Schistosomiasis is a neglected parasitic disease transmitted by trematodes of the Schistosoma genus. The disease is associated with fecal contamination of water sources by infected people and/or animals. The main etiological agents of schistosomiasis are Schistosoma hematobium, Schistosoma japonicum, and Schistosoma mansoni (Gomes et al., 2022). It is a predominant disease in low-income populations with poor sanitation, causing a great socioeconomic impact on developing countries (Rocha et al., 2021). It is estimated that 779 million people in 78 countries live in endemic areas. In this way, the World Health Organization (WHO) established the eradication of schistosomiasis as a priority for world public health (WHO, 2022a).

The WHO recommends the control of intermediate host snails of the Biomphalaria genus with molluscicide agents, such as niclosamide, in epidemic areas (WHO, 2022a). However, chemical molluscicides are the last resource to control schistosomiasis due to their high cost, toxicity to non-target organisms, and the emergence of resistance.

An alternative approach is related to searching and developing new plant-based products. Essential oils are in the spotlight of novelty for new products with different applicability, among them pesticides, to produce cheaper, more effective, biodegradable, safer, and environmentally less aggressive new alternatives (Pavoni et al., 2019). However, these volatile lipophilic oils' have an intrinsic limited use in aqueous media. For this reason, nanoemulsions are an interesting approach enabling the utilization of essential oils in aqueous matrices (Tomiotto-Pellissier et al., 2017). They are kinetically stable dispersed systems composed of two immiscible phases with a main difference to kinetic-unstable conventional emulsions due to a reduced droplet size (∼20–200 nm). Therefore, it has been widely used in several industry segments over the years (Marhamati et al., 2021).

The Ocotea indecora (Schott) Mez (Lauraceae) is a native and endemic plant from Brazil occurring in the Atlantic Forest. To the best of our knowledge, few studies were performed with the essential oil of O. indecora leaves, showing diverse secondary metabolites such as sesquirosefuran, bicyclogermacrene, valerianol, and β-pinene (Gonçalves et al., 2018, Machado et al., 2023; Pinto et al., 2023). The biological potential was described in terms of biocidal action against pests such as the Aedes aegypti (dengue mosquito vector), Rhipicephalus (Boophilus) microplus (bovine ticks), Dysdercus peruvianus (cotton stainer bugs), in addition to antifungal activity against Aspergillus species (Figueiredo et al., 2018; Machado et al., 2023; Nascimento et al., 2020; Pinto et al., 2023).

Thus, as part of our ongoing studies with bioactive prospection of O. indecora essential oil against pests, this work aimed to evaluate the action of both essential oil and its nanoemulsion against Biomphalaria glabrata mollusks, intermediate hosts of human schistosomiasis.