They started by giving a short history of the disease, which originally migrated from the Lowveld every summer. The pattern has now changed, and is now brought south by infected animals. Many people blame Zebra’s and Donkeys for being carriers, but nothing is yet proved. Infected Horses  moving into new areas also can cause a spread of infection. The incubation period before horses start to show symptoms is from 4 to 12 days, and this is the time when they are most likely to pass on the virus.

 

The AHS virus is carried by midges

There are several types that have been identified in particular.

One breeds in cattle manure, and is active only after dark , the other breeds in moist damp muddy soils. They take 4 days from laying to hatching, so wet areas are a danger. This is why properties on a riverside have an increased risk.

These midges are the same type as the ones that carry sweet itch, so the main areas they bite are those where you find sweet itch, i.e. mane, top of tail, inside of legs, so these should be the areas you concentrate your insect spray.

The general opinion now is that AHS is not caused by one infected bite, but by many, so the higher the density of midges in your area, the greater the risk.  Densities in some areas are terrifying- one  midge trap in Kaarkloof, Natal was found to  contain 1million midges

The Weather plays an important part in AHS. The peak time for these midges is March and April- they are not able to breed in cold weather (12C or less for 24 hrs will stop them).

 

There are 9 recognised strains of AHS, 8 of which are covered in the vaccines we give. Strain 5 is not covered, as it was harmful to the people handling it, but strain 8 does give some protection from Strain 5

Different strains are prevalent in different areas. No strain has yet been isolated for the infected horses here in the WP in this outbreak, we are still awaiting test results. Horses living in infected areas may in time develop immunity to their resident strain, but this gives them no additional immunity to other strains.

 

The midges tend not to travel far from where they hatch, but they are carried by wind and water. They have a life cycle of 7 to 21 days, and need a blood-meal before they can breed, after which they die. This explains outbreaks following rivers, or prevailing winds.

 

AT RISK Horses are those with decreased immunity, whether from illness, stress, cortisone, traveling, changing stables or whatever, so your horse could be perfectly healthy, but still at risk.

 

PRECAUTIONS

Yearly vaccination is important. It gives good immunity. There are no advantages to vaccinating more frequently. Where a strain is identified, and you vaccinate against it, it is extremely successful. Vaccinations should be done by a vet, and the vaccine should be kept cold at all times.

A barrier between the midges and your horses is very effective. In affected areas, 80% shade cloth over stable doors and windows can increase you immunity up to 14 fold.. Even an enclosed shade cloth barn will radically increase immunity.

Spraying can help, but most midges die AFTER they have bitten the horse. Citronella sprays are not popular, and are banned for horse use in the EU

Metered sprays in stables can cause a decrease in a horses natural immunity

Smoke appears to have little effect on the midges, and keeping your horses near cattle only helps by giving the midges a greater choice of animal to bite!!

Immune boosters may help, although no definitive proof.

Bugzappers attract midges to the light.

The midges are attracted to smell, warmth and light and are active between 2hrs before sunset, and 2 hrs before sunset.

Some farms shine bright lights in an area well away from the stables to draw midges away!

 

Present Outbreak.

 

There appear to be several virus’ active in Cape Town at the moment

AHS- there are 5 deaths, on 4 properties, all in the Stellenbosch/Paarl area, but the virus appears to be moving SE with the wind, which is why Joostenbergvlaakte is now also in quarantine. Within the quarantine area you should stay on your own property, but Joostenbergvlaakte riders are allowed to move within their area, WITH PERMISSION FROM THE STATE VET.

 

Equine Encephalosis – there are many reports of this virus from all over the peninsula. The symptoms are a high temp, rapid onset, horse may get wobbly, but they recover quickly, within a few days

Lassitude- Horses are reported to be “off- colour” and reluctant to do much. No temperature, and most continue to eat and drink well. This lasts a week or so.

 

 

REMEMBER. Anyone wanting to move horses MUST have a (free) Permit from the State Vets Dept Contact Lizelle Nutt on lizellen@elsenburg.com to arrange. 

 

African Horse Sickness Trust:        www.africanhorsesickness.co.za