Mannheimia haemolytica late 1800’s – introduced from sheep Population decline; 2 M to ~70,000 Pneumonia leading cause mortality; up to 90% Domestic sheep - developed immunity http://blogs.opb.org/fieldjournal/2011/01/24/new- evidence-disease-jumps-from-domestic-to-wild- sheep/http://blogs.opb.org/fieldjournal/2011/01/24/new- evidence-disease-jumps-from-domestic-to-wild- sheep/ Environmental stressors Mortality - All age classes Neonate mortality – 1 to 15 yrs suppressed recruitment
Mannheimia haemolytica Commingling - bighorn herd die-offs Harvest strategies (DD) Public grazing policies = limit interaction with sheep BLM = Bureau of Land Mgt USFS = U.S. Forest Service
Bovine TB The lung contains multiple coalescing foci of caseous necrosis surrounded by thin pale fibrous tissue capsules (tubercles). Most of the lymph node is replaced by caseonecrotic debris.
Bovine TB More severely infected cervids can have multiple pea-sized nodules or large cheesy or pus-filled masses in lymph nodes of head, neck, lungs. In cervids, lesions can occur throughout the chest cavity, under the skin of the chest, and in the abdominal cavity as well.
Bovine TB In some instances, superficial lymph nodes in the neck will develop large abscesses that may rupture and drain through the skin.
Bovine TB – Population Models R 0 : basic reproductive ratio –Depends on social behavior (e.g., contact rates) & bio. parameters (e.g., latency) –Crucial statistic – control of epidemics; represents threshold –R 0 > 1epidemic propagates –R 0 < 1epidemic dies out –R 0 = b/d
Bovine TB – Population Models Decrease k (monitor) or reduce R 0 by increasing mortality (culling)
Bovine TB BadgersBrushtail possums Models: Chance (Prob) of bovine TB epidemic for initial introduction of infectious individuals into populations R 0 = 1.6 – 2.3 (possums) and 1.1 – 1.2 (badgers)
Bovine TB Models: Probability bovine TB epidemic for introductions of 2, 4, 6, 8 or 10 individuals, with culls. Chance of epidemic declines to 0 when cull mortality occurs at a rate of 2.4 y −1. Life expectancy = 5 mo. R 0 = (pb + β) / (α + d)
Bovine TB in MI History of bovine TB in Michigan cattle Bovine TB into wild deer herd; reservoir for reinfection of cattle Triggers testing of deer
Bovine TB in MI Michigan Bovine TB Eradication Project Multi-agency team of experts from the MDA, DNR, DCH, MSU, USDA
Bovine TB in MI Surveys of deer pop. Testing of harvested deer Ban baiting Reduce interactions with cattle (conc. feed) Testing of cattle herds, depopulate if +
Response variables (different potential modes of TB transmission): –direct aerosol transmission due to close spatiotemporal association between potentially infected deer and uninfected cattle –indirect transmission by temporally segregated contact with dispersed feed by deer and cattle. –indirect transmission by temporally segregated contact with concentrated feed by deer and cattle VerCauteren et al. 2008
Bovine TB in MI Coyotes as sentinels 58 of 175 coyotes tested positive Prevalence by county ranged from 19% to 52% (mean 33%, SE 0.07) Prevalence in deer (n = 3,817) was lower (i.e., 1.49% Focus on coyotes rather than deer, sampled 97% fewer individuals and increased the likelihood of detecting M. bovis by 40%. VerCauteren et al. 2008
Bovine TB in MN Since 2005, 12 cattle farms Since fall 2007, 27 wild deer (+) 8000+ deer tested; within 5 mi TB free since 1976
Bovine TB in MN Fall 2006: Ban on rec. feeding in 4,000 mi 2 area 2006-07: aerial survey = 900+ deer in core area; 29 illegal bait sites Feb 2007, contract with APHIS-WS = sharpshooting in core area Removed 488 deer (6+) Fall 2007, new deer permit area created for TB zone 1,166 deer harvested (4+) Prevalence estimated at 0.37%
Bovine TB in Manitoba Since 1991, >40 elk and >8 white-tailed deer have positive in Riding Mountain area