Blue tongue is a non-contagious, infectious, arthropod-borne viral disease of sheep, goat, cattle and deer, with a worldwide distribution. Initially, the disease was reported in sheep in South Africa in 1881 and it was ascribed as “epizootic catarrh”. In 1905, the disease was renamed as “blue tongue”. In India, the first outbreak of blue tongue disease in sheep and goat was reported by Sapre (1964) from Maharashtra. It is listed under category ‘A’ of disease by OIE. The presence of this disease disrupts international commerce by putting a trade barrier on the movement of animals, their germplasm as well as animal products (OIE Bulletin, 1998).
1. Bluetongue in India
Dr. Bhoj R Singh, Principal Scientist (VM)
Head Division of Epidemiology
Indian Veterinary Research Institute,
Izatnagar-243122, Bareilly, UP, India.
2. Bluetongue Virus
Family Reoviridae
◦ Genus Orbivirus
26 serotypes worldwide
◦ 6 serotypes isolated in the U.S.
Non-contagious
Insect-borne viral disease
Ruminants: Primary host is sheep
Others infected: Cattle, goats, deer
3. History
First described in South Africa in 1881 and it was
ascribed as “epizootic catarrh”
In 1905 the disease was renamed as “Blue tongue”
(Spruell, 1905).
The name blue tongue originated from the dutch word
“blaau tong” means mouth sickness
The disease was first reported in Pakistan in 1959 and
in India in 1964 (Sapre S.N.,1964)
First report of BT in Maharashtra.
Between 1967 and 1970 disease was reported in exotic
sheep.
In 1974 BT was reported in the Dorset breed in Andhra
Pradesh.
In 1981 BT was widely spread in Southern India.
4. Blue Tongue - Indian Scenario
BT is endemic in many parts of India and its outbreak in
22 serotypes are recorded in India out of 26 serotypes of BTV.
Morbidity and mortality – High in Sheep, low in Goats
Cattle and Buffaloes – Seroprevalence without clinical disease (Prasad
et.al . 1992).
In Tamil Nadu during the monsoon season of 1997–98 BTcaused the death
of 300,000 sheep and goats
According to the all-India livestock census of 2003, West Bengal state,
situated in eastern India has a population of 1.4 million sheep, susceptible
to BT. Anti-BT antibodies have been detected in sheep, goats and cattle of
West Bengal (Chakrabarti et al,2007 & Batabyal et al, 2008).
The seropositivity of goat for Bluetongue was found to be 27.95% in
Nagpur.
Seroprevalence of 27.97% in Bidar district of Karnataka (Bhoyar et. al.,
2004)
Higher prevalence of Bluetongue in goats (58.01%) has also been
reported from Goa (Barbuddhe et. al., 2005)
5. Morbidity and Mortality by BT
Sheep
Severity of disease varies
Breed
Strain of virus
Environmental stress
Morbidity: as high as 100%
Mortality: usually 0 to 30%
Cattle, goats
◦ Morbidity: up to 5%
◦ Death is rare
Deer, antelope
◦ Severe infection
◦ Morbidity: up to 100%
◦ Mortality: 80 to 90%
7. Transmission of BT
A vector borne disease.
Principal vector Culicoides insects are the major
vectors of BTV. Of over 1,400 species present
worldwide, at least 39 have been reported to
occur in India
C. imicola
C. oxystoma
Mosquitoes , sheep ked and argasid tick
8. Major Vectors
Midges
South India
Culiciodes
brevitarsis
Culicoides imicola
(Ilango et.al 2006)
North India
Culicoides
oxistoma
Culicoides
monocoli
(Maheswari, 2012)
9. Vector Breeding places
Manure pits
Biogas slurry waste
Incessant rain in
rainy season
Wind based
movement of
midges
10. Serotypes reported in India
Through Virus Isolation
(11)
1,2,3,4,8,9,15,16,17,18,2
3
Through detection of
Neutralising
antibodies(11)
5,6,7,10,11,12,13,14,15,
19,20
State
Serotypes
Neutralizing Ab’s
Virus Isolation
J&K - 23
Himachal 4 3,4,9,16,17
Harayana 2,8,12,16 1,4
Rajastan - 1
UP 23 9,8,13
UK - 23
MP 18,23 23
Gujarat 1,2,3,5,8,9,10,11,12,
13,15,16,17,20
6
Maharashtra 2,3,4,5,5,7,8,10,12,13,
16
1,9,16,18,4,17
Andhra 4,6,12,13,14,17,18,19 2,9,15
Karnataka 1,2,4,12,16,17,20 18,23
TN 1,3,4,5,6,7,11,12,14,
15,16,17,19,20
1,2,3,16,23
Newer Concepts in Animal Diseases, 2011, IVRI
11. Clinical Signs
Sheep
•Incubation period: 5 to 10 days.
• High fever.
• Edema of the face, lips, muzzle and ears.
• Excessive salivation.
• Hyperemic oral mucosa.
• Mucopurulent nasal discharge .
•After the first few days and the tongue may become cyanotic.
•Oral lesions may progress to petechial hemorrhages, erosions,
and ulcers.
• Lameness characterized by petechial
hemorrhages at the coronary band.
•Hooves may eventually slough off.
• Fragile wool and diarrhea.
Cattle and goats
Usually subclinical.
Erosions, crusts around nose and teats
Coronitis.
Reproductive failure.
Antelope and deer
Hemorrhage, death.
12. Post Mortem Lesions
Sheep
◦ Face and ears edematous
◦ Dry, crusty exudate on nostrils
◦ Coronary bands hyperemic
◦ Internal hemorrhaging
◦ Hydranencephaly, cerebellar dysplasia
Cattle
◦ Skin: edematous, ulcerated, dry, thick
folds
◦ Mouth: vesicles, ulcers, necrosis
13. Diagnosis
Clinical signs
History
◦ Insect activity
◦ Wasting or foot rot
Laboratory
◦ Virus isolation
◦ ELISA, IFA, VN
◦ PCR
◦ Complement fixation test
15. Sampling
Before collecting or sending any
samples, the proper authorities
should be contacted
Samples should only be sent under
secure conditions and to authorized
laboratories to prevent the spread
of the disease
16. Treatment
No specific treatment
Supportive therapy:
includes protection from the elements (e.g., the wind or
sun), keeping animals warm and dry, and giving fluids and
electrolyte solutions if needed.
Mouth / foot Lesions should be washed thoroughly with 4%
solution of potassium permanganate or 2 –4 % solution of
soda bicarb and then apply boro-glycerine over the mouth
lesions.
Otherwise turmeric powder with oil can also be applied.
Due to lesions in mouth animals are off feed. Hence feed
such animals with palatable green fodder e.g. Lucerne,
green grass etc.
In order to avoid secondary bacterial infection in ailing
animals, broad-spectrum antibiotics along with liver tonics
should be given
Strict bio-security measures should also be followed
17. Bluetongue in Humans
Not a significant threat to humans
One human infection documented
◦ Reasonable precautions should be
taken
Disease in humans is not fatal
Treatment is supportive care
20. BT in India, DAHF, Govt of India
8.7
3.7
8.6
10.2
8.2
7.0
6.2
5.4 5.2
3.7 3.8
4.5
5.2
4.5
3.6
5.7
7.9
3.7
4.5
4.8
5.2
5.9
6.3
5.6
11.4
10.9
0.0
2.0
4.0
6.0
8.0
10.0
12.0
Outbreaks of BT (Log2 values)
Cases per outbreak of BT (Log2 values)
Outbreak of BT in India and cases per
outbreak
13.19
7.27
14.29
18.10
11.9111.5011.04
10.55
11.11
10.00
9.36
15.89
16.13
9.36
5.52
11.30
15.97
9.09
8.42
9.43
6.29
7.09
6.07
7.18
12.62
13.11
0.00
2.00
4.00
6.00
8.00
10.00
12.00
14.00
16.00
18.00
20.00
Anaimal affected with BT (Log2 values)
Animals died with BT (Log2 values)
Morbidity and Mortality due to BT in India
21. Seasonality
Cyclical occurrence
June to September
South-western
monsoon
October to December
North eastern Monsoon
Monsoon leads to High
Vector population
Overall Morbidity 9.3%
Mortality 2.7%
CFR 28.8%
(Srinivasalu et.al 2004)
22. Month wise outbreak in
Karnataka
( Source: PDADMAS 2010-11)
Higher incidence in
winter months
November and
December
Moist soil after flood
with ideal wind
speed- large scale
breeding of
Culicoides
23. Prevalence of BTV antibodies in Sheep and Goats
Northern India- Harayana,
H.P, J&K, Punjab, Rajastan,
UP
Central India– M.P
Western India– Gujarat,
Maharashtra
Southern India– Andhra,
Karnataka, Kerala and T.N
North Eastern India– No
reports (Prasad et.al 2000)
(Bitew.,et.al, 2013, African J. Biotech)
24. Seroprevalence in Cattle and
Buffaloess
First Reported in Annual Report of IVRI,1978
3.7% Cattle positive for BTV
• Native23%
• Exotic71.9%
• Cattle70%
• Buffaloes
37.5
%
Punjab Andhra Pradesh
Srinivasalu., et.al 2004
25. Seroprevalence in Cattle and
Buffaloes
Currently
Seroprevalence has
been (Sub clinical)
reported in North Eastern
States too.
Joardar SN, et.al Vet.World, 2013
Rev.Sci.Tech.Off.Int.Epiz:1992 Prasad et.al
58.2 %
31.79 %
70 %
26. Why endemic in India?
22 serotypes reported
Clinical signs not reported in Goat, Cattle, Buffalo
and deer RESERVOIR??
Seroprevalence in Camels, Deers and Elepahant (Prasad
et.al,1992)
Knowledge of fauna & biology of Culicoides spp. is
poorly known in India.
Vaccines – Not very good have Poor immunogenicity
Prasad,et.al 1992
27. Periodic Hyper Endemicities are
associated with
Monsoon
Poor flock nutrition
High parasitic burden
Lack of affordable veterinary care
Sheep rearing in poorest areas in India
as major source of income
Poor immunogenicity of the inactivated
vaccines Ilango et.al 2006
28. How BTV reached India?
1964 – BTV reported in Maharashtra ,U.P –
Movement of
infected
animals/Vector form
Paksitan?
It is probable
because India
shares long border
with Pakistan.
Import of cattle, Sheep
and Goat for cross
breeding?
1973 – outbreak in
Hisar in Russian
Merino
1975- outbreak in
CSBF, Hisar -
Corridale Sheep –
Indo Australian
project
1974 - outbreak in
Dorset breed,
Andhra
Prasad,et.al 1992
29.
30. Control
Quarantine
Quarantine and movement controls. Prevent
spread of virus
Confine animals indoors (i.e., barn when vectors
are active
Disinfection
Does not stop virus transmission
Cleaning the premises
◦ Sodium hypochlorite (bleach)
◦ 3% Sodium hydroxide (lye)
Insect control
◦ Pyrethroids
◦ Organophosphates
31. Prevention and Control
Effective vaccination may reduce
incidence
Many Countries eradicated BT and
possible in India. (UK 2008)
Restricting animal movement
Insecticide sprays,
Habitat removal - Vector
Timely announcement of satellite
based weather forecasting and
educating sheep farmers
Community Participation
Vaccination
Bhanuprasad., et al 2009
32. Vaccines in India
Technology
transferred from
IVRI, July 2012.
BTV serotypes are 1,
2, 10, 16 and 23
Under All India
Network Project on
Blue Tongue, ICAR,
efforts are
concentrated on
developing effective
vaccine
33. Quiz
Why Blue Tongue (BT) is endemic in
India?
What are environmental factors
responsible for spread of BT?
Is it possible to control BT in India? If yes,
how and if No, why?
What may be the good qualities of BT
vaccine to be used nationwide?
How to control an outbreak of BT?