Abstracts: Equine Infectious Anemia cases in polo ponies housed in San Isidro’s training center, Buenos Aires, Argentina (en inglés)

According to recent studies, the prevalence of Equine Infectious Anemia virus infection (EIAV) in Argentina is variable, presenting a regional distribution. While the northern region is considered a high prevalence zone Buenos Aires province is considered a low prevalence zone. 

National animal health regulations to control EIAV infection in Argentina enforce the notification of every EIAV positive case, as determined by the OIE prescribed agar gel immunodiffusion test (AGID), to the National Animal Health Authorities (SENASA), along with the immediate euthanasia of confirmed cases and the strict quarantine of the affected premises. The training centre of San Isidro Racecourse permanently hosts a Thoroughbred population (n: 2200) which is subject of a strict sanitary policy. 

A unique microchip number identifies each horse, and the AGID test is performed at a 60-day interval to corroborate the absence of EIAV infection. This training centre also counts with a separate area for the housing of polo ponies during their yearly sport season, which normally lasts from September to December. Unexpectedly, EIAV positive cases were notified in several polo ponies during 2015. This report describes the occurrence of EIAV infection in polo ponies housed in San Isidro’s training centre during 2015 and the preventive measures applied in order to preserve the EIA free status in the permanent Thoroughbred population. 

Even though the polo ponies must enter the San Isidro facilities with all the sanitary requirements (which includes EIAV negative certificate), the incoming population in 2015 (n: 230) was re-tested and a microchip was applied to every horse upon arrival. Upon a second monitoring EIA testing performed 30 days later, five horses were found positive. SENASA was subsequently notified, euthanasia was undertaken immediately for every confirmed case, and the facilities were placed under quarantine as enforced by current regulations.

Epidemiological investigations determined that all EIA positive cases were originated from a single horse farm. After this event, the entire equine population within the quarantined area was re-tested, and one additional horse was identified as EIAV positive. The 17 horses from the same farm as this last positive case were re-tested 5 days later, with no confirmation of additional positive cases. 

The case described exemplifies the current situation regarding EIAV in Argentina: some years ago, this infection was restricted to work horses confined in cattle farms mainly in the North area of our country. It also emphasizes the need of immediate control measures, due to the hazard of re-emergence of this infection and its impact on the equine industry, causing not only direct economic losses to the owners but also disruption of equestrian events. To date, serological surveillance, by AGID, is the most sensitive diagnostic tool for the identification of EIAV infected horses, and has been used successfully to eradicate EIA from valuable horse populations, as in some states of the United States and some European countries.