Data Sheet 1_Emergence of autochthonous Leishmania infantum infection in dogs from Costa Rica confirmed by multimodal diagnostics: a case series.docx

BackgroundCanine visceral leishmaniasis (CVL) is a vector-borne zoonotic disease caused by Leishmania infantum. This parasite has been reported in humans and dogs from Costa Rica over the past four decades as sporadic reports. In this study, we analyzed eight cases of autochthonous infections in dogs presumably originating from Santa Cruz, Guanacaste, and Santa Ana, San José, Costa Rica, none of which had a history of travel abroad.
MethodsEight dogs with suspected CVL were analyzed using serological assays (Speed Leish K® (VIRBAC Diagnostics, France) or Antigen Rapid CaniV-4 (Leish)® (BIONOTE, Mexico)), five dogs were detected in 2023, and three during 2025. Histopathological staining was applied in cases with spleen, dermal, and lymph node involvement to determine the presence of Leishmania amastigotes. Blood, lymph node aspirates, conjunctival swabs, or cutaneous lesion swabs were also analyzed for the presence of Leishmania spp. ITS1, hsp70, and kDNA fragments. Phylogenetic and haplotype network analyses were conducted for hsp70 and kDNA data.
ResultsFour dogs showed various clinical manifestations that included persistent anemia, thrombocytopenia, splenomegaly, exfoliative dermatitis, and onychogryphosis, whereas the other four dogs remained subclinical or asymptomatic. Histopathological analysis revealed numerous intracellular amastigotes in lymph node aspirates, spleen sections, and ear skin biopsy. Moreover, seven out of eight dogs were positive in the serological analysis, and the other seven to the Leishmania ITS1 PCR. Phylogenetic analysis of kDNA fragments revealed that sequences derived from our country clustered with those of L. infantum from the Old World, rather than with ones from Brazil, indicating a likely introduction from outside the Americas. All infected dogs received allopurinol and, when available, also meglumine antimoniate.
ConclusionInfection with L. infantum in Costa Rican dogs was confirmed by clinical and laboratory evidence and thus represents the first autochthonous cases of CVL in our country. This study highlights the urgent need for routine canine testing, sandfly surveillance, access to proper treatments, and increased awareness, emphasizing the importance of public health policies for controlling leishmaniasis in both animals and humans from a One Health perspective.

背景：犬内脏利什曼病（Canine visceral leishmaniasis, CVL）是由婴儿利什曼原虫（Leishmania infantum）引起的一种虫媒人畜共患病。过去四十年来，哥斯达黎加的人类和犬类中均有该寄生虫的散发病例报道。本研究对8例疑似本土感染的犬内脏利什曼病病例展开分析，这些病例均来自哥斯达黎加瓜纳卡斯特省圣克鲁斯地区以及圣何塞省圣安娜地区，且所有受试犬只均无境外旅行史。
方法：本研究对8只疑似犬内脏利什曼病的犬只进行血清学检测，分别使用法国VIRBAC诊断公司的Speed Leish K®快速检测试剂盒，以及墨西哥BIONOTE公司的Antigen Rapid CaniV-4 (Leish)®抗原快速检测试剂盒。其中5只犬为2023年检出，3只为2025年检出。针对脾脏、皮肤及淋巴结受累的病例，通过组织病理学染色检测利什曼原虫无鞭毛体。同时采集血液、淋巴结穿刺液、结膜拭子或皮肤病变拭子，检测利什曼原虫属ITS1、hsp70及kDNA片段。针对hsp70和kDNA数据开展系统发育分析及单倍型网络分析。
结果：4只犬表现出多种临床症状，包括持续性贫血、血小板减少症、脾肿大、剥脱性皮炎及爪甲肥厚症；其余4只犬则呈亚临床或无症状状态。组织病理学分析显示，淋巴结穿刺液、脾脏切片及耳皮肤活检样本中可见大量细胞内无鞭毛体。此外，8只犬中有7只血清学检测呈阳性，7只利什曼原虫ITS1 PCR检测呈阳性。对kDNA片段的系统发育分析表明，本研究获得的序列与旧世界的婴儿利什曼原虫序列聚为一支，而非与巴西菌株聚类，提示该病原体可能从美洲以外地区传入。所有受感染犬只均接受别嘌醇治疗，条件允许时还联用葡甲胺锑酸盐。
结论：本研究通过临床及实验室证据证实了哥斯达黎加犬只感染婴儿利什曼原虫的情况，这是该国首次报道的犬内脏利什曼病本土病例。本研究强调了开展常规犬只检测、白蛉监测、保障规范治疗途径以及提升公众认知的迫切需求，并从同一健康（One Health）视角出发，强调公共卫生政策在防控人畜共患利什曼病中的重要性。