Effect of Intensive Fly Control on Trachoma and Ocular Chlamydia Infection in Tanzania
Condition: Trachoma
MeSH terms: Trachoma
Study type: Interventional
Phase: Phase 4

Summary: 
      The purpose of this community-based randomized trial was to determine, in trachoma
      hyper-endemic communities of Tanzania, the added value of intensive spraying to control flies
      on the fly population and on trachoma and ocular chlamydia infection at 6 months and one year
      after mass antibiotic treatment.
    

Detailed description: 
      Trachoma is the leading infectious cause of blindness in the world. The World Health
      Organization (WHO), recognizing the important public health impact of trachoma, has adopted a
      resolution to eliminate blinding trachoma by the year 2020 (3). In order to accomplish this
      ambitious goal, WHO recommends the use of "SAFE" strategy for countries implementing trachoma
      control programs. This multi-faceted approach includes Surgery for trichiasis cases,
      Antibiotics to treat the community pool of infection, Face washing to reduce transmission,
      and Environmental change.

      The environmental change component currently rests largely on efforts to reduce the fly
      populations in these communities. A pilot study and clinical trial using intense insecticide
      spraying reduced both flies and trachoma in a trachoma hypo-endemic area of The Gambia. In
      The Gambia setting, flies appear to be an important vector for trachoma, but it is not clear
      that flies are equally important in areas with hyper-endemic trachoma, nor is it known if fly
      control adds value to the provision of mass antibiotic treatment for active trachoma as part
      of the SAFE strategy.

      The purpose of this community-based randomized trial was to determine, in trachoma
      hyper-endemic communities of Tanzania, the added value of intensive spraying to control flies
      on the fly population and on trachoma and ocular C. trachomatis infection at 6 months and one
      year after mass antibiotic treatment. Neighborhoods with intensive spraying (Intervention)
      and neighborhoods with no spraying (control) all received mass antibiotic treatment with
      azithromycin immediately prior to the start of the study, enabling us to evaluate the
      additional impact of fly control on trachoma.

      Kongwa district in central Tanzania has been shown to have a high prevalence of active
      trachoma, and was chosen as the site of this study. We randomized sixteen balozi to receive
      either mass treatment with azithromycin alone (control), or mass treatment plus an intensive
      fly spraying program (intervention). Pre-school aged children are the reservoirs of infection
      and disease within these communities. Therefore, within each balozi, all children aged less
      than eight served as sentinel markers for the status of trachoma at baseline, 6 months, and
      one year after baseline. In the eight intervention balozi, 119 children from 87 families were
      enrolled at baseline, and in the eight control balozi, 183 children from 145 families were
      enrolled.

      The balozis were surveyed and an area surrounding the intervention balozis was targeted for
      insecticide spray. A solution of 10% permethrin in water was used with a Hudson and MicronAir
      sprayer machines, At the outset, spraying was carried out every two days for two weeks
      (attack phase) then once per week (maintenance phase) for the rest of the study.

      Two sticky traps, fly paper strips were placed in each balozi to capture flies. The traps
      were changed every week, and the number of flies captured were counted. If the average number
      in the intervention balozis exceeded 25% of that in the control balozis, an attack phase, as
      described above, was reinstituted to keep the fly population low in the intervention group.

      The primary outcome was the prevalence of trachoma in the pre-school aged children at 6
      months and one year post mass antibiotic treatment.Outcomes are reported based on masked
      photographic gradings. Secondary outcome was ocular C. trachomatis infection, based on use of
      Amplicor C. trachomatis qualitative PCR assay.

      comparison: Balozi randomized to receive intensive fly spray intervention,compared to Balozi
      with no fly spray intervention
    

Intervention name(s): 10% permethrin in water applied as low volume spray
Intervention type(s): Procedure
Intervention MeSH terms: Permethrin
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Prevention
Keywords: trachoma; chlamydia; flies; permethrin