African Horse Sickness for Equine Medicine

1. REPORTER: LOPEZ, GWYNETH KOLEEN D.
5 DVM A

2. African horse sickness (AHS) is an insect
borne, viral disease of equids that is
endemic to sub-Saharan Africa. It can be
peracute, acute, subacute, and mild, it is
characterized by clinical signs and lesions
associated with respiratory and circulatory
impairment.

3. • African horse sickness virus (AHSV)
belongs to the genus in the
family.
⚬ Therearenineserotypesofthevirus
• The virus primarily targets endothelial
cells, leading to vascular damage and
subsequent clinical signs such as edema
andhemorrhages.
• The virus can cause an immune response
that, in some cases, contributes to the
severityofthedisease.
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4. AHS is not considered zoonotic, it primarily
affects equids, including horses, mules, donkeys,
andzebras.
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5. AFRICAN HORSE SICKNESS

6. AFRICAN HORSE SICKNESS
• AHSisprevalentinsub-SaharanAfrica
• Transmittedby midges.
• The disease can have seasonal patterns; heavy rain that alternate
with hot and dry climatic conditions favor transmission of the
insect(bitingmidge)vector.
• Has high mortality rates and restrictions on international horse
movement.

7. AFRICAN HORSE SICKNESS
d is directly influenced by the insect vector
s biting midge prefers claylike moisture-retaining
means, such as contaminated needles or
usedoninfectedhorses.

8. • Viral spread is directly influenced by the insect vector
This biting midge prefers claylike moisture-retaining
soils.
• Mechanical means, such as contaminated needles or
equipmentusedoninfectedhorses.
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9. mary mode of entry for AHSV is through the respiratory
Infected Culicoides midges introduce the virus to the
entheybite.
s targets local macrophages and dendritic cells, where it
sinitialreplication.
s initial replication, the virus spreads to regional lymph
adingtoviremia.
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10. • The primary mode of entry for AHSV is through the respiratory
system. Infected Culicoides midges introduce the virus to the
hostwhentheybite.
• The virus targets local macrophages and dendritic cells, where it
beginsitsinitialreplication.
• After this initial replication, the virus spreads to regional lymph
nodes,leadingtoviremia.
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11. • An increase in body temperature, typically observed 12 hours
afterinfection.
• Swollenandpainfulsubmandibularlymphnodes.
• Serousoculardischarge.
• Drycough.
• Occasionallylowerlegswelling.
• Some increase in respiratory rate with increased bronchial
soundsonauscultation.
• Reducedfeedconsumptionduringthefebrilephase.
• Mild lymphopenia and increased plasma fibrinogen
concentrations
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12. PERACUTEFORM:
• IP:5days
• Fever:40°C-40.5°C(104°F-105°F)occursfor1-2days.
• Respiratory Symptoms: Dyspnea, spasmodic coughing, and
dilatednostrils
• Characteristic stance: standing with legs apart and head
extended.
• Ocular Congestion: The conjunctivae exhibit congestion, and
theremaybeedemainthesupraorbitalfossae
• Mortalityrate:90%inepidemics
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13. • Prominentpulmonaryedemaisvisibleintheintralobularspaces,
• Thelungsappeardistendedandheavy
• Frothy fluid is often present in the trachea, bronchi, and
bronchioles
• PleuralEffusion
• EdematousThoracicLymphNodes
• CongestioninGastricFundus
• FrothyNostrilExudate
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14. • In outbreaks, a mixed pulmonary and cardiac form is most
commonlyseen
⚬ IP:7days
⚬ Mortalityrate: 50%-95%
• SubclinicalAHSVinfectionoccursinpartiallyimmuneequids
⚬ myocardialdysfunction,fever,edema,andlethar
• Zebras and certain other equids are also characterized by
subclinicalinfections.
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16. • Diagnosisisbasedonserologyandvirusisolation.
⚬ Group-specific reverse-transcriptase polymerase chain
reaction(RT-PCR).
⚬ Can be isolated by intracerebral inoculation of suckling mice
orinmammalianorinsectcellcultures
• With the recent development of type-specific RT-PCR, the
serotypeofanAHSVcannowbeconfirmedwithin24hours
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17. • ThereisnospecifictreatmentforanimalswithAHSapartfromrest
andgoodhusbandry.
• Aninactivatedvaccineisavailable.
• Duringanepidemic,theprimarygoalistoeradicatedisease
⚬ animalmovementrestrictions
⚬ eliminatingpopulationsofvector
• Ifnoteradicated,perimetervaccinationisimplemented
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18. The Merck veterinary manual
Equine Internal Medicine
African horse sickness.
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