News | Iowa State University - PCV3, who cares?PCV3, who cares? B Arruda 1Department of Veterinary...
Transcript of News | Iowa State University - PCV3, who cares?PCV3, who cares? B Arruda 1Department of Veterinary...
PCV3, who cares?
B Arruda1Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary
Medicine, Iowa State University, Ames, Iowa
The Story of a Great Masquerader
https://top10bestpro.com/best-masquerade-masks-for-men/
Sporadic disease 1985
Devastating epidemicsLate 1990s
Present at least by 1962
EM of PCV21994
‘Unusual’ disease1990s
Effective vaccinesLate 2000s
The Story of a Great Masquerader
Schwartz
Madson
https://slideplayer.com/slide/4456534/
MadsonMadson
Madson
SchwartzSchwartz
StevensonSchwartz
Majority of infections are SUBCLINICAL
PCV3 vs PCV2
PCV2
• PCV3 strains are very similar
• PCV3 is very different from PCV2
• PCV2 vaccination does not appear to protect against PCV3 infection
Is It Important?
E F E F E F E F
Consistent detection by PCR Accurate case
definition Absence or
inconsistent detection of other known pathogens
High viral load (low CT) Repeat diagnosis Multiple sites
Absence of unknown viruses
Agent in diseased tissue
Reproductive Failure
• January and November of 2018• 22 cases
• 36 fetuses/fetal groups• Multiple groups per case
• 20 different sites• IA, IN, NE, KS, SD, MI, NC, OH
Reproductive Failure
• Clinical history• Uptick in mummies and stillborns
• 5%
• Gilts and/or low parity sows
Reproductive Failure
IF YOU ARE LOOKING AT AVERAGES YOU MISS THINGS.Example
0.7 mummified fetus/litterSows: 0+1+0+0+0+0+0+0+0+0 = 0.1 mummified fetus/litterGilts: 0+1+3+0+3+0+0+4+0+5 = 1.6 mummified fetuses/litter
Look at the individual litter/sow level diagnosis
What is a ‘normal’ number of mummified fetuses in a litter?
What is an ‘acceptable’ number of mummified fetuses in a herd?
= 0+0+0+3+4+0+0+0+0+0
Reproductive Failure
• Samples• Mummies from the same or different litters and
stillborns• CRL varied from 7 cm to 30 cm
• 7 cm to 17 cm 45 and 70 days of gestation
Reproductive Failure
• PCV3 PCR• Commonly detected in multiple litters/groups
• PCV3 Ct values• 9.4 – 34.4• 10-20
1.3 trillion/mL1.7 billion/mL
Reproductive Failure
• PRRSV, PCV2, PPV, Leptospira• Negative
• Bacterial culture• No significant growth
• Next generation sequencing sequences ‘all’ of the genetic material in a sample• PCV3 (n=14 fetal pools)
0
5
10
15
20
25
30
PRRSV PPV PCV2 PCV3
No. of
Case
s
Reproductive Failure Cases by VirusJan 1, 2018 – Oct 1, 2018
5%
11%
13%
Is It Important? Reproductive Failure
Lesion + PCV3 in situ
E F E F E F E F
Strongly associated with mummies and stillborns
PCV3 high viral load
Repeated detection Litters Submissions Multiple sites
No other common/known cause of reproductive failure
No other novel agent detected by NGS
No evidence PCV3 is a cause of abortion
Perinatal Infection
• Three cases• Two sites from two different production systems
• Newly populated herd• Genetic multiplier
• Weak-born and/or abnormal piglets• PCV3 Ct values
• Cerebrum• 7.5-13.3
Billions to trillions of copies / mL
Most UNCOMMON clinical presentation based on VDL case submissions
Inflammation surrounding blood vessels Foci of inflammation PCV3
* ** *
Perinatal Infection
Viral infection
Growing Pig• February and October 2018• Twelve cases
• Ten different sites• Five from the same sow source
• Age range• 3- to 10-weeks-old• Commonly 4- to 6-weeks-old
• Clinic signs vary• Dermatopathy, acute death, lameness,
enteric, respiratory, small sickly looking pigs, loss of condition
• Lesions at the cell level Distinctive• No notable gross lesions
• PCV3 PCR Ct • Low 20s (lung)
No good clinical case definition
We don’t know the number/percent of pigs affected on affected farms probably low
Point/Counterpoint
It has been around for decades
It is endemic
Our herd infectious/immunity status has and continues to change
Numerous cases of PDNS & innumerable cases of reproductive failure without detection of known causes over the past decades
We do not know at what prevalence
Yup, as is rotavirus, SIV, PCV2, S. suis…endemic agents cause disease in a subset of individuals due to various factors
Detection of PCV3
• Detected by PCR in multiple sample types• Processing fluids, serum, colostrum, tissues,
feces, nasal swabs, oral fluids• Detection ≠ Disease (causation)• Its there…now what? Implications?
Detection of PCV3
• Processing or oral fluids • You have it• Probably isn’t helping• Don’t know how much it is hurting
• Productivity/economic impact undetermined• Additional info/data needed
Prevention
• Gilt acclimation?• How?• When
• Leave plenty of time between exposure and breeding
• Viremia appears to be greater than a month• Vaccine?
• A few companies are working on it• One currently available
• Efficacy as demonstrated with vaccinates and non-vaccinates is not known
Submission?
• Reproductive workup You see mummies• 3 affected litters
• 2-3 mummies and stillborns• 4-6 fetuses from each affected litter
Importance of PCV3?
• It’s a pathogen of pigs• It causes clinical disease in a subset of pigs
it infects• It does not appear to cause enteric disease,
primary respiratory disease or loss of condition like PCV2 (PMWS)
• Impact? No great answer fetal wastage• NOT PRRSV or IAV
Next Steps
• Serologic assay development• Infection dynamics• Monitor interventions (gilt exposure)
• Reproduction of disease• Model of disease
• Vaccine efficacy trials
Meat and Potatoes• What is it?
• Virus• Causes mummified fetuses
• How do I know if I got it?• Submit as previously outlined
• How do I treat it?• Probably can’t
• How do I prevent it?• Most likely gilt acclimation