Use of the aqueous biphasic system as an alternative for concentration of Ascaris lumbricoides eggs, with non‐toxic separation of faecal residues and fats

Abstract

Objectives Human enteroparasites are considered a serious public health problem in underdeveloped countries located in world regions with tropical, subtropical and equatorial climates. These parasites are commonly diagnosed by the Parasitological Examination of Faeces (PEF), performed by conventional techniques and/or commercial kits that result in tests with low‐to‐moderate sensitivity, due to the use of destructive chemical solvents to parasite structures, and to present excess adipose substance and digestive residues in their microscopic slides. In order to improve the efficacy of these tests/examinations, this study aimed to investigate a new alternative for the PEF, with the use of Aqueous Biphasic System (ABS). Methods For this, four ABSs containing poly (ethylene glycol), PEG (PEG‐4000 and PEG‐6000), dipotassium phosphate and sodium citrate at different concentrations in the biphasic systems were evaluated with faecal samples containing eggs of Ascaris lumbricoides. Results The ABS consisting of PEG‐4000 and dipotassium phosphate, at concentrations of 55% w/w and 20% w/w, respectively, achieved 100% satisfactory results compared to the conventional TF‐Test technique in terms of preservation and concentration of A. lumbricoides eggs, with adequate separation of digestive residues, without using a centrifuge or chemical solvents that may cause harm to the parasites. Conclusions This study presents ABS as a new low‐cost technical principle for the detection of parasite eggs in PEF. The new technique is simple, fast, non‐toxic, not harmful to the parasite and does not require a centrifuge.

Detection of intestinal parasites in human faecal samples using dissolved air flotation

“…Other advances in DAF include eliminating the centrifugation stage and faecal processing without using organic (flammable) solvents or high-density aqueous solutions, which harm parasites' morphological integrity. Support is needed for studies that develop new tools for recovering intestinal parasite structures in faeces with higher diagnostic accuracy [1,9,10,28].…”

“…However, these principles have physical, chemical, and biological limitations, such as (a) numerous artefacts in a faecal smear on the microscope slide; (b) restricted range of species detected in coinfections (e.g. agar plate culture and larval thermotropism, as well as specific gravity flotation that does not recover heavy eggs); (c) excessive use of chemical reagents that are harmful to human health and the environment; and (d) use of high-density solutions that cause morphological changes in various parasite structures [4,8,9]. 4,8,9].…”

“…agar plate culture and larval thermotropism, as well as specific gravity flotation that does not recover heavy eggs); (c) excessive use of chemical reagents that are harmful to human health and the environment; and (d) use of high-density solutions that cause morphological changes in various parasite structures [4,8,9]. 4,8,9]. As a result of these issues that affect the diagnostic result, several studies have been conducted to improve faecal processing or use alternative physical-chemical principles to obtain the parasite structures for diagnosis [1,9,10].…”

“…4,8,9]. As a result of these issues that affect the diagnostic result, several studies have been conducted to improve faecal processing or use alternative physical-chemical principles to obtain the parasite structures for diagnosis [1,9,10].…”