.

47
SIXSalmonella are usually killed by exposure to
the volatile fatty acids of fully functional
normal rumens
1. Normal Dry Matter Intake 2. Normal VFA
level 3. No Growth of Salmonella in
rumen 1. Lowered Dry Matter Intake 2. Lowered
VFA level 3. Increase in number of Salmonella in
rumen
1. Dont have regular access to feed 2. During
transport 3. Parturition 4. Subclinical
ketosis 5. Hypocalcemia 6. Sudden ration
changes 7. Ration maladaptation 8. Inadequate
bunk space and pen space 9. Mixing submissive
heifers with dominant cows at parturition
ACTION Maximize rumen function by maximizing a
consistent dry matter intake in periparturient
and early fresh cows
48
SEVEN Salmonella survives for long periods under
conditions common on the livestock farm

• Colostrum
• 30 C, 2 to 5 weeks.
• 5 C to 11 C, for 10 days, low pH will reduce
  the number of Salmonella
• Pasture and soil ---- 200 days
• Garden soil ---- 251 days
• Liquid manure --- 27 days ( S. Dublin), --- 286
  days ( S. Anatum)
• Slurry - 84 to 250 days
• Infected feces stored in cans - 159 days ( S.
  Dublin)

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EIGHT People who are at risk of illness

• Farm workers
• Expectant mothers handling sick animals
• Working with sick calves and cows
• Poor personal hygiene
• Consuming raw bulk tank milk
  
  
  
  
  
• Public
• Consuming raw milk, fresh cheese made of raw
  milk.

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NINE Personal hygiene practices on farm
Wash hands with soap and water A must before and
after 1. Attending sick calves and animals 2.
Milking cows ( also wear gloves) 3. Manure
handling
Dress and boots 1. Change into
farm boots on the farm 2. Wash farm boots
regularly 3. Leave farm boots on the farm
4. Wash and disinfect farm clothes
IF available shower before leaving the farm
Avoid drinking raw milk
51
Salmonella Typhimurium DT 104

• Emerging foodborne pathogen
• Detected in several countries
• Why is DT 104 of concern ?
• Multiple antibiotic resistance
• Ampicillin
• Chloramphenicol
• Streptomycin
• Sulfonamides
• Tetracycline
• DT 104 has been isolated from
• poultry, swine, cattle and wild animals

52

• United States
• Humans
• S. Typhimurium 8510 (1990) ------
  9510 (1996)
• S. Typhimurium DT 104 766 (1990) ------ 3138
  (1996)
• Cattle ( Northwest)
• DT 104 No isolations till 1986
• 13 --- 1986 to 1991
• 64 ---1991 to 1996
• Outbreaks ( human) in the US
• 4 ( 3 - west coast, 1- east coast)
• ALL 4 OUTBREAKS LINKED TO UNPASTEURIZED DAIRY
  PRODUCTS
• SOURCE OF DT 104 IN TWO OUTBREAKS, TRACED TO
  DAIRY FARMS

53

• No unique control methods available for S.
  Typhimurium DT 104 in animals.
• Control measures that are effective against other
  types of Salmonella will reduce the likelihood of
  transmission of S. Typhimurium DT 104.

54
Risk factors for Salmonella Typhimurium DT 104

• Cattle in dealer premises were at increased risk
  of disease (Odds ratio 14.25)
• Introduction of newly purchased cattle ( 4 weeks
  after purchase) to the farm increases the risk of
  disease (OR 2.51)
• Purchase via dealers was at high risk as
  compared with purchasing stock directly from
  other farms (OR 3.90)

Evans S., and R. Davies. 1996. Case control study
of multiple - resistant Salmonella typhimurium DT
104 infection of cattle in Great Britian. Vet.
Rec. 139 557558.
55
Risk factors for Salmonella Typhimurium DT 104

• Persistently contaminated buildings may be a
  source of infection (OR 2.48)
• Lack of isolation facilities for ill animals was
  associated with an increased risk of disease
• In particular if cows calved in buildings that
  previously housed diseased stock (OR 1.51)
• A high population density of cats around the farm
  increased the risk of infection (OR 1.35)
• Evidence of access to cattle feed stores by wild
  birds was associated with an increased risk of
  disease (OR 1.67)

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Risk factors for Salmonella Typhimurium DT 104

• Risk factors over which the dairy producer
  can exert control
• 1. Purchasing replacement stock from direct
  sources
  
  
  
  rather than a dealer
• 2. Quarantine of purchased cattle for a 4 week
  period
• 3. Housing sick animals in dedicated isolation
  areas
• 4. Preventing wild bird access to cattle feed
  stores
• 5. Vaccination

57
Typical Scenario-1
No of animals
weeks

• OUTBREAK
• Newly assembled herd, animals from unknown
  source, or from a dealer
• High morbidity ( at least 40 - 60 in the herd
  infected)
• Drop in milk production, 10 , high risk of
  bulk tank milk contamination
• Typically observed with S. Typhimurium, last 2-4
  weeks
• Samples taken during outbreak show extensive herd
  contamination
• Samples collected 4-6 weeks later, most of which
  test negative
• Subsequent outbreaks or infections may be
  sporadic, or may go unnoticed

58
Typical Scenario-2

• Recurrent Salmonella infection in calves and cows
• Cycling of Salmonella in a herd
• Typically seen with Salmonella group D and group
  E
• Presence of animal reservoir or extensive
  environmental contamination
• Hot spots Maternity area, calf housing areas,
  watering troughs
• Identify carriers, massive environmental
  cleanup, put in place appropriate management
  practices.

59

Other Scenarios...
Salmonella detected in milk filters and bulk
tank milk
Pre-fresh and or fresh cows sick
Family member diagnosed with Salmonellosis
after drinking raw milk
Calves and cows you recently sold caused
Salmonellosis
Recurrent diarrhea and loss of calves
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PART THREEStrategies for Prevention and Control
of Salmonellosis
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Principles of Salmonella Control on Dairy Farms

• Herd risk factors
• Larger herd size
• Freestalls
• Recycled-water flush system
• Open herds
• Lack of quarantine facilities
• Rendered-product use
• Concurrent diseases
• Inadequate calf-feeding utensil cleaning

62
Principles of Salmonella Control on Dairy Farms -2

• Individual animal risk factors
• Age ( 3 to 6 week-old calves)
• Starvation/ nutritional deficiencies
• Concurrent diseases
• Poor immunoglobulin levels
• Transport and other stresses
• Manure access

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Principles of Salmonella Control on Dairy Farms -3

• Sources of Salmonella bacteria
• Contaminated feed
• Carrier animals
• Vectors (birds, wild animals, pet animals,
  rodents)

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Principles of Salmonella Control on Dairy Farms -4

• Control measures during a Salmonella outbreak
• Identify sick animals
• Isolate sick animals
• Identify source of bacteria, and if possible
  eliminate
• Prevent reintroduction of the bacteria
• Institute hygiene measures (fecal-oral spread)
• Vaccination ?
• Treatment of infected animals ?

65
Control measures during a Salmonella outbreak -2

• Human health precautions during a Salmonella
  outbreak
• Avoid exposure of young, old, or immune
  compromised people
• Limit number of people handling sick animals
• Avoid having same people handle sick and well
  animals
• Hygienic measures
• foot bath
• handwash
• separate clothes/footwear for sick animal
  handling
• Prevent pet animal exposure to cattle
• DONT DRINK RAW MILK FROM AFFECTED FARM

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END
67
Whole herd outbreak

• 1 General
• A Make sure all farm personnel are made
  aware of the outbreak
• B Discourage all farm visitations and visitors
• C Disinfect
• 1 All soiled work clothes in 500- 1000 PPM
  of chlorine solution, rinse, wash and dry.
• 2 Boots, rinse with high pressure hose and
  soak overnight in orthophenylphenol.

68
Whole herd outbreak

• 2 Secure the milking facility
• A Milker(s) clothes and boots
• B Disinfect boots before entering the milking
  facility
• C Do not milk cows with diarrhea
• D EXTRA PRECUATION DURING CLEANING OF UDDER
  AND TEATS
• E No visitors or other farm personnel

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Whole herd outbreak

• 3 Restrict movement of animals
• A Minimize movement
• B Retain animals within the same barn/ unit
• till laboratory tests tests are negative
• C No visitors

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Whole herd outbreak
clean

• 4 Equipment
• Clean equipment
• Between operations one unit to another
• Same equipment is used for different tasks
• 5 Feed areas
• Remove feed in the feeding alleys at the time of
  outbreak
• Disinfect the feeding alley
• Replenish with fresh feed

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Whole herd outbreak

• Calving area and Calf house
• Remove manure
• Scrap off dry manure and top soil
• Clean wall with sodium triphosphate (1 oz. / gal)
• Spray the floor with same
• Transfer all refuse to a marked area on the farm