Pereira Luiza de Oliveira Ramos, Moreira Regina Barbosa, de Oliveira Márcia Pereira, Reis Soraya de Oliveira, de Oliveira Neto Manoel Paes, Pirmez Claude
Laboratório de Pesquisa em Leishmaniose, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Laboratório Interdisciplinar de Pesquisas Médicas, IOC, FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Int J Infect Dis. 2017 Apr;57:132-137. doi: 10.1016/j.ijid.2017.01.036. Epub 2017 Feb 3.
Leishmania (Viannia) braziliensis is the main etiological agent of tegumentary leishmaniasis in the Americas. Parasite molecular diversity and host immune status contribute to extensive variations in its clinical presentation within endemic areas of Brazil. Pentavalent antimonials have been used for more than 60 years as the first-line drug for all cases, despite the potential for severe side effects and refractoriness. In Rio de Janeiro, Brazil, most L. (V.) braziliensis infections are benign with a scarcity of parasites, although metastasis and refractory infections can arise. In this scenario, the use of novel molecular tools can be useful for diagnosis and to assess tissue parasitism, and is of benefit to clinical and therapeutic management.
In this study, parasite load was assessed by real-time PCR based on the leishmanial small subunit ribosomal RNA gene.
The data revealed a tendency to higher tissue parasitism in the skin compared to mucous lesion sites and a reduction with disease progression. Parasite load was lower in poor compared to good responders to antimonials, and was also reduced in recurrent lesions compared to primary ones. However, parasite load became higher with sequential relapses, pointing to an immune system inability to control the infection. Therefore the parasite burden does not seem to be a good predictor of disease progression.
巴西利什曼原虫（维安尼亚利什曼原虫）是美洲皮肤利什曼病的主要病原体。寄生虫分子多样性和宿主免疫状态导致巴西流行地区其临床表现存在广泛差异。尽管五价锑有潜在的严重副作用和难治性，但60多年来一直被用作所有病例的一线药物。在巴西里约热内卢，大多数巴西利什曼原虫（维安尼亚利什曼原虫）感染是良性的，寄生虫数量稀少，尽管会出现转移和难治性感染。在这种情况下，使用新型分子工具可有助于诊断和评估组织寄生虫感染情况，对临床和治疗管理有益。
在本研究中，基于利什曼原虫小亚基核糖体RNA基因，通过实时PCR评估寄生虫载量。
数据显示，与黏膜病变部位相比，皮肤组织寄生虫感染倾向更高，且随疾病进展而降低。与锑剂治疗反应良好者相比，反应不佳者的寄生虫载量更低，复发病变的寄生虫载量也低于原发性病变。然而，随着连续复发，寄生虫载量会升高，这表明免疫系统无法控制感染。因此，寄生虫负荷似乎不是疾病进展的良好预测指标。
