Results of the search
The initial electronic searches generated 335 citations and abstracts. These were independently screened by two authors and the full texts of 11 potentially relevant articles were retrieved. Two authors again independently assessed these articles. Many of these articles were observational studies, reviews and overviews of studies or journal editorials. We considered three trials for inclusion Emerson 1999; Resnikoff 1995; Sutter 1983). A third author resolved any disagreements in the selection of the three studies. Of the three studies, we excluded one study (Sutter 1983) after contacting the investigators as it was confirmed to be an observational study. One other ongoing study (Emerson 2004) was finally published and after assessment we included it. Thus three studies were included in the original published version of this review (Emerson 1999; Emerson 2004; Resnikoff 1995).
Updated searches 2006/2007
Updated searches were done in November 2006 and July 2007. For the 2006 search the Trials Search Co-ordinator (TSC) scanned the search results (a total of 80 reports) and removed any references which were not relevant to the scope of the review. Nineteen reports were identified for potential inclusion in the review and the abstracts of these articles were assessed independently by two authors. One new trial West 2006 met the inclusion criteria and was included in the review. The 2007 search identified 19 new reports of studies but none met the inclusion criteria for the review.
Updated searches 2011
Updated searches were conducted on 23 September 2011. After deduplication the searches identified a total of 148 references. The TSC scanned the search results and removed 80 references which were not relevant to the scope of the review. We assessed 68 references which were made up of 13 abstracts from clinical trial registers and 55 abstracts from journals. These abstracts were independently assessed by two authors. We obtained full text copies of two studies and have included them in the review (Abdou 2010; Stoller 2011). The remaining 53 references did not meet the inclusion criteria for the review.
See the 'Characteristics of included studies' table for further details of the six included studies.
Setting and participants
Resnikoff 1995 was a cluster-randomised study conducted in the Oulessebougou district of Mali. A total of 1810 people of all ages in four villages were randomised into three intervention groups and one control group. Of these, 1334 people in three villages were assigned to different intervention groups and 476 people in one village were assigned to the control group.
Emerson 1999 was a community based cluster- (quasi) randomised study conducted in Sangal area of The Gambia. A total of 1134 people of all ages in four villages (clusters) were allocated to intervention (insecticide spray for fly control) or control (no intervention) in sets of two villages for wet and dry seasons. Two villages with a population of 588 people received insecticide spray, while the remaining two villages with a population of 546 people did not receive any intervention.
Emerson 2004 was a community based cluster-randomised controlled trial conducted in the North Bank and Central River division of The Gambia. A total of 7080 people (aged four months and older) in 21 clusters (one or more close neighbouring rural communities) were randomised in sets of three clusters to receive insecticide spray, latrines or control. As such, all the seasons in the study area were covered in seven stages. Seven clusters, with a total of 2244 people, received insecticide spray, seven other clusters, with a population of 2230, received latrines; while the remaining seven clusters, with a population of 2606, received no intervention.
West 2006 was a community based randomised controlled trial undertaken in Kongwa Tanzania in which 302 children one to seven years old in 16 Balozi (clusters) were randomised in two years. Each year eight Balozi were randomised into four intervention and four control clusters. In total 119 children in eight intervention Balozi and 183 children in eight control Balozi were enrolled. The households in the intervention clusters were sprayed with insecticide throughout the year, while the households in the control Balozi did not receive any intervention. At baseline all residents of both intervention and control Balozi were treated with one dose of azithromycin.
Abdou 2010 was a community based cluster-randomised study in Maradi district of Niger in West Africa. A total of 557 children aged one to five years old in 12 villages were randomised into six villages for intervention and six villages as control, although data were only collected on 10 of these villages. The intervention villages had at least one clean water well constructed and a three month modest health education programme was executed three months prior to the two year survey. The control villages had no well constructed and no specific health education programmes. But villages in both arms of the study had access to the regular trachoma radio messages.
Stoller 2011 was a cluster-randomised trial in Ethiopia investigating the effects of intensive latrine promotion on emergence of infection with ocular C. trachomatis after mass treatment with antibiotics. A total of 24 communities were included in the study and followed up for 24 months. The construction of a simple pit latrine by participating households using locally available materials was currently in progress in the study area; in the intervention villages health workers and additional sanitation volunteers intensified the promotion and provided free latrine slabs and training on the construction of the latrine.
In Resnikoff 1995, people in each intervention village were assigned to antibiotics and health education, health education alone, or antibiotics alone. They were compared with people from the control village who did not receive any intervention. We were interested specifically in the comparisons between health education alone versus no intervention. The health education programme was based on community participation and consisted of repeated information concerning personal and family hygiene, including household sanitation. The information also concerned trachoma and its complications as well as elements of primary health care. The programme was specifically directed towards women and school children. Posters and booklets were specially designed for this. The programme was conducted at a frequency of one week per month for the six-month period of the survey.
In Emerson 1999, the insecticide spray villages had 0.175% volume to volume deltamethrin applied by ultra-low-volume application within and up to 20 metres outside each village. The spray consisted of an attack phase of spraying every two days for two weeks followed by a maintenance phase of spraying twice weekly in the wet season and once weekly in the dry season.
In Emerson 2004, the insecticide spray clusters had space spraying with permethrin for six months. The spray was based on an attack phase of spraying every two days for two weeks to kill the adult fly population followed by a maintenance phase of spraying twice a week. The clusters assigned to latrine provision had Gambian improved household pit latrines (non-ventilated). One latrine was allocated per household or 20 people, whichever allowed the most latrines. Latrines were located less than six metres from the households. The control clusters did not receive any intervention.
In West 2006, in each intervention Balozi (neighbourhood), a solution of 10% permethrin in water was sprayed inside houses, compounds, cattle pens, around yards, latrines and in between houses using a sprayer machine. The spraying was commenced with an attack phase of spraying every two days for two weeks and then a maintenance of once per week for the rest of the study period.
In Abdou 2010 the intervention villages had at least one hand pump well constructed (range of one to three wells) over the two year period. However, all villages at the start of the trial were not far from the source of water but it was not easily portable. The new wells provided much safer water than the existing ones.
The health education programme was implemented three months prior to the two year survey. A male village health worker was given the role of health educator; and provided a two day training programme on the spread of trachoma through lack of hygiene and flies. The health worker used flip charts and interactive discussions in one or two village meetings to highlight the importance of using portable water, latrines, environmental sanitation, garbage control and washing faces to minimise trachoma transmission.
In Stoller 2011 the construction of a simple pit latrine by participating households using locally available materials was currently in progress in the study area; in the intervention villages health workers and additional sanitation volunteers intensified the promotion and provided free latrine slabs and training on the construction of the latrine.
In Resnikoff 1995, outcome was assessed in the study as incidence of active trachoma determined by the cumulative number of new cases of active trachoma within the six-month study period. Active trachoma was defined using the Thylefors (1987) grading scheme. Incidence as an outcome was not in our protocol but post-hoc we realised that it could be a valuable outcome in assessing impact of trachoma intervention programmes.
In Emerson 1999, outcome measures recorded in the study included prevalence of active trachoma, fly density measures (fly-eye contact, fly population) and adverse effects of insecticides. Active trachoma was graded using the WHO (Thylefors) simplified grading scheme. Fly-eye contact was measured only in the dry season by hand-net collection of flies that touched the eyes of 10 seated children for 15 minutes, measured fortnightly. Fly population was measured by determining the number of flies caught by four fish-baited traps placed in each village at an animal-tethering area, in a latrine, at the centre of a domestic compound and at the main meeting point, measured for 24 hours every two weeks. How adverse effects of insecticides were determined was not stated.
In Emerson 2004, outcome measures included prevalence of active trachoma, fly-eye contact (a measure of fly density) and latrine utilisation. Active trachoma was defined by using the Thylefors (1987) simplified grading scheme. Fly density was determined by measuring the number of flies making contact with the eyes of volunteer children of less than five years i.e. fly-eye contact. This was achieved by catching all the flies making contact with the eyes of the children using eight hand nets. Contact with the eyes was defined as flies touching the eye, lid margins or lashes. The fly catch was done once every two weeks in each cluster. The catch was done on the same days, same time and locations for each cluster. Latrine utilisation was determined by visual inspection once a week for the first month and once a month thereafter. The inspection involved monitoring presence of adequate screening, faeces in the pit, flies around the latrine slab and a path worn to the latrine.
In West 2006, outcome measures were prevalence of active trachoma in children under eight years at baseline, six months and one year after mass antibiotic treatment, infection prevalence rates, fly count in each Balozi. Active trachoma was defined by using the Thylefors (1987) WHO simplified grading scheme. Infection prevalence rates referred to presence of Chlamydia trachomatis from an ocular swab as measured with a qualitative polymerase chain reaction (PCR) assay. While the fly count was mean number of flies captured per day in the intervention versus the control Balozi. The flies were captured by two fly paper strips placed in every Balozi at the same spot every week over the course of the year.
In Abdou 2010, outcome measures used were prevalence of active trachoma (presence of TF and or TI) and infection rates from a randomly selected sample of one to five year olds at baseline, one year and two year periods. Active trachoma was graded by assessing both eyes using the WHO simplified grading scheme (Thylefors 1987), while infection rate was assessed by taking a right eye swab using Dacron swab and analysing for Chlamydia trachomatis using Amplicor qualitative PCR. Infection was defined as a positive laboratory result.
In Stoller 2011 the main outcome measures were ocular C. trachomatis infection and active trachoma in children aged 0 to 9 years. Household latrine coverage and use were also estimated.