D9271.PDF

Rev. sci. tech. Off. int. Epiz., 1999,18 (3), 667-671
Prevalence of bovine viral diarrhoea virus
antibodies in India
K.J. S u d h a r s h a n a ( 1 ) , K.B. S u r e s h
( 1 )
& M . Rajasekhar
( 2 )
(1) S c i e n t i s t , R i n d e r p e s t ELISA L a b o r a t o r y , ICAR Project o n A n i m a l D i s e a s e M o n i t o r i n g a n d S u r v e i l l a n c e
( A D M A S ) , I n s t i t u t e o f A n i m a l H e a l t h a n d V e t e r i n a r y B i o l o g i c a l s C a m p u s , H e b b a l , 5 6 0 0 2 4 B a n g a l o r e , India
(2) P r o j e c t C o - o r d i n a t o r , R i n d e r p e s t ELISA L a b o r a t o r y , ICAR P r o j e c t o n A n i m a l D i s e a s e M o n i t o r i n g a n d
Surveillance ( A D M A S ) , Institute of Animal Health and Veterinary Biologicals Campus, Hebbal, 560024
B a n g a l o r e , India
Submitted for publication: 9 October 1998
Accepted for publication: 2 August 1999
Summary
A study w a s undertaken regarding the prevalence of bovine viral diarrhoea virus
(BVDV) antibodies in bovine sera which tested negative for rinderpest and peste
des petits ruminants virus antibodies. The samples w e r e collected between
January 1996 and December 1997. A total of 439 samples (327 cattle and 112
buffalo from 17 states of India) w e r e tested using a commercial enzyme-linked
immunosorbent assay (ELISA) kit. The mean prevalence of BVDV antibodies in
cattle w a s 15.29% (50/327) in 16 states compared to 23.21% (26/112) in buffalo in 9
states, with an overall prevalence of 17.31% (76/439) in 17 states. The serological
evidence that BVDV infection is widespread in India is of utmost practical
importance because of the clinical resemblance to rinderpest. A differential
diagnosis between these t w o diseases is critical in view of the declaration by
India of provisional freedom from rinderpest disease; active sero-surveillance is
to begin in 2000 to achieve certification of freedom from rinderpest infection by
the Office International des Epizooties.
Keywords
Bovine viral diarrhoea - Bovine viral diarrhoea virus antibodies - Buffalo - Cattle Enzyme-linked immunosorbent assay - India.
Introduction
Bovine viral diarrhoea (BVD) is caused by bovine viral
diarrhoea virus (BVDV), a positive-sense, single-stranded,
enveloped RNA virus of the genus Pestivirus and family
Flaviviridae ( 1 2 ) . Cattle are the animals most commonly
infected but the virus can also be found in sheep, goats and
wild ruminants,
which
may serve as reservoirs.
Non-cytopathogenic (non-cp) and cytopathogenic (cp)
biotypes of the virus exist ( 1 1 ) and persistent infection with
non-cp biotype is mainly responsible for the maintenance and
transmission of the virus in nature. Calves which become
pre-natally infected with non-cp BVDV develop a persistent
infection for life and become major reservoirs of BVDV within
the herd. W h e n exposed to cp BVDV during the adult stage,
these cattle may suffer from fatal mucosal disease (MD).
The disease has a world-wide distribution and the BVDV
antibody prevalence ranges from 5 0 % to 9 0 % in cattle (4, 7 ) .
Prevalences of 5 6 % and 7 9 . 2 % BVDV antibodies have been
recorded, using an enzyme-linked immunosorbent assay
(ELISA), in bovine sera from Brazil (3) and Zimbabwe (9),
respectively. A very high herd prevalence of 9 5 % was
recorded in England and Wales, when the bulk tank milk
samples from 1,070 dairy herds were tested using ELISA (10).
The economic losses associated with BVDV are due to
abortion, still births, congenital abnormalities, increased
neonatal mortality, prenatal and postnatal growth retardation
and persistently infected calves.
Cattle infected with BVDV may develop multiple and diverse
clinical manifestations. The wide spectrum of disease
associated with BVDV infection includes sub-clinical
Rev. sci. tech. Off. int. Epiz., 18 (3)
668
infections, BVD, congenital deformities in calves and acute
and chronic MD. The majority of infections ( 7 0 % - 9 0 % ) in
susceptible cattle are sub-clinical with the development of
neutralising antibodies (1). However, infection with BVD is
acute in seronegative, immunocompetent cattle. Clinical signs
may include pyrexia, depression, inappetence, oculonasal
discharge and occasionally oral lesions characterised by
erosions or shallow ulcerations and foul smelling watery
diarrhoea; high morbidity is experienced but mortality is low.
The virus causes immunosuppression in the host and may
potentiate or enhance the pathogenicity of co-infecting
micro-organisms (e.g. infectious bovine rhinotracheitis,
parainfluenza type-3, corona and rotaviruses, and Pasteurella
and Salmonella spp.).
In contrast, the clinical manifestation of cp BVDV in
persistently infected animals is MD, a highly fatal disease with
low morbidity and high mortality. The incidence of clinical
MD in a herd is expected to be less than 5% in animals of up
to 2 years of age, however, in occasional epidemics, 2 5 % or
more may develop the disease (2). The acute form of MD is
characterised by pyrexia, depression, necrotic erosions on
lips, buccal mucosa and gums, mucopurulent nasal discharge,
profuse watery diarrhoea, lacrimation, corneal oedema and
lameness. Dehydration and death generally occur 5 to 7 days
after the onset of clinical signs. Chronic MD is characterised
by inappetence, weight loss, progressive emaciation,
continued or intermittent diarrhoea, nasal and persistent
ocular discharge and chronic erosive lesions involving the
skin, which may fail to heal.
In India, the presence of BVDV neutralising antibodies in
4 3 . 5 6 % (44/101) of bovine sera was first reported in 1 9 8 9 in
the State of Gujarat. Buffalo showed 6 5 . 9 6 % (31/47)
prevalence, compared to 4 0 . 6 3 % (13/32) in cattle, while 22
sera from apparently healthy in-contact cattle were
seronegative (8). Apart from this study, the current status of
the infection in India has not been investigated.
Materials and methods
Bovine sera ( 4 3 9 ) from 3 2 7 cattle and 112 buffalo, from 17
states of India, which had been confirmed negative for
rinderpest and peste des petits ruminants (PPR) virus
antibodies by competitive ELISA, were selected randomly
from the national serum bank facility of the Project on Animal
Disease Monitoring and Surveillance (ADMAS). The clinical
history of these animals was not known.
A commercial ELISA kit was used to test for BVDV antibodies.
The principle of the ELISA technique in a typical positive
reaction is that the specific binding of BVDV antibodies in the
test sample to the BVDV antigen makes the latter unavailable
for binding to the precoated capturing monoclonal antibody
(mAb) as well as to the peroxidase-conjugated detecting mAb.
In contrast, the absence of specific BVDV antibodies in the test
sample ensures the availability of the virus antigen for binding
to the precoated and peroxidase conjugated mAbs, resulting
in a negative reaction with colour development.
In brief, the ELISA protocol included incubation of undiluted
test sera together with BVDV antigen in a capturing mAb
coated microtitre ELISA plate, at room temperature, for
1 h, on a rotary shaker. The plates were washed 6 times with
washing buffer and then incubated with peroxidase
conjugated detecting mAb for 1 h, at room temperature. After
washing the plates, the chromogen (tetra methyl benzidine)/
substrate solution was added. Finally, the enzyme reaction
was stopped after 15 min and the plates were read at 4 5 0 nm.
Appropriate positive and negative controls provided by the
manufacturer were included in every test run. Serum samples
showing percentage inhibition (PI) equal to or greater than
50% were considered positive for BVDV antibody and those
with a PI less than 5 0 % , as negative.
Results
The commercial ELISA kit for BVDV antibodies was
user-friendly and the results were reproducible. Detection of
antibodies to BVDV using commercial ELISA kits has been
previously described by Graham et al. (5, 6 ) .
The mean prevalence of BVDV antibodies in cattle was
15.29% (50/327) in 16 states, with 2 3 . 2 1 % ( 2 6 / 1 1 2 ) in
buffalo in 9 states (Table I). The overall prevalence was
1 7 . 3 1 % (76/439) in 17 states. Antibodies for BVDV were not
detected in the sera of either cattle or buffalo from the states of
Jammu and Kashmir and Punjab, and were detected only in
cattle sera from Assam, Madhya Pradesh, Manipur, Mizoram
and Nagaland. This preliminary observation should be
followed up by a further large-scale survey to establish
whether BVD exists in these states.
Discussion
This limited study was undertaken to investigate the BVD
situation in view of the ongoing rinderpest eradication
campaign in India. A representative sample of rinderpest and
PPR negative sera ( 4 3 9 ) was selected randomly to provide a
wide geographic coverage over 17 states. The serological
evidence indicates widespread BVD infection with the
interesting characteristic of higher incidence in buffalo.
Although BVD was recorded for the first time in India in
1989, in the state of Gujarat (8), BVD/MD has not been
critically investigated as an important disease, perhaps due to
clinical similarities with rinderpest. Some of the sporadic and
isolated cases of rinderpest-like disease, especially in the more
endemic southern states are very probably BVD/MD. The
clinical forms of BVD/MD now assume greater importance as
India provisionally declared freedom from rinderpest disease
in mid-1995 and a national sero-surveillance campaign is to
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Rev. sci. tech. Off. int. Epiz, 18 (3|
Table I
Prevalence of bovine viral diarrhoea virus antibodies in cattle and
buffalo in India, 1996-1997
Buffalo
Cattle
State
No.
tested
Positive results
No.
%
No.
tested
Positive results
No.
%
Karnataka
88
21
23.86
-
-
-
Tamil Nadu
33
12
36.36
-
-
Orissa
22
9
40.91
-
Nagaland
20
0
0
-
Mizoram
20
0
0
-
-
Meghalaya
20
1
5
-
-
40
5
2
-
-
-
20
7
35
0
-
-
8.33
9
1
11.11
0
11
5
45.46
0
11
0
0
11
0
Urtar Pradesh
17
2
Assam
15
0
11.77
0
Andhra Pradesh
13
1
7.69
Manipur
13
0
Maharashtra
12
1
M a d h y a Pradesh
11
0
J a m m u and
11
0
11
0
The
problem deserves immediate attention and field
veterinarians need to be educated about the complexities of
this disease. Adequate BVD diagnostic facilities are to be
provided in all state level disease investigation laboratories in
India.
-
0
Conclusions
The serological evidence of BVD infection in 1 5 . 2 9 % of cattle
and 2 3 . 2 1 % of buffalo was recorded in 16 and 9 states of
India respectively. Currently, this disease is of particular
interest in terms of the differential diagnosis of BVD from
rinderpest, as the country has been provisionally declared free
from rinderpest disease. An epidemiological study is
suggested to identify immunotolerant persistent infected
animals, which are likely to develop MD; this could be
undertaken using commercially available diagnostic kits.
Kashmir
Punjab
0
Gujarat
11
2
18.18
11
2
18.18
Rajasthan
10
1
10
12
4
33.33
22
5
22.73
112
26
23.21
-
-
327
50
Haryana
Total
15.29
commence in 2 0 0 0 as a prelude to the declaration of freedom
from rinderpest infection. It is therefore crucial that BVD/MD
be considered in the differential diagnosis of all suspected
cases of rinderpest.
The results of this study cannot answer the question of how
long BVD has existed in the indigenous cattle/buffalo
population of India. The introduction of BVDV into the
country through import of semen and persistently infected
exotic cattle in the past few decades cannot be ruled out.
Extensive and continuous use of BVDV contaminated semen,
primary bovine cell culture vaccines and biological products,
especially tissue culture rinderpest vaccine, may have aided
the rapid spread of BVDV throughout the country.
Acknowledgements
This study was sponsored by the European Union-supported
National Project on Rinderpest Eradication (NPRE),
Government of India, New Delhi. The authors wish to thank
the National Project Co-ordinator, NPRE, for providing the
ELISA kit and the Deputy Director General (Animal Sciences)
and Assistant Director General (Animal Health), Indian
Council of Agricultural Research, New Delhi, for their
support.
Rev. sci. tech. Off. int. Epiz., 18 (3)
670
Prévalence des anticorps du virus de la diarrhée virale bovine
en Inde
K.J. S u d h a r s h a n a , K.B. S u r e s h & M . R a j a s e k h a r
Résumé
Les auteurs présentent une étude effectuée en vue de déterminer la prévalence
des anticorps du virus de la diarrhée virale bovine (DVB) dans des prélèvements
de sérum bovin exempts d'anticorps des virus de la peste bovine et de la peste
des petits ruminants. Les sérums ont été prélevés entre janvier 1996 et décembre
1997. Au total, 439 prélèvements (issus de 327 bovins et de 112 buffles provenant
de 17 États de l'Inde) ont été soumis à une épreuve immuno-enzymatique (ELISA)
disponible dans le commerce. La prévalence moyenne des anticorps du virus de
la DVB chez les bovins était de 15,29% (50/327) dans 16 États et de 23,21 %
(26/112) chez les buffles dans 9 États, avec une prévalence globale dans les 17
États de 17,31 % (76/439). Il est de la plus haute importance d'apporter la preuve
sérologique de la présence de la DVB en Inde, en raison de la ressemblance des
signes cliniques de cette maladie avec ceux de la peste bovine. Il est
indispensable de pouvoir effectuer le diagnostic spécifique de chacune de ces
deux maladies, afin que l'Inde soit déclarée provisoirement indemne de peste
bovine; une campagne de surveillance sérologique active doit commencer en
2000 afin d'obtenir le statut de pays indemne d'infection de peste bovine auprès
de l'Office international des épizooties.
Mots-clés
Anticorps du virus de la diarrhée virale bovine - Bovins - Buffles - Diarrhée virale bovine Épreuve immuno-enzymatique - Inde.
Prevalencia de anticuerpos contra el virus de la diarrea viral
bovina en la India
K.J. S u d h a r s h a n a , K.B. S u r e s h & M . R a j a s e k h a r
Resumen
Los autores describen un estudio para determinar la prevalencia de anticuerpos
contra el virus de la diarrea viral bovina (VDVB) en sueros bovinos que no
presentaban anticuerpos contra los virus de la peste bovina y de la peste de
pequeños rumiantes. Para dicho estudio se reunieron muestras entre enero de
1996 y diciembre de 1997. Se analizó un total de 439 muestras (tomadas de 327
vacunos y 112 búfalos de 17 estados de la India), utilizando un kit comercial de
ensayo inmunoenzimático (ELISA). La prevalencia media de anticuerpos contra el
VDVB en el ganado vacuno resultó de un 15,29% (50/327) en 16 estados, y en los
búfalos de un 23,21% (26/112) en 9 estados. La prevalencia total se cifraba en un
17,31% (76/439) para los 17 estados. La demostración serológica de que la
infección por el VDVB está muy extendida en la India reviste gran importancia,
dada la semejanza clínica que guarda esa enfermedad con la peste bovina. Para
que la India pueda declararse provisionalmente libre de la peste bovina, es
esencial un diagnóstico diferencial, capaz de discriminar entre ambas
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Rev. sci. tech. Off. int. Epiz., 18 (3)
enfermedades. En 2000 empezarán a aplicarse medidas de serovigilancia activa,
encaminadas a conseguir que la Oficina Internacional de Epizootias declare el
país libre de infección de peste bovina.
Palabras clave
Anticuerpos contra el virus de la diarrea viral bovina - Búfalo - Diarrea viral bovina Ensayo inmunoenzimático - Ganado vacuno - India.
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