African Horse Sickness African horse sickness (AHS) is an infectious but noncontagious, arthropod- borne, peracute to subacute, often fatal disease of Equidae characterized by respiratory distress or cardiovascular failure. It is transmitted in the field by at least two species of Culicoides.
16
Embed
African Horse Sickness African horse sickness (AHS) is an infectious but noncontagious, arthropod-borne, peracute to subacute, often fatal disease of.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
African Horse Sickness African horse sickness (AHS) is an infectious but
noncontagious, arthropod-borne, peracute to subacute, often fatal disease of Equidae characterized by respiratory distress or cardiovascular failure.
It is transmitted in the field by at least two species of Culicoides.
EtiologyAfrican Horse Sickness is caused by an Orbivirus of the family Reoviridae
Family: Reoviridae Genus: Orbivirus
Nine different serotypes of the virus have been described
A viscerotropic virus
Host Range
HorsesMulesDonkeysZebras
Approximately 70-95 % of all horses
developing the disease will die
the mortality percentage for mules is only about 50 percent
the mortality percentage for donkeys only 10 percent.
Dogs infected with this virus may have the pulmonary form of the disease.
In a survey in Egypt, antibodies to AHS virus were detected in sheep, goats, camels, buffalo and dogs.
Pathogenesis: Zebras are the natural host and reservoir;
transmission is via biting arthropods and midges
(Culicoides sp.) are the most important vector
Infection results in damage to the circulatory and
respiratory systems resulting in serous effusion
and hemorrhage in various organs and tissues
Pathogenesis: Horse is bitten by an infected midge > initial
viral replication in regional lymph nodes >
primary viremia > infection of target organs
(endothelial cells and mononuclear cells of the
lung, spleen, and lymphoid tissue) > secondary
viremia > virally induced endothelial cell
damage and activation of infected macrophages
with subsequent cytokine production (IL-1,
TNFa) > increased vascular permeability >
edema
Clinical SignsInfected horses remain viremic for
approximately 18 days, although the fever may be present for another 4 to 8 days, if the animal should live that long. Despite their reduced mortality, the viremic stage in donkeys may last for up to 28 days. Zebras appear to be very similar to donkeys in this regard.