Akabane orthobunyavirus

CSIRO ScienceImage 1936 Akabane Cattle Virus

Akabane orthobunyavirus is a virus belonging to the family Bunyaviridae and the genus Orthobunyavirus. It is primarily known for affecting livestock, including cattle, sheep, and goats, leading to congenital abnormalities, abortions, and stillbirths. The virus is transmitted by insect vectors, mainly culicoides (biting midges) and mosquitoes, which facilitate its spread across different geographical regions. Akabane virus has been identified in many parts of the world, including Asia, Australia, the Middle East, and Africa, indicating its wide distribution and potential impact on animal health and agricultural productivity.

Transmission and Epidemiology

The transmission of Akabane virus occurs through the bite of infected culicoides or mosquitoes, which acquire the virus by feeding on viremic hosts. The virus can cross the placental barrier, infecting the fetus and causing various developmental issues. The incidence of infection and disease is closely related to the distribution and activity of the vector populations, which can be influenced by environmental factors such as temperature and humidity. Outbreaks are often seasonal, correlating with periods of high vector activity.

Clinical Signs and Diagnosis

In adult animals, Akabane virus infection is often asymptomatic or associated with mild, non-specific symptoms. However, the major impact of the virus is observed in the offspring of infected pregnant animals. The virus can cause a range of congenital abnormalities, including arthrogryposis (limb deformities), hydranencephaly (absence of brain hemispheres), and cerebellar hypoplasia. These conditions lead to stillbirths, abortions, and the birth of non-viable offspring.

Diagnosis of Akabane virus infection is based on clinical signs, serological tests (such as neutralization tests, enzyme-linked immunosorbent assays (ELISA)), and molecular techniques (such as reverse transcription-polymerase chain reaction (RT-PCR)). Serological surveys can also provide information on the prevalence and distribution of the virus in different regions.

Prevention and Control

There is no specific treatment for Akabane virus infection. Therefore, prevention and control strategies focus on managing vector populations and protecting susceptible animals during critical periods of gestation. This can include the use of insect repellents, insecticide-treated nets, and housing animals indoors during peak vector activity times. Vaccination is another effective tool for controlling the disease. Inactivated and live attenuated vaccines have been developed and are used in some countries to protect pregnant animals from infection and prevent congenital abnormalities in offspring.

Impact

The economic impact of Akabane virus can be significant, particularly in regions where livestock farming is a major industry. Losses result from reduced fertility, the need for veterinary care, and the loss of affected offspring. The virus also poses challenges for international trade in livestock and livestock products, as affected regions may face trade restrictions.