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

Abstract

BackgroundTungiasis, a parasitic skin disease caused by the female sand flea Tunga penetrans, is a prevalent condition in impoverished communities in the tropics. In this setting, the ectoparasitosis is associated with important morbidity. It causes disfigurement and mutilation of the feet. Feasible and effective treatment is not available. So far prevention is the only means to control tungiasis-associated morbidity.MethodologyIn two villages in Central Madagascar, we assessed the efficacy of the availability of closed shoes and the twice-daily application of a plant-based repellent active against sand fleas (Zanzarin) in comparison to a control group without intervention. The study population was randomized into three groups: shoe group, repellent group and control group and monitored for ten weeks. The intensity of infestation, the attack rate and the severity of tungiasis-associated morbidity were assessed every two weeks.FindingsIn the repellent group, the median attack rate became zero already after two weeks. The intensity of the infestation decreased constantly during the observation period and tungiasis-associated morbidity was lowered to an insignificant level. In the shoe group, only a marginal decrease in the intensity of infestation and in the attack rate was observed. At week 10, the intensity of infestation, the attack rate and the severity score for acute tungiasis remained significantly higher in the shoe group than in the repellent group. Per protocol analysis showed that the protective effect of shoes was closely related to the regularity with which shoes were worn.ConclusionsAlthough shoes were requested by the villagers and wearing shoes was encouraged by the investigators at the beginning of the study, the availability of shoes only marginally influenced the attack rate of female sand fleas. The twice-daily application of a plant-based repellent active against sand fleas reduced the attack to zero and lowered tungiasis-associated morbidity to an insignificant level.

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

“…21 However, a randomized controlled study in rural Madagascar showed that the regular wearing of shoes had a significantly lower effect on the attack rate and on the regression of tungiasis-associated inflammation than the regular application of a repellent based on coconut oil when compared with a control group without intervention. 16 Our study also shows that the availability of closed shoes does not guarantee that the shoes are worn regularly by their owners. One reason relevant to this case series is that individuals with severe tungiasis-associated morbidity refrain from wearing closed shoes, because this increases their pain.…”

“…The social and economic characteristics of the study area have been described elsewhere. 16 Study population and study design. When preparing an intervention study involving several communities in Moramanga district, we identified eight individuals with an extremely high intensity of infestation (more than 75 sand flea lesions).…”

“…The regular application was verified through rigid quality control. 16 Both feet were carefully inspected for the presence of burrowed viable and non-viable sand fleas and lesions manipulated by the patient. As a result of clustering of lesions and intense inflammation, the total number of lesions could only be estimated.…”

“…As the burrowed female sand flea dies in situ within 4 weeks and clinical pathology regresses when no new sand fleas penetrate, the prevention of new infestations will automatically lead to a reduction of tungiasis-associated morbidity. 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.…”

High-resolution infrared thermography: a new tool to assess tungiasis-associated inflammation of the skin

“…Besides, many families cannot afford shoes for all household members. A detailed description of the study area and population has been published elsewhere [13].…”