First report of Leishmania (Mundinia) martiniquensis in South American territory and confirmation of Leishbunyavirus infecting this parasite in a mare

BACKGROUND Epidemiological data related to leishmaniases or Leishmania infection in horses are scarce. However, studies carried out in different regions in the world showed equids parasitised by Leishmania braziliensis, L. infantum and L. martiniquensis. OBJECTIVES Identify the Leishmania species causing cutaneous leishmaniasis in a mare, living in Rio de Janeiro State (Brazil), and search the presence of Leishmania viruses in the isolated parasite. METHODS Isoenzymes and polymerase chain reaction (PCR) targeting ITSrDNA region followed by sequencing were conducted for typing the isolated parasite. A search for Leishmania virus infection was also performed. FINDINGS The mare presented skin nodules and ulcers in the left pinna caused by Leishmania spp. that was detected by culture and PCR. The parasite was identified as Leishmania (Mundinia) martiniquensis, infected by Leishbunyavirus (LBV), representing the first description of this species in South America. The animal travelled to different Brazilian regions, but not to outside the country. MAIN CONCLUSIONS The worldwide distribution of L. martiniquensis and its infection by LBV were confirmed in this study, indicating the autochthonous transmission cycle in Brazil. The clinical profile of the disease in the mare, showing fast spontaneous healing of cutaneous lesions, may indicate that skin lesions related to L. martiniquensis infection in horses might be underdiagnosed.

研究背景：目前关于马属动物的利什曼病（leishmaniases）或利什曼原虫（Leishmania）感染的流行病学数据较为匮乏。但全球不同地区的已有研究显示，马科动物可被巴西利什曼原虫（Leishmania braziliensis）、婴儿利什曼原虫（L. infantum）以及马提尼克利什曼原虫（L. martiniquensis）寄生。
研究目的：明确居住于巴西里约热内卢州的一匹母马所患皮肤利什曼病的致病利什曼原虫种类，并检测分离获得的原虫株中是否存在利什曼病毒感染。
研究方法：采用同工酶分析、靶向内转录间隔区核糖体DNA（ITSrDNA）区域的聚合酶链反应（PCR）扩增结合测序技术，对分离得到的原虫进行分型；同时开展利什曼病毒感染检测。
研究结果：该母马左侧耳廓出现皮肤结节与溃疡，经培养与PCR检测确认由利什曼原虫属（Leishmania spp.）感染引发。经鉴定，该原虫为马提尼克利什曼原虫（Leishmania (Mundinia) martiniquensis），且携带有利什曼本扬病毒（Leishbunyavirus, LBV）——这是该物种在南美洲的首次报道。该母马曾游历巴西境内多个地区，但从未离开过巴西国境。
主要结论：本研究证实了马提尼克利什曼原虫的全球分布特征及其利什曼本扬病毒感染情况，表明巴西境内存在该原虫的本土传播循环。该母马的临床病例表现为皮肤病变可快速自发愈合，这提示马属动物感染马提尼克利什曼原虫引发的皮肤病变可能存在诊断不足的情况。