The monitoring of water wells as health evaluation strategy in Rural Community in São Luís City, MA, Brazil

Schistosomiasis is a disease endemic in several states of Brazil. The population control of the transmitter mollusks is done with Bayluscide WP 70®, in the control programs. OMS preconize molluscicidal assays using Becker with 500 mL of final volume, restringing the number of natural products and synthetic drugs to be tested in function of high quantity of material necessary. A new technique to assess the toxic effects for Biomphalaria sp. is the purpose of this work, for developing adaptation for this aquatic organism, using a low volume of test solution in 24‐well plates. We used Biomphalaria glabrata (10–12 mm size) in a static system, consisting of the following components: Becker containing 10 snails or 24‐well plates where snails were individualized for a volume of 2 mL per well for 24 and 48 hours. For the assays, we added aqueous solutions of Bayluscide WP 70, at a concentration of 1–5 mg/L, distilled water, and 1% dimethyl sulfoxide. Data were evaluated using Kappa’s coefficient, Z factor validation, and comparison study. This technique to assess the toxic effect has proven to be a useful tool to detect lethal and sublethal effects, which could be used as a new evaluation protocol.

The study analyzed the quality of drinking water used in Brazilian urban slum residences according to the standards established in Brazilian regulations. Bacteriological (n=231) and physicochemical parameters (n=134) were analyzed, as the Standard Methods for the Examination of Water and Wastewater establishes. The results revealed that contaminants in the water consumed, for the most part, exceed the limits of drinking water quality standards, putting the population's health at risk and reinforcing the urgency of the need for public policies.

Intestinal parasitic infections (IPIs) are neglected diseases caused by helminths and protozoa, with the relationships between parasite, host and environment having the potential to produce high morbidity and incapacity to work and mortality in vulnerable areas. This study assessed the prevalence of IPIs concerning socio-environmental conditions and analyzed the knowledge, attitudes and practices related to these diseases among men living in the slums of Rio de Janeiro city, Rio de Janeiro State, Brazil. A cross-sectional study was conducted in an agglomeration of urban slums between 2018 and 2019, with men aged between 20 and 59 years. A socioeconomic status questionnaire and an IPIs knowledge, attitudes and practices questionnaire (KAPQ) were applied. Coproparasitological diagnoses (n=454) were performed using four methods and samples of water for household consumption (n=392) were subjected to microbiological and physicochemical analysis. A total of 624 participants were enrolled. About 40% of the households had “water unsuitable for consumption”. Only one Major Area, MA 3 was not statistically significant for IPIs (AOR=0.75; 95% CI: 0.30-1.88; p=0.55). The overall prevalence of IPIs was 23.8%. Endolimax nana (n=65, 14.3%) and hookworm (n=8, 1.7%) were the most frequently identified parasites. The analysis of the frequency of responses to the KAPQ has shown that men reported to seeking medical care if they were suspicious of IPIs, and around 35% would self-medicate. The results have shown the need to adopt integrated health education practices targeting male residents in urban slums to qualify the care with water for human consumption and promote self-care about IPIs. The household can be considered strategic for Primary Health Care activities for men.

Schistosomiasis is a tropical disease transmitted in an aqueous environment by cercariae from the Schistosoma genus. This disease affects 200 million people living in risk areas around the world. The control of schistosomiasis is realized by chemotherapy, wastewater sanitation, health education, and mollusk control using molluscicidal agents. This work evaluates the effects of a nanoemulsion containing essential oil from Myrciaria floribunda leaves as a molluscicidal and cercaricidal agent against Biomphalaria glabrata mollusks and Schistosoma mansoni cercariae. The Myrciaria floribunda essential oil from leaves showed nerolidol, β-selinene, 1,8 cineol, and zonarene as major constituents. The formulation study suggested the F3 formulation as the most promising nanoemulsion with polysorbate 20 and sorbitan monooleate 80 (4:1) with 5% (w/w) essential oil as it showed a smaller droplet size of approximately 100 nm with a PDI lower than 0.3 and prominent bluish reflection. Furthermore, this nanoemulsion showed stability after 200 days under refrigeration. The Myrciaria floribunda nanoemulsion showed LC₅₀ values of 48.11 µg/mL, 29.66 µg/mL, and 47.02 µg/mL in Biomphalaria glabrata embryos, juveniles, and adult mollusks, respectively, after 48 h and 83.88 µg/mL for Schistosoma mansoni cercariae after 2 h. In addition, a survival of 80% was observed in Danio rerio, and the in silico toxicity assay showed lower overall human toxicity potential to the major compounds in the essential oil compared to the reference molluscicide niclosamide. These results suggest that the nanoemulsion of Myrciaria floribunda leaves may be a promising alternative for schistosomiasis control.