Detection of Leishmania spp. (Trypanosomatidae) and bloodmeal identification in sandflies from a new focus of leishmaniasis in the Colombian Caribbean

Background: Although the visceral leishmaniasis (VL) is an endemic disease in the Colombian Caribbean, an increase in its distribution area has been observed in the last years, including reports of cases in new locations. Objetives: In this study, we characterized sandflies, parasites from the Leishmania genus, and some domestic vertebrates associated with the first case of VL in the rural settlement of Toro, San Juan Nepomuceno, Bolívar, Colombia. Methodology: The sandflies were subjected to DNA extraction, amplification, and sequencing for detection of Leishmania spp. infection, and identification of bloodmeals. Additionally, we determined anti-Leishmania antibody titres in canines by the indirect immunofluorescence assay technique. Results: A total of 2178 sandflies were collected, of which 99.6% were identified as Lutzomyia evansi. Leishmania infantum and Leishmania braziliensis were the parasites detected in this sandfly species, with a minimum infection rate of 0.003% (3/1070), and 0.0009% (1/1070), respectively. Regarding bloodmeals, 16.73% of the Lu. evansi females had fed on Homo sapiens sapiens, 16,32% on Capra hircus, 12.45% on Sus scrofa domesticus, 11.63% on Bos indicus, and 9.79% on Canis familiaris. One of the serologically assessed canines was positive for canine leishmaniasis. Conclusion: The detection of mixed bloodmeals from humans and canines in Lu. evansi evidences the epidemiological link among sandflies infected with the parasite, potential reservoirs, and human population. This would explain the appearance of the first VL case in this locality of the Colombian Caribbean

背景：尽管内脏利什曼病（VL）在哥伦比亚加勒比地区是一种地方性疾病，但在过去几年中，其分布范围有所扩大，包括在新地点报告的病例。目标：在本研究中，我们对托罗、圣胡安内波穆塞诺、博利瓦尔农村定居点第一例VL病例相关的沙蝇、利什曼原虫属寄生虫以及一些家养脊椎动物进行了特征描述。方法论：对沙蝇进行了DNA提取、扩增和测序，以检测利什曼原虫属感染并识别宿主血液。此外，我们还通过间接免疫荧光试验技术确定了犬类中的抗利什曼原虫抗体滴度。结果：共收集到2178只沙蝇，其中99.6%被鉴定为Lutzomyia evansi。在本沙蝇种中检测到的寄生虫为利什曼原虫婴儿型（Leishmania infantum）和巴西利什曼原虫（Leishmania braziliensis），最低感染率分别为0.003%（3/1070）和0.0009%（1/1070）。关于宿主血液，16.73%的Lu. evansi雌性沙蝇以智人（Homo sapiens sapiens）为食，16.32%以山羊（Capra hircus）为食，12.45%以家猪（Sus scrofa domesticus）为食，11.63%以印度水牛（Bos indicus）为食，9.79%以犬（Canis familiaris）为食。在血清学检测的犬中，有一只犬检测出犬利什曼病阳性。结论：Lu. evansi中检测到来自人类和犬类的混合宿主血液证实了感染寄生虫的沙蝇、潜在宿主和人类人群之间的流行病学联系。这可以解释为什么在哥伦比亚加勒比地区这一地区首次出现VL病例。