Table 2.

Numbers of publications that reported specific factors as influential for occurrence of Rift Valley fever.

Factor	Number of reports	Epidemic or endemic?	Geographic data coverage available?
Climatic factors:
Higher rain than normal/floods	17	Epidemic	Indirectly
Annual rainfall	10	Both	Yes
Vegetation/NDVI	6	Both	Yes
Length and timing of rain	4	Epidemic	Indirectly
Temperature	3	Both	Yes
Hydrological factors:
Proximity to lake/dam	6	Both	Yes
Irrigation	6	Both	No
Dambos/accumulated water	5	Epidemic	Indirectly
Proximity to river	3	Both	Yes
Topographic factors:
Land-cover type	4	Both	Yes
Low-lying elevation	3	Both	Yes
Ecological zone	3	Both	Yes
Host and vector factors:
Human factors	10	Epidemic	No
Vector abundance	7	Both	No
Importing infected animals	6	Epidemic	No
Moving livestock to endemic focus	4	Epidemic	No
Breed and other livestock factors	4	Both	No
Sheep present	2	Epidemic	Indirectly
Livestock density	1	Both	Yes
Natural hosts/small mammals	1	Both	No

Data were obtained via a systematic review of the literature. The availability of geographical information system-compatible electronic data for each variable was determined by a wide source of potential sources, including the internet.