Yellow Highlighter Ink as an Alternative Staining Reagent in Identifying Soil-Transmitted Helminths on Direct Fecal Smear

Gerardo  A. Tabat III,

Yellow Highlighter Ink as an Alternative Staining Reagent in Identifying Soil-Transmitted Helminths on Direct Fecal Smear

Abstract:

Soil-transmitted helminths (STH) are a significant public health concern, particularly in areas with poor sanitation. Diagnostic tools such as Lugol’s iodine are widely used to detect STH eggs in direct fecal smears (DFS), but alternative, cost-effective staining agents are being explored. This study evaluates the efficacy of yellow highlighter ink as an alternative staining reagent. An experimental design compared three concentrations of yellow highlighter ink (10%, 5%, 3%) to 10% Lugol’s iodine in DFS of stool samples positive for STH. Morphological presentation, architectural preservation, and background staining were evaluated by blinded medical technologists. Results showed that yellow highlighter ink effectively stained STH eggs, with 10% Lugol’s iodine (M = 1.80, SD = 0.41) slightly outperforming 10% yellow highlighter ink (M = 1.73, SD = 0.45) in terms of morphological clarity. Architectural preservation was similarly high across concentrations, with 10% Lugol’s iodine (M = 3.97, SD = 0.18) and 10% yellow highlighter ink (M = 3.83, SD = 0.38) both demonstrating consistent results. However, higher concentrations of yellow highlighter ink (10%) produced more background staining (M = 2.63, SD = 0.49), while the 5% concentration offered clearer visualization with minimal interference (M = 2.27, SD = 0.45). These findings suggest that yellow highlighter ink, particularly at 5%, may serve as a low-cost alternative to Lugol’s iodine for STH diagnostics, warranting further investigation to optimize its use in resource-limited settings. Its affordability and accessibility make it a promising option for expanding diagnostic access.

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