salmonella bhushan jayarao extension veterinarian department of veterinary science pennsylvania...
TRANSCRIPT
Salmonella
Bhushan JayaraoExtension Veterinarian
Department of Veterinary Science
Pennsylvania State University
University Park, PA
Salmonella
PART TOPIC________________________________________
1 Case Study: The Hudson Farm
2 What Should You Know About
Salmonella ?
3 Prevention and Control Strategies
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 HudsonOwner Since 1982
Calfbarn
Dry cow& heifer barn
Hudsonhome
Feedbarn
Milk cow barn
Holdingarea
BTR
Milkingparlor
Toolshed
Grazing area
Hudson dairy farm layout
M&S
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
People with whom Jeff interacts …...
Milk Agent Farm Worker Cull Cow Farm Credit Dealer Agent
Banker Salesmen County Ext. Agent Veterinarian
October 1, 7.00 am
Jeff, I have got a deal for you ! How about 3 calvesfor $ 90 ?IF you don’t, I have someone who will take it !
????I’ take it !
Calfbarn
Dry cow& heifer barn
Hudsonhome
Feedbarn
Milk cow barn
Holdingarea
BTR
Milkingparlor
Toolshed
Grazing area
There’s no one to tell him where to put the calves, so he leaves them in the calf barn !!!!!!
M&S
October 45.00 am3 new calves, and 2 other calves have
high temp. and bloody diarrhea …!
8.00 amThe 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”
October 4
This has not been a good day for Jeff !
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.
October 5
5.00 am8 dead calves
Dave loads the dead calves on the UNI-LOADER
and takes them to the pit.
6.00 amThe cows have just returned from milking,
he quickly TURNS AROUND hoses down
the uniloader, and picks up feed for feeding the cows
4.00 amChildren admitted.
Dave volunteers to help
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.
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.
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.
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 bugsKiller bug on the loose …… dairy cows responsible
Date Event
October 1 Apparently healthy calves brought
Apparently clean looking truck
New calves mixed with other calves
Date Event
October 1- 3 Incubation period for Salmonella (Children probably infected)
October 4 Clinical symptoms in calves & children
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
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 !
What’s Salmonella ? Salmonella is a bacteria
Rod shaped Appears pink to red when stained with Gram’s 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
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)
Where does Salmonella come from ? Inhabitant of intestinal tract of
animals
birds
reptiles
insects
Host adapted Human: S. TyphiCattle: S. DublinPoultry: S. PullorumPigs: S. Choleraesuis
Non host adaptedS. Typhimurium
What’s 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 !
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
Wisconsin --- 4.7%Tennessee --- 8.9%South Dakota - 6.1%
Salmonella in raw milk
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
How does Salmonella gain access to a farm ?
Replacement calves trucksheifer/ cows
birds /pests feed water visitors
Most importantsources ofinfection
Salmonella & host interaction
Contaminated
feed
water
feces
colostrum / milk Animal
Salmonella Environment
Intestine
Microscopic picture of small intestine
OUTCOME ?
Outcome of an Salmonella infection ….
Clinical symptoms
No clinical signs
recover
death
No Salmonella in feces and milk
Salmonella infeces and or milk
Salmonella present in the body but not excreted
Salmonella infrequently present feces and or milk
ACTIVE CARRIER
SYMPTOMLESS CARRIER
LATENT CARRIER
Fever, diarrhea, bloody stool,dehydration, anorexia/ emaciation rapid breathing, sloughing of skin from extremities
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.
LATENT CARRIER
SYMPTOMLESS CARRIER
ACTIVE CARRIER
How do healthy animals become infected ?
Feces
Contamination of: 1. Barn/ manure 2. Water troughs 3. Feed 4. Run off waste 5. Uni-loader 6. Other equipment
FECES AND DISCHARGE
Healthy cows
DirectIndirect
Sick but apparently look healthy
Sick
On farm newly purchased
colo
strum
Milk
Feces
Healthy calves
“Characteristics of Salmonella and Salmonellosis --- points to remember”*
* Partly taken from: John M. Gay, Bovine Herd Salmonellosishttp://www.vetmed. wsu.edu / courses-jmgay/ fdiuherdsalmonella.htm
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
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
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
FOUR: Majority of Salmonella infections in a herd over a period of time are symptomless
Clinical infections are only the tip of the iceberg, even during clinical outbreaks of disease
ACTION: in an outbreak handle all animals as if they were shedding not just the sick ones. Reduce water and feed contamination.
ICEBERG EFFECT
Clinical
Normal
Subclinical
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.
SIX:Salmonella are usually killed by exposure to the volatile fatty acids of fully functional normal rumens
1. Normal Dry Matter Intake2. Normal VFA level3. No Growth of Salmonella in rumen
1. Lowered Dry Matter Intake2. Lowered VFA level3. Increase in number of Salmonella in rumen
1. Don’t have regular access to feed2. During transport3. Parturition4. Subclinical ketosis5. Hypocalcemia6. Sudden ration changes7. Ration maladaptation8. Inadequate bunk space and pen space9. Mixing submissive heifers with dominant cows at
parturition
ACTION: Maximize rumen function by maximizinga consistent dry matter intake in periparturient andearly fresh cows
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)
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.
EIGHT: People who are at risk of illness
Wash hands with soap and water A must before and after:1. Attending sick calves and animals2. 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
NINE: Personal hygiene practices on farm
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
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
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.
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 :557:558.
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)
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
Typical Scenario-1
0
10
20
30
40
50
60
w1 w2 w3 w4 w5 w6 w7 w8 w9 w10
No of cows
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
No of animals
weeks
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.
0
2
4
6
8
10
Jan
Mar
May Ju
l
Sep
Nov
% calves
% calves
% cows
Recurrent diarrhea and
loss of calves Recurrent diarrhea and
loss of calves
Pre-fresh and orfresh cows sick
Pre-fresh and orfresh cows sick
Family member diagnosed with
Salmonellosis afterdrinking raw milk
Family member diagnosed with
Salmonellosis afterdrinking raw milk
Salmonella detected in milk filters and bulk tank milk
Salmonella detected in milk filters and bulk tank milk
Other Scenarios...
Calves and cows you recently sold caused
Salmonellosis
Calves and cows you recently sold caused
Salmonellosis
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
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
Principles of Salmonella Control on Dairy Farms -3
Sources of Salmonella bacteria Contaminated feed Carrier animals Vectors (birds, wild animals, pet
animals, rodents)
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 ?
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 DON’T DRINK RAW MILK FROM AFFECTED FARM
1 GeneralA 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.
Whole herd outbreak Whole herd outbreak
2 Secure the milking facilityA 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
Whole herd outbreak Whole herd outbreak
3 Restrict movement of animalsA Minimize movement
B Retain animals within the same barn/ unit
till laboratory tests tests are negative
C No visitors
Whole herd outbreak Whole herd outbreak
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
Whole herd outbreak Whole herd outbreak
clean