Table 1. Categorization of potential factors influencing pre-TAS results.

Domain	Factor	Covariate	Description	Reference Group	Summary statistic	Temporal Resolution	Source
Prevalence	Baseline prevalence	5% cut off	Maximum reported mapping or baseline sentinel site prevalence	<5%	Maximum	Varies	Programmatic data
Prevalence	Baseline prevalence	10% cut off	Maximum reported mapping or baseline sentinel site prevalence	<10%	Maximum	Varies	Programmatic data
Agent	Parasite	Parasite	Predominate parasite in district	W. bancrofti & mixed	Binary value	2018	Programmatic data
Environment	Vector	Vector	Predominate vector in district	Anopheles & Mansonia	Binary value	2018	Country expert
Environment	Geography	Elevation	Elevation measured in meters	>350	Mean	2000	CGIAR-CSI SRTM [9]
Environment	Geography	District area	Area measured in km2	>2,500	Maximum sum	Static	Programmatic data
Environment	Climate	EVI	Enhanced vegetation index	> 0.3	Mean	2015	MODIS [10]
Environment	Climate	Rainfall	Annual rainfall measured in mm	≤ 700	Mean	2015	CHIRPS [11]
Environment	Socio-economic	Population density	Number of people per km2	≤ 100	Mean	2015	WorldPop [12]
Environment	Socio-economic	Nighttime lights	Nighttime light index from 0 to 63	>1.5	Mean	2015	VIIRS [13]
Environment	Co-endemicity	Co-endemic for onchocerciasis	Part or all of district is also endemic for onchocerciases	Non-endemic	Binary value	2018	Programmatic data
MDA	Drug efficacy	Drug package	DEC-ALB or IVM-ALB	DEC-ALB	Binary value	2018	Programmatic data
MDA	Implementation of MDA	Coverage	Median MDA coverage for last 5 rounds	≥ 65%	Median	Varies	Programmatic data
MDA	Implementation of MDA	Sufficient rounds	Number of rounds of sufficient (≥ 65% coverage) in last 5 years	≥ 3	Count	Varies	Programmatic data
MDA	Implementation of MDA	Number of rounds	Maximum number of recorded rounds of MDA	≥ 6	Maximum	Varies	Programmatic data
Pre-TAS implementation	Quality of survey	Diagnostic method	Using Mf or Ag	Mf	Binary value	Varies	Programmatic data
Pre-TAS implementation	Quality of survey	Diagnostic test	Using Mf, ICT, or FTS	Mf	Categorical	Varies	Programmatic data

EVI = enhanced vegetation index; MDA = mass drug administration; TAS = transmission assessment survey; DEC = diethylcarbamazine; ALB = albendazole; IVM = ivermectin; Mf = microfilaremia; Ag = antigenemia; FTS = Filariasis Test Strips; ICT = Immunochromatographic Card Test