Lymphatic Filariasis Support Centre, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, QLD 4811, Australia.
Acta Trop. 2011 Sep;120 Suppl 1:S39-47. doi: 10.1016/j.actatropica.2010.12.004. Epub 2010 Dec 21.
Successful elimination of lymphatic filariasis (LF) requires accurate identification of residual foci of transmission and stringent surveillance strategies to combat potential resurgence. This is challenging in areas where the day-biting Aedes polynesiensis is endemic, such as Samoa, since in previous studies no geographical clustering of infection has been demonstrated. Another challenge for this low prevalence phase is the choice of diagnostic assay as testing for circulating filarial antigen (CFA) or microfilariae (Mf) alone may not have adequate sensitivity. This could be solved by using the commercially available filariasis Cellabs enzyme linked immunosorbent assay (CELISA) to measure antibody. In the current study five Samoan villages were chosen based on previous epidemiological assessments to represent a range of infection prevalences. CFA, Mf, and antibody levels in children ≤ 10 years had been recorded and results linked to household of residence and/or primary school of attendance. To ascertain the location of exposure, two scenarios based on potential foci of transmission around communities and schools were explored. Both scenarios revealed significant spatial clusters of households with infected individuals and a relationship to antibody positive children when they were included in the spatial analysis. Fasitoo-Tai had the highest LF prevalence and largest geographical spatial clusters for both scenarios. In Falefa, spatial clusters were detected only for the primary school scenario. In Tafua, which spanned an area of 19.5 km(2), no spatial clusters were detected. Lastly, in Siufaga, the village with the lowest LF prevalence, significant clustering of infected individuals was observed and, for the primary school scenario, this was geographically related to exposure. These promising findings are the first published evidence of spatial clustering of LF in a day-biting Ae. polynesiensis endemic area.
成功消除淋巴丝虫病（LF）需要准确识别传播的残留病灶，并采取严格的监测策略来应对潜在的复发。在像萨摩亚这样的白纹伊蚊地方性流行地区，这是一项挑战，因为在之前的研究中，没有证明感染存在地理聚集性。对于这个低流行阶段的另一个挑战是诊断检测方法的选择，因为单独检测循环丝状抗原（CFA）或微丝蚴（Mf）可能没有足够的敏感性。这可以通过使用商业上可获得的丝状细胞酶联免疫吸附试验（CELISA）来测量抗体来解决。在当前的研究中，根据先前的流行病学评估，选择了五个萨摩亚村庄来代表一系列不同的感染流行率。记录了 10 岁以下儿童的 CFA、Mf 和抗体水平，并将结果与居住家庭和/或就读小学相关联。为了确定暴露的位置，根据社区和学校周围的潜在传播焦点，探索了两种情况。两种情况都揭示了受感染个体的家庭存在显著的空间聚集，并且当将抗体阳性儿童纳入空间分析时，与他们有关。 Fasitoo-Tai 的 LF 流行率最高，两个情景的地理空间聚集最大。在 Falefa，仅在小学情景中检测到空间聚集。在 Tafua，其面积为 19.5 平方公里，没有检测到空间聚集。最后，在 Siufaga，这个 LF 流行率最低的村庄，观察到受感染个体的显著聚集，并且对于小学情景，这在地理上与暴露有关。这些有希望的发现是首次在白纹伊蚊地方性流行地区发表的 LF 空间聚集的证据。
