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Revisiting Brucellosis in the Greater Yellowstone Area (2017)

Chapter: 3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem

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Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
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Page 48
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 49
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 50
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 51
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 52
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 53
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 54
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 55
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 56
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 57
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 58
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 59
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 60
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 61
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 62
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 63
Suggested Citation:"3 Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem." National Academies of Sciences, Engineering, and Medicine. 2017. Revisiting Brucellosis in the Greater Yellowstone Area. Washington, DC: The National Academies Press. doi: 10.17226/24750.
×
Page 64

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3 Eco ology and Epidem d miology of Brucell abortus la s in the Greater Yellowsto Ecosy G Y one ystem 1. REVIEW OF BRUC W CELLOSIS C CASES SINC 1998 CE At th time of the last Nationa Research Council (NRC report in 19 he e al C C) 998, there had been no B. abor- d tus infecte cattle herd detected in the Greater Yellowstone A ed ds Y Area (GYA) f several ye for ears. Between 2002 n and 2016, a total of 22 cattle herds and 5 private , 2 ely-owned bi ison herds we infected (see Figure 3- and ere -1 Table 3-1). These case were distri es ibuted across all three stat in the GY (Idaho, M tes YA Montana, and Wyo- ming) and the number of cases app d r pears to be in ncreasing ove time (Cross et al., 2013 Available field er s 3c). e and molecular epidem miologic informmation on th hese herds sug ggest that elk are the most likely sour of k rce infection in each of the cases (Rhy et al., 201 Kamath e al., 2016). i ese yan 13; et FIGURE 3-1 Number of cattle and domestic bison herds infected w B. abortu in the Greate Yellowstone Area 3 f h with us er e by state fro 1990 to 201 om 16. 48 Prepubli ication Copy— —Subject to F Further Edito orial Revision

TABLE 3-1 Brucellosis Herds Detected in the Greater Yellowstone Area, 2002-2016 State Month Year Herd Type Herd Size County Method of Detection Disposition Trace Out States ID Apr 2002 Beef cattle 50 Fremont Herd test conducted due to culture positive Depopulated ID, NE, WY elk in the area Nov 2005 Beef cattle Unavailable Bonneville MCI trace Depopulated ID, CO, MT, NE, UT, CA Nov 2005 Beef cattle 60 Butte Epidemiologic link to Bonneville herd Depopulated Unavailable Nov 2009 Beef cattle 589 Jefferson Slaughter surveillance Partially depopulated Unavailable Apr 2012 Beef cattle 65 Fremont (outside California slaughter trace Test & Remove ID, UT, AZ, TX of DSA) Mar 2012 Bison 268 Bonneville DSA related test Test & Remove ID MT May 2007 Beef cattle 260 Park (Carbon) Pre-interstate shipment test at a livestock Depopulated MT, MO, SD, MN, NE, ID, KS, auction market. Cow had aborted twice prior CA, WI, CO, TX, IL, WY to sale May 2008 Beef cattle 28 Park Herd tested as part of MT effort to develop Depopulated ND, ID, HI, MT, WY, SD, WA, risk mitigation herd plans near Yellowstone MN National Park Nov 2010 Bison 3,250 Gallatin DSA herd management plan test Test & Remove MT, NE, WY, TX, CO, ID, SD, KS Sep 2011 Beef cattle 275 Park DSA related movement test Test & Remove ID, MN, MT, NE, SD, UT, WA Prepublication Copy—Subject to Further Editorial Revision Nov 2011 Bison 1,550 Madison Trace herd test due to epidemiological link Test & Remove Unavailable to the 2010 bison herd Sep 2013 Beef cattle 1,500 Madison DSA related pre-slaughter test of a Test & Remove CA, CO, IA, KS, MN, MT, NE, SD 2-year-old female Oct 2013 Beef cattle 700 Park Brucellosis certified annual herd test Test & Remove CA, MN, MT, NE, SD, TX Oct 2014 Beef cattle 650 Park/Carbon DSA related movement test Test & Remove Pending Nov 2014 Beef cattle 2,340 Madison DSA related movement test Test & Remove Pending Nov 2016 Bison 178 Beaverhead Voluntary DSA herd test Test & Remove SD, GA WY Nov 2003 Beef cattle 400 Sublette Slaughter Surveillance Depopulated Unavailable Jan 2004 Beef feedlot 800 Washakie Trace herd test due to epidemiologic link Depopulated Unavailable with the 2003 Sublette County herd Jun 2004 Beef cattle 600 Teton Interstate movement test Depopulated SD, TX, MT, KS, NE, WY, CO, ID Nov 2004 Beef cattle 800 Teton Trace herd test, contact with June 2004 Depopulated Unavailable Teton County herd (Continued) 49

50 TABLE 3-1 Continued State Month Year Herd Type Herd Size County Method of Detection Disposition Trace Out States Jun 2008 Beef cattle 800 Sublette First-point test at a WY livestock auction Depopulated WY, NE, CA, CO, SD, MN, ID, market KS, MT Oct 2010 Beef cattle 500 Park DSA related change of ownership testing at a Test & Remove WY, MT WY livestock auction market Nov 2010 Bison 1,067 Park DSA related pre-sale movement testing of Test & Remove MT, WY, CO, NV yearling heifers Feb 2011 Beef cattle 500 Park DSA related movement test at a MT livestock Test & Remove MT auction market, 5-year-old cull cow Jul/Sep 2011 Beef cattle 500 Park DSA related on-farm, pre-sale test of Test & Remove Unavailable 13-month-old heifers Oct 2015 Beef cattle 515 Park DSA herd plan test Test & Remove Unavailable Nov 2015 Beef cattle 717 Sublette DSA herd plan test Test & Remove WY, CO Prepublication Copy—Subject to Further Editorial Revision

Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem 1.1 Idaho Between April 2002 and 2012, four cattle herds and one privately-owned bison herd in Idaho were infected with brucellosis. Idaho lost Class Free status in January 2006, and a brucellosis action plan was created resulting in Class Free status being regained in July 2007. Due to changes to the federal brucello- sis regulations in 2010 relative to the requirements for retention of class-free status, Idaho has maintained Class Free status despite finding three additional affected herds since 2009, including a Fremont County cattle herd that was located outside of Idaho’s designated surveillance area (DSA). No herds remain quar- antined for brucellosis as of March 2016. 1.2 Montana Between May 2007 and November 2016, seven beef cattle herds and three privately owned bison herds were diagnosed with brucellosis in Montana. The infected herds found in 2007 and 2008 were slaughtered with federal indemnity, while all herds identified thereafter have undergone a test and remove protocol under state quarantine. The Montana Department of Livestock developed and implemented a Brucellosis Action Plan in May 2009, and the state successfully regained Class Free status in July 2009. 1.3 Wyoming From 1989 to November 2003, no brucellosis infected herds were identified in Wyoming; but be- tween November 2003 and November 2015, 10 cattle herds and 1 domestic bison herd were infected. Wyoming lost Class Free status in 2004, and the Governor of Wyoming appointed a Wyoming Brucello- sis Coordination Team to develop a Brucellosis Management Plan. The state regained Class Free status in 2006 and subsequently identified six cattle herds and one privately-owned bison herd as infected with B. abortus. 1.4 Impacts Outside the GYA As a result of the disclosure of brucellosis in cattle and privately-owned bison herds, animals that left those herds prior to diagnosis are required to be traced and their disease status investigated. More than 15,000 animals that had left the affected herds were required to be traced, and a number of those animals were found in non-GYA states (see Figure 3-2). The extensive movement of cattle from the DSA has implications for the implementation of the DSA, because it relates to the likelihood of an infected animal moving out of the area as well as the cost of testing to ensure that contact herds remain uninfected. 2. DISEASE DYNAMICS IN BISON AND ELK As noted in the previous NRC report (1998), wild bison in the GYA have a relatively high seroprev- alence of brucellosis. In bison from the National Elk Refuge in Wyoming, the seroprevalence of brucello- sis ranged from 40% to 83% from 2000 to 2008 (mean = 64%, 95% CI = [0.58, 0.69]) (Scurlock and Edwards, 2010). The seroprevalence among adult females is relatively steady over time in YNP at 60%, despite large changes in population size (Hobbs et al., 2015). This suggests that the population size of bison may not be a strong determinant of brucellosis transmission rates in bison (Hobbs et al., 2015). By combining serological data with culture results, active infections are more likely among 2-4 year-old Yellowstone bison. Older bison, while likely to be seropositive, are less likely to be culture positive (Treanor et al., 2011). However, this does not necessarily mean that those animals are not infected. In chronically infected animals, there are often fewer organisms per gram of tissue, making it more difficult to obtain a positive culture. Prepublication Copy—Subject to Further Editorial Revision 51

Revisiting Brucellosis in the Greater Yellowstone Area FIGURE 3-2 States to which animals leaving Brucellosis-affected herds in the GYA were traced, 2002-2016. One of the significant findings of the 1998 NRC report was that “B. abortus is unlikely to be main- tained in elk if elk winter-feedgrounds were closed.” This was also the consensus of the respondents to the 1998 NRC questionnaire as well as the conclusion of McCorquodale and Digiacomo (1985). This conclusion was due in part to the low seroprevalence in elk anywhere outside of the supplemental feed- grounds prior to 2000 (see Figure 3-3). Data collected after the 1998 NRC report, however, cast this earli- er conclusion into doubt, because elk seroprevalence in some management units is now comparable to areas with supplemental feedgrounds (see Figure 3-3). This does not appear to be due to a lack of sam- pling in areas that were previously at low seroprevalence (see Figure 3-4). While the numbers of samples in any given year may be low, the data, in aggregate, across many years suggest that these increases are not an artifact of sampling error, but are consistent changes over a long time period (e.g., see Figures 3-5 and 3-6). Whole genome sequencing of brucellosis isolates collected from 1985 to 2013 in cattle, elk, and bi- son across the GYA suggest that brucellosis was introduced into GYA bison and elk on at least five sepa- rate occasions, presumably from cattle (Kamath et al., 2016). One of these five lineages is associated with bison within Yellowstone and a few elk isolates from the same area. The Brucella isolates from many of the unfed elk in Montana and Wyoming, however, originated from the Wyoming feedgrounds instead of Yellowstone bison. This suggests that control efforts implemented in bison within Yellowstone National Park (YNP) are unlikely to have any effect on these unrelated lineages in elk populations outside of YNP. Two different lineages were able to move from Wyoming feedgrounds to western Montana, potentially in the 1990s to early 2000s, followed by subsequent local transmission rather than repeated invasions from the feedgrounds (Kamath et al., 2016). This timing is coincident with increases in the seroprevalence in elk in these regions (see Figure 3-5), and suggests that elk are able to maintain the infection locally after those introductions. The B. abortus isolates from elk in the Wiggins Fork region of Wyoming also derive from the feedgrounds, but the extent of local transmission among elk there is less clear as there are a large number of isolates that connect directly back to the feedgrounds rather than other local isolates (Kamath et al., 2016). Finally, genetics data have been used to estimate a diffusion rate of the disease over time, which averaged 3-8 km/yr overall, but appeared more recently to be increasing in speed. The two fastest lineages were expanding at a rate of 12 km/yr as of 2013 (Kamath et al., 2016). 52 Prepublication Copy—Subject to Further Editorial Revision

Ecology and Epidemiolog of Brucella abortus in th Greater Ye d gy a he ellowstone Ec cosystem FIGURE 3-3 Maps of seroprevalence in elk using data prior to 2000 (left) an from 2010 t 2015 (right The s e nd to t). designated surveillance area is repres d sented by the red line whi the polygo show elk management units. e ile ons SOURCE: Data provided by the state an federal wild d nd dlife agencies o Idaho, Mont of tana, and Wyo oming. FIGURE 3-4 Maps of sa 3 ampling effort in elk prior to 2000 (left) an from 2010 to 2015 (right). The designate sur- nd o . ed veillance area is represen by the red line while the polygons show elk managem units. SOU a nted w ment URCE: Data pprovid- ed by the state and federa wildlife agen s al ncies of Idaho, Montana, and Wyoming. d Prepublic cation Copy— —Subject to Fu urther Editori Revision ial 53

Revisiting Brucellosis in the Greater Yellowstone Area g i r e Bruccellosis serop prevalence in elk appears to be increasin in several herds in Montana. From 2001- t ng 2013, serooprevalence in elk from di i istrict 323 wa estimated a 28% (n = 3 95% CI = [0.14, 0.45]) even as at 36, ) though the elk tracking data from th area do no suggest mu overlap w either bis or elk fro the g hat ot uch with son om Wyoming feedgrounds (MDFWP, 2015; Proffitt et al., 2015) More recen testing in th Mill Creek area g s 2 t ). nt he k of Paradis Valley, Mo se ontana, show elk seropr wed revalence at 553% (n = 32, 95% CI = [0.32, 0.68]). Mon- , tana's elk management units 362 an 313 are tw areas whe there are sufficient da through tim to t nd wo ere ata me conclude that the seropprevalence do appear to be increasing (see Figure 3 oes b 3-5). Seve studies have been pu eral h ublished on the seropreva t alence of bruucellosis in WWyoming elk The k. seroprevaalence in elk on supplemen feedgrou ntal unds is strong correlated with the len gly d ngth of the feeeding season, which overlaps with the presumed abortion period in t third trim w s the mester of pregn nancy (Cross et al., 2007). An increase in the end date of the feeding season is co n t g orrelated with an increase from 10% to 30% h o seroprevaalence. Furthe ermore, the end date of the feeding s e t season is hig ghly correlate with the w ed winter snowpack from one ye to the next Excluding the NER, poin estimates o elk populat k ear t. t nt of ensity tion size or de are not siignificantly associated wit seropreval a th lence. Thus, ddisease transmission in th system m be his may driven by an interactio between ho density an the timing of disease tra on ost nd ansmission. SSample testing data g from 1993 3–2009 are aggregated ov time for both on and o of supplem a ver b off mental feedggrounds in ord to der have suffi icient sample sizes to mak comparison across regi ke ns ions (Scurloc and Edwar 2010). Ho ck rds, owev- er, there is some indica i ation that seroprevalence may be incre asing over tim in some e herds (Scu m me elk urlock and Edwa ards, 2010). In examining seroprevalenc at the broa herd unit s n ce ad scale as well a at the finer hunt as r area scale areas south of the feedgr e, rounds with relatively low elk densities did not appe to have an in- r w s ear ny crease in brucellosis (CCross et al., 2010a,b). Most of the obse 2 erved increases in elk sero oprevalence a appear to be in th mid-2000s in both Mon he s ntana and Wyoming (Cross et al., 2010a see Figur 3-6). Mean s a,b; re nwhile some regi ions show no evidence of increasing se eroprevalence despite sign e nificant samplling efforts an be- nd ing adjace to supplem ent mental feedgr rounds (see Fiigure 3-7). FIGURE 3-5 Elk seropre 3 evalence in the East Madison Hunt District 362 (left plot) and Gardiner Area HD 313 (right e n t ) r 3 plot). Each point represen the raw ser h nts roprevalence fo that year. Th or gray error bars on each point repre- hick and thin g sent the 50 and 95% co 0% onfidence inter rvals on that es stimate. The bl lack line repres sents the tempo trend as es oral stimat- ed from a linear time tre in a logisti regression. Dotted lines a the 95% co end ic are onfidence interrval on the pre edicted seroprevaleence using a quasibinomial error distributi q e ion. SOURCE: Data courtesy of Montana Department of Fish, : y f Wildlife, and Parks. a 54 Pre epublication Copy—Subje to Further Editorial Rev ect r vision

Ecology and Epidemiolog of Brucella abortus in th Greater Ye d gy a he ellowstone Ec cosystem FIGURE 3-6 Elk seropr revalence in th Cody (left plot) and Clar Fork (right plot) regions of Wyoming. Each he rks t s point repre esents the raw seroprevalence for that year. Thick and thin gray error ba on each point represent th 50% s e n ars he and 95% confidence inter rvals on that es stimate. The bl lack line repressents the tempo trend as es oral stimated from a line- ar time trend in a logistic regression. Dotted lines are the 95% con c D nfidence interv on the pred val dicted seroprevvalence using a quaasibinomial err distribution SOURCE: Data courtesy of WGFD. ror n. D f FIGURE 3-7 Elk seropr revalence in th South Wind River (left plo and West G he d ot) Green River (r right plot) regi ions of Wyoming, both of which are south an adjacent to regions with s h nd r supplemental ffeedgrounds. E Each point repr resents the raw serroprevalence for that year. Th and thin gray error bars on each point represent the 50% and 95% confi- fo hick g dence interrvals on that esstimate. The bllack line repres sents the tempo trend as es oral stimated from a linear time tr rend in a logistic regression. Dot r tted lines are the 95% confid t dence interval on the predicted seroprevale ence using a quuasibi- nomial erro distribution. SOURCE: Da courtesy of WGFD. or . ata f Prepublic cation Copy— —Subject to Fu urther Editori Revision ial 55

Revisiting Brucellosis in the Greater Yellowstone Area g i r e Bruccellosis was first observed in Idaho elk in 1998. Prio to 2002, el seroprevale f d or lk ence was relaatively low in all areas tested except Raine Creek, wh l ey hich was the s of an elk feedground that operated from site k d 1978-2006 and fed bet tween 150-60 elk (Etter and Drew, 20 00 006). Since 2 2002, there have been obs served increases in elk seroprrevalence in Montana and Wyoming, an although s M and surveillance i being cond is ducted in those areas, there ha been no recent studies published u a ave r s using Idaho ddata aside from Etter and D m Drew. Data provvided to the committee for this review suggest that elk seroprev c r valence remai low in districts ins 66A and 76, which are mostly outs 7 e side of the DS (see Figu 3-8). Othe regions wit SA ure er thin the Idaho por- o tion of th DSA appea to have inc he ar creasing leve of elk sero els oprevalence ( districts 6 62, and 67 see (in 61, 7; Figure 3-9 Due to the limited sam 9). e mpling in some regions, it i difficult to assess wheth the dynam of e is her mics brucellosi in some are are changi (in distric 64, 65, and 66; see Figu 3-10). is eas ing cts d ure 3. EFF FECTS OF POPULATIO SIZE AN P ON ND AGGREGAT A TION ON BIS SON AND E LK TRANSM MISSION To understand th dynamics of infectious diseases and implement c u he o control strateg for effec gies ctively addressing brucellosis, it will be im g , mportant to unnderstand the relationship between host density and para- t site transm mission (And derson and Ma 1991; Mc ay, cCallum et al. 2001). If tra ., ansmission an host densi are nd ity correlated models pre d, edict that the parasite ca e annot persist below a cer rtain threshol of host de ld ensity (Kermack and McKen k ndrick, 1927; Getz and Pic ckering, 1983 This forms the basis fo using socia dis- 3). s or al tancing (ee.g., school closures) to control pandem (Glass and Barnes, 2007; Cauch c mics hemez et al., 2008; Halloran et al., 2008). In natural po e opulations, the distribution and abundan of a host species can b af- n nce t be fected by manipulating hunting pres g ssure (Conner et al., 2007) artificial fo and water sources (Miller et r ), ood r al., 2003; Rudolph et al., 2006; Cros et al., 2007 and predat distributio (White et al., 2012). a ss 7), tor ons FIGURE 3-8 Elk seropre 3 evalence over time for two management un in Idaho, di t m nits istrict 66A (lef district 76 ( ft), (right). Each point represents the raw seropreva t e alence for that year. Thick an thin gray err bars on eac point represe the nd ror ch ent 50% and 95% confidence intervals on that estimate. The black line r 9 e t T represents the temporal trend as estimated f d from a linear time trend in a log e gistic regressio Dotted line are the 95% confidence in on. es % nterval on the predicted sero opreva- lence using a quasibinom error distrib g mial bution. SOURC Data court CE: tesy of Idaho F and Game Fish e. 56 Pre epublication Copy—Subje to Further Editorial Rev ect r vision

Ecology and Epidemiolog of Brucella abortus in th Greater Ye d gy a he ellowstone Ec cosystem For directly trans smitted parasiites, contact rates may be mmore related t local meas to sures of host d densi- ty (i.e., de ensity or num mber of hosts in a group) ra i ather than bro oader scale me easures (i.e., density of a r region with many groups). Fu y urthermore, many ungulate group size d m e distributions, including elk are highly right- k, skewed whereby most groups are sm w mall, but ther are a few v re very large grooups (Cross e al., 2009, 2 et 2013c; Brennan et al., 2015). This may resu in super-s e ult spreader dynaamics at the ggroup-level wwhereby a few large w groups dr rive disease dynamics (Llo d oyd-Smith et al., 2005). T This issue has been addres s ssed in human sys- n tems unde the “core-g er groups” moniker (e.g., intr ravenous drug users, Hethc g cote, 1978; M and Ande May erson, 1984; Bec cker and Die 1995; Du etz, ushoff and Le evin, 1995), b has not h much app but had plication to n natural population In social species like elk and bison managemen approache that alter g ns. e n, nt es group size dis stribu- tions may be more effe y ective at reduc cing disease transmission t t than lowering overall popu g ulation densitties. FIGURE 3-9 Elk seropr revalence over time for man r nagement units in Idaho whe the seropre s ere evalence may be in- creasing (D Districts 61, 62 and 67). Eac point repres 2, ch seroprevalence for that year. Thick and thin gray sents the raw s e n error bars on each point represent the 50% and 95% confidence inte o r 5 c ervals on that estimate. The black line repr resents the tempor trend as esti ral imated from a linear time tren in a logistic regression. D nd c Dotted lines are the 95% conf e fidence interval on the predicted seroprevalenc using a quas n ce sibinomial erro distribution. SOURCE: Da courtesy of Idaho or ata f Fish and Game. G Prepublic cation Copy— —Subject to Fu urther Editori Revision ial 57

Revisiting Brucellosis in the Greater Yellowstone Area g i r e FIGURE 3-10 Elk serop prevalence ove time for sev er veral managemment units in Id daho (Districts 64, 65, and 66 that 6) are too weeakly sampled to assess any temporal trend Each point represents the raw seroprev ds. e valence for tha year. at Thick and thin gray error bars on each point represen the 50% and 95% confide r nt d ence intervals o that estimat The on te. black line represents the temporal tren as estimated from a linear time trend in a logistic regr nd d r ression. Dotted lines d are the 95% confidence interval on the predicted sero % i oprevalence usi a quasibino ing omial error dis stribution. SOUURCE: Data courtesy of Idaho Fish and Game. Ther are a numb of scientif challenges involved in r re ber fic s relating host density to dis sease transmiission. First, tran nsmission is not directly observable, therefore ser roprevalence is often use as a surro ed ogate; however, exposure cou have occu uld urred anytime from birth to the sampli date. Meanwhile indiv e ing vidual elk shift among groups relatively fr a s requently. Th makes it d his difficult to rel serology to group size met- late e rics (Cros et al., 2013a). Second, it is unclear what the denom ss t w minator shou be when c uld calculating elk den- k sity. Cross and colleag ated the relationship betwe the rate of increase in elk seropreva gues investiga een alence and elk de ensity at the broad herd un scale (201 b nit 10a), as well as the finer hhunt area scal (2010b). In both le n cases, the area used in the calculat e n tion of elk deensity was th total area o the manag he of gement unit, w which probably includes a lar amount of area that is not elk habita By further investigating multiple dif rge f n at. g fferent 58 Pre epublication Copy—Subje to Further Editorial Rev ect r vision

Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem metrics of elk density, Brennan and colleagues (2014) found that while all the spring time elk density metrics were correlated with the increases in brucellosis, there was not one particular metric of elk density that did much better than the others. Third, elk population size, density, and seroprevalence are factors that change over time, and seroprevalence is likely to respond to changes in elk density at a lag. This is not an easy problem to solve, because the temporal changes in both elk population size and brucellosis seroprevalence are relatively slow, requiring a long time-series in any one location to be informative. As a result, the spatial variation among regions may be more informative than the annual variation. With- in Montana, elk density is associated with the seroprevalence of brucellosis (Proffitt et al., 2015). An equilibrium assumption is being made that sites have higher prevalence due to elk density, and the as- sumption does not account for how some sites may be changing over time whereby some areas may still be of low seroprevalence, because the disease was only recently introduced in that location. Due to many of these challenges, it is likely that the effects of host density on brucellosis transmission will tend to be underestimated. At a more local scale, measuring contact rates in free-ranging wildlife populations has traditionally been difficult. Proximity loggers, however, are a recent technological advance that records the duration and time when two loggers are within a predesigned distance from one another (Prange et al., 2006). Ide- ally, a proximity logger would be placed on aborted fetuses to record subsequent contacts. Fetuses recov- ered from other management activities could be used as a proxy to record elk-fetus contact rates (Creech et al., 2012). By feeding elk across a broader area (low density feeding), >70% reductions in elk-fetus contact rates occurred on the feedgrounds (Creech et al., 2012). No contacts were recorded with fetuses that were randomly placed away from feedgrounds (Maichak et al., 2009). Elk-elk contacts could be con- sidered as a surrogate for elk-fetus contacts. The contact rate (within ~2m) for a given elk pair declines with increasing group size, but the individual contact rate strongly increases with elk group size, because the number of total pairs increases with group size (Cross et al., 2013b). This suggests that large elk groups may be driving much of the transmission of brucellosis within elk populations, but this pattern is hard to observe in seroprevalence data due to the frequent mixing of individuals across groups of different sizes. Therefore, additional research may consider treatments (e.g., targeted hunting, increased predator tolerance in some areas, hazing operations) that affect the group size distribution (and in particular, large groups). Within bison, a frequency dependent model of brucellosis transmission appears to be more con- sistent with the available data compared to a density dependent model (Hobbs et al., 2015). During the time-series where seroprevalence data were available, the bison population size ranged from 2,000-5,000 individuals, while the seroprevalence remained relatively constant. This may be due to the grouping behavior of bison in YNP, whereby the bison group size distribution appears to be relatively constant even when the population size is dramatically reduced by boundary removals (Cross et al., 2013c). Thus, although fetus exposure rates may be higher in larger groups of bison (i.e., density dependent transmis- sion at the group scale), more groups are created as the bison population gets larger. As a result, group sizes are relatively constant, so that disease transmission at the population scale appears frequency dependent. Therefore, the indiscriminant reduction of bison populations is unlikely to affect brucellosis transmission in bison. 4. SUPPLEMENTAL FEEDGROUNDS The previous NRC review in 1998 highlighted the role of the supplemental feedgrounds in exacer- bating brucellosis in elk. None of the research conducted since that review refutes that conclusion. The seroprevalence of disease on the feedgrounds remains high (~20%) relative to elk populations in other regions, particularly outside of the GYE (Scurlock and Edwards, 2010). As noted above, feedground sites that were fed for longer and later into the spring had higher levels of seroprevalence (Cross et al., 2007). This is probably because abortion events appear to be about five times more frequent in March, April, and May than they are in February; no abortion events have been recorded in January (Cross et al., 2015). Prepublication Copy—Subject to Further Editorial Revision 59

Revisiting Brucellosis in the Greater Yellowstone Area Supplemental feedgrounds played a role in the historic seeding of B. abortus infections in other, dis- tant elk populations (Kamath et al., 2016), and increased local elk-elk transmission (Cross et al., 2007). Feedgrounds, however, potentially mitigate local cattle risk compared to an area with similar elk sero- prevalence without feedgrounds, because they separate elk from cattle during the majority of the trans- mission season. From 2002-2014, only 3 of the 22 affected cattle herds were in regions with feedgrounds despite the high seroprevalence in elk during that entire timespan on feedgrounds, whereas the seropreva- lence in elk in other regions has only more recently increased (Brennan, 2015). 5. POTENTIAL EFFECTS OF PREDATORS AND SCAVENGERS ON BRUCELLOSIS Wolves were reintroduced in the GYA in 1995, and wolves were only briefly mentioned in the pre- vious NRC report (1998), but the potential role that wolves may have on elk or bison demography, space- use, and aggregation patterns has been an active area of research since that time. Predators may preferen- tially kill infected prey and may in turn reduce the level of disease (Packer et al., 2003). The mortality hazard of brucellosis-infected African buffalo (Syncerus caffer) is about two times higher than uninfected individuals (95% CI = 1.1-3.7) (Gorsich et al., 2015). Predation on brucellosis-infected hosts may occur due to arthritis and lower body conditions that are associated with brucellosis infections (Gorsich et al., 2015). However, if these complications occur after the infectious period of the disease, predation is un- likely to affect the transmission dynamics. The direct effects of predation on disease dynamics are higher for diseases where infected individuals are weakened prior to and during the infectious period. For Wyo- ming feedground elk, evidence does not suggest a decreased survival rate of elk infected with brucellosis (Benavides et al., 2017). A better test of selective predation would be in areas of more intensive wolf presence, but the seroprevalence of brucellosis in YNP elk has historically been relatively low, making it difficult to study the survival rates of seropositive and seronegative elk or bison (Ferrari and Garrott, 2002; Barber-Meyer et al., 2007). Outside the borders of national parks, hunting is the dominant cause of adult elk mortality and hunters are unlikely to be selective for infected elk. Thus, there is no current evi- dence to suggest that predators are selective for brucellosis-infected elk or bison. Wolves may affect brucellosis transmission by altering population size, distribution, or altering ag- gregation patterns (see Chapter 2), which may then affect contact and disease transmission rates. The be- havioral effects of wolves on elk aggregation patterns would likely occur on shorter rather than longer timeframes, and are unlikely to have longer-term population level effects of reduced survival and/or re- cruitment. Creel and Winnie (2005) found that the mean elk group size declined on days when wolves were present from 22 to 9. Similarly, Proffitt and colleagues (2009) found that in the presence of wolves, elk were more disaggregated in sagebrush areas. In grassland areas, however, elk were aggregated in larg- er average group sizes in response to increasing wolf predation risk (Gower et al., 2009; Proffitt et al., 2009). Even though the majority of elk groups are relatively small in size, the majority of elk (as individ- uals) tend to be in the largest groups (Hebblewhite and Pletscher, 2002; Brennan et al., 2015). In combi- nation with increasing contact rates in the largest groups, this suggests that the majority of disease trans- mission may occur in large groups (Cross et al., 2013b). Thus, average elk group sizes may not be an important metric for inference about disease transmission. Wolves may shift the spatial distribution of elk either by affecting elk behavior and dispersal or altering the population growth rate of elk. While the im- pacts of wolves on elk calves are well documented (Wright et al., 2006), evidence is limited indicating that wolves have behaviorally shifted elk distributions at broad spatial scales. Wolves appear to be attracted to large elk group sizes, as the 90th percentile of the elk group size distribution is positively correlated with wolf abundance on open and private lands (Brennan et al., 2015). Over the longer term, wolves are likely to reduce elk population sizes, although the degree of reduction that is directly attributable to wolves remains contested due to the potential confounding effects of hunt- ing, changing climate, and other predators (Vucetich et al., 2005; Middleton et al., 2013; Christianson and Creel, 2014). An interesting correlation has been found between fecal progesterone, the number of calves per 100 adult female elk, and the ratio of wolves to elk, which suggest that wolves may reduce elk repro- duction (Creel et al., 2007). While the strength of this finding has been disputed (White et al., 2011; Creel 60 Prepublication Copy—Subject to Further Editorial Revision

Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem et al., 2013; Christianson and Creel, 2014; Proffitt et al., 2014), if it is true, wolves would potentially di- rectly reduce brucellosis transmission by reducing the primary mechanism of transmission—pregnancy and the associated abortion events. Finally, in the northern range of Yellowstone the percentage of elk spending the winter outside of YNP has increased coincident with the arrival of wolves (MacNulty, 2015). Migratory elk in the Clarks Fork region of Wyoming had reduced pregnancy and calf:cow ratios relative to non-migratory elk, which had lower exposure to wolves and bears (Middleton et al., 2013). Over time, this would result in higher populations of elk remaining on private lands throughout the year. Due to the relatively slow changes in elk populations and brucellosis seroprevalence along with many potential confounding factors, it is difficult to currently assess these short- and long-term effects of wolves on brucellosis in elk. The previous NRC report (1998) reviewed the number of carnivores seropositive for brucellosis, presumably due to consuming infectious material. Even though Davis and colleagues (1988) demonstrat- ed that coyotes were able to infect cattle when held in a confined space and B. abortus could remain via- ble in coyote feces and urine, carnivores are probably dead-end hosts and not likely to re-infect ungulates (NRC, 1998). To date, there has been no subsequent research that would further support or contradict that conclusion. Aune and colleagues (2012) found that half of fetuses were moved over 100 m and one was moved almost 2 miles by a red fox, confirming that carnivores play a role in locally transporting infec- tious material to new locations (NRC, 1998). However, the 1998 NRC report suggested that “a healthy complement of predators [is] almost certain to be a major factor in reducing the probability of B. abortus transmission within the wildlife community and between wildlife and domestic stock. Predation and scavenging by carnivores likely biologically decontaminate the environment of infectious B. abortus with an efficiency unachievable in any other way.” Since 1998, several studies of fetus contact and fetus re- moval rates have been completed. Cook and colleagues (2004) found that the disappearance rate of bo- vine fetuses was on average 27 hrs at the National Elk Refuge, 40 hrs at other Wyoming feedgrounds, and 58 hrs at Grand Teton National Park and coyotes were the dominant scavenger. Similarly, Maichak and colleagues (2009) found that 70% (28 of 40) elk fetuses were removed within 24 hours from the Wyo- ming state feedgrounds, while only 38% (3 of 8) were removed within 24 hours from neighboring winter range locations. In contrast, fetus removal rates around YNP averaged 18 days with a maximum of 78 days (Aune et al., 2012). Also, B. abortus remained viable on the underside of fetuses for a median of 30 days, but exposed areas had a median survival time of 10 days (Aune et al., 2012). Collectively, these da- ta suggest that scavengers are removing fetuses faster from the feedgrounds than from other areas, which may be one reason why the seroprevalence in elk at the feedgrounds (20%) is roughly equivalent to the seroprevalence in some non-fed elk populations despite the more intense aggregations on the feed- grounds. Despite the potential positive role coyotes might have on scavenging to reduce brucellosis transmission, coyotes are removed by U.S. Department of Agriculture Animal and Plant Health Inspec- tion Service (USDA-APHIS) Wildlife Services at the request of landowners to reduce predation and live- stock losses. In addition, coyotes are not regulated and can be shot year-round without a license in Idaho, Montana, and Wyoming. The effects of these removals may have on brucellosis transmission is poorly known and requires further study. 6. EFFECT OF DISEASE ON BISON AND ELK POPULATIONS Although B. abortus induces abortion events and has the potential to have significant impact on in- dividual animals (such as testicular abscesses, retained placentas, arthritis, death of neonates), it is not generally considered a direct threat to the sustainability of either elk or bison populations. Fuller and colleagues (2007) estimated that the complete eradication of brucellosis from bison would increase bison population growth rate by 29%, and similar results were found by others (Ebinger et al., 2011; Hobbs et al., 2015). This increase in population growth would most likely result in increased bison removals at the boundary. Cross and colleagues (2015) estimated that 16% (95% CI = [10, 23]) of seropositive pregnant female elk will abort every year. Based on those estimates, the expectation is that an area with 30% sero- prevalence would only experience a 5% decline in the population growth rate even if there were no com- Prepublication Copy—Subject to Further Editorial Revision 61

Revisiting Brucellosis in the Greater Yellowstone Area pensatory shifts in calf mortality due to brucellosis. However, Foley and colleagues (2015), found no rela- tionship between brucellosis seroprevalence and the ratio of elk calves to adult females at the elk man- agement unit scale. REFERENCES Anderson, R.M., and R.M. May. 1991. Infectious Diseases of Humans: Dynamics and Control. Oxford: Oxford University Press. Aune, K.E., J.C. Rhyan, R. Russell, T.J. Roffe, and B. Corso. 2012. Environmental persistence of Brucella abortus in the Greater Yellowstone Area. Journal of Wildlife Management 76(2):253-261. Barber-Meyer, S.M., P.J. White, and L.D. Mech. 2007. Survey of selected pathogens and blood parameters of northern Yellowstone elk: Wolf sanitation effect implications. American Midland Naturalist 158:369-381. Becker, N.G., and K. Dietz. 1995. The effect of household distribution on transmission and control of highly infectious diseases. Mathematical Biosciences 127:207-219. Benavides, J.A., D. Caillaud, B.M. Scurlock, E.J. Maichak, W.H. Edwards, and P.C. Cross. 2017. Estimating loss of Brucella abortus antibodies from age-specific serological data in elk. EcoHealth 15 May:1-10. Brennan, A. 2015. Landscape-scale Analysis of Livestock Brucellosis. USDA, Animal and Plant Health Inspection Service. Brennan, A., P.C. Cross, M.D. Higgs, W.H. Edwards, B.M. Scurlock, and S. Creel. 2014. A multi-scale assessment of animal aggregation patterns to understand increasing pathogen seroprevalence. Ecosphere 5(10):art138. Brennan, A., P.C. Cross, S. Creel, and P. Stephens. 2015. Managing more than the mean: Using quantile regression to identify factors related to large elk groups. Journal of Applied Ecology 52(6):1656-1664. Cauchemez, S., A. Valleron, P. Boëlle, A. Flahault, and N.M. Ferguson. 2008. Estimating the impact of school closure on influenza transmission from sentinel data. Nature 452:750-754. Christianson, D., and S. Creel. 2014. Ecosystem scale declines in elk recruitment and population growth with wolf colonization: A before-after-control-impact approach. Plos One 9(7). Conner, M.M., M.W. Miller, M.R. Ebinger, and K.P. Burnham. 2007. A meta-BACI approach for evaluating management intervention on chronic wasting disease in mule deer. Ecological Applications 17(1):140-153. Cook, W.E., E.S. Williams, and S.A. Dubay. 2004. Disappearance of bovine fetuses in northwestern Wyoming. Wildlife Society Bulletin 32(1):254-259. Creech, T., P.C. Cross, B.M. Scurlock, E.J. Maichak, J.D. Rogerson, J.C. Henningsen, and S. Creel. 2012. Effects of low-density feeding on elk-fetus contact rates on Wyoming feedgrounds. Journal of Wildlife Management 76(5):877-886. Creel, S., and J.A. Winnie. 2005. Responses of elk herd size to fine-scale spatial and temporal variation in the risk of predation by wolves. Animal Behaviour 69:1181-1189. Creel, S., D. Christianson, S. Liley, and J.A.J. Winnie. 2007. Predation risk affects reproductive physiology and demography of elk. Science 315(5814):960. Creel, S., J.A. Winnie, Jr., and D. Christianson. 2013. Underestimating the frequency, strength and cost of antipredator responses with data from GPS collars: An example with wolves and elk. Ecology and Evolution 3(16):5189-5200. Cross, P.C., W.H. Edwards, B.M. Scurlock, E.J. Maichak, and J.D. Rogerson. 2007. Effects of management and climate on elk brucellosis in the Greater Yellowstone Ecosystem. Ecological Applications 17(4):957-964. Cross, P.C., J. Drew, V. Patrek, G. Pearce, M.D. Samuel, and R.J. Delahay. 2009. Wildlife population structure and parasite transmission: implications for disease management. Pp. 9-29 in Management of Disease in Wild Mammals, R.J. Delahay, G.C. Smith and M.R. Hutchings, eds. Tokyo: Springer. Cross, P.C., E.K. Cole, A.P. Dobson, W.H. Edwards, K.L. Hamlin, G. Luikart, A.D. Middleton, B.M. Scurlock, and P.J. White. 2010a. Probable causes of increasing elk brucellosis in the Greater Yellowstone Ecosystem. Ecological Applications 20(1):278-288. Cross, P.C., D.M. Heisey, B.M. Scurlock, W.H. Edwards, M.R. Ebinger, and A. Brennan. 2010b. Mapping brucellosis increases relative to elk density using hierarchical Bayesian models. PLoS ONE 5(4):e10322. Cross, P.C., D. Caillaud, and D.M. Heisey. 2013a. Underestimating the effects of spatial heterogeneity due to individual movement and spatial scale: infectious disease as an example. Landscape Ecology 28(2):247:257. Cross, P.C., T.G. Creech, M.R. Ebinger, K. Manlove, K. Irvine, J. Henningsen, J. Rogerson, B.M. Scurlock, and S. Creel. 2013b. Female elk contacts are neither frequency nor density dependent. Ecology 94(9):2076-2086. 62 Prepublication Copy—Subject to Further Editorial Revision

Ecology and Epidemiology of Brucella abortus in the Greater Yellowstone Ecosystem Cross, P.C., E.J. Maichak, A. Brennan, B.M. Scurlock, J. Henningsen, and G. Luikart. 2013c. An ecological perspective on Brucella abortus in the western United States. Revue Scientifique et Technique Office Interna- tional des Epizooties 32(1):79-87. Cross, P.C., E.J. Maichak, J.D. Rogerson, K.M. Irvine, J.D. Jones, D.M. Heisey, W.H. Edwards, and B.M. Scurlock. 2015. Estimating the phenology of elk brucellosis transmission with hierarchical models of cause-specific and baseline hazards. Journal of Wildlife Management 79(5):739-748. Davis, D.S., F.C. Heck, J.D. Williams, T.R. Simpson, and L.G. Adams. 1988. Interspecific transmission of Brucella abortus from experimentally infected coyotes (Canis latrans) to parturient cattle. Journal of Wildlife Diseases 24(3):533-537. Dushoff, J., and S. Levin. 1995. The effects of population heterogeneity on disease invasion. Mathematical Biosciences 128(1-2):25-40. Ebinger, M.R., P.C. Cross, R.L. Wallen, P.J. White, and J. Treanor. 2011. Simulating sterilization, vaccination, and test-and-remove as brucellosis control measures in bison. Ecological Applications 21(8):2944-2959. Etter, R., and M.L. Drew. 2006. Brucellosis in elk of eastern Idaho. Journal of Wildlife Diseases 42(2):271-278. Ferrari, M.J., and R.A. Garrott. 2002. Bison and elk: Brucellosis seroprevalence on a shared winter range. Journal of Wildlife Management 66(4):1246-1254. Foley, A.M., P.C. Cross, D.A. Christianson, B.M. Scurlock, and S. Creel. 2015. Influences of supplemental feeding on winter elk calf:cow ratios in the southern Greater Yellowstone Ecosystem. Journal of Wildlife Management 79(6):887-897. Fuller, J., B. Garrott, P.J. White, K.E. Aune, T.J. Roffe, and J.C. Rhyan. 2007. Reproduction and survival of Yellowstone Bison. Journal of Wildlife Management 71(7):2365-2372. Getz, W.M., and J. Pickering. 1983. Epidemic models: thresholds and population regulation. American Naturalist 121:892-898. Glass, K., and B. Barnes. 2007. How much would closing schools reduce transmission during an influenza pandemic? Epidemiology 18(5):623-628. Gorsich, E.E., V.O. Ezenwa, P.C. Cross, R.G. Bengis, and A.E. Jolles. 2015. Context-dependent survival, fecundity and predicted population-level consequences of brucellosis in African buffalo. Journal of Animal Ecology 84(4):999-1009. Gower, C.N., R.A. Garrott, P.J. White, S. Cherry, and N.G. Yoccoz. 2009. Elk group size and wolf predation: A flexible strategy when faced with variable risk. Pp. 401-422 in The Ecology of Large Mammals in Central Yellowstone - Sixteen Years of Integrated Field Studies, R.A. Garrott, P.J. White and F. Watson, eds. San Diego: Academic Press. Halloran, M.E., N.M. Ferguson, S. Eubank, I.M. Longini, D.A. Cummings, B. Lewis, S. Xu, C. Fraser, A. Vullikanti, T.C. Germann, D. Wagener, R. Beckman, K. Kadau, C. Barrett, C.A. Macken, D.S. Burke, and P. Cooley. 2008. Modeling targeted layered containment of an influenza pandemic in the United States. Proceedings of the Academy of Natural Sciences of Philadelphia 105(12):4639-4644. Hebblewhite, M., and D. Pletscher. 2002. Effects of elk group size on predation by wolves. Canadian Journal of Zoology-Revue Canadienne De Zoologie 80(5):800-809. Hethcote, H.W. 1978. Immunization model for a heterogeneous population. Theoretical Population Biology 14(3):338-349. Hobbs, N.T., C. Geremia, J. Treanor, R. Wallen, P.J. White, M.B. Hooten, and J.C. Rhyan. 2015. State-space modeling to support management of brucellosis in the Yellowstone bison population. Ecological Monographs 85(4):525-556. Kamath, P.L., J.T. Foster, K.P. Drees, G. Luikart, C. Quance, N.J. Anderson, P.R. Clarke, E.K. Cole, M.L. Drew, W.H. Edwards, J.C. Rhyan, J.J. Treanor, R.L. Wallen, P.J. White, S. Robbe-Austerman, and P.C. Cross. 2016. Genomics reveals historic and contemporary transmission dynamics of a bacterial disease among wildlife and livestock. Nature Communications 7:11448. Kermack, W.O., and A.G. McKendrick. 1927. Contributions to the mathematical theory of epidemics. Proceedings of the Royal Society of Edinburgh 115:700-721. Lloyd-Smith, J.O., S.J. Schreiber, P.E. Kopp, and W.M. Getz. 2005. Superspreading and the effect of individual variation on disease emergence. Nature 438(7066):355-359. MacNulty, D. 2015. Presentation at the First Committee Meeting on Revisiting Brucellosis in the Greater Yellow- stone Area, July 1-2, 2015, Bozeman, MT. Maichak, E.J., B.M. Scurlock, J.D. Rogerson, L.L. Meadows, A.E. Barbknecht, W.H. Edwards, and P.C. Cross. 2009. Effects of management, behavior, and scavenging on risk of brucellosis transmission in elk of western Wyoming. Journal of Wildlife Diseases 45(2):398-410. Prepublication Copy—Subject to Further Editorial Revision 63

Revisiting Brucellosis in the Greater Yellowstone Area May, R.M., and R.M. Anderson. 1984. Spatial heterogeneity and the design of immunization programs. Mathematical Biosciences 72(1):83-111. McCallum, H., N. Barlow, and J. Hone. 2001. How should pathogen transmission be modelled? Trends in Ecology and Evolution 16(6):295-300. McCorquodale, S.M., and F. Digiacomo. 1985. The role of wild North American ungulates in the epidemiology of bovine brucellosis: A review. Journal of Wildlife Diseases 21(4):351-357. MDFWP (Montana Department of Fish, Wildlife, and Parks). 2015. Presentation at the First Committee Meeting on Revisiting Brucellosis in the Greater Yellowstone Area, July 1, 2015, Bozeman, MT. Middleton, A.D., M.J. Kauffman, D.E. McWhirter, M.D. Jimenez, R.C. Cook, J.G. Cook, S.E. Albeke, H. Sawyer, and P.J. White. 2013. Linking anti-predator behaviour to prey demography reveals limited risk effects of an actively hunting large carnivore. Ecology Letters 16(8):1023-1030. Miller, R.E., J.B. Kaneene, S.D. Fitzgerald, and S.M. Schmitt. 2003. Evaluation of the influence of supplemental feeding of white-tailed deer (Odocoileus virginianus) on the prevalence of bovine tuberculosis in the Michigan wild deer population. Journal of Wildlife Diseases 39(1):84-95. NRC (National Research Council). 1998. Brucellosis in the Greater Yellowstone Area. Washington, DC: National Academy Press. Packer, C., R.D. Holt, P.J. Hudson, K.D. Lafferty, and A.P. Dobson. 2003. Keeping the herds healthy and alert: Implications of predator control for infectious disease. Ecology Letters 6:797-802. Prange, S., T. Jordan, C. Hunter, and S.D. Gehrt. 2006. New radiocollars for the detection of proximity among individuals. Wildlife Society Bulletin 34(5):1333-1344. Proffitt, K.M., J.L. Grigg, K.L. Hamlin, and R.A. Garrott. 2009. Contrasting effects of wolves and human hunters on elk behavioral responses to predation risk. Journal of Wildlife Management 73(3):345-356. Proffitt, K.M., J.A. Cunningham, K.L. Hamlin, and R.A. Garrott. 2014. Bottom-up and top-down influences on pregnancy rates and recruitment of northern Yellowstone elk. Journal of Wildlife Management 78(8):1383- 1393. Proffitt, K.M., N. Anderson, P. Lukacs, M.M. Riordan, J.A. Gude, and J. Shamhart. 2015. Effects of elk density on elk aggregation patterns and exposure to brucellosis. Journal of Wildlife Management 79(3):373-383. Rhyan, J.C., P. Nol, C. Quance, A. Gertonson, J. Belfrage, L. Harris, K. Straka, and S. Robbe-Austerman. 2013. Transmission of brucellosis from elk to cattle and bison, Greater Yellowstone area, U.S.A., 2002-2012. Emerging Infectious Diseases 19(12):1992-1995. Rudolph, B.A., S.J. Riley, G.J. Hickling, B.J. Frawley, M.S. Garner, and S.R. Winterstein. 2006. Regulating hunter baiting for white-tailed deer in Michigan: Biological and social considerations. Wildlife Society Bulletin 34(2):314-321. Scurlock, B.M., and W.H. Edwards. 2010. Status of brucellosis in free ranging elk and bison in Wyoming. Journal of Wildlife Diseases 46(2):442-449. Treanor, J.J., C. Geremia, P.H. Crowley, J.J. Cox, P.J. White, R.L. Wallen, and D.W. Blanton. 2011. Estimating probabilities of active brucellosis infection in Yellowstone bison through quantitative serology and tissue culture. Journal of Applied Ecology 48(6):1324-1332. Vucetich, J.A., D.W. Smith, and D.R. Stahler. 2005. Influence of harvest, climate and wolf predation on Yellowstone elk, 1961-2004. Oikos 111(2):259-270. White, P.J., R.A. Garrott, K.L. Hamlin, R.C. Cook, J.G. Cook, and J.A. Cunningham. 2011. Body condition and pregnancy in northern Yellowstone elk: Evidence for predation risk effects? Ecological Applications 21(1):3-8. White, P.J., K.M. Proffitt, and T.O. Lemke. 2012. Changes in elk distribution and group sizes after wolf restoration. The American Midland Naturalist 167(1):174-187. Wright, G.J., R.O. Peterson, D.W. Smith, and T.O Lemke. 2006. Selection of Northern Yellowstone Elk by Gray Wolves and Hunters. Journal of Wildlife Management 70(4):1070-1078. 64 Prepublication Copy—Subject to Further Editorial Revision

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Brucellosis is a nationally and internationally regulated disease of livestock with significant consequences for animal health, public health, and international trade. In cattle, the primary cause of brucellosis is Brucella abortus, a zoonotic bacterial pathogen that also affects wildlife, including bison and elk. As a result of the Brucellosis Eradication Program that began in 1934, most of the country is now free of bovine brucellosis. The Greater Yellowstone Area (GYA), where brucellosis is endemic in bison and elk, is the last known B. abortus reservoir in the United States. The GYA is home to more than 5,500 bison that are the genetic descendants of the original free-ranging bison herds that survived in the early 1900s, and home to more than 125,000 elk whose habitats are managed through interagency efforts, including the National Elk Refuge and 22 supplemental winter feedgrounds maintained in Wyoming.

In 1998 the National Research Council (NRC) issued a report, Brucellosis in the Greater Yellowstone Area, that reviewed the scientific knowledge regarding B. abortus transmission among wildlife—particularly bison and elk—and cattle in the GYA. Since the release of the 1998 report, brucellosis has re-emerged in domestic cattle and bison herds in that area. Given the scientific and technological advances in two decades since that first report, Revisiting Brucellosis in the Greater Yellowstone Area explores the factors associated with the increased transmission of brucellosis from wildlife to livestock, the recent apparent expansion of brucellosis in non-feedground elk, and the desire to have science inform the course of any future actions in addressing brucellosis in the GYA.

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