SEROLOGICAL EVIDENCE OF EXPOSURE TO Anaplasma phagocytophilum IN HORSES FROM THE RIO DE JANEIRO STATE MOUNTED POLICE BRED IN THE URBAN ZONE

AbstractAnaplasma phagocytophilum is an emergent hemoparasite in regions where ticks are regularly found. In order to investigate the rate of anti-A. phagocytophilum antibody in horses of the Mounted Police of Rio de Janeiro state and therefore the presence of this agent, 41 horses from the Cavalry Squadron (CS) and 50 from the Regiment of Mounted Police (RMP) were selected. For the serologic diagnosis the Indirect Fluorescent Antibody test was performed. In the present work, among 91 equine sera samples anti-A. phagocytophilum antibodies, with titer ≥ 1:80, were detected in 11 animals (12%), being five (5%) from males and six (7%) females, with no statistical difference. The adult animals with ages varying between five and 14 years presented the highest rate of positive reaction, although antibodies were detected in animals of all ages. We did not observe statistic differences in relation to the presence of anti-A. phagocytophilum antibodies among the animals bred in the CS and RMP. The presence of anti-A.phagocytophilim antibodies in horses of the Mounted Police with no clinical signs is indicative that the parasite is present in the enzootic form among the horses of the urban area. The circulation of the parasite among the animals is not dependent of the presence of tick infestations.

摘要：嗜吞噬细胞无形体（Anaplasma phagocytophilum）是蜱虫频发区域的新兴血液寄生虫。本研究为调查里约热内卢州骑警马匹的抗嗜吞噬细胞无形体抗体阳性率，以明确该病原体的存在情况，共选取骑兵中队（Cavalry Squadron，CS）的41匹马与骑警团（Regiment of Mounted Police，RMP）的50匹马作为受试对象。采用间接荧光抗体试验（Indirect Fluorescent Antibody test）开展血清学诊断。结果显示，在91份马血清样本中，11份（12%）检出滴度≥1:80的抗嗜吞噬细胞无形体抗体，其中公马5份（5%）、母马6份（7%），组间无统计学差异。5至14岁的成年动物阳性率最高，但各年龄段受试动物均检出抗体。骑兵中队与骑警团饲养的马匹之间，抗嗜吞噬细胞无形体抗体阳性率无统计学差异。无临床症状的骑警马匹检出该抗体，表明该寄生虫以地方流行性形式存在于城区马匹种群中；且该寄生虫的传播循环并不依赖于蜱虫寄生现象。