Departamento de Parasitología, Facultad de Farmacia, Universidad de Valencia, Av. Vicente Andrés Estellés s/n, Burjassot, 46100, Valencia, Spain.
Cátedra de Parasitología, Facultad de Medicina, Universidad Mayor de San Andrés (UMSA), Av. Saavedra, Miraflores, La Paz, Bolivia.
Parasit Vectors. 2020 Apr 6;13(1):171. doi: 10.1186/s13071-020-04045-x.
Fascioliasis is a snail-borne zoonotic trematodiasis emerging due to climate changes, anthropogenic environment modifications, and livestock movements. Many areas where Fasciola hepatica is endemic in humans have been described in Latin America altitude areas. Highest prevalences and intensities were reported from four provinces of the northern Bolivian Altiplano, where preventive chemotherapy is ongoing. New strategies are now incorporated to decrease infection/re-infection risk, assessment of human infection sources to enable efficient prevention measures, and additionally a One Health initiative in a selected zone. Subsequent extension of these pilot interventions to the remaining Altiplano is key.
To verify reproducibility throughout, 133 specimens from 25 lymnaeid populations representative of the whole Altiplano, and 11 used for population dynamics studies, were analyzed by rDNA ITS2 and ITS1 and mtDNA cox1 and 16S sequencing to assess their classification, variability and geographical spread.
Lymnaeid populations proved to belong to a monomorphic group, Galba truncatula. Only a single cox1 mutation was found in a local population. Two cox1 haplotypes were new. Comparisons of transmission foci data from the 1990's with those of 2018 demonstrated an endemic area expansion. Altitudinal, northward and southward expansions suggest movements of livestock transporting G. truncatula snails, with increasing temperatures transforming previously unsuitable habitats into suitable transmission areas. Transmission foci appear to be stable when compared to past field observations, except for those modified by human activities, including construction of new roads or control measures undertaken in relation to fascioliasis.
For a One Health initiative, the control of only one Fasciola species and snail vector species simplifies efforts because of the lower transmission complexity. Vector monomorphism suggests uniformity of vector population responses after control measure implementation. Hyperendemic area outer boundary instability suggests a climate change impact. All populations outside previously known boundaries were close to villages, human dwellings and/or schools, and should therefore be considered during disease control planning. The remarkable southward expansion implies that a fifth province, Aroma, should now be included within preventive chemotherapy programmes. This study highlights the need for lymnaeid molecular identification, transmission foci stability monitoring, and potential vector spread assessment.
肝片形吸虫病是一种由气候变化、人为环境改变和牲畜流动引起的蜗牛传播的人畜共患吸虫病。在拉丁美洲的高海拔地区，已经描述了许多人类流行肝片形吸虫病的地区。在玻利维亚北部高原的四个省份，报告了最高的流行率和强度，那里正在进行预防性化疗。现在已经纳入了新的策略来降低感染/再感染的风险，评估人类感染源以实施有效的预防措施，以及在选定区域开展一项"同一健康"倡议。随后将这些试点干预措施扩展到高原的其余地区是关键。
为了验证整个过程的可重复性，对来自整个高原的 25 个豆螺种群的 133 个标本进行了 rDNA ITS2 和 ITS1 以及 mtDNA cox1 和 16S 测序分析，以评估它们的分类、变异性和地理分布。
豆螺种群被证明属于单态群，即 Galba truncatula。仅在当地种群中发现了一个 cox1 突变。发现了两种新的 cox1 单倍型。将 20 世纪 90 年代的传播焦点数据与 2018 年的数据进行比较，表明流行区有所扩大。海拔、向北和向南的扩张表明，牲畜运输豆螺的活动增加，随着温度的升高，原本不适宜的栖息地变成了适宜的传播区。与过去的实地观察相比，传播焦点似乎保持稳定，除了那些因人类活动而改变的传播焦点，包括修建新道路或为防治肝片形吸虫病而采取的控制措施。
对于"同一健康"倡议，由于传播的复杂性较低，只控制一种肝片形吸虫和蜗牛媒介物种简化了工作。媒介的单态性表明，在实施控制措施后，媒介种群的反应具有一致性。高度流行区外部边界的不稳定性表明气候变化的影响。所有位于先前已知边界之外的种群都靠近村庄、人类住区和/或学校，因此应在疾病控制规划中考虑到这些种群。引人注目的向南扩张意味着现在应该将第五个省份，Aroma，纳入预防性化疗计划。本研究强调了豆螺分子鉴定、传播焦点稳定性监测和潜在媒介传播评估的必要性。
