Salmonella Bhushan Jayarao Extension Veterinarian Department of Veterinary Science Pennsylvania State 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
Hudson Farm
Meet the Hudsons ! Linda Mary Fred Jeff Dave Susan John
The Hudson Dairy Farm l History n n n l 1920 - Established 1956 - Upgraded 1981 - New structures & equipment Employees n n n Jeff Hudson, owner 1 farm worker 1 milker Dave, Linda, Fred Susan & John feed the calves Jeff Hudson Owner Since 1982
Dry cow & heifer barn Calf barn M&S Milk cow barn Holding area Feed barn B T R Hudson home Milking parlor Tool shed Grazing area Hudson dairy farm layout
Dairy Herd Statistics l HERD PERFORMANCE t l DAIRY CATTLE t Grade A milk t t t 4600 - 4800 lbs of milk per day t No antibiotic residue violations t BTMSCC: 200, 000 - 500, 000 last year. t l 12 calves 19 dry cows 20 heifers 87 cows in milk OTHER ANIMALS t 4 stray cats 2 dogs 1 pony 3 ducks and 8 chickens
People with whom Jeff interacts …. . . Milk Agent Banker Farm Worker Salesmen Cull Cow Dealer County Ext. Agent Farm Credit Agent Veterinarian
October 1, 7. 00 am Jeff, I have got a deal for you ! How about 3 calves for $ 90 ? IF you don’t, I have someone who will take it ! ? ? I’ take it !
October 1, 10. 00 am
M&S Dry cow & heifer barn Calf barn Milk cow barn Holding area Feed barn B T R Hudson home There’s no one to tell him where to put the calves, so he leaves them in the calf barn !!!!!! Milking parlor Tool shed Grazing area
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”
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 !
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
October 8 l Nothing much happening on the farm. l The remaining sick calves nursed back to health. l On October 8 th, the children return home. Diagnosis: Salmonellosis. October 10 l The veterinarian calls to tell that Salmonella from his calves is a new type of Salmonella called DT 104.
October 12 l 4. 00 am t 18 cows in milk are scouring ! 9. 00 am l Sick cows are moved from the milk barn to the maternity /sick pen. 11. 00 am l t t l The Vet examines the cows. Verdict: Salmonellosis. 12. 00 noon t 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 l 9. 00 am l Jeff learns, 18 of 24 boy scouts are hospitalized & 2 in serious condition. 11. 00 am l The County Health Officer, the State Regulatory Veterinarian, The Milk Agent, his Veterinarian, FDA and USDA officials come to the farm. 11. 30 am t t t Herd is to be quarantined, till further notice.
All newspapers carry the outbreak story ! Milk makes kids sick ……… Salmonella outbreak traced to da. Ir. Y 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
How did Salmonella typhimurium DT 104 get into raw milk ?
Date October 1 Event Apparently healthy calves brought Apparently clean looking truck New calves mixed with other calves
Date October 1 - 3 Event Incubation period for Salmonella (Children probably infected) October 4 Clinical symptoms in calves & children
Date October 5 Event 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 DT 104 October 10 Salmonella Typhimurium DT 104 Multiple antibiotic resistance: Ampicillin Chloramphenicol Streptomycin Sulfonamides Tetracycline Incidence increasing in the US 3 human outbreaks reported !
Date October 5 -12 Event Cows infected with Salmonella
Date October 12 - Event 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 ? n Salmonella is a bacteria Rod shaped u Appears pink to red when stained with Gram’s stain (Gram-negative) u Light Microscope u Belongs to a family; Enterobacteriaceae (intestinal bacteria) Electron Microscope F Salmonella (genus) F enterica ( species) F serovar ( over 2200 serovars) Example: Salmonella enterica serovar Dublin S. Dublin
Historical Perspective One of the first veterinary students from Cornell University, and holder of the first D. V. M. degree (1876) DANIEL ELMER SALMON, D. V. M. (1850 -1914) Father of disease eradication Pioneer in public health practice and medical research Discoverer of salmonellae Experimental Immunologist, Epidemiologist, Administrator Bureau of Animal Health [ Veterinary Medicine and Human Health, C. W. Schwabe, 1969]
Where does Salmonella come from ? n Inhabitant of intestinal tract of u animals u birds Host adapted Human: S. Typhi Cattle: S. Dublin Poultry: S. Pullorum Pigs: S. Choleraesuis Non host adapted S. Typhimurium u reptiles u insects
What’s Salmonellosis ? n When Salmonella causes a physical illness in animals or human beings it is termed as Salmonellosis Is Salmonella communicable between animals and humans ? YES ! n 38 Outbreaks, 14 (37%) traced to products of bovine origin ! Human outbreaks of Salmonellosis in the United States are frequently associated with food products of animal origin including eggs, meat, milk and milk products
Bovine Salmonellosis n Magnitude of the problem u National Salmonella in raw milk F 2. 1% u Cull survey fecal samples from 7. 4% of farms dairy cows F 4. 6% of cull cows (Washington State) u Neonatal F Ohio- Wisconsin --- 4. 7% Tennessee --- 8. 9% South Dakota - 6. 1% u calves 4. 8% farms; California- 16 % farms Missing information F Estimates of economic losses • calf and adult cattle • milk production • contaminated raw bulk tank milk
Bovine Salmonellosis n Common serotypes isolated from cattle in the United States u S. Dublin - ( group ‘D’) ------u S. Typhimurium - ( group ‘B’) --u S. Newport u S. Muenster u S. Saintpaul u S. Anatum u S. Kentucky u S. Montevideo Most common
How does Salmonella gain access to a farm ? Most important sources of infection Replacement heifer/ cows birds /pests calves feed trucks water visitors
Other routes of entry
Salmonella & host interaction Contaminated feed water feces Animal colostrum / milk Intestine OUTCOME ? Salmonella Environment Microscopic picture of small intestine
Outcome of an Salmonella infection …. No Salmonella in feces and milk No clinical signs Salmonella infrequently present feces and or milk SYMPTOMLESS CARRIER recover Salmonella present in the body but not excreted LATENT CARRIER Fever, diarrhea, bloody stool, dehydration, anorexia/ emaciation rapid breathing, sloughing of skin from extremities Clinical symptoms death Salmonella in feces and or milk ACTIVE CARRIER
Salmonella carriers ? n ACTIVE CARRIER LATENT CARRIER SYMPTOMLESS CARRIER 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.
How do healthy animals become infected ? Sick FECES AND DISCHARGE Sick but apparently look healthy Feces On farm colostrum Feces Milk Healthy calves Contamination of: 1. Barn/ manure 2. Water troughs 3. Feed 4. Run off waste 5. Uni-loader 6. Other equipment newly purchased Direct Indirect Healthy cows
“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
TWO: Salmonella infection & subsequent clinical disease is a result of : n ACTION: Maximize host resistance by paying careful attention to the transition of susceptible animals (periparturient cows newborn calves). Organism * serotype * virulence * No. of organisms Animal * age * immunity * 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 ICEBERG EFFECT 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. Clinical Normal Subclinical
FIVE : Some symptomless animals shed Salmonella through saliva, nasal secretions, urine, milk and feces n n Such animals POSE THE GREATEST PROBLEM in controlling spread of Salmonella infection as they contaminate u water bowls u nipples u oral treatment equipment (balling guns, esophageal feeders) u human hands ACTION: Clean all equipment with Chlorhexidine ( 3 oz. / gal) and other items such as boots and mats with orthophenylphenol.
1. 2. 3. Normal Dry Matter Intake Normal VFA level No Growth of Salmonella in rumen 1. 2. 3. Lowered Dry Matter Intake Lowered VFA level Increase in number of Salmonella in rumen SIX: Salmonella are usually killed by exposure to the volatile fatty acids of fully functional normal rumens 1. 2. 3. 4. 5. 6. 7. 8. 9. Don’t have regular access to feed During transport Parturition Subclinical ketosis Hypocalcemia Sudden ration changes Ration maladaptation Inadequate bunk space and pen space 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
SEVEN: Salmonella survives for long periods under conditions common on the livestock farm n Colostrum u u n n n 30 C, 2 to 5 weeks. 5 C to 11 C, for ~ 10 days, low p. H 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)
EIGHT: People who are at risk of illness n Farm workers F Expectant mothers handling sick animals F Working with sick calves and cows F Poor personal hygiene F Consuming raw bulk tank milk n Public F Consuming raw milk, fresh cheese made of raw milk.
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
Salmonella Typhimurium DT 104 n n n Emerging foodborne pathogen Detected in several countries Why is DT 104 of concern ? u Multiple antibiotic resistance Ampicillin F Chloramphenicol F Streptomycin F Sulfonamides F Tetracycline F n DT 104 has been isolated from; u poultry, swine, cattle and wild animals
n United States u Humans F S. Typhimurium: 8510 (1990) ------ 9510 (1996) F S. Typhimurium DT 104: 766 (1990) ------ 3138 (1996) u Cattle F ( Northwest) DT 104: No isolations till 1986 • 13% --- 1986 to 1991 • 64% ---1991 to 1996 n Outbreaks ( human) in the US: u 4 ( 3 - west coast, 1 - east coast) F F ALL 4 OUTBREAKS LINKED TO UNPASTEURIZED DAIRY PRODUCTS SOURCE OF DT 104 IN TWO OUTBREAKS, TRACED TO DAIRY FARMS
n n 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 n n n 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 n n 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 u n n 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 exert control: dairy producer can 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 OUTBREAK No of animals weeks • 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
Typical Scenario-2 n Recurrent Salmonella infection in calves and cows u u u 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.
Other Scenarios. . . Salmonella detected in milk filters and bulk tank milk Pre-fresh and or fresh cows sick Calves and cows you recently sold caused Salmonellosis Family member diagnosed with Salmonellosis after drinking raw milk Recurrent diarrhea and loss of calves
PART THREE Strategies for Prevention and Control of Salmonellosis
Principles of Salmonella Control on Dairy Farms n Herd risk factors u Larger herd size u Freestalls u Recycled-water flush system u “Open” herds u Lack of quarantine facilities u Rendered-product use u Concurrent diseases u Inadequate calf-feeding utensil cleaning
Principles of Salmonella Control on Dairy Farms -2 n Individual animal risk factors u Age ( 3 to 6 week-old calves) u Starvation/ nutritional deficiencies u Concurrent diseases u Poor immunoglobulin levels u Transport and other stresses u Manure access
Principles of Salmonella Control on Dairy Farms -3 n Sources of Salmonella bacteria u Contaminated feed u Carrier animals u Vectors (birds, wild animals, pet animals, rodents)
Principles of Salmonella Control on Dairy Farms -4 n Control measures during a Salmonella outbreak u Identify sick animals u Isolate sick animals u Identify source of bacteria, and if possible eliminate u Prevent reintroduction of the bacteria u Institute hygiene measures (fecal-oral spread) u Vaccination ? u Treatment of infected animals ?
Control measures during a Salmonella outbreak -2 n Human health precautions during a Salmonella outbreak u u u 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 F foot bath F handwash F separate clothes/footwear for sick animal handling Prevent pet animal exposure to cattle DON’T DRINK RAW MILK FROM AFFECTED FARM
Whole herd outbreak 1 General A B C Make sure all farm personnel are made aware of the outbreak Discourage all farm visitations and visitors Disinfect 1 2 All soiled work clothes in 500 - 1000 PPM of chlorine solution, rinse, wash and dry. Boots, rinse with high pressure hose and soak overnight in orthophenylphenol.
Whole herd outbreak 2 Secure the milking facility A B C D E Milker(s) clothes and boots Disinfect boots before entering the milking facility Do not milk cows with diarrhea EXTRA PRECUATION DURING CLEANING OF UDDER AND TEATS No visitors or other farm personnel
Whole herd outbreak 3 Restrict movement of animals A B C Minimize movement Retain animals within the same barn/ unit till laboratory tests are negative No visitors
Whole herd outbreak clean 4 Equipment F Clean equipment F Between operations; one unit to another F Same equipment is used for different tasks 5 Feed areas F Remove feed in the feeding alleys at the time of outbreak F Disinfect the feeding alley F Replenish with fresh feed
Whole herd outbreak n Calving area and Calf house u Remove manure u Scrap off dry manure and top soil u Clean wall with sodium triphosphate (1 oz. / gal) u Spray the floor with same u Transfer all refuse to a marked area on the farm
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