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PMWS and PDNS in the UK
UK - Veterinary Laboratories Agency (VLA) Quarterly Surveillance report on PMWS and PDNS from October - December 2005
In 2004 the percentage of PMWS
diagnoses from relevant diagnostic
submissions was the lowest since the
diagnosis was first ‘listed’ in late 2000
following the first confirmed British
diagnosis in July 1999.
The lowest quarterly percentage of
relevant diagnostic submissions
diagnosed with PMWS was 9.2% in the
third quarter of 2004, although this
subsequently increased to 16.0% for the
last quarter; the latter sometimes linked
to incidents of late-onset mortality in
finishers. Thus, PMWS commonly
presents in pigs aged six to 12 weeks but
in one finishing herd 10 percent of pigs
aged 16 weeks were affected with
wasting and dyspnoea with some scour
starting at two weeks after arrival on the
unit. PMWS in association with porcine
circovirus type 2 (PCV2) inclusions was
confirmed histologically.
In a second
finisher herd respiratory disease
commenced from 12 weeks of age, and
by 14 weeks 40 of 1000 had died.
PMWS was confirmed in two of three pigs
necropsied, and Pasteurella multocida
was the only respiratory pathogen
isolated from the lungs.
On another unit
four of 12 eighteen-week-old finishing
pigs died over a few days, PMWS was
confirmed histologically but the recent
use of antimicrobials precluded a
diagnosis of the cause of the suspected
septicaemia. The more usual PMWS in
pigs aged less than 12 weeks continues
to cause problems with reports of
mortalities on two units of 4 percent and 8
percent respectively. One herd with 20
percent mortality in pigs aged 10 to 13
weeks was found to have lesions
associated with Haemophilus parasuis,
Arcanobacterium pyogenes, Pasteurella
multocida and Streptococcus suis
serotype 2 infections as well as
underlying PMWS.
Nervous signs have been reported with
PMWS, and examination of a 12-weekold
rarebreed pig with nystagmus and
circling was attributed to a mild nonsuppurative
meningoencephalitis. PCV2-associated inclusions were readily
detected in lymph nodes.
PDNS was relatively infrequently
diagnosed prior to 1999 and then usually
as sporadic cases within a herd.
Epizootic PDNS was encountered from
1999 onwards and, apart from a
statistically significant increase in 2000,
the percentage of PDNS diagnoses from
relevant diagnostic submissions has
subsequently remained similar - see
figure.
Diagnoses of PDNS for the last quarter of
2004 at 6.4% was the highest quarterly
rate since 2000.
PDNS is typically described as affecting
pigs 12 to 14-weeks-old although cases
are reported to 9 months and older. On
one unit cases occurred earlier when five
of 600 ten-week-old pigs died, 10 were
unthrifty, and one had extensive skin loss
of the hindlegs; PDNS was confirmed.
Towards the end of the year there were
increasing reports of PDNS occurring
later in the finishing stage and causing
high mortality with the increased
economic impact of losing pigs late in
production. For example, in one herd
PDNS presented as fever, dermatitis,
coughing and wasting in 16 to 20-weekold
pigs. Further investigation of these
incidents of increased mortality in
finishing pigs is planned in order to
further characterise the disease situation
on farms, and the pathology and
pathogens present including the
involvement, or otherwise, of
PMWS/PDNS.
To read the complete PDF document - Click Here
Source: Veterinary Laboratories Agency (VLA) - February 2005
