qPCR is being used for the quantification of parasite load in different tissues of dogs infected by Leishmania infantum with or without clinical manifestations. It may be employed in the diagnosis, monitoring of the infection during treatment, and clinical studies for validation of vaccines. Aimed at enhancing the molecular diagnosis and the subsequent monitoring of the infection, this study evaluated the parasite load in several tissues from dogs infected by Leishmania infantum, showing different clinical status. Thus, the qPCR was performed on skin, conjunctival swab, popliteal lymph node, and bone marrow puncture samples taken from 65 dogs naturally infected by L. infantum. Dogs were divided into three groups per clinical score: group 1 (n = 12), included animals with zero points and no clinical manifestations of the disease; group 2 (n = 35), included animals with a score ranging from 1 to 5 points and moderate clinical manifestations; and group 3 (n = 18), included dogs with a score ranging from 6 to 11 points and intensive clinical manifestations. Another analysis was performed classifying the animals into two groups, considering the presence of, or lack of clinical signs of the disease. Analyses of these results showed that the skin was the tissue with a higher parasite load, followed by popliteal lymph node and bone marrow punctures, and conjunctival swab samples having the lowest loads. Furthermore, the skin was also the tissue with the highest parasite load when evaluating the groups individually. Animals in group 3, with intensive clinical manifestations, showed a higher parasite load in different tissues when compared to animals from groups 1 and 2. Finally, animals with clinical manifestations of the disease showed a higher parasite load when compared to dogs with no manifestations. The importance of the dog as a reservoir of L. infantum in nature is reinforced by the demonstration of skin having the highest amount of parasites/μL in this study's analysis, as well as the fact that skin is the main point of access to the parasite vector. Also, a strong and positive correlation between the intensity of clinical manifestations and the increase of parasite load in the skin was observed. In conclusion, skin was the tissue that was demonstrated to be the best option for the molecular diagnosis of L. infantum infection in dogs with varying clinical statuses used in this study.

qPCR 被用于量化受婴儿利什曼原虫感染的狗的不同组织中的寄生虫负荷，有或没有临床表现。它可用于诊断、治疗期间感染的监测以及疫苗验证的临床研究。本研究旨在加强分子诊断和感染的后续监测，评估了感染婴儿利什曼原虫的狗的几种组织中的寄生虫载量，显示出不同的临床状态。因此，对取自 65 只自然感染婴儿乳杆菌的狗的皮肤、结膜拭子、腘淋巴结和骨髓穿刺样本进行了 qPCR. 根据临床评分将狗分为三组：第 1 组（n = 12），包括得分为零且没有疾病临床表现的动物；第 2 组（n = 35），包括评分范围为 1 至 5 分和中等临床表现的动物；第 3 组（n = 18）包括评分范围为 6 至 11 分且具有强烈临床表现的狗。考虑到疾病的临床症状的存在或缺乏，进行了另一项分析，将动物分为两组。对这些结果的分析表明，皮肤是寄生虫负荷较高的组织，其次是腘淋巴结和骨髓穿刺，结膜拭子样本的负荷最低。此外，在单独评估各组时，皮肤也是寄生虫负荷最高的组织。与第 1 组和第 2 组的动物相比，具有强烈临床表现的第 3 组动物在不同组织中表现出更高的寄生虫负荷。最后，与没有表现的狗相比，具有该疾病临床表现的动物表现出更高的寄生虫负荷。狗作为水库的重要性在本研究的分析中，皮肤具有最高数量的寄生虫/μL，以及皮肤是进入寄生虫载体的主要点这一事实，强化了自然界中的婴儿乳杆菌。此外，还观察到临床表现的强度与皮肤中寄生虫负荷的增加之间存在强烈的正相关关系。总之，皮肤组织被证明是本研究中使用的具有不同临床状态的狗的婴儿乳杆菌感染分子诊断的最佳选择。