It has been wonderful to see the closer alignment between water, sanitation and hygiene (WASH) and NTDs including trachoma that has been building over the last few years. This has long been an area that needed more attention. So much of the trachoma work to date has focused on delivering antibiotics despite all the evidence that this approach on its own is not enough to eliminate trachoma. However, while the close linkages with the WASH sector should be strongly endorsed and applauded, greater agreement on what is meant by the environmental improvement element of our intervention strategy is needed.
Environmental improvement is one of the four elements of the SAFE strategy, the WHO-endorsed approach for eliminating trachoma. WHO’s guidelines on the SAFE strategy published in 2000, Preventing trachoma - a guide for environmental sanitation and improved hygiene, identified fly control as playing a role in reducing the transmission of the disease. With this, environmental improvement is taken to include a need to build pit latrines and end open defecation to control and reduce fly populations.
This link between fly control and environmental improvement persists in current thinking about WASH and trachoma. Flies are still often seen as the central cause or source of trachoma transmission. However, I believe that flies play a minor role and, in some areas, play no role at all.
Flies cannot be seen as the central means of transmission and their role is at best ancillary
There is no doubt that trachoma occurs in areas where there are lots of flies but it is also critically important to remember that severe blinding trachoma also occurs in areas in which flies are essentially absent. A classic example is southern Mexico where some of the first studies on facial cleanliness were conducted and flies were found to be totally absent. Equally, flies seemed to have played a very minor role in trachoma transmission in northern Europe a century ago.
Flies are attracted to dirty faces and in some circumstances they have been shown to transmit eye secretions. However, flies cannot be seen as the central means of transmission and their role is at best ancillary. Ending open defecation is important, no one would argue against that, but linking the lack of household pit latrines with trachoma transmission, as was done in a study in Tanzania, is equivalent to making a link between houses having a tin roof or families holding traditional religious beliefs with trachoma prevalence. A pit latrine is a marker of general family hygiene and economic status, not a specific risk factor for trachoma.
Environmental improvement should focus on ensuring that water is available for people to wash their faces. As infection is predominantly spread by the direct transfer of secretions from infected eyes, ensuring clean faces is the key to stopping transmission of the disease.
Quite simply, faces just need to be washed whenever they are dirty
Another area of concern relates to messaging around different positions on how often faces need to be washed. Stipulating how often faces need to be washed, once a day for example, is not the right approach as, quite simply, faces just need to be washed whenever they are dirty. If a face is not clean it does not matter whether it is washed previously or not because, if it is dirty, it needs to be washed then and there. Clean faces are essential to stop the transmission of trachoma. To ensure a consistent approach, consistent messaging must be developed around important questions like these.