Data will be extracted onto an Excel spreadsheet containing relevant information for the objective of the systematic review (see data items below). This will be performed by two independent reviewers, and any disagreements will be resolved by a third reviewer. When data will not be available (or unclear) in the manuscripts, the authors of the studies may be contacted for clarification.
Data curation
Prior to data extraction per se, a reference manager software (EndNote/Zotero) will be used to manage the retrieval of literature and to screen for and exclude duplicates. This will be done first automatically using the “find duplicate” or “de-duplication” function under EndNote or Zotero, respectively, by comparing the title or various combinations of the author(s), year, secondary title, volume, issue and page numbers. In the second instance, the records of suspected duplicates will be visually inspected.
Data items
After curation of the database, the full texts of the studies adhering to all the above eligibility criteria will be read, and a Microsoft Excel spreadsheet will be used for data extraction. The following items will be extracted: (1) publication title, (2) year of publication, (3) year(s) of data collection, (4) authors’ names, (5) location of the study (region, health district, community), (6) geographical coordinates (latitude and longitude) and altitude, (7) type of environment (forest, savannah, forest-savannah mosaic, type of vegetation), (8) climate data (temperature, precipitation, humidity), (9) river basin and proximity of study location to rivers/vector breeding sites, (10) intervention information (MDA, drug used for MDA, number of treatment rounds, duration of treatment, frequency, time interval between treatment and parasitological assessment, geographic coverage, minimum and maximum therapeutic coverage, treatment adherence, vector control, method for vector control), (11) human sample size, (12) age (and sex) of enrollees (maximal, minimal and median age (for males and females if available)), (13) assessment tool (skin snips for assessment of microfilaridermia with details on type of punch, incubation medium, incubation time, enumeration of microfilariae, weight of snips; nodule palpation; serological assay), (14) nodule data (prevalence, minimum, maximum and mean number of nodules), (15) skin snip data (microfilarial prevalence, minimum, maximum and mean number of microfilariae per skin snip or per milligrams of skin, community microfilarial load (CMFL)), (16) serological data (age groups tested, antigen used, seroprevalence), (17) blackfly data (sample size; biting rate; diagnostic tool for detection of infection in blackflies; number of flies with L1, L2 and L3; number of L3 per fly; minimum, maximum and mean number of L3 in the head/body), (18) vector identification and method (morphotaxonomy, cytotaxonomy, other), vector species composition, vector bionomics, as well as (19) co-endemicity with loiasis.