Department of Microbiology and Hygiene, Campus Benjamin Franklin, Charité University Medicine, Berlin, Germany.
PLoS Negl Trop Dis. 2010 Nov 9;4(11):e879. doi: 10.1371/journal.pntd.0000879.
Tungiasis, an ectoparasitosis caused by the female sand flea Tunga penetrans, is an important health problem in many impoverished communities in the tropics. Sand flea disease is associated with a broad spectrum of clinical pathology and severe sequels are frequent. Treatment options are limited.
METHODOLOGY/PRINCIPAL FINDINGS: We assessed the effectiveness of the intermittent application of the plant-based repellent Zanzarin to reduce infestation intensity and tungiasis-associated morbidity in a resource-poor community in Brazil, characterized by a very high attack rate. The study population was randomized into three cohorts. Initially, during a period of four weeks, the repellent was applied twice daily to the feet of all cohort members. This reduced the number of embedded sandfleas to 0 in 98% of the participants. Thereafter members of cohort A applied the repellent every second week twice daily for one week, members of cohort B every fourth week for one week, and members of cohort C served as controls. Infestation intensity and tungiasis-associated morbidity were monitored during five months. The intermittent application of Zanzarin for one week every second week significantly reduced infestation intensity from a median 4 lesions (IQR 1-9) during the whole transmission season. In contrast, in cohort B (application of the repellent every fourth week) the infestation intensity remained twice as high (median 8 lesions, IQR 9-16; p = 0.0035), and in the control cohort C 3.5 times as high (median 14 lesions; IQR 7-26; p = 0.004 during the transmission season). Tungiasis-related acute pathology remained very low in cohort A (median severity score 2; IQR 1-4) as compared to cohort B (median severity score 5; IQR 3-7; p<0.001), and control cohort C (median severity score 6.5; IQR 4-8; p<0.001).
CONCLUSIONS/SIGNIFICANCE: Our study shows that in a setting with intense transmission, tungiasis-associated morbidity can be minimized through the intermittent application of a plant-based repellent.
壤虫病是由雌性沙蚤（Tunga penetrans）引起的一种外寄生虫病，是热带地区许多贫困社区的一个重要健康问题。沙蚤病与广泛的临床病理学有关，严重的后遗症很常见。治疗选择有限。
方法/主要发现：我们评估了间歇性应用植物驱避剂 Zanzarin 来降低在巴西一个资源匮乏社区中的感染强度和与壤虫病相关的发病率的效果，该社区的感染率非常高。研究人群被随机分为三组。最初，在四周的时间里，驱避剂每天两次应用于所有组别的脚部。这使得 98%的参与者体内嵌入的沙蚤数量降为 0。此后，A 组的成员每两周一次每天两次应用驱避剂一周，B 组的成员每四周一次应用驱避剂一周，C 组的成员作为对照组。在五个月的时间里监测感染强度和与壤虫病相关的发病率。每隔一周应用 Zanzarin 一周的间歇性应用显著降低了整个传播季节的感染强度中位数为 4 个病变（IQR 1-9）。相比之下，B 组（每四周应用一次驱避剂）的感染强度仍然高出两倍（中位数 8 个病变，IQR 9-16；p=0.0035），而对照组 C 的感染强度则高出三倍半（中位数 14 个病变；IQR 7-26；p=0.004 在传播季节）。与壤虫病相关的急性病理学在 A 组（严重程度评分中位数 2；IQR 1-4）仍然非常低，与 B 组（严重程度评分中位数 5；IQR 3-7；p<0.001）和对照组 C（严重程度评分中位数 6.5；IQR 4-8；p<0.001）相比。
结论/意义：我们的研究表明，在传播强度大的环境中，通过间歇性应用植物驱避剂可以将与壤虫病相关的发病率降至最低。
