Bovine ephemeral fever is a viral disease spread by insects that affect cattle and water buffalo. It is most frequent in Africa, the Middle East, Australia, and Asia. The condition causes reduced milk production, recumbency, and, in severe cases, death. Infections in certain animals may not cause any symptoms.
The diagnosis is made via PCR testing, and the therapy includes NSAIDs and supportive care for recumbent cows. There are vaccines available, but their efficacy varies. The disease is not infectious, but it can infect other animals, including deer, goats, and sheep.
Bovine Ephemeral Fever Management in Cattle
Causes of Bovine Ephemeral Fever in Cattle
- Bovine ephemeral fever (BEF) is caused by a single serotype of the BEF virus belonging to the Ephemerovirus genus in the Rhabdoviridae family. The disease is transmitted by arthropods and affects mainly cattle and buffaloes, with younger animals being more susceptible. The virus is inactivated at pH levels outside of 5 to 10.
- It can be transmitted through IV inoculations but not through contact or fomites. The disease is prevalent during the wet season in the tropics and in summer to early autumn in the subtropics or temperate regions. BEF can cause significant morbidity, with mortality rates ranging from 1% to 2% and higher in certain groups of animals.
Disease Cycle of Bovine Ephemeral Fever in Cattle
- Direct contact or discharges between animals do not spread Bovine Ephemeral Fever (BEF); instead, it is spread by arthropods such sand flies and mosquitoes like Culex and culicoides.
- The BEF virus may travel quickly by wind during outbreaks, which normally happen in the summer. Within five months, reports of the virus having moved thousands of kilometers have been made.
- Within five days, the virus is present in the blood of infected cattle, and flies can spread the virus from the blood; just 0.002 ml of blood is needed to infect susceptible animals with the illness.
- Recovered animals do not carry the virus, and it is suggested that some fauna may be responsible for carrying over the virus from season to season. Whole blood injections can also transmit the disease.
What are the Symptoms of Bovine Ephemeral Fever in Cattle?
- Bovine Ephemeral Fever in cattle is characterized by a sudden onset of clinical symptoms, including a high fever ranging from 103-107˙F or more, shivering, and muscle trembling.
- The affected cattle may refuse to move or have difficulty moving with an arched back. Anorexia and a reduction in milk yield are also observed. The disease can cause excessive salivation, nasal discharge, and tearing of the eyes.
- The muscles in the affected limb become stiff, hard, and painful, and the animal may show lameness and acute laminitis. Severely affected cattle may lie down with extended rigid hind limbs.
- The lameness may shift from one leg to another within a few hours, and recumbent animals may show suspended rumination, grinding of the teeth, and signs of groaning.
- The disease causes significant discomfort and pain in affected cattle, resulting in milk production losses and sometimes death.
Diagnosis of Bovine Ephemeral Fever in Cattle
- During an epidemic, clinical indicators are used to diagnose ephemeral bovine fever. Blood samples are taken from ill and healthy cattle in affected herds to perform a differential white blood cell count and plasma fibrinogen levels.
- PCR and viral isolation can also establish the virus’s existence. Infection is confirmed by a 4-fold rise in antibody titer between matched samples.
- To isolate the virus, inoculate mosquito cell cultures with defibrinated blood before transferring them to baby hamster kidney or monkey kidney cell cultures.
- PCR, neutralization assays, and ELISA are used to identify isolated viruses.
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