| Agent category | Infectious agent | Geographic distribution of determinant | Locations where determinant reported | Die-off attributed to determinant1 | Selected references |
| Parasite | Psoroptes spp. | Range-wide | Arizona | Yes | [143] | | | | California | Yes | [28] | | | | Colorado | Yes | [27, 157] | | | | Montana | Yes | [130] | | | | Nevada | Yes | [130] | | | | New Mexico | Yes | [139, 158–161] | | | | Oregon | Yes | [109, 140] | | | | Texas | Yes | [110] | | | | Washington | Yes | [140] | | | | Wyoming | Yes | [118, 130, 131, 141, 162] | | Lungworm (Protostrongylus) | Range-wide in mesic habitats | Alberta, Canada | Yes | [163] | | | | California | No | [164] | | | | Colorado | No | [27] | | | | Colorado | Yes | [146, 165] | | | | Montana | Yes | [113, 166] | | | | Montana | No | [148, 167] | | | | Nevada | No | [168] | | | | Oregon | No | [149] | | | | Utah | No | [169] | | | | Wyoming | Unclear2 | [118, 122, 170] | | Lungworm (Muellerius capillaris) | Localized | Montana | No | [128] | | | | South Dakota | No | [171] |
| Bacteria | Pasteurellaceae | Range-wide | Alberta | Yes | [151] | | | | Arizona | No | [172] | | | | California | No | [164] | | | | Colorado | No | [27] | | | | Colorado | Yes | [19] | | | | Hells Canyon (Washington, Idaho) | Yes | [18, 152, 173] | | | | Idaho | No | [174] | | | | Montana | Yes | [17] | | | | Montana | No | [128] | | | | Nevada | No (endemic) | [175] | | | | Oregon | Yes | [176, 177] | | | | Wyoming | Yes | [43] | | Arcanobacterium (Corynebacterium) | Presumed range-wide | Colorado | Yes | [157] | | pyogenes | | Montana | Yes | [113, 166] | | Mycoplasma | Uncertain | Arizona | Yes | [178] | | | | Hells Canyon | Yes | [18, 179] | | Chlamydophila (Chlamydia) Psittaci | Uncertain | Wyoming | Yes | [180] |
| Virus | PI33, RSV4 | Presumed range-wide | British Columbia, Canada | No | [181] | | PI3, BRSV4 | Presumed range-wide | Hell’s Canyon | Yes | [18] | | PI33, BRSV4, BVD5, IBR6 | Presumed range-wide | Montana | Yes (some populations) | [17] | | PI33, RSV4, BVD5, IBR6, OPP7, BT8, EHD9 | Presumed range-wide | California | No | [164, 182, 183] | | PI33, BVD5, BT8, parvo virus | Presumed range-wide | Colorado and Wyoming | No | [184] | | RSV4 | Presumed range-wide | Arizona, California, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington | No | [185] | | | | Colorado | No | [186] | | BRSV4, BT8, EHD9, CE10 | Presumed range-wide | Arizona | No (EHD and BT isolated from 2 mortalities) | [60, 187] | | BT8 | Presumed range-wide | Trans-Pecos, Texas | No | [188] | | CE10 | Presumed range-wide | Alberta, British Columbia, Canada | No (high morbidity, but low mortality) | [189, 190] |
|
|