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Study Title and Description

Effect of fly control on trachoma and diarrhoea



Key Questions Addressed
1 What is the effect of environmental sanitary interventions for preventing active trachoma?
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Primary Publication Information
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TitleData
Title Effect of fly control on trachoma and diarrhoea
Author Emerson PM, Lindsay SW, Walraven GE, Faal H, Bogh C, Lowe K, et al
Country
Year 1999
Numbers

Secondary Publication Information
There are currently no secondary publications defined for this study.


Extraction Form: Environmental sanitary interventions for preventing active trachoma 2012
Arms
Number Title Description Comments
1 Fly control interventions Insecticide spray with 0.175% deltamethrin
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2 No intervention
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Design Details
Question... Follow Up Answer Follow-up Answer
Page 1401-3
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Methods Quasi-randomisation of 4 villagesLosses to follow up was 18%, but not similar in the study groupsOutcome assessor was masked
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Interventions 1. Insecticide spray (588 people in 2 villages) versus no intervention (546 people in 2 villages) for 3 monthsInsecticide spray with 0.175% deltamethrin
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Outcomes Prevalence of trachoma, fly-eye contact, fly population
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Notes
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Participants 1134 people of all ages in 4 villages in The Gambia
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Recruitment bias:Authors' judgement Low risk
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Recruitment bias:Support for judgement "1124 people of all ages were screened for trachoma at baseline, of whom 924 (82%) were also screened at 3 months. Loss to follow-up, mainly owing to inclusion of temporary migrants in the baseline data, was similar for intervention and control groups (rate ratio for intervention v s control 1·13 [0·83–1·54])." Results, page 1402
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Baseline imbalance:Authors' judgement Unclear risk
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Baseline imbalance:Support for judgement Although there was some evidence to suggest that the villages were similar (see quotes below) only 4 villages were randomised "arbitrarily" so other differences in other important confounders cannot be excluded "Village communities were of similar size, age composition(table), and ethnicity (Wolof)". Results, page 1402 "Data on trachoma prevalence (figure) shows that there was no difference in the community prevalence of active trachoma at baseline in either village pair (wet season intervention 26/295 [8·8%] v s control 33/271 [12·2%]; dry season 34/189 [18·0] v s 27/169 [16·0])." Results, page 1402
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Blinding of participants and personnel (performance bias)Active trachoma:Authors' judgement High risk
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Blinding of participants and personnel (performance bias)Active trachoma:Support for judgement Community based interventions like spray of insecticide in the villages cannot be masked from the villagers
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Blinding of participants and personnel (performance bias)Other outcomes:Authors' judgement High risk
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Blinding of participants and personnel (performance bias)Other outcomes:Support for judgement Community based interventions like spray of insecticide in the villages cannot be masked from the villagers
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Blinding of outcome assessment (detection bias)Active trachoma:Authors' judgement Unclear risk
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Blinding of outcome assessment (detection bias)Active trachoma:Support for judgement "The whole of each village community was screened for trachoma at baseline and at 3 months by the same community ophthalmic nurse, who was unaware of the treatment status of each village." Methods, page 1401 Although the assessor did not know the status of the villages with respect to interventions, the assessor may have heard the status of villages from the people and may have noticed the fly traps set in the villages
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Blinding of outcome assessment (detection bias)Other outcomes:Authors' judgement High risk
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Blinding of outcome assessment (detection bias)Other outcomes:Support for judgement Fly related outcome measures: "Fly populations were monitored 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 for 24 h every 2 weeks. To measure fly-eye contact in the dry season, hand-net collections of eye-seeking flies were made fortnightly from ten seated children for 15 min. Flies that touched the children's eyes were collected and taken to the laboratory for identification". Methods, page 1401 No mention of blinding for this outcome
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Incomplete outcome data (attrition bias):Authors' judgement Unclear risk
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Incomplete outcome data (attrition bias):Support for judgement % with ocular examination at follow-up varied in the different villages. Wet season control village 85%, wet season intervention village 77%; dry season control village 91%, dry season intervention village 74%. This was attributed to temporary migrants being examined at baseline
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Selective reporting (reporting bias):Authors' judgement Low risk
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Selective reporting (reporting bias):Support for judgement The study reported active trachoma but did not report ocular infection, however, the study report did not give any indication that data on ocular infection was recorded. The focus of the report was entomological
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Study design Cluster Quasi-randomized trial
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Unit of analysis Village
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Number randomly assigned Villages: 2; Individuals: 1134; Intervention: 588 people in 2 villages; No intervention: 546 people in 2 villages
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Losses to follow-up Total: 18%, but not similar in the study groups
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Number analyzed Percent with outcome assessed varied across villages: wet season control village 85%, wet season intervention village 77%, dry season control village 91%, dry season intervention village 74%
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Country Gambia
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Age of participants All ages
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Equivalence of baseline characteristics Village communities were of similar size, age composition, and ethnicity. There was no difference in the community prevalence of active trachoma at baseline in either village.
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Intervention 1 Insecticide spray with 0.175% deltamethrin
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Intervention 2 No insecticide spray
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Length of follow up 3 months
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Primary outcome, as defined in study report Prevalence of eye trachoma
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Secondary outcome(s), as defined in study report Fly-eye contact, fly population
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Times at which outcome(s) are assessed Every 2-weeks
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Intervention 3
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Results & Comparisons


Results Data
Outcome: Number of participants with TF or TI      Population: All Participants
Time Point Measure Fly control interventions No intervention


3 months

N Analyzed
Mean 6.2% 15.7%
SD
SE
Outcome: Fly density      Population: All Participants Between-Arm Comparisons
Time Point Measure Fly control interventions No intervention Comparison Measure Fly control interventions vs. No intervention


3 months

N Analyzed Percent fewer flies caught in eyes of children 96%
Mean
SD
SE
Outcome: Fly density      Population: All Participants Between-Arm Comparisons
Time Point Measure Fly control interventions No intervention Comparison Measure Fly control interventions vs. No intervention


3 months

N Analyzed Percent fewer Musca sorbens flies 75.5%
Mean Percent fewer Musca dormestica flies 64%
SD
SE

Adverse Events
Arm or Total Title Description Comments
Fly control interventions Adverse effects of insecticides "No adverse effects." Not clear how this conclusion was reached.
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No intervention
Total