Bovine ephemeral fever (Three day sickness)

What is Bovine ephemeral fever?

Bovine Ephemeral Fever is a viral disease of cattle and buffalo transmitted by mosquitos. Typically, affected animals are only sick for a few days, hence the alternative name — Three Day Sickness. Outbreaks often follow periods of heavy rainfall providing favourable conditions for the insect populations to increase.

Once bitten by insects that carry the virus, symptoms of Three Day Sickness progress rapidly. Animals develop a very high temperature, appear depressed, lethargic, are reluctant to eat, and they will often appear lame and stiff when they walk. A nasal discharge and drooling is also common.

Where does it occur?

Three Day Sickness is seen along the eastern regions of NSW and Queensland, with localised outbreaks occurring on the NSW North Coast and Hunter. Depending on the seasonal conditions, the disease spreads south from these centres. Cases in inland NSW are much less common but outbreaks do occur in the North West and Central West.

When to watch for it

BEF usually occurs in the summer months between January and April, with the greatest number of cases in March. Outbreaks of Three Day Sickness tend to occur after periods of heavy summer rainfall, however cases can occur from late November through to early June.

Clinical signs

What are the signs of Bovine Ephemeral Fever?
Clinical signs of Three Day Sickness include:

• sudden onset of fever as high as 41°C
• drooling with a stringy nasal discharge
• watery eyes
• animals stop eating and drinking
• shivering
• lameness (often on day 2 of infection)
• stock may lie down and refuse to move
• swelling around joints or jaw
• sudden and severe drop in milk production for dairy cattle.

Cattle between 6 months and 2 years of age are more commonly affected because infection provides life-long immunity.

Secondary complications

Because the Three Day Sickness virus can affect the nerves that control swallowing, affected animals are at risk of getting food, water or saliva into their lungs. This can result in pneumonia.

Heavier cattle are at an increased risk of secondary complications as a result of being down. Once recumbent, larger animals such as bulls, bullocks and pregnant cows will critically deteriorate. While laying down for long periods, nerves and blood flow to the legs can be impacted and animals have difficulty regaining their feet. If left untreated, these animals may die. A small proportion of animals that go down may suffer permanent paralysis due to spinal cord damage either as a direct result of the virus or from awkward falls. Recumbent animals are at an increased risk of pneumonia.

Cows in advanced pregnancy may abort following Three Day Sickness. Bulls commonly suffer temporary infertility lasting from three to six months because of the high fever.

Deaths from bovine ephemeral fever are uncommon and generally involve less than 1% of the herd.

How to manage

Managing cases of Three Day Sickness on farm requires good nursing care and early attention. The virus causes considerable inflammation and pain in muscles and joints and cattle may become recumbent or stop moving. This can prevent access to water, food and shade. They may also have trouble swallowing as the virus can paralyse the pharynx, hence they often dribble saliva.

To mediate the effects of the disease:

• Shade affected animals from the hot sun.
• Provide a large tub of cool fresh water within easy reach of immobile cattle. Make sure the tub is stable, has low sides for easy access, can’t be easily knocked over, and is full at all times. Shade and water are both essential to prevent dehydration.
• Provide good quality food such as lucerne hay as recovery from illness requires good nutrition.
• If cattle are immobile in a paddock, erect a temporary fence to protect their food and water supply from other stock. Otherwise, lifting the animal to a safe and protected spot or shed with soft bedding is worthwhile.
• Lift and roll recumbent cattle at least once or twice a day to prevent secondary nerve and muscle compression if they have been down more than a day or so.
• Speak to your private vet about the suitability of injectable anti-inflammatory medication to mediate fever and muscle inflammation.
• Having a couple of flo-paks of a 4-in-1 calcium supplement (available from your vet or produce store) on hand for injection under the skin of down cattle can help with muscle function. The virus depletes calcium from the animal, and if cattle cease eating, calcium levels can also fall. An injection of calcium can just be the added help they need to get up or stay upright.
• Injections of anti-inflammatory medication or calcium need to be administered early in the course of the illness to be effective.
• While affected cattle will benefit from anti-inflammatory and/or calcium injection, practicality must be considered. If they are recumbent in the paddock and can be safely treated whilst down, that is one option. However, moving sore animals to yards — albeit very slowly — may be difficult or unpleasant. This should be assessed case by case, considering distance to yards, ambient temperature, and cattle demeanour. These steps may be warranted particularly in larger and valuable cattle, bulls and pregnant cows.
• Insect protection (pour-on or rub-on backline treatments) might also assist in protecting cattle from mosquito bites and reducing viral load.

Watch our video from a district vet with Local Land Services:

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Video transcript

Managing bovine ephemeral fever

I'm Lindell, a District Veterinarian with Local Land Services. Three-day sickness is currently circulating in New South Wales, so it's time to increase the monitoring of your herd to daily and to prepare your cattle with a first aid kit on farm.

So this means having suitable veterinary medicines and equipment on hand. But most importantly, it means knowing how to nurse cattle, particularly if they become recumbent in your paddocks. Have a chat to your veterinary practitioner now before you have any animals affected by three-day sickness and develop a management plan with them for your herd.

It's best to be pre-armed with advice and supplies. So depending on the situation, your vet might suggest anti-inflammatory medication, which is injected into the animal. An injection of anti-inflammatories can reduce the fever and the inflammation that the virus causes in the animal, and it can prevent them from becoming recumbent if given very early in the course of the illness.

This medication needs to be prescribed by your veterinary practitioner, so talk to them now. It's important to note that vets can only prescribe such medications if they have a bona fide relationship with their clients and they've been to your farm recently.

The second item that's a medication that's handy to have on hand is a couple of packs of four-in-one calcium magnesium flow packs that you can inject under the skin. This can help with muscle function because the action of the virus can deplete the calcium from the animal's body. So injections of calcium magnesium—one bag under the skin or two bags if they're a large animal—can help the animal to maintain the standing position.

But most importantly, it's important to be prepared to nurse recumbent or sore, lame cattle through the course of the illness. Good nursing care is sometimes the difference between recovery and not recovery. After all, many more cattle have died from secondary issues associated with dehydration and being out in the elements in hot, dry weather without adequate food, water, and nursing care than have died from the actual effects of the virus.

So what is good nursing care for cattle that may be affected by three-day sickness and be recumbent in the paddock? Or maybe they're not recumbent, but maybe they're just not moving much because they're so sore and feeling unwell.

So there are some key steps to ensure good nursing care. The first is to provide shelter from the hot sun. The second is to ensure easy access to a constant supply of cool, fresh water. So this is a big bucket of fresh water. Dehydration from hot weather and lack of fluids will make the effects of the disease so much worse, and cattle have died from the effects of dehydration.

Next, it's important to ensure they have good access to good quality feed. If the animal is in the paddock with other cattle, you may have to erect a temporary fence around them so that the other cattle don't steal their feed and water.

If the animals are recumbent, it's important to lift the animal. If you have adequate equipment, you can actually move the animal to a safe spot, such as a shed with soft bedding. And this is a really worthwhile step because, one, that protects them from the elements, and two, they have nice soft bedding underneath their limbs.

The other aspect to consider is that if they're in the paddock, it's important to roll the animals several times a day or lift them to prevent secondary muscle and nerve damage from the compressive effects of lying on their one side all the time and compressing their nerves and muscles of their limbs.

The Dairy Australia website has some great fact sheets and clips on how to nurse recumbent cattle. Look, I hope this brief summary on managing three-day sickness helps your herd if mosquitoes carrying the three-day sickness virus make their way to your farm.

As always, it's important to seek advice from your veterinary practitioner to ensure that the illness affecting your cattle is in fact three-day sickness and not another illness or injury that is masquerading as three-day sickness.

How to treat

Treatment of animals is important. Intervene early and aggressively.

Producers are encouraged to seek veterinary advice as medication is highly effective in bringing down the fever and reducing muscle and joint pain. Recovery tends to be quicker with less weight loss when treatment is started early.

A paddock with plenty of shade, water and feed and free of steep gullies is ideal for cattle to recover in. Any affected cattle should be provided with shade, water and feed, and turned or lifted twice daily to help prevent secondary complications.

There are several other livestock diseases that may resemble Three Day Sickness requiring alternative treatment, so veterinary diagnosis is essential.

Summary

If cattle are down or unable to move:

• Provide shade and clean water within easy reach.
• Erect temporary fencing to protect feed and water from other cattle.
• Lift and roll animals at least once daily to prevent nerve damage.
• Use soft bedding and ensure cattle are not left on hard ground.

Work with your private vet to determine:

• The best treatment options for your herd.
• Whether injectable medications are practical on your property.
• Steps to limit insect exposure and manage recovery areas safely.

How to prevent

A vaccine is available and its use is strongly recommended for bulls and any cattle introduced from areas which do not normally experience the virus. Late winter or spring is the ideal time to consider your cattle vaccination plans for Bovine Ephemeral Fever Virus. In those areas where the virus is already active, the vaccine is unlikely to provide protection.

Insect protection (pour-on or rub-on backline treatments) may also help reduce the spread of infection by limiting mosquito bites.