Three-day stiff sickness: low mortality, yet high morbidity

While the mortality rate of three-day stiff sickness is usually less than 1%, morbidity is high, with most animals never reaching the same level of production after recovery. 

- Janine Ryan

 FAST FACTS

Three-day stiff sickness is transmitted by biting insects.

The disease is seasonal, depending on the time of year when the insect vectors proliferate.

Infected animals often display a rapid onset of fever, followed by muscle stiffness, and a tendency to lie down and refuse to stand up.

Three-day stiff sickness (TDS), also known as bovine ephemeral fever, is a viral disease in cattle that is transmitted by midges and mosquitoes. The Culicoides midge (also responsible for the transmission of bluetongue in sheep and African horse sickness in equines) and Anopheles mosquito are the primary vectors of TDS. The disease cannot be transmitted via direct contact.

While mortality is low (generally less than 1%), TDS can have a severe impact on livestock production. For example, cows in advanced stages of gestation may suddenly abort, and milk production in dairy cows may decline significantly. TDS may also have a temporary effect on the fertility of bulls. Infected animals may experience a sudden onset of fever (40°C to 41°C). They also experience muscle stiffness (hence the name), lie down and are reluctant to stand up or move around.

The fever usually breaks, with the temperature returning to normal, within 36 hours.

The disease is seasonal and occurs throughout South Africa. As the insect vectors proliferate after rain, there may be more frequent TDS outbreaks after periods of above-average rainfall.

TDS is primarily an inflammatory disease, and clinical signs and symptoms are a vascular inflammation response to infection. TDS causes damage to minor blood vessels of the tendons, muscles, joints and skin, and can result in permanent paralysis. This paralysis can be likened to that experienced by cows with milk fever.

An animal's potassium, iron and zinc levels also decline dramatically.