Bovine Ephemeral Fever (Three Day Sickness)

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.

Treatment of animals is important. Intervene early and aggressively.

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 of Three Day Sickness in cattle

Because Three Day Sickness virus can affect the nerves that control swallowing, affected animals are at risk 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 difficultly regaining their feet. If left untreated, these animals may die. A small proportion of animals that go down may suffer a 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.

Where does Bovine Ephemeral Fever 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 look out for Bovine Ephemeral Fever?

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.

Treatment and prevention of Bovine Ephemeral Fever

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

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.

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 /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.

There are several other livestock diseases that may resemble three-day sickness requiring alternative treatment, so veterinary diagnosis is essential.

Managing cases of Three Day Sickness on farm

Nursing care is very important for any cattle that are down or relatively immobile. 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 please:

• 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 and 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 you may have to erect a temporary fence to protect their food and water supply from the unsympathetic access of their paddocks mates. Otherwise lifting the animal to a safe and protected spot or shed with soft bedding is worthwhile.
• Lift and roll recumbent cattle at least one-two times 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.
• In addition, 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 action of 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 up right.
• Injections of anti-inflammatory medication or calcium needs 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 it becomes a practical consideration how you can effectively administer the medication. 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 is unpleasant and may be difficult to justify. This has to be assessed on a case by case basis, how far to the yards, ambient temperature, cattle demeanour etc. 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 be of assistance in protecting cattle from being bitten by mosquitos and reducing the viral load that cattle receive.