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South
African Horse Sickness.
What is (South) African Horse Sickness (AHS)? It
is a highly infectious non-contagious, vector born viral
disease. It is characterised by respiratory and
circulatory damage, accompanied by fever and loss of
appetite. Animals affected are all breeds of horses
(mortality rate of 70-90%), mules and donkeys. The
vector host which spreads the virus is a midge. AHS does
not spread directly from one horse to another, but is
transmitted by the midge, which becomes infected when
feeding on other infected animals. Most animals become
infected in the period associated with sunset and
sunrise, when the midges are most active. [This is an
abbreviated description of AHS taken from Google. In the
early 20th Century AHS was thought to be
spread by biting flies or mosquitoes. But it was already
understood that it was non-contagious. ]
South African Horse Sickness first appeared in Aden in
1879; it was said to have been brought in from
Mauritius. In October that year the Aden Troop lost 17
horses.
The Glanders & Farcy Act of 1899 provided for horses
affected by the Glanders and Farcy disease or other
epidemics such as South African Horse Sickness.
Inspectors appointed by the Government under this Act
would arrange for a vet to examine the affected animal.
Whereas the killing of diseased animals was obligatory
for Glanders and Farcy diseases, for African Horse
Sickness, the Inspector had the option of either killing
or treating the animal.
In 1907 Aden was not subject to the 1899 Act and was
therefore under no obligation to control the export of
animals or hides. Between October 1906 and May 1907
there were 130 cases of South African Horse Sickness in
Aden, only 30 of which survived. 78 died from the
sickness and the remaining 22 were destroyed. This was
the first major epidemic since 1879. The sickness
usually appeared in the autumn and would continue
through to early summer.
Various measures were taken which in subsequent years
would contain the spread of the disease to a great
extent. One advantage of Aden was that the topography
lent itself to being divided into a number of areas,
with entry and exit from each area controlled through
one of the Gates. So an obvious measure was to ban
movement of horses between areas once an outbreak had
been identified. Another was for sick horses, or those
suspected of having the sickness, to be quarantined, the
minimum period being 15 days. An additional measure was
the automatic quarantining of all horses arriving by sea
from Mukalla, Somaliland and Jibuti. This proved to be a
very worthwhile precaution as two horses developed the
sickness in quarantine in 1910, three in 1911 and eight
in 1913. That year there was a fairly serious epidemic
with 40 horses dying in either Aden or Sheikh Othman.
The stables of the Aden troop at Khormaksar were pretty
isolated and only one horse succumbed there. There were
cases every year at Dthala and Lahej so control measures
were required at the border between Aden and its
hinterland. At the end of the 1907 outbreak the carriage
stand at Khormaksar was reopened from 1 June for
carriage traffic between Aden and Sheikh Othman, this
being 15 days after the last case had developed.
At that time Aden had no resident vet, which was perhaps
why the Glanders & Farcey Act was not applicable to
Aden. On the next outbreak in November 1908 Aden asked
for a vet to be sent from India. As he was a civilian
and not a military vet all his costs including travel
had to be met from the Aden budget. Aden was not amused.
AHS is prevalent today on the African continent. In
2007-2008 the outbreak in South Africa itself lasted
from October 2007 to May 2008. In these eight months
there were 707 cases, of which 404 horses died. |
