Blue tongue is an infectious, arthropod-borne viral disease that affects sheep, cattle, and goats. It is transmitted by midges of the Culicoides genus and causes fever, ulceration of the mouth and tongue (giving it its name), and lameness in infected animals. The disease is caused by the bluetongue virus, which is part of the Reoviridae family of viruses and has a genome consisting of segmented double-stranded RNA. While outbreaks can cause high mortality in sheep, cattle serve as the primary reservoir without showing severe clinical signs.

1. Blue tongue
ABHIJITH SP
CVAS POOKODE

2. INTRODUCTION
• Infectious arthropod borne viral disease of cattle ,sheep and goats.
• Although sheep are most severely affected, cattle are the main mammal
reservoir of the virus and are critical in the disease epidemiology.
• The disease is non-contagious and is only transmitted by insect vectors
(midges of the Culicoides species).
• Bluetongue virus is a notifiable disease in many countries.
• Synonyms: Sore muzzle, Dancing Disease
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3. AETIOLOGY
• Reoviridae Family- Orbivirus genus- BTV.
• Genome consists of dsRNA, divided into 10-12 segments
• Cytoplasmic replication, with formation of large intracytoplasmic perinuclear
inclusion bodies.
• Nonenveloped, spherical virions.
• The BTV genome evolves rapidly via mutations.
• Orbi-Orbit or stoma region.
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4. SUSCEPTIBLE HOST
• BTV affects sheep, cattle, deer, goats and camelids (camels, llamas, alpacas,
guanaco and vicuña).
• Humans are not affected.
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5. TRANSMISSION
• Bluetongue is a noncontagious disease.
• Transplacental transmission occurs in cattle and sheep. Semen that contains
RBC or WBC infected with the virus may infect susceptible cattle.
• Culicoides spp. [biting midges, no-see-ums], especially Culicoides variipennis var
sonorensis, are the biological vectors.
• Culicoides spp. usually feed at dawn and dusk and they require standing water in
which to breed.
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6. INCUBATION PERIOD
• 6-10 days.
• Morbidity: Up to 80%; mortality: up to 50%.
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7. PATHOGENESIS
• Through biting of Culicoides, they gain access into blood vessels .
• They multiply in endothelial cells and WBC.
• They break the cell and comes out and create a gap in endothelium.
• So Protein rich fluid oozes out through that—Oedema
• Rbc moves out-Hemorrhage
• Followed by thrombosis and infarction.
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8. CLINICAL SIGNS
• Fever, ulcerated mouth, cyanosis of tongue [bluetongue], profuse salivation
and frothing, and nasal discharge [serous, later becoming mucopurulent].
• Coronitis and laminitis resulting in lameness and recumbency.
• Fetal infection. Fetal death and/or abortion; CNS malformations such as
hydranencephaly; porencephaly, etc.
• Cyanosis of tongue-Thus the name Blue Tongue.
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Darkly congested gingiva

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Foot
Coronitis
Ulceration and necrosis of teats

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Coronary Band Lesions
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Ulcerative Dermatitis

14. MACROSCOPIC LESIONS
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Brain vasculitis haemorrhage

15. MACROSCOPIC LESION
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Intimal Haemorrhage on pulmonary artery

16. MACROSCOPIC LESION
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Focal haemorrhage on pulmonary artery

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Hydrocephalus

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Aspiration Pneumonia

19. MICROSCOPIC LESIONS
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Intracytoplasmic inclusion body in epithelial cells of mouth

20. MICROSCOPIC LESIONS
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Skeletal Cell Necrosis

21. DIAGNOSIS
• Virus isolation. Heart blood [washed RBCs or buffy coat], spleen, liver, etc.
IV inoculation into 10- or 11-day-old chicken embryos or cell culture.
• Antigen and nucleic acid detection. ELISA, FAT, immunoperoxidase,
immune electron microscopy, PCR, etc.
• Seroconversion [acute and convalescent sera].
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22. PREVENTION AND CONTROL
• Bluetongue is a notifiable disease. Sheep should be put in barns at dusk [prime
Culicoides feeding period].
• Vaccination. Attenuated monovalent virus vaccines to serotypes 10, 11, and
17 are used in the United States.
• Attenuated vaccines should not be used in pregnant animals; or during the vector
season because the vectors may pick up the vaccine virus and transmit it to
other animals.
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24. FACTS AND TIPS.
• Serotype of BTV-29.
• REO=Respiratory Enteric Orphan
• Immunity is serotype specific.
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25. THANK YOU