First Asian PigElite® Tour

Thomas Gillespie, DVM, Thomas Gillespie, DVM, Diplomate ABVPDiplomate ABVP

Rensselaer Swine Services, Rensselaer Swine Services, Rensselaer, INRensselaer, IN

tom.gillespie@rssvet.comtom.gillespie@rssvet.com

www.rssvet.com

Demographics

100 Million Pigs

5.5 Million Sows

U.S. Pork Industry Structure Study, 2003

University of Missouri, Iowa State University, Pork magazine, Pig Improvement Company, National Pork Board, Monsanto Choice Genetics, and Land O’ Lakes.

Firm size

(thousand head mktd. annually)

Number of operations Market share

Less than 1 59,950 1%

1 - 3 6,630 8%3 - 5 950 4%

5 - 10 1,526 9%

10 - 50 915 19% 50 - 500 134 19%

500+ 25 40%Total 70,130 100%

Estimated Total Number of Operations & Share of U.S. Slaughter in 2003

by Size Category

Biggest barriers of swine production

PRRSPCVADMycoplasma

hyopneumoniae

What is the AASV doing The American Association of Swine Veterinarian

organization is taking several steps to confront two deadly diseases: PRRS and PCVAD affecting hog farms.

Formed PRRS committee Formed the PRRS Eradication Task Force Formed a Committee on PCVAD to develop a plan

of action and educate members Plans to offer the PRRS risk-assessment tool from

Boehringer Ingelheim for free to members to implement on their clients’ farms

AASV activities The AASV will continue to support the

country's core PRRS research initiative, the PRRS Coordinated Agricultural Project through the Department of Agriculture and the National Pork Board. The USDA National Research Initiative has committed about $4.4 million to the project, and the National Pork Board has committed about $2 million in Pork Check-off funding

the AASV is positioning itself for a leadership role in eradicating the disease by adoption of the following statement:

Porcine reproductive and respiratory syndrome (PRRS) is a significant production-limiting disease of swine that is estimated to cost the US industry approximately 560 million dollars per year. Control of the disease via traditional methods has not been effective in all cases; therefore, it is the position of the AASV that eradication of the disease from the North American swine industry is the long term goal. The AASV will take a leadership role by partnering with the swine industry to promote collaborative PRRS eradication efforts at the local, regional, and national levels, communicating the need and identifying sources of funding to support such initiatives, and assisting in the transfer of new PRRS-related information and technology across its membership, in order to achieve this goal.

PRRSV and PCV2

‘A Terrible Gang of Two’

PRRSv: A very complex problem A quick review of PRRS virus

Where it multiplies Properties of the virus Sow herd infection Grow finish animal infection Symptoms Transmission and circulation of virus

Control methods Co-infections and what does this mean

enveloped RNA-Virus of the family Arteriviridae very sensitive virus outside of host (low tenacity)

The PRRS Virus

50-60 nm

Nukleocapsid

GlycoproteinsRNA

Membrane

Primary target cells are porcine alveolar macrophages (PAM`s) Infection itself does not cause generalized immuno-suppression

but

defence mechanism of the lung

is impaired

=> secondary pulmonary pathogens have easy access to the lung

The PRRSv infection

PRRS infected (dead) PAMPRRS infected (dead) PAM

Properties of PRRS virusProperties of PRRS virus Replication in porcine alveolar macrophages (PAMs)Replication in porcine alveolar macrophages (PAMs)

Long term viremia Long term viremia (more than in some cases 3 weeks)

Persistent infections Persistent infections (157 days; Wills et al., 1997)

Subclinical infections Subclinical infections (Morrison et al., 1992)

Differences in virulence Differences in virulence (Mengeling et al., 1996/1998)

High infectivity High infectivity (<10 infectious particles) but slow transmission but slow transmission (Yoon

et al,1998; Wills et al., 1997)

Short duration of immunity due to viral mutations Short duration of immunity due to viral mutations (Lager et al., 1997)

Short colostral protection of piglets Short colostral protection of piglets

Abortions between day 105-Abortions between day 105-

110 of pregnancy are 110 of pregnancy are

commoncommon

Prolongation of pregnancy Prolongation of pregnancy

up to day 120 often due to up to day 120 often due to

dead fetiidead fetii

Delivery of stillborn, weak-Delivery of stillborn, weak-

born or mummified pigletsborn or mummified piglets

Increase of return to Increase of return to

breedersbreeders

PRRSv:PRRSv: symptoms in symptoms in sowssows

PRRSv Infection:PRRSv Infection:Time lag between infection and clinical Time lag between infection and clinical symptomssymptoms

Infection time ofsusceptible sows

(return tobreeders)

Lactation Pregnancy

Mating

Lactation

Farrowing

Late term abortions or litters with

weakborn, stillbornor mumified pigs

NO clinical symptoms

NO clinical symptoms

3-6 weeks

up to 6.5 weeks

-33 -19 -5 0 14 28 42 56 70 84 98 115

Time (days)

Reproductive disorders :Reproductive disorders :PRRSv differential diagnosisPRRSv differential diagnosisSymptom/Pathogen abortions re-breeders mummies small litters poor milkingAujeszky Virus + + + + +Ergotism + + + + +PEV + + + + -Parvovirus (+) + + + -Hog Cholera + + + + -Brucellosis + + + - -PRRSV + (late) + + (large) - -Strep./Staph. + + - - +E.coli + + - - +Erysipelas + + - - -Eperythrozoon + + - - -Mycotoxins + + - + -Leptospirosis + - + - +Past. multocida + - + - -Listeriosis + - - - -Salmonellosis + - - - -Influenza V. (+) (+) - - +PCV2PCV2 + + + + +Mycoplasma (+) (+) - - (+)Management + + + + -

PRRSv symptoms in boars without obvious without obvious

symptoms symptoms Influenza like Influenza like

symptomssymptoms exhaustionexhaustion in some cases transient in some cases transient

reduction in quantity reduction in quantity and and motility of sperms motility of sperms

PRRSv: PRRSv: reproductive losses reproductive losses

Decrease of fertility by -10% to -25%Decrease of fertility by -10% to -25%

Decrease of piglets per sow (-1.5 to -3.8 pigs/ sow per year)Decrease of piglets per sow (-1.5 to -3.8 pigs/ sow per year)

Decrease of feed convertion ratio (+0.02 to +0.5)Decrease of feed convertion ratio (+0.02 to +0.5)

Reduction of general health status and increased Reduction of general health status and increased susceptibility to other pathogens susceptibility to other pathogens

increased medication costs increased medication costs

Total financial losses due to PRRS infection of sows are Total financial losses due to PRRS infection of sows are (depending on field virus pathogenicity) is 255 $/sow/ year (depending on field virus pathogenicity) is 255 $/sow/ year (National Pork Board, 2003 PRRS Compendium)(National Pork Board, 2003 PRRS Compendium)

PRRSv:PRRSv: symptoms in pigs symptoms in pigs Conjunctivitis, eyelid edemaConjunctivitis, eyelid edema

Discoloration of ears, snout ...Discoloration of ears, snout ...

Increase losses in growth and Increase losses in growth and

mortalitymortality

Non-responding respiratory Non-responding respiratory

symptoms and symptoms and

secondary secondary

infectionsinfections

growth within pensgrowth within pens

and groups of finishingand groups of finishing

animals are not evenanimals are not even

Respiratory Disorders

Pathogen Resp.distress

Dis-coloration

ears

CoughConjuncti-vitis

SIV +- + ++

APP + - +++

Aujeszky virus - + ++-

Erisipelas + +++-

Past. multocida +- +- -

Ergotism + -- --

H. parasuis - + +- -

Salmonella sp. + -- --

M.hyopneumiae - + +- -

Hog Cholera ++ ++ -

Eperythrozoon + -- +-

E. coli ++ + +-

PRRS ++ - (+) -

PCV 2 +- + ++

Difficult breathing

PRRSv: PRRSv: losses in losses in pigs pigs Increase of losses (+1% to +8%)Increase of losses (+1% to +8%) Increase of feed conversion ratio (+0.01 to +0.5)Increase of feed conversion ratio (+0.01 to +0.5) Decrease of daily weight gain (-15g to -150g/ Decrease of daily weight gain (-15g to -150g/

animal /day)animal /day) Increase of uneven growth within groups and pensIncrease of uneven growth within groups and pens Decrease of general health status and by this Decrease of general health status and by this

increased susceptibility for secondary pathogens increased susceptibility for secondary pathogens (Thacker, 2000)(Thacker, 2000)

Increased rates of culls and light pigs (Keffaber, 1989)Increased rates of culls and light pigs (Keffaber, 1989) Increse of medication costs due to worsening health Increse of medication costs due to worsening health Reduction of carcass qualityReduction of carcass quality Average cost of PRRS in the growing pig: Average cost of PRRS in the growing pig: 6.25 – 6.25 –

15.25$ per pig15.25$ per pig

Transmission of PRRSV

Animals- direct contact and aerosolsAnimals- direct contact and aerosols Airborn transmission supporting factors: - low Airborn transmission supporting factors: - low

temperatures, low UV radiation and weather changes temperatures, low UV radiation and weather changes (wind and clouds) (wind and clouds)

Transmission up to 2 - 3 km possible but still needs Transmission up to 2 - 3 km possible but still needs supporting evidencesupporting evidence

Scott Dee‘s current research – 5 replicates so farScott Dee‘s current research – 5 replicates so far

Spread by flies in two reps Spread by flies in two reps

Aerosol spread in two repsAerosol spread in two reps

Personal communications – August, 2006Personal communications – August, 2006

Infected semen - Boars usually are shedding virus via Infected semen - Boars usually are shedding virus via semen between day 3 to 21 post infection but can be semen between day 3 to 21 post infection but can be sporadic shedding for long timesporadic shedding for long time

Vehicles – are very common problem in US, especially Vehicles – are very common problem in US, especially in winterin winter

People and fomites – boxes, tools, insects, etc.People and fomites – boxes, tools, insects, etc.

PRRS-virusPRRS-virus circulationcirculation

-- ++++ ----

--

+++++/-+/-+/-+/- +/-+/-++++

sowssowsgiltsgilts

finishersfinishers

pigletspiglets

3-43-4 5-65-6 7-97-9

(+)(+) +/-+/-+/-+/- +/-+/--- ---- ++++++++ --

++++immune animal

++partly immune animal

-- non- immune animal

+/-+/-infected animal (virus shedding)

(+)(+)maternal immune animal

pig flow virus circulation

age of pigs (weeks)age of pigs (weeks)

PRRS-virus circulationPRRS-virus circulation

++++ ++++++++ ++++++++

--

++++++++++++ ++++++++

sowssowsgiltsgilts

finishersfinishers

pigletspiglets

3-43-4 5-65-6 7-97-9

(+)(+) +/-+/-(+)(+) ++++(+)(+) +/-+/-+/-+/- ++++++ ++++

++++immune animal

++partly immune animal

-- non- immune animal

+/-+/-infected animal (virus shedding)

(+)(+)maternal immune animal

pig flow virus circulation

age of pigs (weeks)age of pigs (weeks)

++ ---- ++++

--

------ --++

sowssowsgiltsgilts

finishersfinishers

pigletspiglets

3-43-4 5-65-6 7-97-9

(+)(+) ++(+)(+) ++++(+)(+) ++++ ++++++ ++++

++++immune animal

++partly immune animal

-- non- immune animal

+/-+/-infected animal (virus shedding)

(+)(+)maternal immune animal

pig flow virus circulation

age of pigs (weeks)age of pigs (weeks)

Interruption of infection chain due tovaccination of piglets

Sows become highly susceptible about 3-4 month after start of vaccination

PRRS-virus circulationPRRS-virus circulation

Proper diagnosis prior to vaccination!!

Whole herd vaccination of sows (and boars): Depends on producing SEW piglets (3 times per year) or nursery on site

(4 times per year)

Piglet vaccination: 10-21 days of age or initial mass vaccination

then 10-21 days of age

Gilt vaccination on arrival:

2 x (4 wks apart) in farms with high infection pressure

Serological success: titers should be low in sows at the time of

revaccination and in fatteners at the time of slaughter? Should be checked or monitored often – 2 x per year at least

General recommendations for General recommendations for PRRSv vaccinationPRRSv vaccination

Ingelvac® PRRS MLV vaccination in farrow to finish farmsaccination in farrow to finish farms

Start of vaccination:Start of vaccination: All All sowssows on one day on one day

irrespective of irrespective of gestation stagegestation stage All All nursing pigletsnursing piglets 3 3

weeks of age and weeks of age and olderolder

All All nursery pigsnursery pigs (when clinically (when clinically healthy)healthy)

All All finishing pigsfinishing pigs (when clinically (when clinically healthy)healthy)

Maintenance program for vaccinations:

Sows:Sows: first revaccination after 4 to 8 weeks, all first revaccination after 4 to 8 weeks, all following revaccinations with consideration of:following revaccinations with consideration of:44 الال month interval when piglets are continuously month interval when piglets are continuously

vaccinated at 3 weeks of age or nursery and vaccinated at 3 weeks of age or nursery and finishing animals are located at a different sitefinishing animals are located at a different site

33 الال month interval when piglets are not vaccinated month interval when piglets are not vaccinated and at the same siteand at the same site

Gilts:Gilts: two times ( two times (3 to 4 week interval3 to 4 week interval) upon ) upon arrivalarrival

Piglets: at 10 days of age to 3 weeks of age, If no infectious pressure, one dose at 5 weeks of age (need to explain further...)

PRRS vaccine is used in a mass vaccination program Depends on the site, if single site then will vaccinate all

animals on the site two times to start program Sows – does not matter what stage of gestation If two sites, then will vaccinate all of the animals on each site

It depends on your goal if two doses are needed in the nursery finisher flows

Important to remember that it takes about 4 weeks to develop protective immunity

Place vaccine 4 weeks prior to exposure When active field virus, two doses of vaccine are given 4

weeks apart

Take home messages on vaccines:Typical PRRS vaccination program in a US (continuous farrow-finish) herd

PRRSv Control Interventions Control principles Subpopulation effects Persistence Major considerations Population immune

management tools reviewed

Case presentations Summarize what I have

learned

PRRSv Control Principles Employ protocols that minimize viral replication and

transmission within a population of animals Fundamental to this is Population Immune

Management Population based implementation of immune management

tools Implement in an effort to create a homogenous population

giving field virus No Place to Go........ Create a non-infectious population

Often employed with a form of herd/population closure

PRRSv Control Principles Goal is to minimize and stop all viral replication and

transmission within a population Develop a homogenous population based on immune status Can be negative or positive which depends on what you are

trying to achieve Nursery – negative Sows – positive or negative

Create a non-infectious population Subpopulations exist in all population of animals

Subpopulations will maintain an environment for chronic field virus circulation

Subpopulation Principles Subpopulations exist

PRRS virus infection results when inconsistent exposure throughout the population occurs

Subpopulations are fundamental for maintenance of chronic field virus circulation

Subpopulations can co-exist for extended periods of time

Animals will “shift” from one subpopulation status to another subpopulation over time

Importance of these Principles Persistence PRRSv can persist in breeding age females

and persistently infected sows can shed virus to naïve contacts

Studies demonstrate PRRSv transmission at 49, 56, 86, & 99 days. Also demonstrate persistence beyond 100 days.

Major Considerations Establish the farm or site’s goal for PRRSv

Control viral activity so clinical improvement is observed Diagnostic support of present clinical signs to determine

recent status of PRRSv and classify as negative, stable, unstable or active Gilt Pool Breeding Gestation Lactation Growing Pigs Semen source

Control options for population immune management tools Initial stabilization Maintenance of stabilization Herd closure and immune management tools

Natural exposure, killed vaccine, live virus inoculation (LVI) and modified live vaccine

PRRS Control Program:Systematic Approach Goals of the Farm/System

Stabilize attain and maintain a stable PRRS positive population production of PRRSv negative offspring

Eliminate Depopulation Test and Remove Extended Herd Closure

Current data would suggest that at least 120 days is necessary to deal with persistently infected animals

Immune Management Tools Natural exposure

Takes considerable amount of time even in small groups of replacement females

Inconsistent in large populations of animals Little control over viremia

Killed vaccine Very little data that supports predictable efficacy

Live virus inoculation (LVI or serum therapy) High risk (virulent) and unreliable

Modified live vaccine The best immune management tool with proven success

Summary: importance of these principles Must eliminate subpopulations to attain and maintain

homogenous population

Population immune management is fundamental to attain and maintain this homogenous population and PRRS control/stability

Must decide which of the immune management tools has the best fit and probability of success for your unit or system

A: Goal – Determine the desired PRRS status B: Current PRRS Status – must know with

current diagnosticsC: PRRS Risk Assessment – AASV tool that

will soon become web basedD: Control Options

>> Initial Stabilization >> Immune management tool: MLV

>> Maintenance Stabilization>> Utilizing immune management tools and

herd closureE: Create Realistic ExpectationsF: Measure and Monitor Intervention

Summary: PRRS Control Methodology

Systematic Approach

Multiple Strains This is more common then one thinks It has been my experience that multiple strains in

a site or a population will alter the perceived program’s success Complete control and elimination is still possible but

often more difficult Could take longer to stabilize a population May need a more intense vaccine program May be the reason that abortions occur post mass

vaccination

Case report Single site unit – farrow to finish, 1000 sow Very well managed Sow herd responded well to vaccinations Continued to find field viruses in the nursery

flow with mild clinical signs Clinical signs will vary, so mortality rates vary Occasionally associated with PRDC in the

finisher animals Complicated with PCV 2 associated diseases

Narrative:

• Sequences beginning with AAA, AAC, AAD, AAF, AAK and CAA are available in the public domain database and are included to illustrate the diversity of PRRSV ORF 5 sequences

• VR-2332 is the prototype U.S. PRRSV strain

• Ingelvac and IngelvacATP are modified-live vaccine strains

0.1

AAF36254

AAC54599

VR-2332

AAD37086

CAA1108869325 Ingelvac

AAA67155

AAC41215

7179471065

6621362136

63628

AAC54591

66909

65554AAC57953

AAK25810

AAF36277 AAF36239

AAC5795772978

75088 InglvacATP

Group Dendogram

01/16/2004

05/19/200410/29/2003

09/23/2004

11/24/2004 12/22/2004

02/8/2005

04/20/2005

04/20/2004

06/18/2004

What I Have Learned Communication is vital

Expectations of the owner and staff “Sterilizing immunity” “Gold bullet”

Compliance issues with breaks Is all members of the unit on the “same page” Biosecurity example – employee lived on a separate

unit where different pigs were housed We still do not know how pathogens like PRRSv

“gets up to” or next to units

What I Have Learned Multiple strains exist on

farms An intense diagnostic program

is needed to find the different strains over time

Confusion will often occur early in any program

Develop a team approach to controlling the circulating virus

All members of the team need to “buy in” to the control measures

Current Knowledge This started a paradigm shift in our thinking in the late ’90’s

1998/19990 and my first client’s response One major change was the selling of breeding stock as naïve

not positive stable Management techniques that are successful

Herd closure, nursery depopulations, complete herd depopulations, etc.

Biosecurity issues – new knowledge Exposure of naïve replacements with MLV vaccine prior to

entry into a positive herd Natural exposure did not work well due to inconsistent exposure (not

like TGE)

Current Knowledge Elimination of virus from a population and

even a unit/ system is achievable Many units have been clean for years

Located in low dense areas High hog dense areas – can not keep clean as long

It is not if I can eliminate the virus from a unit, but can I keep the unit clean long enough to return a profit from the dollars spent on elimination

Summary: What I have learned Routine population immune management by

vaccination Long term stability can be attained and maintained for

resident PRRSv Prevent new entry of virus

Replacement animals Semen Biosecurity

Create realistic expectations for the unit Evaluate co-factors; i.e. other major pathogens,

environment, genetics and management issues

Summary: What I have learned Controlling PRRSv is challenging and involves

many factors Effective control requires a systemic approach that

effectively implements numerous PRRS management tools

First goal is to attain stability of the breeding herd Minimize circulating virus Eliminate subpopulations Influences PRRSv status of growing pigs

Gilt pool management is critical in maintaining sow herd stability

Summary: What I have learned I “attack” what I know first

I control what I can control first Mycoplasma, PRRSv and SIV

Aujesky virus, Classical Swine Fever, FMD Mhyo vaccine: 1-dose

Secondary bacterial infections I use antibiotic therapies

Management issues Environmental issues Mycotoxin control

Porcine Circovirus 2 Is PCV2 involved? AASV Task Force

committee work Porcine Circovirus

Associated Disease (PCVAD) The disease Diagnosis Economic costs Control measures Sequencing of virus European experience

PCV2 is involved 1) At least six different teams of researchers have reproduced

clinical signs, typical PMWS lesions and mortality with PCV2 alone. These lesions (lymphoid depletion, granulomatous inflammation and inclusion bodies) are considered as characteristic of PMWS, and have only been reproduced, at least so far, with PCV2. Please note that several of the studies have used small

sample size populations.

2) There are at least 18 (maybe 19 now) papers showing that there is a direct relationship between the quantity of PCV2 in blood and tissues, and the severity of clinical signs and lesions. If PCV2 was not important in that condition, why would that be? Viral loading can only be taken so far in understanding the

clinical signs.

Personal conversation with Dr. Robert Desroiers, April, 2006 My comments follow each category.

PCVAD Task Force Committee Members

Butch Baker (ISU); David Pyburn (USDA); Francois Cardinal (Qubec); Joaquin Bacerril (Mexico); John Harding (U. of Saskatchewan); Mark Engle (PIC); Pam Zaabel (NPB); Pat Halbur (ISU); Rodger Main (Murphy Brown West); Russ Nugent (Tyson); Tim Loula (Minn); William Starke (Land O’Lakes); Kelly Lager (USDA)

Others on list to step in if someone decides to leave the committee

PCVAD Task Force Committee for AASV was formed

First order of business was to decide on what to call this problem Porcine Circovirus

Associated Disease Covers all clinical

expressions, although the primary economic concern is PMWS

PCVAD Porcine Circovirus Associated Disease Why did we select this name?

At the time there were several veterinarians describing what the clinical expressions were being observed

Input from veterinarians and researchers from Canada and Europe

Dealing with a very complex problem

Early challenge Develop a database to

track occurrence of the disease

Eastern Canada Minnesota – Dr. Peter

Davies Purdue – Dr. Sandy

Amass

Main challenges associated with conducting an epidemiological survey on this syndrome:

the variation in clinical presentation observed

how do you define “high” mortality

the difficulty in determining a case definition that appropriately describes the syndrome. It was decided that the committee should review existing case definitions in light of the newly described syndrome being reported (i.e. high mortality with little to no wasting) to determine if an appropriate case definition could be derived. This was considered important if accurate and meaningful case reporting was to occur

producer’s potential sensitivity

associated with reporting this information into any type of database to which there would be public access

on what do you base epidemiological reports (i.e. diagnostic sample results, clinical presentation, etc).

Early challenge USDA’s Center for

Emerging Issues (CEI) and the National Surveillance Unit (NSU) to determine what role they should play in tracking this disease and, in a broader sense, analyzing the syndrome in general

The committee also discussed the need to explore the role of allied groups such as:

USDA’s Agricultural Research Service (ARS) for a research focus

National Pork Board to facilitate funding and outreach.

Early challenge Educational material

Discussed the linking of web sites www.pcvd.org (Gordon Allen) www.thepigsite.com (very popular site) www.pmwsinpigs.com www.pighealth.com Developed a page within the AASV website as an

educational page (menu AASV >committee >PCVAD) The page has a focused on recognition, diagnosis and

current therapies which includes vaccine response

Literature articles Current research projects that are being conducted

Early challenge Vaccine response

Need to report to industry at some point

Literature and research updates National Pork Board

will help facilitate this information

Information from some articles will be included

The disease As early as 1991 the problem was mentioned

Retrospective testing of stored sera may go as far back as 1969 (Staebler, S. et al, 2005)

Sporadic cases of PCVAD in Spain and England may be as early as 1986 (Rodriguez-Arrioja, G. et al, 2003)

Global explosion since the mid-1990’s Drs. Harding and Clark coined PMWS in 1996

PCV 2 not a “new” pathogen and PCVAD is not a “new” disease Epidemiological studies in UK and Denmark

strongly suggest since 1999 that the spread of PCVAD has been consistent with the introduction of a “new” infectious agent

MONTANA

WYOMING

IDAHO

WASHINGTON

OREGON

NEVADA

UTAH

CALIFORNIA

ARIZONANEW MEXICO

TEXAS

OKLAHOMA ARKANSAS

LOUISIANA

NEBRASKA

COLORADOKANSAS

MISSOURI

NORTH DAKOTA

SOUTH DAKOTA

IOWA

MINNESOTA

TENNESSEE

MISS ALABAMAGEORGIA

FLORIDA

SOUTHCAROLINA

NORTH CAROLINA

WISCONSIN

ILLINOISINDIANA

KENTUCKYVIRGINIA

WV

OHIO

MICHIGAN

MARYLAND

NEW YORK

PENN

DELAWARE

NEWJERSEY

CONN RI

MASS

MAINE

VT

NH

ALASKA

HAWAII

PCVAD – High or rapidly increasing, low, not yet reported

PCVAD – High or rapidly increasing, low, not yet reported

Self reporting incidence in US

Supplied by Dr. John Kolb, Boehringer Ingelheim Vetmedica

The individual pig: A starting point!

Growth retardation, dyspnea, enlargement of lymph nodes, diarrhea, and/ or jaundice (Allan, G. et al, 2000. Segales, J. et al, 2002)

Clinical signs will vary Enlarged lymph nodes and non-

collapsing lungs are most common Need to necropsy and submit tissue

from at least 5 animals

Tissue submissions: PCVAD is a broad categorization of

multisystemic diseases with the following histopathological findings in affected pigs: Depletion of lymphoid cells Detection of PCV2 within the lesions Disseminated granulomatous inflammation in

multiple tissues (e.g. spleen, thymus, ileum, lymph nodes (sternal, bronchial, inguinal and mesenteric), lung, kidney, liver, tonsil, etc.).

Reproductive diagnosis requires the presence of PCV2 antigen in lesions associated with fetal myocarditis

The herd: “Muddy waters” This is a “work in

progress” Primary reason is that

many herds can have an occasional animal with fulfills an individual case definition but does not have a herd problem

AASV committee reviewed CDC’s approach to describing a new clinical problem

Also looked at our European colleagues approach 1a) historical level of

mortality +1.6 X SD2 1b) if no records,

increase that exceeds regional level by 50%

Work in progress: herd definition PCVAD can be subclinical or include one or more of

the following clinical manifestations concurrently: Multisystemic disease with weight loss (formerly

known as PMWS) High mortality: Doubling of historical mortality

rate without introduction of a new known pathogen.

Respiratory signs including pneumonia Porcine Dermatitis and Nephropathy Syndrome

(PDNS) Enteric signs including diarrhea and weight loss Reproductive disorders including abortions,

stillbirths and fetal mummification (diagnosis requires the presence of fetal myocarditis associated with PCV2 antigen in lesions)

PCVAD: Diagnosis PMWS/ High mortality is the most common

and most economically damaging clinical expression Is considered the major clinical manifestation of

PCVAD Co-factors are probably the most important

aspect to consider Infectious co-factors

Viruses - PRRSv, Parvovirus, SIV Bacteria - Mycoplasma, Salmonella

PCV2 coinfections in 484 U.S. field cases: ISU-VDLPCV2 coinfections in 484 U.S. field cases: ISU-VDL

99

164164

1010

7777

1313 33

92926868

37371111

002020404060608080

100100120120140140160160180180

PCV2 Alon

e

PCV2 Alon

e

PCV2+PRRSV

PCV2+PRRSV

PCV2+PRRSV+SIV

PCV2+PRRSV+SIV

PCV2+PRRSV +

M.h

yo.

PCV2+PRRSV +

M.h

yo.

PCV2+SIV

PCV2+SIV

PCV2+SIV

+M

.hyo

.

PCV2+SIV

+M

.hyo

.

PCV2+M

. hyo

.

PCV2+M

. hyo

.

PCV2+Bac

teria

l sep

ticem

ia

PCV2+Bac

teria

l sep

ticem

ia

PCV2+Bac

teria

l pne

umon

ia

PCV2+Bac

teria

l pne

umon

ia

PCV2+ O

ther

s

PCV2+ O

ther

s

Num

ber

of C

ases

Num

ber

of C

ases

Rarely see PCV2 singular infection

PCV 2Strains Co-factors

InfectionsNon-infectious

Immune stimulation

Low viremia

Seroconversion

Host susceptibility

Subclinical disease

High viremia leukopenia

+/- seroconversion

Systemic spread

Clinical disease- 70/80% mortality

PCV 2 VirusInfection in lymphoid tissues +/- other tissues

Lymphoid depletion + histiocytic replacement, antigen

PCV 2 particle

1 to 20 % of the animals

Porcine Circovirus Associated Disease

Information courtesy of Dr. Pat Halbur

Economics of PCVAD PMWS is perplexing,

interesting but very costly when clinical signs contribute to mortality and attrition.

Attrition is best defined as pigs that do not make full market weight on time Culls, lights, under

market weights, etc

Other expressions of PCVAD Enteric disease in

grow finish stage Infectious and

nutritional causes

PCV2 Induced Granulomatous Enteritis in Growing Pigs

Kolb, J. Genzow, M. and Roof, M. IPVS, 2006 pg. 272.

Pathogen # cases % cases

Lawsonia 12 32%

Salmonella 7 19%

PCV2 14 38%

Brachyspira 1 2%

total 37* 100%

*includes mixed infections; sum does not total to 100%

Other expressions of PCVAD

Reproductive expression is rare Abortions, stillborns, mummified fetuses The presence of fetal heart lesions

Necrotizing myocarditis The presence of PCV2 antigen in the

myocardial lesions and in other fetal tissues if possible

Other expressions of PCVAD

PCV2 is considered a contributor to Porcine Respiratory Disease Complex (PRDC) Pneumonia is one of the more common

expressions associated with PCV2 PDNS

The incidence is often increased when other expressions of PCVAD occur

Has not been supported by research

Control – Develop an action plan

Get an accurate diagnosis!! Identify concurrent infections and implement an

action plan to control and or eliminate PRRSv/ SIV/ HPS/ Salmonella/ Mycoplasma

Evaluate timing of when you are vaccinating Mycoplasma vaccines especially Enteric vaccines do not seem to be as “sensitive”

Treat bacterial infections Therapeutic “CTC” levels and therapies to control

bacterial co-infections Use vitamin E and Selenium Nutritional enhanced diets

Control – Develop an action plan

Try removing effected animals very early in the clinical expression – does not always work

Practice strict All In All Out Stop mixing and resorting animals post weaning Make sure you provide 0.28 square meter (3

square feet) in the nursery and 0.74 square meter (8 square feet) in the finisher

Use detergents and disinfectants Virkon S, Roccal D and Synergize Anthium Dioxide + Acidic Detergent (foam with air)

Weaning age may become a factor?

Madec 20-point rules Control without PCV2 vaccination

sometimes works, sometimes does not work!

Control programs have focused on co-factors and other risk factors

Madec rules will significantly decrease mortality because the measures are designed to reduce “infection pressure” of PCV2 and other infectious pathogens, improve hygiene and reduce stress

Summary– Develop an action plan Transmission studies

No research studies that I can find An “on farm” study placed 140 day old from

source with no clinical signs and tested with animal > 140 days old that had recovered from PCVAD PCR positive serum in >140 day olds Did not “transfer” PCV2 to sentinels or clinical signs

Canadian/ Midwest/ N.C. strains are very similar to European strain Virus will change over time??

Maternal antibody studies Kelly Lager – found in 3 week old pigs

May not be held back by maternal antibodies?

Summary

Environmentally stable virus We do not know this for sure Do not know how long it will survive in

manure One common comment is how well

the sow herds are performing for a severe problem in the finishers

Vaccines – piglets have been vaccinated two times (efficacy varies)

Summary-Genetic influences Landrace and

Large White Pat Halbur – one

study implicated Landrace as more suspectable

Duroc and Pietrain More information

is needed!

Period of timeDuroc A

mortality

Duroc B mortality

Jan-June 2005 (before PMWS)

2.5% (245,945)*

3.5% (316,29

7)

Jan-Dec 2005 2.6% (278,704)

4.3% (898,28

0)

Jan-April 2006 (with PMWS) 3.0% (29,504)

7.5% (490,31

9)

Mortality in finishing units in the progeny of two different Duroc boar lines

*number of animals per group

Matt Turner, personal communication, July 2006

Information supplied by Dr. Tim Loula, Swine Vet Center

a) Sequencing and building dendograms are useful but limited in providing information on severity of virus isolated

b) There may be distinct and conserved PCV2 genotypes, which may equate to distinct PCV2 strains and this may be important in the understanding of PCVAD

Summary thoughts Management issues are important and may start in the sow

herd Get an accurate diagnosis Cross fostering techniques stopped in the sow herd Stop resorting in nursery Remove the affected animals from the general population Be aggressive on treatments if improvement is observed Needle management? Sanitation program updated Replacement animal “stabilized” Genetic changes Others?

Summary thoughts Vaccine will be a tool to consider

Sow vaccination vs. piglet vaccines

Control other pathogen activity – important! Especially PRRS if present Easier said then done!

Transmission and viremia Lots to learn yet! Started at 6 weeks and still viremic by PCR tests

on serum at 135 days in one case of mine

You may also concern:Mycoplasma vaccination

Piglet vaccination will work if given at the right time Single dose vaccines are common and given at 5 to 6

weeks of age In some flows the exposure to mycoplasma is so high

that a two dose program is needed I have been vaccinating sow herds for three years

Reduces the amount of organism in the piglets at weaning

Have stopped vaccinating the piglets in two flows Are using naïve sentinels in both flows to see if we have

completely eliminated the organism or reduced to very low levels

Most boar studs that I service are mycoplasma naïve Again we used vaccine at first to stabilize the stud After a couple of years, purchased mycoplasma naïve

boars and used them as sentinels initially

Questions?Questions?

THANK YOU! THANK YOU! Special thank you to Dr. Marika Genzow Special thank you to Dr. Marika Genzow

and Dr. Mike Murtaughand Dr. Mike Murtaugh