Equine infectious anemia in the western region of Rio Grande do Sul, Brazil

ABSTRACT: This study aimed to characterize the outbreaks of equine infectious anemia (EIA) identified, between the years 2009 and 2015, in the western region of the state of Rio Grande do Sul, Brazil. We identified 26 positive horses on 24 properties. Each positive property was considered an outbreak of the disease. The diagnoses were made using the agar gel immunodiffusion (AGID) test as a part of the sanitary checks conducted during animal transportation or certification of the horse´s sanitary status. The positive properties included farms or horse barns, and the infected animals were used for ranch work, sports, or reproduction. One outbreak was identified in animals that were being illegally transported from Argentina to Brazil. Fifteen outbreaks occurred on properties that were not registered with the Official Veterinary Service (OVS). Eleven outbreaks were identified in urban areas and 13 in rural areas. Twelve of the 24 outbreaks were diagnosed in 2015 alone, nine of which occurred in São Borja county. On two properties, a diagnosis could not be confirmed with a retest; therefore, these outbreaks were discharged. During sanitation checks on three properties, 12 additional positive animals were identified among a population of 1,108 susceptible animals. Based on these findings, we concluded that a subclinical form of the infection is present in that area, which is linked to properties that are not registered with the OVS, and that animals which are transported illegally across international borders represent a potential risk.

摘要：本研究旨在对2009年至2015年间巴西南里奥格兰德州西部地区发现的马传染性贫血（Equine Infectious Anemia, EIA）暴发疫情展开特征分析。本研究在24处场所中共检出26匹马传染性贫血阳性马匹，每一处检出阳性的场所均被认定为一起该疾病暴发疫情。本次诊断采用琼脂凝胶免疫扩散试验（Agar Gel Immunodiffusion, AGID），作为动物运输期间卫生检疫或马匹卫生状况认证环节的一部分。检出阳性的场所包括农场或马厩，受感染马匹用于牧场劳作、马术运动或种马繁育。在从阿根廷非法运往巴西的马匹中检出一起暴发疫情。其中15起暴发疫情发生在未向官方兽医服务（Official Veterinary Service, OVS）登记的场所。11起暴发疫情发生于城区，13起发生于乡村地区。24起暴发疫情中仅2015年就确诊12起，其中9起发生于圣博尔雅县（São Borja）。有2处场所的阳性结果无法通过复检确认，因此排除该起暴发疫情。在对3处场所开展卫生检疫期间，于1108匹易感马匹中额外检出12匹阳性马匹。基于上述研究结果，本研究得出结论：该区域存在马传染性贫血的亚临床感染病例，此类感染与未向官方兽医服务登记的场所相关；此外，非法跨境运输的马匹亦是潜在的疫病传播风险源。