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

PART ONE

Hudson Farm: a Case Study

The Hudson Farm

Hudson Farm

Meet the Hudsons !

Fred

Dave

Linda

Jeff

Mary

Susan John

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 !

October 1, 10.00 am

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

How did Salmonella typhimurium DT104

get into raw milk ?

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 !

Date EventOctober 5-12 Cows infected with Salmonella

Date EventOctober 12- Infected cows contaminate milking

stall, parlor and milk in bulk tank

Putting it all together !

PART TWO

What should you know about

Salmonella ?

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

Other routes of entry

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

PART THREE

Strategies for Prevention and Control of 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

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

Whole herd outbreak Whole herd outbreak