Adaptation of Ritchie's Method for Parasites Diagnosing with Minimization of Chemical Products

Abstract

Latin America, Africa, and Asia present wide dissemination and high prevalence rates of waterborne parasitic diseases, which is a strong indicative of the fragility of public sanitation systems. In this context, parasitological analyses represent extremely relevant instruments. Several parasite diagnosis methods exist, among which Ritchie's method (1948) stands out. This method uses formaldehyde and ether, two reagents of toxicological importance that can cause damages to environmental and occupational health. The present study aimed to compare Ritchie's method modified by Régis Anécimo, without use of solvents, with the traditional Ritchie's method, routinely used for helminth and protozoa diagnosing in Brazil. Some changes were introduced in the modified method, such as controlled increase of water temperature used after stool dilution and substitution of formaldehyde and ether by a neutral detergent before material centrifugation for observation of parasites. In examined samples by both methods, multiple infections were commonly observed; the modified method presented a similar sensitivity to identify the parasites. The development of analytic diagnosis methods that minimize the use of chemical products like ether and formaldehyde represents an important tool to prevent occupational diseases among exposed professionals, as well as to preserve environmental quality through the use of clean techniques.

Comparison between three concentration techniques for diagnosing intestinal parasites

“…Some authors demonstrated that less toxic reagents could be used in replacement of ether as a solvent to extract fat and debris, like ethyl acetate (11), acetone (12), or tween (13). A modified version of Ritchie’s method by Régis Anécimo (14) did even replace both formaldehyde and ether by a natural detergent, yet had similar qualitative and quantitative performances in parasite recovery. Some protocols resort to sodium hydroxide (NaOH) to perform the formol-ether concentration technique, but a comparative study conducted by Suwansaksri et al (15) found no statistically significant difference when comparing its detection rate with a normal saline preparation, allowing to avoid the use of NaOH for security reasons.…”

The Performance evaluation of three laboratory diagnostic methods for intestinal parasitic infections at rural Bahir Dar, Northwest Ethiopia: a cross-sectional study

“…For this, 0.5 g fresh stool sample was added in the sample collecting tube containing 2.5 ml of formalin and 1 ml of ethyl acetate and the sample was well mixed and then centrifuged. Finally, the supernatant was discarded, the sediment mixed and put on the microscope slide for examination (20).…”

Comparison Laboratory Methods for Detection of Hookworms Infection

“…After took stool samples for modified Harada Mori, stool samples added with formalin 10% and examine for Lugol stain [16] and FEC [17] at laboratory.…”