Blue tongue

Bluetongue is an infectious arthropod-borne viral disease primarily of domestic and wild ruminants. Infection with bluetongue virus (BTV) is common in a broad band across the world, which until recently stretched from ~35°S to 40°–50°N. Bluetongue virus is the type-species of the genus Orbivirus in the family Reoviridae. The geographic restriction is in part related to the climatic and environmental conditions necessary to support the Culicoides vectors.

1. BLUE TONGUE (Sore Muzzle, Pseudo Foot-and-Mouth Disease, Muzzle Disease) Submitted by Ranjini Manuel

2. INTRODUCTION Bluetongue(BTV) is an insect borne viral disease of domestic and wild ruminants, especially sheep. The name refers to the blue discoloration of the tongue and mucous membranes, due to cyanosis . BTV is classified as an OIE list A disease/ multiple species and is therefore notifiable .

3. HISTORY First described in South Africa in 1881  “ epizootic catarrh ”, Malarial catarrhal fever ( Spruell , 1905 ). He proposed a method of immunization inoculation of immune serum and virulent whole blood. Theiler -unable to confirm Spreull’s work, introduced another method -only infected blood -been attenuated for sheep by several serial passages in the same species. Vaccine prepared by Theiler’s formula 2 was employed for nearly 40 years

4. In 1933 it was first diagnosed in cattle ( Bekker et al., 1934) - clinical signs were similar – FMD-it was called pseudo-FMD, or sore-mouth The name blue tongue originated from the Dutch word“blaau tong” means mouth sickness It was also called bloutong by south African farmers

5. INDIA The disease was first reported in India in 1964 (Sapre S.N.,1964 ) Southdown, Rambouillet , Russian Merino and Corriedale First report of BT - Maharashtra In 1974 BT was reported in the Dorset breed in Andhra Pradesh . In 1981 BT was widely spread in Southern India .

6. ETIOLOGY Family Reoviridae , 10ds RNA segments Genus Orbivirus 24 serotypes worldwide non-enveloped virus , 90 nm in diameter Non-contagious Insect-borne viral disease Ruminants : Primary host is sheep Others infected: Cattle, goats, deer Cattle – reservoir and amplification host

7. RESISTANCE TO PHYSICAL & CHEMICAL ACTION Temperature : Inactivated by 50°C/3 hours; 60°C/15 minutes. pH : Sensitive to pH 8.0. Chemicals/Disinfectants : Inactivated by ß- propiolactone ; iodophores and phenolic compounds. Survival : Very stable in the presence of protein (e.g. has survived for years in blood stored at 20°C)

8. EPIDEMIOLOGY BT is endemic in many parts of India and its outbreak in 22 serotypes are recorded in India out of 24 serotypes of BTV. Morbidity and mortality – High in Sheep, low in Goats 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)

9. The disease was recorded regularly in Tamil Nadu where a total of 258 outbreaks were reported between 1986 and 1995 In Tamil Nadu during the monsoon season of 1997–98 BT caused the death of 300,000 sheep and goats.

10. Erode District of Tamilnadu - During 2004–2008 - morbidity -1388 among Sheeps . Mortality of 239 sheeps . Sheep was highly prone to bluetongue with a mortality rate of 17.2 % when compared to cattle and goat. Outbreak occurred during the month of November and December , when heavy rainfall conditions makes congenial environment for the multiplication of vectors Culicoides sp . (R . Yasothai 2008)

11. Andhra Pradesh

12. KERALA 2005, Seroprevalence of BTV – sheep and goat- sera samples were collected from 14 districts out of which 12 confirmed the presence of group specific BTV antibodies by dot ELISA and reconfirmed with c-ELISA Seroprevalence – 5.1% 2014, seroprevalence of BTV among domestic ruminants in northern kerala samples were collected from wayanad , Kozhikode and Palakkad- cELISA was used- seroprevalence – 9.3%

13. MORTALITY & MORBIDITY Sheep Severity of disease varies with Breed, Strain of virus, Environmental stress Morbidity: as high as 100% Mortality: usually 0 to 30% Cattle , goats Morbidity: up to 5% Mortality low

14. RISK FACTORS Monsoon Poor flock nutrition High parasitic burden Lack of affordable veterinary care Poor immunogenicity of the inactivated vaccines ( Ilango et.al 2006)

15. TRANSMISSION A vector borne disease. Principal vector  Culicoides insects are the major vectors of BTV. They are most active from about one hour before sunset until one hour after sunrise (Mellor et al., 2000 ) South India Culiciodes brevitarsis Culicoides imicola ( Ilango et.al 2006) North India Culicoides oxistoma Culicoides monocoli ( Maheswari , 2012 )

16. Replicates in digestive tract Progeny virus released in to the haemocoel Salivary glands are infected The whole cycle from infection to transmission takes between 10 to 15 days at 25 °C and individual vectors once infected usually remain so for life (Chandler et al., 1985; Eaton et al., 1990; Mellor, 1990, 2000, 2004).

17. TRANSMISSION I solated from some arthropods, e.g ., sheep ked ( Melophagus ovinus ) ( Luedke et al., 1965) some species of ticks (Stott et al., 1985; Bouwknegt et al., 2010) mosquitoes However, these are mechanical vectors with only a negligible role in disease epidemiology ( Radostits et al., 1994). ( Melophagus ovinus ) Ixodes ricinus mosquito

18. TRANSMISSION Bull semen can also transfer the virus, but it can be infected only when the bull is viraemic (Bowen and Howard, 1984; Howard et al., 1985; Osburn , 1994; Kirkland et al., 2004) and when semen contains red or white blood cells with which the virus is associated ( Osburn , 1994; Wilson et al., 2008).

19. TRANSMISSION The passage of BTV across the placenta is another mode of transmission . It has been recorded in cattle ( Gibbs et al., 1979; Thomas et al., 1986; De Clercq et al., 2008; Desmecht et al., 2008; Menzies et al., 2008; Backx et al., 2009; Darpel et al., 2009; Lewerin et al., 2010; Santman-Berends et al., 2010 ) In an experimental study it was possible to infect a newborn calf with BTV-contaminated colostrum ( Backx et al., 2009).

20. PATHOGENESIS transported by dendritic cells from the skin  local lymph nodes spreads to the blood circulation inducing a primary viraemia (blood elements) Seeds other lymphoid organs, spleen & lungs The virus replicates in vascular endothelial cells, macrophages and lymphocytes Virus particles, sequestered in invaginations of the RBC membrane-prolonged viremia

21. cell necrosis, apoptosis  by activating the p38MAP kinase, the virus  vascular permeability induces the production of TNFα, IL-1, IL-8, IL-6, IFN-I and cyclooxygenase-2, and enhances plasma concentration of prostacyclin and thromboxane, which frequently leads to an excessive inflammatory response and subsequent damage to the cells and tissues BTV-infected endothelial cells  damage to the endothelium, interfere with its function &  vascular permeability, DIC  this leads to the development of edema, inflammation, congestion, necrosis and effusions

22. CATTLE & WILD RUMINANTS E ndothelial cell damage is minimal . The viremia in cattle is highly cell associated , particularly with erythrocytes and platelets. Although the virus does not replicate in the erythrocytes and infected erythrocytes are likely to circulate for their life span. In cattle, viraemia may last as long as 60 or, even 100 days (Sellers and Taylor, 1980), which makes this animal an important host from the epidemiological point of view.

23. Viraemia and immune response Viraemia in infected animals has a prolonged course, but is not persistent D uration depends on the longevity of erythrocytes to which virus is bound ( MacLachlan et al., 2009) Viraemia lasts -14 to 54 days in sheep,Goats - 19 to 54 days ( Barzilai and Tadmor , 1971; Luedke and Anakwenze , 1972; Koumbati et al., 1999).

24. The infected animals react to BTV with interferon production and humoral and cell-mediated immune responses ( MacLachlan and Thomson, 1985; MacLachlan , 1994 ). The sera of infected ruminants also contain serogroup -specific antibodies induced by the VP7 protein, as well as antibodies against other structural and non-structural proteins ( MacLachlan et al., 1987; Richards et al., 1988; MacLachlan , 2004).

25. CLINICAL SIGNS SHEEP Incubation period- 5-20 days High fever (after 48hrs of fever)  nasal discharge, with reddening of the buccal and nasal mucosae & salivation Nasal discharge - m ucopurulent and often blood stained Oral erosions and ulcerations, Hyperemic oral mucosa.

26. CLINICAL SIGNS Excoriation of the buccal mucosa- offensive odor . Tongue - Swollen, protruding, Cyanotic Feet- Sore hooves, lameness, Coronitis Fragile wool and diarrhoea. Abortion, foetal mummification & congenital defects

27. Salivation Facial swelling Mucopurulent Nasal Discharge

28. Coronitis Hemorrhages at the coronary band Painful hooves Hooves may eventually slough off

29. Wryneck , with twisting of the head and neck to one side, occurs in a few cases, appearing suddenly around day 12 . apparently attributable to the direct action of the virus on muscle tissue, which is severe enough to prevent eating

30. CONVALESCENCE Partial or complete loss of the fleece is common and causes great financial loss for the farmer. D uring convalescence include separation / cracking of the hooves Although the subsequent birth of lambs with porencephaly and cerebral necrosis is usually recorded after vaccination with attenuated virus, it also occurs rarely after natural infections.

31. Cattle and goats Most infections are in apparent , although serotype 8, are highly virulent in cattle . Usually subclinical . Lethargic, anorexic and shows weakness Erosions, crusts around muzzle and teats Coronitis . Reproductive failure, deformities & abortion observed if the infection is contracted in early gestation. ‘‘ The Dancing Disease’’.

32. CLINICAL PATHOLOGY  PCV and initial leukopenia followed by leucocytosis . The skeletal myopathy that occurs in this disease is reflected by  creatinine phosphokinase H yperaemia , or occasionally cyanosis , of the oral mucosa with petechiae and ecchymoses .   Focally extensive area of haemorrhage - cattle

33. The spleen, lymphatic nodes and tonsils are enlarged and haemorrhagic , occasionally with petechiae . The tongue root, pericardial sac, kidney, gut (particularly at the iliocaecal junction) and subcutaneous tissues may have petechiae . inflammation of the upper respiratory tract, pulmonary oedema , pleuritis , pericarditis or enteritis may be present

34. SAMPLES Living animals: blood in heparin Freshly dead animals: spleen, liver, red bone marrow, heart blood, lymph nodes Aborted and congenitally infected new born animals: pre-colostrum serum plus same samples as for freshly dead animals All samples have to be preserved at 4°C, and not frozen (As per OIE)

35. DIAGNOSIS I dentification of BTV in blood or tissue samples - ( RT-PCR) method and can detect BTV RNA in samples as late as 6 months after infection (Katz et al., 1994; MacLachlan et al., 1994). The identification of a BTV serotype is carried out in the virus neutralisation test ( gold standard) . Other available diagnostic methods include antigen-capture ELISA, immunospot and immunofluorescence tests Virus identification from cell cultures can then be conducted by methods such as immunofluorescence and immunoperoxidase assays using BTV-specific monoclonal antibodies .

36. CFT – Compliment fixation test Agar gel immunodiffusion test(AGID), easy to perform, inexpensive but relatively insensitive and detects cross-reacting antibodies to other orbiviruses . Competitive ELISA (c-ELISA) – commonly used in labs, ideal to monitor efficiency of vaccination campaign in non infected animals serum neutralization (SNT)- highly sensitive, specific, expensive and time consuming BTV – electron microscope

37. VIRUS ISOLATION Embryonated eggs, 9-12 days old, are used for BTV isolation and intravenously inoculated with the material examined. The material obtained from embryonated eggs can either be further propagated in cell culture or directly examined using molecular methods (PCR or in situ hybridisation) ( Schoepp et al., 1991; Katz et al., 1994; Wang et al., 1988; Clavijo et al., 2000 ).

38. VIRUS ISOLATION Bluetongue virus can also be isolated in cell lines of insect origin, such as the KC line derived from Culicoides sonorensis cells or the C6/36 line from Aedes albopictus (AA) cells; the mammalian BHK-21, CPAE or Vero cell lines can also be used (Wechsler and McHolland , 1988; Mecham , 2006). The cytopathic effect produced by BTV is observed only on cell lines of mammalian origin at 3 to 5 days after inoculation and appears as foci of rounded and refractile cells

39. DIFFERENTIAL DIAGNOSIS Foot-and-mouth disease PPR Epizootic hemorrhagic disease ( wild ruminants ) Contagious ecthyma (sheep) Sheep pox (sheep) Bovine viral diarrhoea/mucosal disease (cattle) Malignant catarrhal fever (cattle) Acute photodermatitis (cattle )

40. TREATMENT Symptomatic and supportive treatment Local irrigations with mild disinfectant solutions may afford some relief. Affected sheep should be housed and protected from weather, particularly hot sun fluid and electrolyte therapy and treatment to control secondary infection may be desirable .

41. vaccination Vaccination is the only satisfactory control procedure once the disease has been introduced into an area . Successful in keeping losses to a very low level An immediate ban on animal import from countries with bluetongue is the priority measure, followed by the monitoring of farms

42. Bluetongue vaccines are serotype-specific Two types of vaccines, inactivated and live attenuated, are currently available Live attenuated vaccine – used in endemic regions, 1 dose assure protection for a year, production is inexpensive, low efficiency at high temperatures over 35 ° C May show clinical signs, malformation of foetus , poor semen quality, decreased milk production recommended to vaccinate ewes 9 to 15 weeks before mating, and rams after the mating period

43. RAKSHA-BLU First vaccine for Blue tongue in India . P rotect the animals against five strains of the ‘bluetongue’ virus. R esult of collaborative efforts of IIL, TANUVAS (Tamil Nadu University of Veterinary and Animal Sciences) and ICAR (Indian Council of Agricultural Research). The vaccine was developed in three years .  Active Ingredient(s):  Contains bluetongue vaccine modified live virus, type 10 . Given to 3 months old lambs , will be followed by a booster dose- three months and annual vaccination Penicillin and streptomycin are added as preservatives . Per dose -expense of 5 rupees .

44. INACTIVATED VACCINE Inactivated vaccine Today monovalent vaccines against BTV-1, BTV-8 and BTV-9 are available Bluevac BTV8 is licensed for both cattle and sheep, and can be used during pregnancy. All animals should be given a primary course of two injections under the skin, three weeks apart. The immunity afforded by the vaccine lasts for a year after completion of the primary course.

45. INACTIVATED VACCINE Zulvac 8 Bovis is licensed for use in cattle whereas the Zulvac 8 Ovis vaccine should be used in sheep. Both vaccines prevent viraemia . The vaccines can be used in cattle from three-months-old and sheep aged six-weeks . Each species require two 2ml doses administered intramuscularly in cattle and subcutaneously in sheep, three weeks apart. Provides immunity for 12 months.

46. Well inactivated vaccines can prevent the development of clinical disease in susceptible hosts, reduce direct economic losses due to infection, facilitate safe trading in animals and prevent the development of viraemia R ecombinant vector vaccines, sub-unit vaccines and others which would offer advantages such as no risk – very expensive

47. CONTROL Reducing the risk of exposure is attempted by spraying cattle and sheep with repellents and insecticides and housing sheep at night Bi weekly application of permethrin During transmission periods, avoidance of low, marshy areas or moving sheep to higher altitudes may reduce risk .

48. There is a high mortality in Culicoides that fed on cattle that have been treated with anthelmintic dose of ivermectin It is sensitive to 3% NaOH , organic iodine complex, phenol and b- propiolactone ( Radostits , 1994; Anonymous, 2009a ). protection of animals in stables can be improved by door and window screens made of a fine mesh or a coarse fabric impregnated with insecticide ( Radostits et al., 1994; Calvete et al., 2010).

49. Thank you