The efficacy of soap against schistosome cercariae: A systematic review.

Background Schistosomiasis is a parasitic disease that is endemic in 78 countries and affects almost 240 million people worldwide. It has been acknowledged that an integrated approach that goes beyond drug treatment is needed to achieve control and eventual elimination of the disease. Improving hygiene has been encouraged by World Health Organisation, and one aspect of good hygiene is using soap during water-contact activities, such as bathing and doing laundry. This hygiene practice might directly reduce the skin exposure to cercariae at transmission sites. A systematic review was carried out to investigate the efficacy of soap against schistosome cercariae and to identify the knowledge gaps surrounding this topic. Methodology Six online databases were searched between 5th and 8th July of 2021. Records returned from these databases were screened to remove duplicates, and the remaining records were classified by reading titles, abstracts, and full texts to identify the included studies. The results were categorised into two groups based on two different protective mechanisms of soap (namely, damage to cercariae and protection of skin). Conclusions Limited research has been conducted on the efficacy of soap against schistosome cercariae and only 11 studies met the criteria to be included in this review. The review demonstrates that soap has the potential of protecting people against schistosome cercariae and there are two protective aspects: (1) soap affects cercariae adversely; (2) soap on the skin prevents cercariae from penetrating the skin, developing into adult worms and producing eggs. Both aspects of protection were influenced by many factors, but the differences in the reported experimental conditions, such as the cercarial endpoint measurement used and the cercaria numbers used per water sample, lead to low comparability between the previous studies. This review indicates that more evidence is needed to inform hygiene advice for people living in schistosomiasis endemic areas

The efficacy of soap against schistosome cercariae: A systematic review

BACKGROUND: Schistosomiasis is a parasitic disease that is endemic in 78 countries and affects almost 240 million people worldwide. It has been acknowledged that an integrated approach that goes beyond drug treatment is needed to achieve control and eventual elimination of the disease. Improving hygiene has been encouraged by World Health Organisation, and one aspect of good hygiene is using soap during water-contact activities, such as bathing and doing laundry. This hygiene practice might directly reduce the skin exposure to cercariae at transmission sites. A systematic review was carried out to investigate the efficacy of soap against schistosome cercariae and to identify the knowledge gaps surrounding this topic. METHODOLOGY: Six online databases were searched between 5th and 8th July of 2021. Records returned from these databases were screened to remove duplicates, and the remaining records were classified by reading titles, abstracts, and full texts to identify the included studies. The results were categorised into two groups based on two different protective mechanisms of soap (namely, damage to cercariae and protection of skin). CONCLUSIONS: Limited research has been conducted on the efficacy of soap against schistosome cercariae and only 11 studies met the criteria to be included in this review. The review demonstrates that soap has the potential of protecting people against schistosome cercariae and there are two protective aspects: (1) soap affects cercariae adversely; (2) soap on the skin prevents cercariae from penetrating the skin, developing into adult worms and producing eggs. Both aspects of protection were influenced by many factors, but the differences in the reported experimental conditions, such as the cercarial endpoint measurement used and the cercaria numbers used per water sample, lead to low comparability between the previous studies. This review indicates that more evidence is needed to inform hygiene advice for people living in schistosomiasis endemic areas

The efficacy of soap against schistosome cercariae: A systematic review. Search results

Classification process and codes, a list of excluded and included studies, experimental setups and extracted data for "The efficacy of soap against schistosome cercariae: A systematic review"

Insights into the Horizontal and Vertical Profiles of Microplastics in a River Emptying into the Sea Affected by Intensive Anthropogenic Activities in Northern China

Studies focused only on surface water may underestimate microplastic abundance in aquatic environments. This was the first survey to investigate the vertical (surface, intermediate, and bottom waters) distribution and composition of microplastics (MPs) in the water columns and surface sediments collected from an urban seagoing river in northern China. Microplastic abundance in the water columns ranged from 5.6 to 31.4 items∙L-1 and from 2141 to 10035 items∙kg-1 dry weight (dw) in the surface sediments. Polyethylene dominated throughout the water columns to the surface sediments, in which low- and high-density polyethylene (LDPE and HDPE) were dominant in the water columns and surface sediments, respectively. The dominant shape of MPs was fibers/lines in both the water column and the surface sediment samples. Different from the estimations, the average abundance of MPs in the surface and intermediate waters was significantly lower (p < 0.01) than that in the bottom water, which may be due to the resuspension of small-sized MPs in the bottom water. As the MPs size increased, their vertical distributions in the water columns were more affected by the water depth. The results showed that MPs were detained in the water columns of river system, and the high concentrations of MPs in the bottom water could not be neglected

Soap concentrations and exposure times required to achieve 100% cercaria mortality [34,37,38,42,44].

Data are generated from soaps which were tested in six studies. S. haematobium cercariae were used in the study by Lemma [42], while S. mansoni were used in the other five studies. Several assumptions were made as follows: (1) the study by Mimpfoundi & Dupouny stated that the cercariae survived more than 12 hours in some experimental conditions, and therefore it was assumed that cercariae only survived 12 hours in order to include this research [38]; (2) LC90 was used as the dose for 100% mortality in the study by Monkiedje, Anderson & Englande [34]; (3) only one individual compound existed in both soaps tested in the study by Pacheco & Jansen [44]; (4) in the studies by Mimpfoundi & Dupouny and Okwuosa & Osuala, the exposure time of “immediate cercaricidal effect/death” was assumed to be three seconds based on our estimation that at least three seconds are required to determine cercariae death [37,38]; (5) The concentrations in mg/L and mol/L were converted to ppm, assuming that the liquid density is 1 g/mL.</p

Summary of the soaps considered in the included papers.

Summary of the soaps considered in the included papers.</p

The reduction in worm burden (A) and egg load (B) under different soap treatment conditions [32,37].

The reduction in worm burden was calculated by comparing the average of worms recovered in the soap-treated group with that in the untreated group. The species in these two studies was S. mansoni.</p

Occurrence and characteristics of microplastics in the Haihe River: An investigation of a seagoing river flowing through a megacity in northern China

Freshwater systems serve as important sources and transportation routes for marine microplastic pollution, and inadequate attention has been paid to this situation. Data on microplastic pollution of typical seagoing rivers in northern China are lacking. In the current study, we investigated the distribution and characteristics of microplastics in the main stream of the Haihe River, which flows through a metropolis with a high population density and level of industrialization and then flows into the Bohai Sea. The microplastic samples were collected by manta trawls with pore sizes of 333 mm, and the microplastic concentrations ranged from 0.69 to 74.95 items/m(3). Fibers dominated in the surface water of the Haihe River; their shapes that were categorized as fibers, film, foam, fragments, and spheres, and contributed 17.4-86.7% of the total microplastics studied. The size distribution of the microplastics was concentrated in a range of 100-1000 mu m, with 54.7% of the total sizes corresponding to the 333-mu m trawl. Micro-Fourier transform infrared (mu-FT-IR) spectra showed that the main components were polyethylene, poly(ethylene-propylene) copolymer, and polypropylene. Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) measurements revealed scratches, micropores, and cracks on the surfaces of the microplastics due to mechanical friction, chemical oxidation and degradation processes. The results of this study confirmed the high abundance and high diversity of microplastics in an urban river and indicated appreciable impacts from point-source inputs on the microplastic pollution, such as effluents from wastewater treatment plants (WWTPs). (C) 2020 Elsevier Ltd. All rights reserved

Effects of Anthropogenic Discharge and Hydraulic Deposition on the Distribution and Accumulation of Microplastics in Surface Sediments of a Typical Seagoing River: The Haihe River

Microplastics pollution in river systems has generated great concern; however, few studies have focused on the contributions of multiple influencing factors to microplastics in river systems. In the current study, we utilized data on microplastics in surface sediments from the Haihe River, a seagoing river in northern China to establish a generalized additive model (GAM) for quantifying the effects of multiple factors on the distribution of microplastics. A high abundance of microplastics (4980±2462 items∙kg−1 dry weight) was found. Small particles (< 1000 μm) accounted for a dominant proportion (44.8%-61.0%). Polyethylene (PE) was the chief component with an averaged fraction of 49.3%, in which low- and high-density polyethylene contributed 90.7% and 9.3% of the PE, respectively. Microplastics abundance was positively correlated with sediment TOC and the silt fraction (p < 0.05) but negatively correlated with the sand fraction (p < 0.05). The GAM could explain approximate 60% of the total microplastics abundance, and dam (28.5%), sediment TOC (22.9%), and sewage effluent (17.6%) were the main contributors to total variations in microplastics abundance. Local sewage effluent acted as an important point source of microplastics discharge, and the dam on the river greatly affected the deposition and accumulation of microplastics