Niger is on the WHO list of areas endemic with trachoma, and this survey confirms that designation. The prevalence of trachoma in the villages was high, an average of 43% in children aged 1–5 years. This rate is similar to rates from neighbouring Mali, where 50% of pre‐school children had trachoma.2
Infection was also high (21%) and linked to clinical signs. The association of infection with clinical trachoma was similar to that observed in other studies, with the highest rates in children with trachoma intense.4,5,6,7,8,9,10,11,12,13
The difference by age in the association of infection with clinical signs was interesting, as the youngest children were almost half as likely to have infection with follicular trachoma and trachoma intense compared with those aged 3–5 years. This finding was also reported by Bird et al
The youngest children may have a longer period of clinical signs without infection, compared with the older children. Bailey et al14
reported that the duration of trachoma in adults is shorter than in children, and although they examined wider age ranges, our finding suggests that the phenomenon may start at a very young age in hyperendemic areas. Children aged 3–5 years are likely to have experienced more previous episodes of infection compared with children aged 1–2 years, which may improve their ability to clear the clinical signs. Longitudinal studies of disease duration and infection would confirm this cross‐sectional finding.
The variability of rates between villages in the same district is similar to variation in trachoma and infection in other settings.13,15,16
In one village, the level of trachoma and infection was below the WHO threshold for mass treatment.17
This village was very different from the others, as it was small, had no village centre and the compounds were widely dispersed among fields. Thus, the opportunity to spread infection was limited. In addition, a different ethnic group lived in this village compared with the other villages. The two villages with high trachoma rates but low infection rates are puzzling. There were no differences in collection, storage or handling of specimens for these two villages, and trachoma was assessed by different graders, suggesting that study procedures were an unlikely explanation. The variability among the villages should also be considered in the context of sampling villages within a certain size range. Even more variability may be observed if smaller or larger villages were included in these prevalence estimates. However, we found no effect of population size on estimates of trachoma or infection.
In general, risk factors for trachoma and for infection with ocular chlamydia were similar, as might be expected. Those with trachoma and infection were more likely to be aged 3–5 years, compared with 1–2‐year‐olds. The 3–5‐year‐olds are often sent off with older siblings and other children, whereas the 1–2‐year‐olds are kept close to the mother, until she has another child. Thus, the 1–2‐year‐olds are less likely to be infected by exposure to other children. No difference by sex was found in this study, similar to findings from Mali and Senegal.18,19
Sex differences seem to be more common in east Africa, as reported in Tanzania and Ethiopia.15,20
An unclean face was the most important personal characteristic associated with trachoma and infection. Children whose faces were clean, but who had flies on the face, were more likely to have trachoma compared with children with clean faces and no flies, but there was no association of facial flies with infection. In light of the observation that eye‐seeking flies carry C trachomatis
we expected an association of facial flies with infection. However, the dose of chlamydia imparted by a fly may be insufficient to establish an infection, but may be capable of eliciting the inflammatory response of clinical trachoma, which would be compatible with this observation. Although several other studies have found flies related to active trachoma in children,22,23,24,25
only one study evaluated flies and the risk of infection, as measured using a direct fluorescent antibody test.26
We found a positive association between infection and flies around the house, but flies on the face were not measured.
Children with an unclean face (with or without flies) were threefold more likely to have trachoma and to have infection, compared with those with clean faces. This finding is similar to many other studies, where unclean faces are a risk for trachoma, and face washing is protective.22,24,27,28
These findings further support the association, and argue for the need for education on hygiene in these villages. As most of the households had access to a water source, and did not have a long distance to travel for water, a strong health communication message about clean faces will not have to labour under unavailability of water for washing. This would make it ideal to further evaluate the effect of health education on trachoma and infection.
The absence of an association of trachoma or infection with distance to water is similar to that found in The Gambia.29
In our population, as people were sufficiently close to water sources, the relationship of increased trachoma with increasing distance to water, as was seen for example in Tanzania,22
could not be observed.
The household characteristic primarily associated with trachoma was increasing number of children aged 1–5 years in the compound, or crowding. Transmission under such conditions is understandable, and has also been found in other studies.15,22,30
Notably, the risk seems to be most pronounced once there are more than three children, with no added risk beyond six children. Moalic et al18
did not find a relationship with sibship size in Senegal, but did not study the size of the compound, but rather only studied the number of children per mother.
There were limitations to our study that might affect the conclusions. Firstly, we limited the size of the villages that were eligible to be included in our survey; most of the villages in Kornaka West either did not have census information, or were smaller than our minimum sample of 600 people. Thus, prevalence rates may be higher or lower for this area as a whole, depending on the prevalences in villages larger or smaller than our sample. Secondly, although we attempted to conduct a census on all compounds in the village, we probably missed compounds that the village leadership did not choose or did not know to tell us about. The fact that the census was always less than that observed in 1995 suggests that some compounds may have been missed. On the other hand, the severe famine and mortality/household movement associated with it can also explain this difference, as Maradi was the epicentre of that disaster. As the 2005 census is not available, we cannot check our counts against the latest government figures. Secondly, we observed the children at the time of the ocular examination, although we tried to mitigate the effect of “washing for visitors” by not using the trachoma grader (seen as the senior team member) as the observer. The fact that more than half the children had unclean faces suggested that our efforts were at least partially successful, although the true rate of unclean faces may be even higher. Thirdly, there were so few compounds with latrines (4%) that the “observation” of latrines may reflect insistence by the head of the compound that one existed rather than a true observation. The absence of a difference by latrine status with trachoma or infection, contrary to what others have found,22,31
suggests that misclassification may be an issue.
In summary, efforts to improve cleanliness of faces in this environment may have a strong effect on trachoma and infection with C trachomatis
. Hsieh et al27
found that improved facial cleanliness over a 6‐year period was associated with a decline in trachoma at follow‐up,27
and a clinical trial of hygiene intervention resulted in less severe trachoma in children who had sustainable clean faces.32
Thus, this area of Niger should consider a health communication programme directed at improving hygiene behaviours. Such a programme could take advantage of the village and women's associations as communication networks because these are relatively common.