Progressive control of equine infectious anaemia through more accurate diagnosis.

This research article discusses the progression of control for Equine Infectious Anaemia (EIA), a viral infection in horses and other members of the horse family. It explores techniques of diagnosing the EIA infection and indicates that its accurate diagnosis has played a key role in progressively controlling this disease.

Disease Overview

• The research starts by providing an overview of Equine Infectious Anaemia (EIA). It explains that EIA is a viral infection found in horses and other equids caused by EIA virus (EIAV), a lentivirus from the family Retroviridae.
• Unlike most lentiviruses that result in slow and progressive diseases, EIA produces an acute phase followed by periods of recurrent clinical disease that eventually subside, turning horses into inapparent carriers of the virus. The study also notes that the clinical signs of EIA were first described in France in 1843.

Diagnosis of EIA

• The paper then delves into how EIA can be diagnosed through several methods including taking into account clinical signs, pathological lesions, serology (studying blood sera), and molecular methods.
• It is stated that infected horses remain viraemic carriers for life and, with rare exceptions, will yield positive results for serological tests. In most cases, horses develop antibodies detected by the agar gel immunodiffusion test (AGIDT) typically 24 days after infection, but detection can sometimes take up to three months.
• According to the article, the antibody response usually persists and horses older than six to eight months who test positive for antibodies are identified as virus carriers. For those below this age, serological reactions might be due to maternal antibodies, requiring confirmation through molecular techniques.

Transmission of EIA

• Last, the authors discuss the transmission of EIA. The virus can reside in infected equids that act as potential virus reservoirs.
• Biting flies are identified as mechanical vectors that can transmit the virus in the field. In addition to this, transmission can occur via iatrogenic transfer of blood using contaminated needles and may also be passed on in utero to fetuses.
• The research highlights that the virus titre (concentration) is higher in horses with clinical disease periods, facilitating its spread.