Disease Control Strategy Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, United Kingdom.
Parasit Vectors. 2012 Sep 7;5:196. doi: 10.1186/1756-3305-5-196.
To clarify the extent and putative transmission zone of bovine fasciolosis on the slopes of Mount Elgon, Uganda, conjoint parasitological and malacological surveys, inclusive of inspection of animals at slaughter, were undertaken at increasing altitudes.
A total of 239 cattle were sampled across eight locations ranging in elevation from 1112-2072 m. Faecal material was examined for presence of Fasciola eggs and sera were tested by ELISA for antibodies against Fasciola antigens. Bolstering this, 38 cattle at slaughter from 2 abattoir sites at 1150 m and 1947 m were inspected; in addition, wild buffalo stool (n=10) opportunistically picked within Mount Elgon National Park (MENP) at 3640 m was examined. By faecal egg detection, prevalence of Fasciola gigantica at low (<1500 m) and high (>1500 m) altitude sites was 43.7% (95% CI 35.4-52.2) and 1.1% (95% CI 0.0-6.0), respectively, while by ELISA was much higher, low altitude--77.9% (95% CI 69.7-85.4) and high altitude--64.5% (95% CI 51.3-76.3). The decline in prevalence with increasing altitude was corroborated by abattoir sampling. Thirty seven aquatic habitats, ranging from 1139-3937 m in altitude were inspected for freshwater snails, 12 of which were within MENP. At lower altitudes, Lymnaea (Radix) natalensis was common, and often abundant, but at higher altitudes became much rarer ceasing to be found above 1800 m. On the other hand, Lymnaea (Galba) truncatula was found only at altitudes above 3000 m and within MENP alone. The snail identifications were confirmed by DNA analysis of the ribosomal 18S gene.
Active infections of F. gigantica in cattle are common in lower altitude settings but appear to diminish with increasing elevation. This is likely due to a growing paucity of intermediate hosts, specifically populations of L. natalensis for which a natural boundary of 1800 m appeared. Although F. hepatica was not encountered, the presence of several populations of L. truncatula at elevations over 3000 m point towards a potential transmission zone within MENP should this parasite be introduced.
为了阐明在乌干达埃尔贡山山坡上牛 Fasciolosis 的范围和假定传播区，在不断增加的海拔高度上进行了联合寄生虫学和软体动物学调查，包括屠宰场动物检查。
在海拔 1112-2072 米的 8 个地点共采集了 239 头牛。检查了粪便中是否存在 Fasciola 卵，并用 ELISA 检测血清中抗 Fasciola 抗原的抗体。这一结果得到了加强，在海拔 1150 米和 1947 米的 2 个屠宰场从 38 头屠宰牛中进行了检查；此外，在海拔 3640 米的埃尔贡山国家公园（MENP）内随机采集了 10 头野生水牛粪便。通过粪便卵检测，低海拔（<1500 米）和高海拔（>1500 米）地区 Fasciola gigantica 的流行率分别为 43.7%（95%CI 35.4-52.2）和 1.1%（95%CI 0.0-6.0），而通过 ELISA 检测则更高，低海拔地区为 77.9%（95%CI 69.7-85.4），高海拔地区为 64.5%（95%CI 51.3-76.3）。屠宰场抽样证实了随着海拔升高流行率的下降。检查了海拔 1139-3937 米范围内的 37 个水生栖息地，寻找淡水蜗牛，其中 12 个位于 MENP 内。在较低的海拔地区，常见且丰富的是纳塔尔蜗牛（Radix），但在较高的海拔地区，它变得非常罕见，在 1800 米以上就找不到了。另一方面，仅在海拔 3000 米以上和 MENP 内发现了截断圆田螺（Galba）。通过核糖体 18S 基因的 DNA 分析证实了蜗牛的鉴定。
在较低海拔地区，牛 Fasciolosis 的活动性感染很常见，但随着海拔升高，感染似乎减少了。这可能是由于中间宿主，特别是纳塔尔蜗牛的数量减少所致，纳塔尔蜗牛的自然边界为 1800 米。虽然没有遇到 Fasciola hepatica，但在海拔 3000 米以上的多个地区发现了截断圆田螺种群，这表明如果引入这种寄生虫，MENP 内可能存在潜在的传播区。
