THE recent equine influenza outbreak in the UK illustrates the dramatic impact infectious disease can have on the sport of racing and the ability for horses to move freely domestically and internationally, writes Dr JOHN GREWAR, Research and Innovation Manager at the SAEHP (South African Equine Health & Protocols.

African horse sickness (AHS) has for many years been a challenge for South African horse owners – not only does it result in domestic movement and vaccination control that can be costly and logistically frustrating but it has resulted in significant disruption to our ability to trade horses globally.  Having said this though, the animal health controls put in place for AHS form the cornerstone of any potential international trade. Decreasing control within South Africa will hamper negotiations with trade partners.

There are a number of similarities between AHS and equine flu – both diseases have a short incubation period (period between infection and showing clinical signs of disease) and the long distance dispersal of both diseases is likely to occur through the movement of infected horses. 

This is why in South Africa movement control between our AHS control zones is one of the main pillars of control in terms of maintaining an AHS free zone in the Western Cape Province. We make every effort in South Africa to balance control with the practical business of the equine industry.

There are times of the year during which the risk of movement of infected horses is greater because the transmission of the disease between horses is linked to midges. During these times, most often in late summer and autumn, there will be parts of South Africa where the control of movements into the AHS controlled area is more strict, but we make use of scientifically justifiable measures, such as pre-movement testing and quarantine, to still promote movement and maintain our AHS zonal freedom.

The use of PCR in AHS testing has reduced quarantine periods for domestic movement but the test is not a silver bullet for movement. In general there is a period in the first part of the virus incubation where tests do not detect infection, so only using testing prior to movement into the control area is not feasible at the moment.

Outbreaks of disease do result in added pressure to change control policies – in the UK there are discussions about reducing the required vaccination interval for equine flu down to 6 months (something already in place in South Africa). In the AHS context the challenges faced with the use of a live-attenuated vaccine has resulted in restricting the vaccination period to the colder months of the year within the controlled area (and it is suggested this is followed in the infected area as well). This restriction impacts on logistics and competing/breeding programs but also significantly decreases the probability of vaccine-associated outbreaks of disease.

 Outbreaks of disease do result in added pressure to change control policies – in the UK there are discussions about reducing the required vaccination interval for equine flu down to 6 months (something already in place in South Africa). In the AHS context the challenges faced with the use of a live-attenuated vaccine has resulted in restricting the vaccination period to the colder months of the year within the controlled area (and it is suggested this is followed in the infected area as well). This restriction impacts on logistics and competing/breeding programs but also significantly decreases the probability of vaccine-associated outbreaks of disease.

 The goal of the industry and government in South Africa with regards to AHS control is to create an environment where the industry can still function within a scientifically justified control program that is palatable with our trade partners. This will not only promote trade but result in a higher health status of our domestic equine population leaving a legacy of healthy horses and a functioning industry.

*SAEHP points out that they are looking at streamlining movement specifications to make it as user-friendly as possible whilst still being fully compliant.

-From Turf Talk Newsletter.

 

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