African Horse Sickness

Tips to Help Prevent African Horse Sickness

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What is African Horse Sickness?

African Horse Sickness (AHS) is a highly infectious viral disease which is naturally occurring in sub-Saharan Africa. Due to the virus being extremely infectious and the high mortality rate, AHS has even been listed by the World Health Organization for Animal Health (OIE). AHS is classified as an Orbivirus of the Reoviridae family and has 9 distinct serotypes.

What animals can be infected with AHS?2

Equids

  • All breeds of horses
  • Mules
  • Donkeys
  • Zebras

Other

  • Dogs if they eat the meat of an infected animal, however they are unlikely to be the reason for transmission.

Transmission and location

African Horse Sickness is not transmitted from one horse to another through contact. It is carried and spread by the Culicoides midge and occasionally, mosquitoes.2 The virus is most commonly spread in moist conditions and warm temperatures. Horses and other animals are therefore most at risk at dusk and dawn during the warm and rainy season. AHS is endemic in the southern most parts of Africa, typically the tropical and subtropical areas which extend south of the Sahara including Senegal across to Ethiopia and extends as far down as South Africa.2

Symptoms

The AHS incubation period in equids is anything from 3 to 14 days with the average being 9 days.2

The disease presents in 3 forms, it will either affect the lungs (respiratory disease), heart (cardiac disease) or cause a cyclic fever.

Subclinical, Fever form

  • Symptoms include fever (40-40.5°C) which is usually cyclic (meaning a higher fever in the afternoon and usually disappearing in the morning), and sometimes depression and lack of appetite.
  • This is the mildest form of AHS and recovery is generally good.

Subacute, Cardiac form

  • Also known as “dikkop”.3
  • Symptoms include fever (39-41°C), and swelling of the eyelids, lips, tongue, cheeks, neck, and shoulder area.
  • The mortality rate is 50% and occurs due to heart failure within 1 week.

Peracute, Respiratory or Pulmonary form

  • Also known as “dunkop”.3
  • Occurs rapidly, within days.
  • Symptoms include fever (40-41°C), difficulty breathing, sweating, coughing and a froth-like discharge from the nostrils.
  • Death (90%) is usually within a few hours or days after symptoms are presented.

Acute or mixed (Cardiac and Pulmonary) form

  • Symptoms include a mixture of both the cardiac and pulmonary as mentioned above.
  • This form of AHS occurs frequently.
  • The mortality is 70-80% of more.

In infected dogs, the pulmonary form is most commonly reported after they had eaten infected meat.2

Diagnosis, reporting and control

Diagnosis can only be confirmed in a laboratory through the analysis of blood samples from the suspected infected animal. These are usually taken by a veterinarian after the animal has started to show signs of AHS, particularly in the fever stage.

Owners of infected animals are required by law to report suspected and diagnosed cases to their local state vet. The Animal Diseases Act (Act No. 35 of 1984) states that AHS is a state-controlled disease. Not only are horse owners obligated to notify the state vet, but they are also to ensure that all horses, donkeys, and mules are vaccinated at least once every year with an approved AHS vaccine.3

Prevention and treatment

While there is no recorded efficient treatment available, there are measures one can implement to try to prevent your animals from being infected with AHS. These include:

  • Restricting the movement of horses and animals into areas with recent reported cases of AHS.
  • For some forms of the disease, euthanasia of the infected horse should be considered.
  • Keep animals stabled in an insect-proof stable especially from dusk until dawn when the infected midges are most active.
  • Get rid of any mud, stagnant water or other moist areas which serve as a breeding ground for the midges. Use animal-safe insect repellents and insecticides.
  • Check the animals’ temperature twice per day for any signs of fever.
  • IMPORTANT: Ensure all equids are vaccinated annually against AHS.
  • Support the animals’ immune system to increase chances of survival if infected.

A strong immune system and AHS

A healthy horse with good immunity has a better fighting chance against any virus or disease which may be presented to the body. The immune system is made up of a complex network of proteins which are designed to protect the body from any danger which could include viruses, bacteria, environmental threats, and toxins.4

    Tips to maintain good immunity

    1. Implement good routine to avoid stress including feeding times, stabling, grazing, keeping relocating/travelling to a minimum, etc.
    2. Work out a good vaccination programme with your vet and stick to it. Timing is important.
    3. Ensure your horse is getting good nutrition. Select a good quality feed that is specific to your horse’s breed, age, activity levels and environment.
    4. Supplement when necessary. It would be best to consult your vet about this.
    5. Offer additional immune support with Equi-Strath. Equi-Strath is a 100% natural, Swiss product which enhances and optimizes immunity. Not only does it strengthen the immune system before and during infection and disease, but it also promotes a rapid immune response when the body comes under threat and is proven to reduce recovery time.
    6. In the case that AHS is reported in your area, or your horse becomes infected, further support immunity and recovery with A.Vogel Echinaforce alongside the Equi-Strath. Echinaforce is 100% natural, antiviral, antibacterial and anti-inflammatory. These products work harmoniously in keeping immunity strong and helping the body fight a virus.

    References

    1. The Centre for Food Security and Public Health. 2011. African Horse Sickness. [online] Available at: https://www.cfsph.iastate.edu/FastFacts/pdfs/african_horse_sickness_F.pdf [Accessed 22 February 2022].
    2. OIE-World Organisation for Animal Health. 2020. AFRICAN HORSE SICKNESS. [online] Available at: https://www.oie.int/fileadmin/Home/eng/Animal_Health_in_the_World/docs/pdf/Disease_cards/AFRICAN_HORSE_SICKNESS.pdf [Accessed 22 February 2022].
    3. Africanhorsesickness.co.za. n.d. African Horse Sickness Trust – About AHS. [online] Available at: http://www.africanhorsesickness.co.za/about_ahs.asp [Accessed 22 February 2022].
    4. McFarland, C., 2014. Strong Immune System = Healthy Horse. [online] Farnam Horse | Equine Supplies & Horse Care. Available at: https://www.farnam.com/stable-talk/strong-immune-system-healthy-horse [Accessed 22 February 2022].