Disease challenges around the world - Veterinary Practice
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Disease challenges around the world

Human pandemic influenza
virus on a Canadian pig farm

Krista Howden and others,
Canadian Food Inspection Agency,

The Canadian Food Inspection
Agency reported an outbreak of the
emerging novel influenza virus H1N1
on a farrow-to-finish pig unit in
Alberta in May 2009. For four weeks,
pigs on the unit had been affected by
respiratory signs consistent with
influenza virus A and the presence of
active virus was confirmed on PCR

Despite the clinical recovery of the
animals, potential purchasers refused
to take the finished pigs and the owner
decided to destroy the herd because of
the economic cost of keeping the
stock and the increasing welfare
concerns due to overcrowding.
Carcases were rendered or composted
and did not enter the human food

The source of the virus was found
to be an infected human and suspected
zoonotic transmission occurred to two
of those involved in dealing with the
outbreak. The authors discuss
strategies for preventing occupational
exposure to the virus.

Canadian Veterinary Journal 50 (11):

Identification of on-farm sources
of Listeria monocytogenes in
dairy herds

Hussni Mohammed and others,
Cornell University, New York

Listeriosis causes sporadic infections in
humans and domesticated animals.
The incidence of disease is increasing
worldwide and causes significant
economic losses. In investigations of
the ecology of the Listeria monocytogenes
in dairy herds, the authors took
samples from 50 units in New York
State. PCR assays were positive in 13%
of composite milk samples, 19% of

udder swabs and 43% of faecal
samples. Overall, the bacterium was
more commonly found in samples
from the cattle and their immediate
environment than from milk samples.

American Journal of Veterinary Research
(3): 383-388.

Effect of foot-and-mouth disease
vaccination on virus

Karin Orsel and Annemarie
Bouma, University of Calgary,

Most parts of the world are currently
free of foot-and-mouth disease. But as
there is no FMD vaccination policy in
force in many countries, they will
always be vulnerable if the virus re-
emerges. Vaccinations will then
become a possible control option and
the authors modelled the effects of a
single inoculation used as an
emergency measure during an
outbreak. They suggest that a
vaccination policy could be highly
effective in controlling the disease in
cattle and sheep but it would be less
useful in controlling disease in pigs.

Canadian Veterinary Journal 50 (10):

Crow population dynamics
as a surveillance tool for West
Nile virus

Antoinette Ludwig and others,
University of Montreal

West Nile virus is a flavivirus causing
disease and mortality in humans,
mammalian livestock and wild birds.
Since its introduction to the United
States in 1999 it has spread rapidly
with the American crow (Corvus
brachyrhynchus) acting as one of the
main reservoirs. The authors examined
the effects of the virus on the
population dynamics of this species in
Quebec. They developed an algorithm
which they suggest could be used as a
disease surveillance tool and to measure the impact of a disease
outbreak on wildlife species.

Transboundary and Emerging Diseases 56
(9/10): 337-345.

Detection of FMD infected cattle
using infra-red thermography

Kaitlin Rainwater-Lovett and
others, Plum Island Laboratory, US
Department of Agriculture

Clinical screening for FMD is time-
consuming and labour-intensive and
may produce false negative results in
the early stages of infection. However,
one of the early indications of
infection is fever and the authors
examine the potential for using infra-
red thermal imaging technology to
detect animals with raised body
temperature. Their findings suggest
that thermography could be a useful
preliminary screening method. Further
tests would be needed to assess its
value in detecting animals with mild
clinical or subclinical infections.

The Veterinary Journal 180 (3): 317-324.

Validation of four real time
PCR assays for serotyping
bluetongue virus

Frank Vandenbussche and others,
Veterinary and Agrochemical
Research Centre, Ukkel, Belgium

The control of bluetongue virus is
complicated by the co-existence of
several different serotypes. There are
four main serotypes currently in
circulation in Europe and a rapid,
sensitive and specific assay is needed
to distinguish between them. The
authors describe the results of tests on
the sensitivity and specificity of PCR-
based assays developed for the BTV-1,
BTV-6, BTV-8 and BTV-11 serotypes.
Used in combination with existing
technologies, their findings suggest
that these tests could provide an
effective tool for monitoring BTV.

Transboundary and Emerging Diseases 56
(9/10): 346-354.

Avian encephalomyelitis virus in
a pheasant rearing unit

David Welchman and others,
Veterinary Laboratories Agency,

Avian encephalomyelitis is a viral
disease causing ataxia and tremors in
young chicks. It is found in domestic
poultry worldwide and has also been
recorded in other avian species,
including game birds. The authors
describe an outbreak on a pheasant
rearing unit which resulted in 21%
mortality in the worst affected hatch.
Avian encephalomyelitis virus
antibodies were identified by ELISA
and viral RNA was detected using a
PCR assay. The virus may have been introduced by adult birds brought on
to the unit at the start of the season.

Avian Pathology 38 (3): 251-256.

Strategies for preventing
transmission of brucellosis from
deer to domestic livestock

Eric Maichak and others, Wyoming
Game and Fish Department
Brucellosis is endemic in elk (Cervus
elaphus nelsoni) in their winter feeding
grounds in western Wyoming. The
bacterium was transmitted to domestic
cattle in 2004, probably as a result of
contact with contaminated foetuses or
birth products. The authors look at the
effects of wildlife management
practices and elk behaviour in
determining the risk of interspecies
transmission. They suggest that
reducing the density of the elk
population and protecting species that
scavenge infective materials would
limit the risks to cattle.

Journal of Wildlife Diseases 45 (2): 398-

Effects of oxytetracycline on Candidatus Mycoplasma
infection in alpacas

Susan Tornquist and others,
Oregon State University

Candidatus Mycoplasma haemolamae
(CMhl) is a novel bacterial infection
causing mild to marked anaemia in
camelids which was first identified in
two US states in 1990. The authors
experimentally infected eight alpacas
with the organism and monitored its
presence by PCR following treatment
with oxytetracycline. They demonstrate
that this assay is more sensitive than
blood smears in detecting infection.
Oxytetracycline was not consistently
effective in clearing CMhl infection
and some animals became chronic

American Journal of Veterinary Research
(9): 1,102-1,107.

Babesiosis in a bull imported
from the Republic of Ireland

J. Irving, Royal Veterinary College

Babesiosis is a rare condition in the
UK cattle herd although the disease is
endemic in certain areas with high
populations of the tick vector. A two-
year-old Belgian Blue bull newly
imported from the Irish Republic was
presented with lethargy and red-tinged
urine. Blood smears showed intra-
erythrocytic bodies typical of Babesia
species and the animal was successfully
treated with imidocarb diproprionate.
The author notes that this and other
arthropod-borne conditions are likely
to become more common with global

Cattle Practice 17 (1): 81-83.

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