Table 3. Association structure assumed by relative risk models fitted to department- and city-level dengue and Zika data for the 2015–2016 Zika virus disease outbreak, Colombia.

Model no.	Spatially structured association between dengue and Zika high-risk areas	Joint association between dengue and Zika high-risk areas
1	No	No
2	No	Yes, linear
3	Yes	No
4	Yes	Yes, linear
5	No	Spatially structured shared component
6	Yes	Spatially structured shared component
7	Yes	Zika risk conditioned by dengue risk
8	Yes	Dengue risk conditioned by Zika risk