Vdpam 445 swine topics respiratory disease control
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VDPAM 445 Swine Topics Respiratory Disease Control. Dr. Alex Ramirez Veterinary Diagnostic and Production Animal Medicine Iowa State University. General introduction. Endemic Pneumonia. App- continual outbreaks, chronic pleuropneumonia Sometimes other bacteria as well Enzootic Pneumonia

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VDPAM 445Swine TopicsRespiratory Disease Control

Dr. Alex Ramirez

Veterinary Diagnostic and Production Animal Medicine

Iowa State University


General introduction


Endemic Pneumonia

  • App- continual outbreaks, chronic pleuropneumonia

    • Sometimes other bacteria as well

  • Enzootic Pneumonia

    • Mycoplasma hyopneumoniae

    • Pasteurella multocida

  • Porcine Respiratory Disease Complex

    • All of the above (especially M. hyo)

    • PRRSV

    • SIV

    • Others: PCV2, PRV, H. parasuis, S. suis,


Diagnostics

  • Gross pathology: APP versus all others

    • APP & A. suis vs. others

  • Organism identification

    • Culture

    • FA

    • PCR

    • IHC: immunohistochemistry (with histopath)

      • Fixed tissue, easy sample preservation

  • Histopath

    • Prove disease, organism presence is insufficient


Question: Is this mycoplasma?


Diagnostics

  • Serology: serological profiling

    • Timing of infection but not necessarily timing of disease

  • Sampling issues

    • Tissue preservation in formalin

      • Buffered

      • Multiple sites

      • <1cm tissue thickness

    • Number of animals

      • Example on next slide

    • Sick (necropsy) versus healthy (slaughter checks)


Diagnostic Sampling Strategies

  • Small numbers of pigs will result in missed diagnosis

    • PRDC case: 21 pigs submitted for necropsy

    • Pathology/microbiology:

      • No lesions =5Gastric ulcer = 2

      • PMWS = 5PRRSV = 2

      • SIV? = 1APP? = 3 (non-typeable)

      • P. mult. = 2Bordetella = 2

      • Strep suis = 1M. hyo = 8

  • Serology: M. hyo+, SIV+, PRRSV (late +)

  • Slaughter check: Low average percent pneumonia, a few pigs severe


Diagnostic Considerations: Value of Tests

  • Laboratory tests should fit with clinical observations

    • Pigs cough: Pursue rule-outs (M. hyo, influenza)

    • Pigs grow slowly without overt disease - diets/environment?

  • Specific versus non-specific tests

    • Necropsy and slaughter exams (disease severity)

    • Laboratory tests (agent identification)

    • Record analysis (rarely identifies a specific cause)

  • Documenting management activities

    • “Gum shoe” approach

      • One revealing observation is often worth more than 100 serological tests

      • SOP vs. Actual


Mycoplasma hyopneumoniae


Mycoplasma hyopneumoniae

  • Primary cause of enzootic pneumonia

    • Most herds are infected except SPF herds

  • Transmission is via aerosol

    • Air is PCR positive

    • Difficult to prevent between herd spread

  • Disease often manifested in finishing

    • Organism very slow to grow (weeks)

    • A few get infected from sows  spreads slowly through nursery pigs

    • Lateral transmission from older pigs


Mycoplasma hyopneumoniae

  • Diagnosis

    • Clinical signs: only cough 10 days after challenge

      • Severe sickness with infection of SPF herds?

      • Mild - minimal consequence in otherwise disease free pigs

    • Macroscopic lesions

      • Anterior-ventral consolidation

      • Not specific to M. hyo


Mycoplasma hyopneumoniae


Mycoplasma hyopneumoniae

  • Diagnosis

    • Histopathology:

      • peribronchiolarlymphocytic cuffing

    • Organism ID

      • FA- need fresh tissue, approx. 50% sensitivity

      • Culture - slow grow, overgrowth by M. hyorhinis

      • PCR - “It’s everywhere”

      • IHC

    • Serology: several ELISA’s available

      • Vaccination will also induce titers that persist for a short time


Mycoplasma Vaccination

  • Second most common vaccine used in growing pigs

    • Common in population

    • Potentiator of other respiratory disease

  • Issues

    • Mandatory (?) in herds with continuous flow, multiple rooms within the same building, virulent PRRSV

    • One vs. two dose products

      • Use one dose in “controlled” situations or if labor is a big concern

      • Two doses will almost always be better

      • Start early (3weeks)

      • Product cost is usually equal

      • Many combine with PCV2 vaccination


Mycoplasma Vaccination

  • Maternal antibody interference

    • Probably will not interfere with vaccine induced protection

    • No real reason to vaccinate sows pre-farrow

      • Only vaccinate gilts before entering herd

  • PRRS eradication  Mycoplasma eradication

    • Consider where pigs will be grown and finished

    • May still need to vaccinate pigs


M. hyo Treatment plan

  • Antibiotics?

    • Now

    • Earlier

    • Routes

      • Water

      • Feed

      • Injectable

  • Control other diseases

  • Vaccination

    • Other groups

    • Timing – watch for PRRS seroconversion


Actinobacillus pleuropneumoniae(APP)


Actinobacillus pleuropneumoniae (APP)

  • Cause of contagious pleuropneumonia

  • Transmission by close contact and short distance aerosols

  • Many pigs harbor organism in upper airways

    • Clinical disease occurs with environmental stress in many cases

      • Malfunctioning curtain controller  temperature fluctuation  organism gains entrance to lung  severe (bad), rapidly developing necrotizing and hemorrhagic pneumonia with pleuritis


Actinobacillus pleuropneumoniae (APP)

  • Clinical signs

    • Sudden death

    • Sudden onset of rapid, deep breathing

    • Minimal cough (not an airway irritant)

    • Fever initially or if mild-to-moderate; subnormal in severely affected pigs

    • Hemoptosis and blood from nostrils in agonal phase (euthanize if possible)

    • Mortality can reach 10% of barn in one day

    • Pigs quit eating AND DRINKING


Actinobacillus pleuropneumoniae (APP)

  • Post-mortem lesions

    • Necrotizing, hemorrhagic, usually multi-focal pneumonia

    • Pleuritis will be present if pig survives for at least 18 hours after challenge

    • Similar lesions can be seen with Actinobacillus suis

    • If APP  mass treatment via injection often indicated; other types of pneumonia treated less aggressively; can’t wait for test results to start therapy


Actinobacillus pleuropneumoniae (APP)


Actinobacillus pleuropneumoniae (APP)

  • Diagnosis

    • Initially: clinical signs and gross pathology

    • Culture: isolation followed by capsular serotyping

      • Some relationship between capsular serotype and virulence: Type 1’s are worst; followed by 5’s

      • USA: 1, 5, 7 and 3 are most common (odd numbers)

      • Europe: 2 and 6 are most common

    • Serology

      • Complement fixation: recent infection

      • ELISA’s: capsule, endotoxin, cross-reactivity problems

      • Hemolysin neutralization: cross-reactions with A. suis


APP Vaccination

  • Most commercial vaccines are bacterins

    • Administer 2X at 2-4 week interval prior to finishing

    • Capsular serotypes must be matched

      • Use autogenous vaccines if:

        • Commercial vaccines don’t contain the correct serotype

        • May have within serotype heterogeneity

    • Marginally effective: lack ApX toxins which are the main virulence factors for causing disease

    • Side effect potential:

      • Injection site reactions

      • Fever, off-feed, reduced daily gain


APP Vaccination

  • Newer vaccines

    • Capsular deficient mutant (MLV): BINOBL

      • Given IM

      • Frozen product: order, shipped on dry ice, use immediately

      • Limited replication at injection site

      • Sufficient production of ApX toxins to induce a protective immune response

    • Riboflavin deficient mutant

      • Not commercially available

      • Knock out riboflavin synthetase

      • Add riboflavin to organism and inject IM


APP Treatment Plan

  • Antibiotics

    • YES!! ASAP

      • INJECTABLE

      • Water

      • Feed

    • Duration of treatment

  • Ventilation

  • Vaccination ?

  • Different source of pigs


Actinobacillus suis


Actinobacillus suis

  • Will behave like APP but less severe and short term

  • Problem with “healthier” herds

  • Generalized septicemia like H. parasuis, erysipelas

  • Produces Type I hemolysin

  • No commercial vaccines available

  • Autogenous vaccines used in refractory cases


A. suis Treatment Plan

  • Antibiotics

    • APP vs A. suis need immediate action

    • Sources

      • Injectable

      • Water

      • Feed ???

  • Correct diagnosis is critical

  • Vaccination with autogenous??


Pasteurella multocida


Pasteurella multocida Pneumonia

  • Not a primary cause of pneumonia

    • Experimental infection only with active M. hyo infection present

    • “Fuzzy thinking”: not important because secondary pathogen but primary causes are nearly always present!!

      • Medication of pigs with non-App pneumonia is mostly directed at P. multocida

        • Acute swine influenza outbreaks

        • Enzootic pneumonia or PRDC

        • Environmental mishaps


Pasteurella multocida Pneumonia

  • Little known about pathogenesis

    • Studies just beginning

    • Generally Type A, non-AR toxin producing

    • Normal inhabitant of upper airways

  • Can cause pleuritis

  • Diagnosis

    • Culture and sensitivity

    • Sort out primary causes


P. multocida Treatment Plan

  • Antibiotics

    • Injectable

    • Water

    • Feed

  • Environment – Ventilation

  • Address other diseases

    • PRRS

    • Mycoplasma

    • Etc.


Atrophic Rhinitis(AR)


Atrophic Rhinitis

  • Bordetella bronchiseptica

    • Causes atrophic rhinitis

    • Enables P. multocida to colonize nasal epithelium

  • Pasteurella multocida

    • Causes progressive atrophic rhinitis

    • Produces AR toxin (dermatonecrotoxin)

      • Highly potent: inject small quantity  turbinate atrophy

    • Mainly capsular Type D but also Type A


Atrophic Rhinitis

  • Clinical signs

    • Deviated snout: side ways or pushed up

    • Tear staining at medial canthus

    • Sneezing

    • Bleeding from nostrils

  • Lesions

    • Turbinate atrophy: primarily ventral scroll of ventral turbinate

    • Septal deviation


Atrophic Rhinitis


Atrophic Rhinitis

  • Severity influenced by:

    • Air quality and environment; especially in nurseries

    • Genetics

      • Yorkshires more susceptible to developing severe lesions

    • Age of sow herd: immunity of dams

      • Colostral antibody levels

      • Level of shedding  vertical transmission

      • Age at infection

    • Weaning age: <14 days eliminates vertical transmission


Atrophic Rhinitis

  • Stepwise approach

    • Sow vaccination pre-farrowing

      • Gilts pre-breeding is always recommended

    • LA200 (200 mg/ml oxytetracycline) to piglets

      • 15 mg/# dose

      • 1, 7, 14, 21 days or 1, 7-10, weaning

    • Naxcel (2 mg/# dose) instead of LA200

      • No benefit against Bordetella bronchiseptica

    • Vaccinate pigs

      • Two doses: 7 days and weaning

      • One dose: weaning


AR Treatment Plan

  • Antibiotics

    • Water

    • Feed

    • Injectable

  • Prevention

    • Antibiotics

    • Vaccination

  • Environment


Psuedorabies(Aujesky’s or PRV)


Pseudorabies Virus

  • Eradicated from the USA commercial herds in late 2003 to early 2004

  • Respiratory disease in any age pigs in addition to CNS signs in neonates and reproductive disease in sows

  • Occasional necrotic rhinitis  crusty nose and nasal discharge

  • Important rule-out (along with SIV and PRRS) for sow herd off-feed

    • Will have fever


PRV Vaccination

  • Vaccines were highly effective

  • Regulatory based vaccination in Stage II areas

    • Vaccinated sow herd 4 times per year- IM

    • Vaccinated pigs once IM by 12 weeks of age

  • In herds with active infections

    • Vaccinated pigs at birth intra-nasally

      • Used vaccines that were approved for IN use, must replicate in the nasal epithelium to be effective

    • Vaccinated pigs twice IM

  • Vaccine reduced shedding in individual pigs

    • Can stop shedding on a population basis


PRV Eradication

  • Blanket vaccination to reduce/eliminate shedding and transmission

  • Improve internal biosecurity

    • AIAO production

    • People, equipment movement

  • Improve external biosecurity

    • Hog truck sanitation

  • Monitor closely via serology to determine where failure (active infection) is occurring


Other Viruses


Other Viruses

  • PRCV

    • Mild respiratory disease in young pigs

    • Natural deletion mutant of TGE virus

      • Can’t attach to intestinal epithelium

    • Significance ?????

      • Test cross reacts with TGE

  • Inclusion body rhinitis

    • Porcine cytomegalovirus

    • Common disease in early nursery pigs

    • High pitched sneezing

    • Minimal clinical impact if no other problems

    • Severely affected will develop necrotic rhinitis


Other bacteria


Other bacteria

  • Will be discussed in other sections

  • Salmonella cholerasuis

    • Interstitial pneumonia – Wet lung

    • Septicemia – purple pigs

    • +/- diarrhea

  • Steptococcus suis

    • Cranioventral consolidation

  • Haemophilus parasuis


Agents Discussed in future


Swine Influenza(SIV)


Swine Influenza Virus (SIV)

  • Type A influenza virus

  • H1N1: traditional strain in US

  • H3N2: new strain in US 1998

    • Present in Europe for many years

    • Some evidence for presence in US before

    • Spread throughout country in 2-3 years

  • H1N2: Detected in Indiana 1999

    • Combination of H1N1 and H3N2

  • Others: Exposure to water fowl  outbreak limited to a one or a few herds


Swine Influenza Virus (SIV)

  • Clinical signs

    • Short term disease: <4-7 days

    • Fever: variable

    • Respiratory signs: 1-2 days after challenge

      • Increased rate

      • “Thumps”: abdominal breathing

      • “Wet Cough”: minimal with pure infection

  • Gross lesions

    • Look like M. hyo


Answer: SIV


SIV Vaccination

  • Strains: H1N1 (traditional), H3N2 (new)

  • Sow herd vaccination: common, concerns?

  • Pig vaccination

    • Two doses recommended, often one dose given

    • Relatively high cost

    • Multivalent vaccines and/or autogenous

    • Role of maternal antibody interference

      • Vaccinate sows pre-farrowing  protective titers until 12 weeks of age

      • MDA’s may interfere until 8-10 weeks of age  small time frame to vaccinate

    • Original antigenic sin


Porcine Reproductive and Respiratory Syndrome Virus (PRRS)

Discussed in another lecture


Circovirus(PCV2 & PCVAD)

See Dr. Baker’s Lecture


Porcine Circovirus Type II

  • Type I: cause of infectious congenital tremors?; porcine cell line contaminant

  • Type II: Cause of PCVAD (Porcine Circovirus Associated Disease); old name = PMWS (post-weaning multi-systemic wasting syndrome)

    • Depletion of germinal centers in lymph nodes and Peyer’s patches are characteristic lesions

      • Much virus located in these tissues

      • Virus also present in normal pigs and tissues

      • Lesions like PRRS

    • Disease in US: PRRS associated, mild, older pigs

    • Disease in Europe: devastating, younger animals


PCV2

  • Small DNA virus none-enveloped

    • Hard to disinfect

  • Present in most pigs

    • Exposure is VERY common

    • Negative herds ???

  • Concern with present case definition (PMWS/PCVAD)

    • Wasting

    • Lymphoid depletion

    • PCV2

  • Excellent web site  www.pcv2.org


Vaccines

  • Just on the market in 2006

  • In Europe have had a vaccine from Merial but for sows only!

  • ISU involved in development of one vaccine (chimeric with Fort Dodge)

  • Results?

    • So far looking VERY PROMISSING!


PCV Vaccines


PCVAD is usually seen in 4-10 week old pigs in Canada and Europe

PCVAD is typically seen in the 10-20 week old pigs in the US

-Morbidity 2-25%

-Mortality 1-10%

Courtesy Dr. J. Harding


Markedly enlarged inguinal lymph nodes are commonly observed in pigs with PCVAD


Porcine Dermatitis and Nephropathy Syndrome (PDNS)

Etiology unknown

PRRS

PCV2

PRRSV + PCV2

P. multocida

Streptococcus sp.


PCV2 coinfections in 484 U.S. field cases: ISU-VDL

164

180

160

140

120

92

77

100

Number of Cases

68

80

60

37

40

13

11

10

9

3

20

0

PCV2+SIV

PCV2 Alone

PCV2+M. hyo.

PCV2+ Others

PCV2+PRRSV

PCV2+SIV +M.hyo.

PCV2+PRRSV+SIV

PCV2+PRRSV +M.hyo.

PCV2+Bacterial pneumonia

PCV2+Bacterial septicemia

Rarely see PCV2 singular infection


PCV2 Treatment Plan

  • Vaccination

    • Earlier the better

  • Work on co-infections!


Acknowledgements

  • I would like to recognize others for their significant contributions to this presentation:

    • Dr. Brad Thacker

    • Dr. Locke Karriker

    • Dr. Pat Halbur


Questions ?


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