Control of Tungiasis through Intermittent Application of a Plant-Based Repellent: An Intervention Study in a Resource-Poor Community in Brazil

Abstract

BackgroundTungiasis, 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 FindingsWe 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/SignificanceOur study shows that in a setting with intense transmission, tungiasis-associated morbidity can be minimized through the intermittent application of a plant-based repellent.

Prevention of Tungiasis and Tungiasis-Associated Morbidity Using the Plant-Based Repellent Zanzarin: A Randomized, Controlled Field Study in Rural Madagascar

“…We have previously shown that the regular application of Zanzarin, a repellent based on coconut oil, reduced the attack rate of invading sand fleas by 92%, and almost completely resolved tungiasis-associated morbidity in resource-poor settings in Northeast Brazil [25], [26]. In this study we compared the protective effect of a twice daily application of the repellent with the availability of closed shoes in a rural area in Madagascar, where the crude prevalence of tungiasis varied between 30 to 69% [6].…”

Regression of Severe Tungiasis-Associated Morbidity after Prevention of Re-Infestation: A Case Series from Rural Madagascar

“…The attack rate became zero-or near zero-immediately after the repellent had been applied to the feet regularly. [17][18][19] The major repellent component of Zanzarin is capric acid, a fatty acid from coconut oil. The repellent also contains jojoba oil and Aloe vera, which have an anti-inflammatory effect and presumably also contributed to the rapid reduction of the inflammation of the feet as soon as sand fleas were effectively repelled.…”

“…16 We have previously shown that the regular application of a repellent-based coconut oil effectively reduces tungiasisassociated morbidity in lightly and moderately infected individuals. [17][18][19] Here, we test the hypothesis, whether this approach is also effective in extremely severe cases and compare the effectiveness of the regular application of the repellent to the protection provided by closed shoes.…”

Topographic Distribution of the Sand Flea Tunga penetrans in Wistar Rats and Humans in Two Endemic Areas in Brazil

“…[13][14][15][16][17][18][19][20] In human tungiasis, more than 97% of all embedded sand fleas are located at the feet. 16 However, at the feet, embedded sand fleas are heterogeneously distributed, with the periungual areas, the heels, and the lateral rim of the foot being predilection sites.…”