A quantitative assessment method for Ascaris eggs on hands

• Published in: PloS one Vol. 9; no. 5; p. e96731
• Main Authors: Jeandron, Aurelie, Ensink, Jeroen H J, Thamsborg, Stig M, Dalsgaard, Anders, Sengupta, Mita E
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 06.05.2014; Public Library of Science (PLoS)
• Subjects: Analysis; Animals; Ascariasis - prevention & control; Ascaris; Ascaris - growth & development; Ascaris - isolation & purification; Ascaris - physiology; Benzethonium - chemistry; Biology; Biology and Life Sciences; Cetylpyridinium chloride; Chlorides; Contamination; Detergents; Detergents - chemistry; Dilution; Disease; Eggs; Engineering and Technology; Epidemiology; Experiments; Hand; Hand - parasitology; Hand Disinfection; Health aspects; Hogs; Humans; Hygiene; Infections; Medical research; Medicine; Medicine and Health Sciences; Methods; Parasite Egg Count; Parasites; Plastics; Polyethylene; Polyethylene glycol; Polyols; Polyoxyethylene sorbitan monooleate; Recovery; Research and Analysis Methods; Risk factors; Salts; Sanitation; Sodium; Soil contamination; Sorbitan; Studies; Systematic review; Tropical diseases; Washing; Water - chemistry; Denmark
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0096731

The importance of hands in the transmission of soil transmitted helminths, especially Ascaris and Trichuris infections, is under-researched. This is partly because of the absence of a reliable method to quantify the number of eggs on hands. Therefore, the aim of this study was to develop a method to assess the number of Ascaris eggs on hands and determine the egg recovery rate of the method. Under laboratory conditions, hands were seeded with a known number of Ascaris eggs, air dried and washed in a plastic bag retaining the washing water, in order to determine recovery rates of eggs for four different detergents (cationic [benzethonium chloride 0.1% and cetylpyridinium chloride CPC 0.1%], anionic [7X 1% - quadrafos, glycol ether, and dioctyl sulfoccinate sodium salt] and non-ionic [Tween80 0.1% -polyethylene glycol sorbitan monooleate]) and two egg detection methods (McMaster technique and FLOTAC). A modified concentration McMaster technique showed the highest egg recovery rate from bags. Two of the four diluted detergents (benzethonium chloride 0.1% and 7X 1%) also showed a higher egg recovery rate and were then compared with de-ionized water for recovery of helminth eggs from hands. The highest recovery rate (95.6%) was achieved with a hand rinse performed with 7X 1%. Washing hands with de-ionized water resulted in an egg recovery rate of 82.7%. This washing method performed with a low concentration of detergent offers potential for quantitative investigation of contamination of hands with Ascaris eggs and of their role in human infection. Follow-up studies are needed that validate the hand washing method under field conditions, e.g. including people of different age, lower levels of contamination and various levels of hand cleanliness.