Currently, the soil-transmitted helminths (STHs) affect more than one billion people throughout the world and approximately 300 million present a severe disease originated from these parasitic infections (PAHO, 2016). They are present especially in areas without basic sanitation and where the population is socially vulnerable (World Health Organization, 2017). For instance, in some African, American and Asian countries the prevalence of STHs may achieve more than 50%, which markedly contrast with some areas of Europe and North America where this kind of infection is almost inexistent due to measures of basic sanitation (World Health Organization, 2010).

Undoubtedly, STHs has been more frequently detected in rural areas or in peripheral regions of urban centers. Nonetheless, over the last years the increase of contamination of soil from the shore of beaches, parks and squares had been responsible for the rise of cases also in large urban centers (Brener et al., 2008; Azian et al., 2008; Silva et al., 2009; Sprenger et al., 2014; Macedo et al., 2019). In urban areas, this contamination occurs mainly due to the deposition of feces from dogs and cats, that depending on the species of helminths may excrete up to 15.000 eggs per gram of feces (Ribeiro, 2004). On the soil, these helminth eggs change into infective forms and may infect humans, especially children that are more exposed (Pedrassani et al., 2008; Silva et al., 2019).

Various studies have been conducted to detect the contamination of soil by infective stages of parasites of medical and veterinary importance (Steinbaum et al., 2016). It is consensus of the scientific community that the proper identification of these parasites at species level has been a challenge, due to the absence of information about putative definitive host. Even though, nematodes belonging to the families Ascarididae, Ancylostomatidae and Trichuridae have been those more frequently reported (Moro et al., 2008; Silva et al., 2009). Studies focusing on the health status of humans and animals are pivotal, especially in critical areas where the contamination of the environment is a trouble. In this context, the monitoring of contamination of soil in beaches, parks and squares is an important tool of vigilance based on the One Health approach that has been employed worldwide (Guimarães et al., 2005; Devera et al., 2008; Dado et al., 2012).

Although developed to detect parasites in feces, the techniques of Hoffman et al. (1934), as well as Faust et al. (1938), and Willis (1921) have been used for a long time to detect parasites in soil (Hoffman et al., 1934; Faust et al., 1938; Willis, 1921). In general, these methodologies are based on the flotation and/or sedimentation of eggs and/or oocysts, and have passed for slight modifications over the time. Although, they present low cost and are easily performed, some limitations may reduce the efficacy of these techniques. Most of them presented a limited sensitivity and the level of detection of eggs in animal's feces is dependent of the number of eggs excreted. For instance, Toxocara spp. may produce up to 200,000 eggs per day (Glickman and Schantz, 1981), which will contribute to high levels of environmental contamination. However, it is important to note that the contamination in soil samples is reduced, compared with fresh feces. For this reason, the detection and identification of infective stages of parasites in this kind of samples has been a challenge.

Over the last decade, the FLOTAC technique has been employed for detection of several parasites in animals and human feces (Cringoli et al., 2010). More recently, the applicability of this tool was enlarged for detection of parasites on the pasture (Ramos et al., 2018) and on vegetables (Ramos et al., 2019), but its use in the soil samples has never been assessed. Therefore, the aim of this study was to apply the FLOTAC technique for detection of medical and veterinary important helminth eggs in the soil.