VIRAL DISEASE OF HORSE WHICH HAS MAINLY DUNKOP AND DIKKOP FORM SLIDE IS PREPARED BY A VET STUDENT AHS IS A VERY FATAL DISEASE OF EQUINES ALL OVER THE WORLD. TREATMENT IF NOT GIVEN AT PROPER TIME, DEATH RATE IS VERY HIGH

1. AFRICAN HORSE
SICKNESS
ABHIJITH SP
CVAS POOKODE

2. INTRODUCTION
• African horse sickness is a devastating disease that causes great suffering
and many fatalities amongst horses in sub-Saharan Africa.
• African horse sickness is a highly infectious and deadly disease caused by
African horse sickness virus.
• It commonly affects horses, mules, and donkeys.
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3. AETIOLOGY
• Reoviridae---Orbivirus—AHSV.
• Nonenveloped, spherical virions; 80 nm in diameter.
• Virions possess 3 concentric capsid layers, all icosahedral: outer, middle, and inner
capsids.
• Genome consists of dsRNA, divided into 10-12 segments.
• Cytoplasmic replication, with formation of large intracytoplasmic perinuclear
inclusion bodies.
• Synonym- Dunkop and Dikkop, Equine Plague
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4. SUSCEPTIBLE HOST
• The common hosts of this disease are horses, mules, donkeys, and zebras.
• However, elephants, camels, and dogs can be infected, as well, but often
show no signs of the disease.
• Dogs usually contract the disease by eating infected horse meat, although a
recent report has been made of the disease occurring in dogs with no known
horse-meat ingestion.
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5. TRANSMISSION
• The most important vector for AHS in endemic areas is the biting
midge Culicoides imicola, which prefers warm, humid conditions.
• Larvae do not carry the virus, and long, cold winters are sufficient to break
epidemics in nonendemic areas.
• Not zoonotic
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6. INCUBATION PERIOD
• Incubation period is usually 7–14 days, but may be as short as 2 days.
• For the purposes of the OIE Terrestrial Code, the infective period for AHSV
shall be 40 days for domestic horses.
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7. PATHOGENESIS
• Bite of insect takes virus into subcutaneous tissue.
• Then migration to nearest lymph node and then to systemic circulation.
• Mainly deposits on heart and lungs along with systemic deposition.
• Then the virus localised in places will produce many lesions .
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8. CLINICAL SIGNS
There are four principal manifestations of disease.
• In the majority of cases, the subclinical cardiac form is suddenly followed by
marked dyspnea and other signs typical of the pulmonary form
• A nervous form may occur, though it is rare .
• Animals that recover from AHS develop good immunity to the infecting serotype
and partial immunity to other serotypes.
• Morbidity and mortality vary with the species of animal, previous immunity and the
form of the disease .
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9. 1. Subclinical form (Horse sickness fever)
Fever (40–40.5°C/104°F–105°F) .
Mild form; general malaise for 1–2 days.
Very rarely results in death.
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10. 2. Subacute or cardiac form/Dikkop Form
• Mainly called as Dikkop Form.
• Fever (39–41°C/102–106°F)
• Swelling of the supraorbital fossa, eyelids, facial tissues, neck, thorax, brisket
and shoulders
• Mortality usually 50% or higher; death usually within 1 week
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11. 3. Acute respiratory or pulmonary form/Dunkop Form
• Mainly called as Dunkop Form.
• Fever (40–41°C/104–106°F) .
• Dyspnea, spasmodic coughing, dilated nostrils with frothy fluid oozing out .
• Redness of conjunctivae .
• Nearly always fatal; death from anoxia within 1 week .
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12. 4. Mixed form (cardiac and pulmonary)
• Both organs get damaged.
• Occurs frequently.
• Pulmonary signs of a mild nature that do not progress, edematous swellings
and effusions .
• Mortality: about 70–80% or greater .
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13. Lesions
Respiratory
• interlobular edema of the lungs
• hydropericardium, pleural effusion
• edema of thoracic lymph nodes
• petechial haemorrhages in pericardium
• mucosa and serosa of small and large intestines
may exhibit hyperemia and petechial hemorrhages.
Cardiac
• subcutaneous and intramuscular gelatinous edema.
• epicardial and endocardial ecchymoses;
myocarditis .
• haemorrhagic gastritis .
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Pulmonary Edema 14

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Congestion and Catarrhal Inflammation

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Hemorrhage in Ligamentum
Nuchae

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Heart, Pericardial Fluid

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Intermuscular Odema

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Pulmonary Edema

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Swelling of Supra orbital Fossa

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Pulmonary Oedema

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Conjunctivitis

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Inter-Lobular Edema

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Lingual Petechia

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Mesentery Hemorrhage

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Edema in Lungs

28. Differential Diagnosis
• Anthrax
• Equine infectious anaemia
• Equine viral arteritis
• Trypanosomiasis
• Equine encephalitis
• Piroplasmosis
• Purpura haemorrhagica
• Hendra virus
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29. DIAGNOSIS
• Virus isolation
• Cell cultures, such as baby hamster kidney-21 (BHK-21), monkey stable (MS) or African green monkey kidney (Vero) or insect cells (KC)
• Intravenously in embryonated eggs
• Intracerebrally in newborn mice
• Virus identification
• Enzyme-linked immunosorbent assay (ELISA) – rapid detection of AHSV antigen in blood, spleen and supernatant from cell culture
• Virus neutralization (VN) – until recently the ‘gold standard’ for typing as well as identifying virus isolates, but takes 5 days RT-PCR is a highly sensitive technique
that allows the detection of a very low number of copies of RNA molecules Real-time PCR – detects all 9 serotypes
• AHSV typing
• VN test has been the method of choice for typing as well as the ‘gold’ standard test for identifying AHSV’s isolated from the field using type specific antisera
Development of a type-specific gel-based RT-PCR and real-time RT-PCR using hybridization probes for identification and differentiation AHSV genotypes provides a
rapid typing method for AHSV in tissue samples and blood.
• There is a good correlation between the results obtained with the type-specific RT-PCR and the VN test, however, the sensitivity of these assays is lower than that
obtained with the diagnostic group-specific real-time RT-PCR Typing of nine AHSV types has also been performed with probes developed from a set of cloned full
length VP2 genes
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30. PREVENTION AND CONTROL
• In endemic areas horses are vaccinated using attenuated live polyvalent
vaccines.
• Immunity is serotype specific.
• Horses should be protected from flies during disease outbreaks.
• U.S.A: A sixty-day quarantine on all horses imported from Africa, Asia, and
the Mediterranean.
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32. FACTS AND TIPS.
• No. of serotypes-9
• Type of immunity-Serotype specific.
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33. THANK YOU