© John Buchan

Trachoma is a painful blinding eye disease caused by the bacterium Chlamydia trachomatis. Repeated infections with the bacteria cause the eyelids to swell and turn inwards. Without intervention, the eyelashes can scrape the front of the eye, leading to severe pain and blindness.

The bacteria spreads from person to person through discharge from the eyes, transmitted by close contact or flies. Methods to reduce its spread include antibiotics, facial cleanliness and environmental interventions such as reducing the number of flies in the area.

Despite face washing being seen as a feasible way to reduce the spread of this disease, there are currently no cheap, easy and scalable ways to measure whether people are washing their face or not. The current ‘gold standard’ is direct observation, where an investigator watches people going about their day and observes whether they have washed their face with soap. This is expensive and time-consuming however, and is limited by the availability of staff to carry out the observations.

A new study by the International Centre for Eye Health has assessed whether alternative methods to direct observation can be good indicators of whether facing washing has occurred.

Looking at 204 households in the Oromia region of Ethiopia, as part of an ongoing trial into trachoma control (Stronger-SAFE), the researchers tested several new methods of assessing face washing, alongside direct observation:

• Self-reported surveys – the participants were asked whether they had washed their face or not
• ‘Pictorial recall’ – participants were asked to recall tasks they did the previous day (and whether they included face washing)
• The quantitative Personal Hygiene Assessment Tool (qPHAT) – a system to test the cleanliness of a face via wipes
• Facial cleanliness metrics – e.g. whether the face was observed to have discharge on it

These methods were tested on adults (caregivers) and children in their care (as trachoma begins in childhood and children can easily spread the bacteria).

Personal bias was high in self-reported methods. For instance, among caregivers, direct observation within households showed that 38.6% were observed to wash their face in the morning, yet 98.5% of people in the self-reported survey said they had washed their face the day before.

The pictorial recall method was closer to the observed figure, but most of the people identified as washing their face with soap according to this method were not observed to have actually washed their face, implying it is still an inaccurate approach.

The observation of facial discharge was also found not to be an accurate measure of whether someone had washed their face, and counterintuitively those in the study who had been observed to wash their face actually had more discharge present than those who did not.

Observed face washing was not found to be associated with the qPHAT assessment either, contradicting findings from another recent study.

Overall, the authors note that the field of trachoma elimination needs measures to determine whether face washing campaigns have changed behaviour, but they cannot recommend self-reported surveys and pictorial recall as accurate measures of face washing based on this study. Furthermore, other facial cleanliness metrics warrant more research to discover how useful they can be.

Publication

Greenland K, Collin C, Sinba Etu E, Guye M, Hika D, Macleod D, et al. Comparison of metrics for assessing face washing behaviour for trachoma control. PLoS Negl Trop Dis. August 2024. https://doi.org/10.1371/journal.pntd.0012399