A quantitative assessment method for Ascaris eggs on hands.

Area of Science:

• Environmental Health
• Parasitology
• Infectious Disease Transmission

Background:

• Hands play a significant role in transmitting soil-transmitted helminths like Ascaris.
• Quantifying helminth eggs on hands is challenging due to a lack of reliable methods.
• This gap hinders research into the transmission dynamics of infections such as ascariasis.

Purpose of the Study:

• To develop and validate a method for assessing Ascaris egg contamination on hands.
• To determine the egg recovery rate of the developed hand-washing technique.
• To evaluate the efficacy of different detergents and detection methods.

Main Methods:

• Laboratory seeding of hands with known numbers of Ascaris eggs.
• Washing hands in a plastic bag with various detergents (benzethonium chloride, cetylpyridinium chloride, 7X, Tween80) or de-ionized water.
• Quantifying recovered eggs using the McMaster technique and FLOTAC.
• Comparing egg recovery rates across different washing solutions and detection methods.

Main Results:

• A modified McMaster technique demonstrated the highest egg recovery from washing bags.
• Detergents like benzethonium chloride (0.1%) and 7X (1%) showed higher recovery rates.
• Hand rinsing with 7X (1%) achieved the highest egg recovery rate at 95.6%, compared to 82.7% with de-ionized water.

Conclusions:

• A hand-washing method using a low concentration of 7X detergent is effective for quantifying Ascaris eggs on hands.
• This method has potential for investigating hand contamination and the role of hands in human ascariasis.
• Further field validation with diverse populations and contamination levels is recommended.