/diseases/surveys/filter-options

Returns **distinct filter values** for building survey filter UIs, aligned with **`GET /diseases/surveys/filter`**. Pass the same optional query parameters to reflect the current filter context. With **no** parameters, the server uses a faster path over the full survey set. With **any** parameter present, each facet’s options are computed so that dimension is not over-constrained by its own filter (you can still narrow other dimensions). - **`regions`** — Populated only when **`country`** is supplied and matching surveys include subdivision-level geography; each item has `region_id` and `region_name`. - **`survey_size`** — Buckets that actually appear in the filtered data; `size` is a display label (some ranges use comma formatting), `size_id` is what you pass as `size` on the filter endpoint. - **`years`** — `survey_start_years` merges distinct start years with publication years; `survey_end_years` uses end year or start when end is missing. #### **Query parameters** | Name | Description | | --- | --- | | `disease` | Disease id; limits options to surveys for that disease. | | `country` | GIDEON country code; enables populated `regions` when subdivision-level data exists. | | `survey_start_year` | Minimum survey start year; influences `years.survey_start_years`. | | `survey_end_year` | Maximum survey end year (uses start year when a survey has no end year). | | `test_type` | Substring match on test-type labels. | | `pathogen` | Substring match on pathogen labels. | | `population` | Survey population group id. | | `region` | Subdivision (state) code. | | `type` | `Prevalence` or `Seroprevalence`. | | `percentRange` | Primary percent filter; same syntax as `GET /diseases/surveys/filter`. | | `size` | Survey size bucket; use a `size_id` value from `survey_size` in the response. | #### **Response** `data` is an object with: `diseases`, `countries`, `populations`, `test_types`, `pathogens`, `regions`, `survey_types`, `survey_size`, `years`. The saved example trims each facet; live responses are larger.