Equine Flu Outbreak At British Charity Farm
A large British equine charitable facility has closed temporarily because of a large influenza outbreak. Approximately 80% of horses at the Bransby Home of Rest for Horses have become infected. In a large facility like this, once you have 80% of the horses infected, there's very little chance of controlling the outbreak within the facility, although it's still very important to take precautions (such as closing the facility) to prevent the disease from spreading to other farms. Unless there is a discrete group of horses that is well removed from everyone else on the property, you have to assume that all the horses have been exposed. At that point, you basically just have to let the outbreak burn itself out, and try to manage any complications that develop in individual animals.
In some ways, if you're going to have a major disease outbreak, influenza's a good one to have. It doesn't often cause serious illness, it rarely causes death, it's not transmissible to people and it doesn't have a "silent" carrier state. The lack of a carrier state is very important since, unlike strangles (Streptococcus equi), once horses recover from influenza, they only shed the virus for a short period of time. With strangles, some recovered horses appear healthy but will continue to shed the bacterium for long periods of time, and may continue to infect other susceptible horses.
Facility manager Sally Howard is quoted as saying "Staff are always extremely careful to ensure all animals that are received by the charity are put into quarantine for at least four weeks and then thoroughly tested before being allowed to mix with the herd."
- This is a great quarantine plan. Unfortunately, something went wrong here. If there was a true 4 week quarantine and if good protocols were used, influenza would not have made it into the herd. An investigation should look into why influenza was able to break through this quarantine. Some possible explanations are neglecting to quarantine a horse, not quarantining a horse for the proper length of time, mixing quarantined horses (i.e. a horse could be quarantined for 4 weeks, but if it gets exposed to a newly quarantined horse near the end of this time period, it could become infected and be introduced to the herd before it shows clinical signs of disease), and people spreading the virus from quarantined horses to resident horses on clothing or other items.
"The source of this infection is not yet known but we will try to discover and eliminate it."
- I understand the sentiment but it's not practical. The initial source is no longer an issue, at least in terms of managing this outbreak. There are no long-term influenza shedders, so the horse that brought influenza onto the farm is likely influenza-free now. What they need to do now is ride out the outbreak and figure out why it happened.
"Vaccines are available but the ongoing cost of protecting 271 horses would add significantly to the already high costs of maintaining the herd."
- That's a tough situation and one that is a constant challenge for centres such as this. If resources are limited, what stays and what goes? Proper herd health for that many horses is certainly expensive, and good infection control practices are very important when you have a lot of horses. This outbreak has shown what can happen when you don't vaccinate, and the costs and disruption of the outbreak certainly would have paid for a lot of vaccine, but hind sight is always 20/20. Deciding how to spend limited resources is a difficult decision.
Fortunately, this outbreak should be controlled soon, in part because it has spread so widely on the farm. There are few susceptible horses left, and when the influenza virus cannot find any more horses it can infect, it will disappear.
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