Maingon R, Feliciangeli D, Ward R, Chance M, Adamson R, Rodriguez N, Convit J, Petralanda I, Hernandez A, Segovia M
Liverpool School of Tropical Medicine, United Kingdom.
Arch Inst Pasteur Tunis. 1993 Jul-Oct;70(3-4):309-24.
Leishmaniasis is on the increase in Venezuela (ca 30,000 new cases per year) due to deterioration in health management, increased risk groups among inmunosuppressed individuals and increased human penetration into the ecological habitats of sandfly vectors. An STD2-funded project (1989-1992) focused on the Andean state of Táchira, which showed the highest annual index of new cases (ca 200-250). The project aimed at contributing to vector/parasite identification through a combination of molecular and well established field techniques: Newly developed molecular methods distinguished among Lu. spinicrassa, Lu. youngi and Lu. townsendi. These three species of the Verrucarum group are sympatric in the Northeast of the state and could be successfully identified by CHA, DNA probes and RAPD. A Le. braziliensis specific KDNA probe used with squash blots indicated that Lu. spinicrassa is the main vector and that Le. braziliensis is the main parasite species in Táchira state, Venezuela. PCR and the Le. brasiliensis specific DNA probe, schizodemes, isoenzymes and polyclonal antibodies agreed as taxonomic criteria for classification of Leishmania isolated from parasitologically confirmed cases in Tachira. Considerable degree of antigen heterogeneity in Venezuelan Le. braziliensis complex and Le. mexicana complex isolates from Tachira suggests multiple candidate antigens for improving the specificity of immunological diagnosis. The methods developed and tested in Táchira state should be valuable in order to help solving other outstanding epidemiological problems such as following of the epidemiological impact of intervention and vector control measures in highly endemic areas. Future work (STD3 funded, 1993-1996) aims to apply these molecular techniques to a vector control pilot study in Lara state, an area showing the highest incidence of new cases in the country.
由于卫生管理的恶化、免疫抑制个体中风险群体的增加以及人类对白蛉传播媒介生态栖息地的渗透增加，委内瑞拉的利什曼病发病率正在上升（每年约有30000例新病例）。一个由STD2资助的项目（1989 - 1992年）聚焦于塔奇拉州安第斯地区，该地区新病例的年指数最高（约200 - 250例）。该项目旨在通过分子技术和成熟的现场技术相结合来辅助病媒/寄生虫鉴定：新开发的分子方法区分了斯氏白蛉、杨氏白蛉和汤氏白蛉。疣蛉类的这三个物种在该州东北部同域分布，并且可以通过CHA、DNA探针和RAPD成功鉴定。一种用于压片印迹的巴西利什曼原虫特异性KDNA探针表明，斯氏白蛉是主要传播媒介，巴西利什曼原虫是委内瑞拉塔奇拉州的主要寄生虫物种。PCR以及巴西利什曼原虫特异性DNA探针、裂殖体、同工酶和多克隆抗体一致作为从塔奇拉经寄生虫学确诊病例中分离出的利什曼原虫分类的分类标准。来自塔奇拉的委内瑞拉巴西利什曼原虫复合体和墨西哥利什曼原虫复合体分离株中存在相当程度的抗原异质性，这表明有多种候选抗原可用于提高免疫诊断的特异性。在塔奇拉州开发和测试的方法对于帮助解决其他突出的流行病学问题应该是有价值的，比如追踪高流行地区干预措施和病媒控制措施的流行病学影响。未来的工作（由STD3资助，1993 - 1996年）旨在将这些分子技术应用于拉腊州的病媒控制试点研究，拉腊州是该国新病例发病率最高的地区。
