African Horse Sickness (AHS)
Disease Name:
African Horse Sickness (AHS)
Species Affected: Equine, Canine, Elephantidae and Camellidae.
About the Disease:
African Horse Sickness (AHS) is an infectious but non contagious, insect borne viral disease
affecting all species of equines. It is characterized by clinical signs and lesions associated with
respiratory and circulatory impairments. Horse will be seen standing with their legs apart and
their head extended. AHS is an OIE reportable disease. Horse is an amplifier of AHS and source
of infection of this virus is from for arthropods and disease is spread by insect vectors. The
biological vector of the virus is the Culicoides species.
Animal Affected:
Horses are the most susceptible host with close to 90% mortality of those affected, followed by
mules (50%) and donkey (10%). Elephants, Camels and Dog (after eating infected horse meat)
can be infected as well, but often show no sign of the disease.
Cause:
African Horse Sickness (AHS) is caused by an orbi virus of the family Rheoviridae. There are
nine different serotypes of the virus have been described. All serotypes of AHS virus occur in
Eastern and Southern Africa. Only AHS virus serotype 9 is found in West Africa. It is spread by
midges (Culicoides species).Mortality can be as high as 95 percent in some of this disease.
Asymptomatic or mild infections may occur in zebras, African donkeys, and horses previously
infected by another serotype of the virus. Dogs are susceptible to infection if they eat infected
meat.
Symptoms:
African Horse Sickness (AHS) in not contagious. In susceptible horses, AHS usually begins
with an acute fever, followed by the sudden onset of severe respiratory distress. Infected animal
often stand with forelegs spread, head extended, and nostrils fully dilated. Other clinical signs
may include rapid breathing, force expiration, profuse sweating, spasmodic coughing and a
frothy nasal drip of serum and fibrin. Breathing difficulty usually progress rapidly, and the
animal often dies with a few hours after the respiratory signs appear. In less acute cases, the
horse may develop extensive swelling of the head, neck and front leg.
Control and Management:
There is currently no treatment of AHS. The following control measures can be taken up for
prevention and occurrence of the disease.
1. When the disease first appears in an area, affected horses should be eliminated
immediately.
2. Non-infected Equidae should be vaccinated with polyvalent vaccine.
3. Vector control is initiated by using insecticide and repellent.
4. Animal movement restriction.
5. Vaccinated horses should be kept in insect-proof housing because vaccine failure may
occur.
Meteorological Occurrence:
This particular warmer conditions favour the virus as well as the vector of the disease
Courtesy:Dr. Peter N
JRF, NADRS, Manipur.
Disease Investigatory Laboratory
Directorate of Veterinary, & A.H. Services,
Manipur