Classification of farrow-to-finish
swine herds regarding to their PRRS
status. A study in Greece.
S.K. Kritas, G. Filioussis, K. Papageorgiou
Department of Microbiology & Infectious Diseases,
Faculty of Veterinary Medicine,
Aristotle University of Thessaloniki,
Thessaloniki, Macedonia, Greece
EuroPRRS.net COST FA902 Thessaloniki, Greece. Aug 23-25, 2012
EuroPRRS.net COST FA902 Thessaloniki, Greece. Aug 23-25, 2012
Introduction
• PRRS is the most important and costly infectious
disease of pig industry worldwide nowadays.
•Cause: Arterivirus (F:Arteriviridae , O: Nidovirales RNA)
There are 2 major antigenically distinct genotypes. Only
66% homology
–European type (type Ι or EU-type, Lelystad virus)
–North American type (type IΙ, NA-type)
–Strains of each genotype show antigenic
differentiation at a lower level.
•Within both genotypes Strains with different
virulence Efficacy problems with vaccinations
What was the appearance of
PRRS in Greece?
• Reproductive disorders (early farrowings, returns to estrus,
abortions, births of stillborn/ mummies/ weak piglets
• Increased pre- and postweaning mortality
• Increased incidence of respiratory infections (primary or
secondary)
• Fatteners delay to reach slaughter weight
• Economic impact of PRRSV has not been estimated, but this is
very high
What policy applies for PRRS
identification?
• No compulsory national policy
for examining the herds e.g.
only farmers who wish to
examine their herd send few
samples to laboratories.
• This presentation is aiming to
record and characterize the
PRRS status in farms
throughout the majority of
Greek territory
• ELISA developed by T.
Stadejek and PCR as
described in the COST
workshops
Materials and Methods
Bulgaria
FYROM
126/9
70/2
18/6
Albania
Turkey
14/1
192/13
114/20
62/8
140/22
81/6
61/8
Greece
Fig 1.
Number of farms /
Pig density (pigs/km2)
FYROM
Albania
Bulgaria
Fig 1.
Pig density
Turkey
(Blinking☺ > 20 pigs/ km2)
PRRS first diagnosed in
Greece in 1993
(mainly importing breeders
at that time)
Greece
FYROM
Albania
Bulgaria
Fig 1. Number of farms
sampled (✩= 1 farm
sampled)
Turkey
Size of farms
(# sows)
Greece
No of farms
(estimate)
Sample size
(# farms)
100 to 300
230
22
301 to 850
70
14
>850
20
6
FYROM
Albania
Greece
Bulgaria
Fig 1. Number of farms
sampled (✩= 1 farm
sampled)
Turkey
FYROM
Bulgaria
Albania
Turkey
Size of
farms
(# sows)
Greece
Fig 1. Number of farms
sampled (✩= 1 farm
sampled)
No of
farms
(estimate)
Sample size
(# farms)
# PRRSposve
farms
% of
farms
100 to 300
230
22
16
73%
301 to 850
70
14
11
79%
>850
20
6
3
50%
Classification of farrow-to-finish swine herds based on their PRRS
status (Holtkamp DJ, et al 2011)
Case
PRRS ELISA
(exposure)
PRRS PCR
(shedding)
Interpretation
0
neg
neg
Farm is negative
1
pos
pos
Farm is positive (virus is still circulating within the
herd-Herds going through a clinical PRRS outbreak
and those with chronically recurring shedding of
virus)
2
pos
neg
Farm is stable positive (virus undergoes elimination)
or provisional negative
3
neg
pos
Farm is very recently (acutely) infected ? (it became
recently infected)
Derald J. Holtkamp, DVM, MS; Dale D. Polson, DVM, PhD; Montserrat Torremorell, DVM, PhD; and committee members
Bob Morrison, DVM, PhD, MBA (chair); Dyneah M. Classen, DVM; Lisa Becton, DVM; Steve Henry, DVM; Max T. Rodibaugh, DVM;
Raymond R. Rowland, PhD; Harry Snelson, DVM; Barb Straw, DVM, PhD; Paul Yeske, DVM, MS; Jeff Zimmerman, DVM, PhD
Parameters recorded
• Herd size, e.g. the number of sows.
• Pig herd density in the municipality (herds per 1,000 sq km),
• The direct (straight) distance from the closest pig farm (km)
as checked in google maps,
• the purchase of breeding animals from sources outside the
farm. Gilts self produced (0), or purchased from other herds
(1).
• Non practicing (0) or practicing (1) of at least one month
quarantine in distant building for the newly purchased breeding
animals.
• Non practicing (0) or practicing (1) of hygienic/ biosecurity
measures within the farm.
• Non practicing (0) or practicing (1) of all-in, all-out (AIAO)
flow in all production stages..
• Non practicing (0) or practicing of vaccination of sows for
PRRS.
• Absence (0) or presence (1) of other health problems in the
farm.
Serological and PCR testing
8 blood samples from 22-week old pigs were
collected. These samples were tested by:
ELISA for the presence of antibodies against
PRRS virus
PCR for the presence of the PRRS virus in pools
of 4 samples.
Since maternal antibodies for PRRS virus rarely remain after
4-6 weeks of age, antibodies detected at the end of the
fattening period were considered to indicate the presence of an
infection by a wild-type virus in the farm.
The detection of virus by PCR during the end of the fattening
period also was considered as indicative of recent infection in
the farm.
Results
PRRS status x Farm size (not significant)
Case Farm designation (ELISA exp/PCR
shed)
S
M
L
Total
0
NEGATIVE (neg/neg)
7
3
4
14
1
POSITIVE (pos/pos)
11
7
1
19
2
POSITIVE STABLE (pos/neg)
4
4
1
9
PRRS status x Farm distance (significant)
Case
Farm designation (ELISA exp/PCR
shed)
≤3km
>3km
0
NEGATIVE (neg/neg)
3
11
1
POSITIVE (pos/pos)
12
7
2
POSITIVE STABLE (pos/neg)
5
4
PRRS status x Gilt purchase (Significant)
Case
Farm designation (ELISA exp/PCR
shed)
Purch No
Purch Yes
0
NEGATIVE (neg/neg)
7
7
1
POSITIVE (pos/pos)
3
16
2
POSITIVE STABLE (pos/neg)
3
6
PRRS status x Quarantine (NS)
Case
Farm designation (ELISA exp/PCR
shed)
Quarant No
Quarant Yes
0
NEGATIVE (neg/neg)
10
4
1
POSITIVE (pos/pos)
17
2
2
POSITIVE STABLE (pos/neg)
5
3
PRRS status x Farm Hygiene (Significant)
Case
Farm designation (ELISA exp/PCR
shed)
Hygiene No
Hygiene Yes
0
NEGATIVE (neg/neg)
6
8
1
POSITIVE (pos/pos)
12
7
2
POSITIVE STABLE (pos/neg)
1
8
PRRS status x AIAO (NS)
Case
Farm designation (ELISA exp/PCR
shed)
AIAO No
AIAO Yes
0
NEGATIVE (neg/neg)
5
9
1
POSITIVE (pos/pos)
10
9
2
POSITIVE STABLE (pos/neg)
3
5
PRRS status x PRRS sow vaccination (NS)
Case
Farm designation (ELISA exp/PCR
shed)
Vacc No
Vacc Yes
0
NEGATIVE (neg/neg)
8
6
1
POSITIVE (pos/pos)
7
12
2
POSITIVE STABLE (pos/neg)
2
7
PRRS status x Other health problems (Significant)
Case
Farm designation (ELISA exp/PCR
shed)
Problems No
Problems Yes
0
NEGATIVE (neg/neg)
7
7
1
POSITIVE (pos/pos)
0
19
2
POSITIVE STABLE (pos/neg)
3
6
In the PRRS positive farms, respiratory and reproductive
problems were by far the most prominent (versus death,
nervous and gastrointestinal problems)
In the PRRS positive farms, growers and finishers were mostly
affected (versus neonatal and nursery)
Our team
Petridou E 1, Filioussis G 1,2,
Papageorgiou Κ 1,2, Burriel ΑR 3,
Christodoulopoulos G 4, Stadejek T5,
Morrison RB5